A question about taking vitamins

shreksaurus

My mam told me before that the best time to take vitamins is in the morning after breakfast (i think it may even say it on the vitamin packaging to take after your main meal).

With the big mad morning rush out the door to work in the morning I always forget. I also forget to pack one in my lunchbox to take at work.

So I dont take vitamins regularly but I should.

My question: Would you get the same benefits from vitamins if you were to take them in the evening after dinner?

AtomicHorror

shreksaurus wrote: »

My mam told me before that the best time to take vitamins is in the morning after breakfast (i think it may even say it on the vitamin packaging to take after your main meal).

With the big mad morning rush out the door to work in the morning I always forget. I also forget to pack one in my lunchbox to take at work.

So I dont take vitamins regularly but I should.

My question: Would you get the same benefits from vitamins if you were to take them in the evening after dinner?

Depending on the supplement, it's fairly debatable as to whether you get a benefit either way. Generally speaking, having a reasonably varied diet should negate any need for supplements unless you're diagnosable as having some specific deficiency or illness. As far as I know, there's no compelling evidence that vitamins supplements are beneficial for healthy people.

Bottle_of_Smoke

Would agree with AH, if you feel run down or something its probably to do with lack of exercise/sleep or stress

I'm studying Human Nutrition and we did vitamins a few weeks back, if youre living in British Isles only thing you're likely to be deficient in is Vitamin D which you can get from oily fish/eggs.

aoibhebree

Why not just leave them at work and take them when you get there?

Fluffybums

Save your money and eat a balanced diet. The water soluble vitamins will be flushed down the toilet.

ZYX

shreksaurus wrote: »

My mam told me before that the best time to take vitamins is in the morning after breakfast (i think it may even say it on the vitamin packaging to take after your main meal).

With the big mad morning rush out the door to work in the morning I always forget. I also forget to pack one in my lunchbox to take at work.

So I dont take vitamins regularly but I should.

My question: Would you get the same benefits from vitamins if you were to take them in the evening after dinner?

Doesn't really matter when you take them. Your mother may be thinking about iron supplements which work best on an empty stomach. (or with Vit C rich food)
There is enough evidence out there to justify taking a multi vitamin every day unless you have a very good diet. There is no point taking mega doses but a simple multi-vitamin may be of benefit, is very unlikely to harm and costs about €20 per year so shouldn't break the bank.

AtomicHorror

ZYX wrote: »

There is enough evidence out there to justify taking a multi vitamin every day unless you have a very good diet.

Really? Where?

ZYX

AtomicHorror wrote: »

Really? Where?

Remember I am not saying everyone should take a multivitamin, but, it can be justified by the evidence available.
The link between neural tube defects and maternal B vitamin intake, especially Folic Acid is pretty certain at this stage. Therefore you can justify every woman of childbearing age taking Vit B. On the same thread B12 may improve fertility.
There is a possible link between taking B vitamins and again folic acid reducing heart disease by way of homocysteine levels. A I said it is not proven but enough to justify supplements.
As a previous poster said Vit D may be needed in many Irish people especially in winter.
Also GDAs have been established for most vitamins and minerals. The evidence for these is widely accepted. People who say supplements are not needed assume people have balanced diets, but look around. Do most people you know eat the recommended 5-10 portions of fruit and veg a day, every day? Add to that the quality of the fruit and veg, shipped in from the far side of the world and devoid of many of its natural vitamins. Don't forget effects of alcohol and smoking on vitamin absorption and I think there is enough to justify a multivitamin (or other form of vitamin/mineral supplementation) for many people, unless their diet is very good.

AtomicHorror

ZYX wrote: »

Remember I am not saying everyone should take a multivitamin, but, it can be justified by the evidence available.
The link between neural tube defects and maternal B vitamin intake, especially Folic Acid is pretty certain at this stage. Therefore you can justify every woman of childbearing age taking Vit B.

Vitamins don't really stick around for long though, do they? We can't store them, so we use them or excrete/egest them. Sure this is a justification for pregnant women to take supplements (which I understand has more support), but not all women, unless they're expecting to get pregnant very soon.

ZYX wrote: »

On the same thread B12 may improve fertility.

We've had these supplements around for decades, I'd expect better than "may" by now if the benefit was meaningful.

ZYX wrote: »

There is a possible link between taking B vitamins and again folic acid reducing heart disease by way of homocysteine levels. A I said it is not proven but enough to justify supplements.

That would be justification for a good diet, not for taking supplements. As I understand it, the diet position is the standard GPs position.

ZYX wrote: »

As a previous poster said Vit D may be needed in many Irish people especially in winter.

Then surely we can eat it in our food? Why does it need to be in pill form?

ZYX wrote: »

Also GDAs have been established for most vitamins and minerals. The evidence for these is widely accepted. People who say supplements are not needed assume people have balanced diets, but look around. Do most people you know eat the recommended 5-10 portions of fruit and veg a day, every day?

Will people who can't manage a balanced diet keep up a properly balanced regimen of tablets? Will they care? The people I've observed who take vitamin supplements regularly are the same people who exercise and eat well. So sure, they'll be healthy. But the supplements have squat to do with it. I've never heard of a beer swilling, chip-eater taking vitamin supplements.

ZYX wrote: »

Add to that the quality of the fruit and veg, shipped in from the far side of the world and devoid of many of its natural vitamins.

No doubt, but my question remains. Is there evidence that people with a balanced diet are deficient in some vitamin?

ZYX wrote: »

Don't forget effects of alcohol and smoking on vitamin absorption and I think there is enough to justify a multivitamin (or other form of vitamin/mineral supplementation) for many people, unless their diet is very good.

Well maybe you could link some of that evidence, because the bits of evidence I've seen have not been compelling. Check out this meta analysis of the effects of beta carotene, vitamin A, vitamin C and vitamin E supplements on mortality:

http://jama.ama-assn.org/cgi/content/full/297/8/842

Overall findings were either no effect or slightly increased mortality.

Or this Cochrane Library meta analysis of the effects of Vitamin C on the common cold:

http://www.cochrane.org/reviews/en/ab000980.html

Nothing much going on there either.

I'm inclined to say that the balance of evidence suggests that vitamin supplements are a waste of money for anyone who is reasonably healthy.

ZYX

AtomicHorror wrote: »

Vitamins don't really stick around for long though, do they? We can't store them, so we use them or excrete/egest them. Sure this is a justification for pregnant women to take supplements (which I understand has more support), but not all women, unless they're expecting to get pregnant very soon.

Pre conception folic acid is recommended. Any sexual active woman can become pregnant. So there is justification for all sexually active women taking supplements of Folic acid and other B Complex.

AtomicHorror wrote: »

We've had these supplements around for decades, I'd expect better than "may" by now if the benefit was meaningful.

But very few people are doing research on vitamin supplements in normal people

AtomicHorror wrote: »

That would be justification for a good diet, not for taking supplements. As I understand it, the diet position is the standard GPs position.

Then surely we can eat it in our food? Why does it need to be in pill form?

It may be hard to get it in the diet. How many people do you know, have breakfast of toast & coffee. Sandwich for lunch and perhaps a takeaway in evening or a pre prepared dinner. These people are unlikely to get all their vitamins & minerals every day. They may benefit from a multivitamin. A diet with 10 portions of fruit & veg a day, with no more than 3 portions of red meat a week and at laest 2 portions of fish a week is better but, I would say the majority of people in Ireland, or at least a large proportion do not do this. For these people a multi vitamin may be justified.

AtomicHorror wrote: »

Will people who can't manage a balanced diet keep up a properly balanced regimen of tablets? Will they care? The people I've observed who take vitamin supplements regularly are the same people who exercise and eat well. So sure, they'll be healthy. But the supplements have squat to do with it. I've never heard of a beer swilling, chip-eater taking vitamin supplements.

I don't get this argument. Are you saying that people with poor diets do not take vitamins and therefore they should not!

AtomicHorror wrote: »

Well maybe you could link some of that evidence, because the bits of evidence I've seen have not been compelling. Check out this meta analysis of the effects of beta carotene, vitamin A, vitamin C and vitamin E supplements on mortality:

I'm inclined to say that the balance of evidence suggests that vitamin supplements are a waste of money for anyone who is reasonably healthy.

Turn this around. Show me the evidence that people should not take a multivitamin. The cost by the way is about 5c per day so I would not count cost as a reason. As I said before I am not saying every person must take a multivitamin or other supplement but it can be justified, may help and is unlikely to harm.

AtomicHorror

ZYX wrote: »

Pre conception folic acid is recommended. Any sexual active woman can become pregnant. So there is justification for all sexually active women taking supplements of Folic acid and other B Complex.

There's an argument for it I guess, but it's a pretty speculative one.

ZYX wrote: »

But very few people are doing research on vitamin supplements in normal people

Given that the supplements market is worth hundreds of millions of euros annually, why do you think that is?

ZYX wrote: »

It may be hard to get it in the diet. How many people do you know, have breakfast of toast & coffee. Sandwich for lunch and perhaps a takeaway in evening or a pre prepared dinner. These people are unlikely to get all their vitamins & minerals every day. They may benefit from a multivitamin. A diet with 10 portions of fruit & veg a day, with no more than 3 portions of red meat a week and at laest 2 portions of fish a week is better but, I would say the majority of people in Ireland, or at least a large proportion do not do this. For these people a multi vitamin may be justified.

If there's evidence that it helps, can be realistically maintained by such people and is better than diet modification then sure.

ZYX wrote: »

I don't get this argument. Are you saying that people with poor diets do not take vitamins and therefore they should not!

I'm suggesting that if we can manage to convince the people with poor diets to care enough for themselves that they'd start buying vitamins, surely we could convince them to eat some fish and green veg instead.

ZYX wrote: »

Turn this around. Show me the evidence that people should not take a multivitamin.

One of the studies above showed increased mortality for intake of vitamin D and E. One could speculate that the proliferation of supplements might undermine good dietary practices, which would not be an issue if supplements were proven effective but they are not. The risk of overdose is also a minor but significant concern.

But since when did positive assumptions become the default position? Why is it on me to prove supplements dangerous so that we can justify not taking them? Do I need to go hunt for fairies so that you will believe me when I tell you to stop buying fairy traps?

If there are no discernible benefits for a given behaviour then why should we practice that behaviour? Putting the wastes of time effort and money aside, it is simply irrational. The burden of evidence is on the proponents of vitamin supplements. If you want to argue their side then that puts the burden on you. They're not publishing much data (beyond in vitro and animal studies), which I find very odd and which should be ringing alarm bells in the heads of any rational sceptic. Given that the industry is worth hundreds of millions of euros annually, and given that there seems to be no shortage of marketing, advertising and general promotion of supplements, that lack of solid data that you yourself have observed is a clear warning sign.

Now, I've provided sources, so maybe you'd return the favour. Randomised controlled trials or meta-analyses would be best.

ZYX wrote: »

The cost by the way is about 5c per day so I would not count cost as a reason.

Do you have a source on that cost? Does it represent an average and if so what is the standard deviation? What's the worst-case outlay for some people?

Put the cost aside for a moment. If supplements become the accepted unchallenged as the norm in the absence of evidence of benefit, what will be the real cost? Just how much more can be sold to us in a total vacuum of information? Homoeopathic remedies? Maybe bottles of special healing air? There's a principle here, even if we ignore the potential for harm.

ZYX wrote: »

As I said before I am not saying every person must take a multivitamin or other supplement but it can be justified, may help and is unlikely to harm.

So back it up.

ZYX

AtomicHorror wrote: »

There's an argument for it I guess, but it's a pretty speculative one.

This is not speculation. Obstreticians recommend preconception folic acid. From the NHS website: Taking folic acid supplements before and during pregnancy can reduce the risk of your baby being born with a neural tube defect (NTD).

AtomicHorror wrote: »

If there's evidence that it helps, can be realistically maintained by such people and is better than diet modification then sure.

I'm suggesting that if we can manage to convince the people with poor diets to care enough for themselves that they'd start buying vitamins, surely we could convince them to eat some fish and green veg instead.

I am not saying supplements are better than a good diet but a large proportion probably the majority are not getting enough vitamins and minerals to meet their recommended intake. It is easier to get these people to take a multivitamin every day than to change their entire diet. I think that is common sense.

AtomicHorror wrote: »

One of the studies above showed increased mortality for intake of vitamin D and E. One could speculate that the proliferation of supplements might undermine good dietary practices, which would not be an issue if supplements were proven effective but they are not. The risk of overdose is also a minor but significant concern.

Your link was regarding huge doses of these vitamins. The risk of overdose is practically non-existant with a simple multivitamin.

AtomicHorror wrote: »

Do you have a source on that cost? Does it represent an average and if so what is the standard deviation? What's the worst-case outlay for some people?

Tesco sell 180 multivitamins for €8.49. This works out at 4.7c per day. I am sure you could find cheaper if you look. This was the only site I looked up.

AtomicHorror wrote: »

So back it up.

I looked up selenium, vitamin D and folate. These are the first results I got and are all published in 2009. As I said numerous times it is not that the evidence is totally conclusive and there are oposing views but there is enough evidence to justify using a multivitamin

Selenium and vitamin E: cell type- and intervention-specific tissue effects in prostate cancer.J Natl Cancer Inst. 2009 Mar 4;101(5):283-5.

Nutrition and depressive symptoms in community-dwelling elderly persons in Japan.[URL="javascript:AL_get(this, 'jour', 'Acta Med Okayama.');"]Acta Med Okayama.[/URL] 2009 Feb;63(1):9-17.

Folate and one-carbon metabolism nutrients from supplements and diet in relation to breast cancer risk.[URL="javascript:AL_get(this, 'jour', 'Am J Clin Nutr.');"]Am J Clin Nutr.[/URL] 2009 Feb;89(2):624-33. Epub 2008 Dec 30

nesf

ZYX wrote: »

Turn this around. Show me the evidence that people should not take a multivitamin.

Eh mate, you can use this kind of logic to recommend people take anything that doesn't harm them.

AtomicHorror

ZYX wrote: »

This is not speculation. Obstreticians recommend preconception folic acid. From the NHS website: Taking folic acid supplements before and during pregnancy can reduce the risk of your baby being born with a neural tube defect (NTD).

That's a recommendation for women planning a pregnancy, not a general recommendation for women of childbearing age. I'm saying that the second case is of questionable benefit.

ZYX wrote: »

I am not saying supplements are better than a good diet but a large proportion probably the majority are not getting enough vitamins and minerals to meet their recommended intake. It is easier to get these people to take a multivitamin every day than to change their entire diet. I think that is common sense.

What's the point of pushing supplements over diet if supplements are not demonstrably equal to or better than diet changes? If we're talking about convincing people to change their life styles then our time, effort and (presumably) taxes need to be put into that which is demonstrated to work.

ZYX wrote: »

Your link was regarding huge doses of these vitamins. The risk of overdose is practically non-existant with a simple multivitamin.

The mortality seen in these studies was not associated with overdoses. It was a meta analysis, there were trials included with widely varying dose ranges. Are you saying these trials used unrealistic or dangerous doses of vitamins? Did they compare poorly with the normal doses in a multivitamin pill? The overdose risk is certainly low, but with the proliferation of supplements I think we can safely assume that small risk is likely to increase proportionally.

ZYX wrote: »

Tesco sell 180 multivitamins for €8.49. This works out at 4.7c per day. I am sure you could find cheaper if you look. This was the only site I looked up.

Great if it works, if it doesn't then that's still a waste of money albeit a small one, and as I've said, the cost of getting into the habit of relying on unproven treatments and whatnot is less tangible than money though no less important.

ZYX wrote: »

I looked up selenium, vitamin D and folate. These are the first results I got and are all published in 2009. As I said numerous times it is not that the evidence is totally conclusive and there are oposing views but there is enough evidence to justify using a multivitamin.

I disagree, unless the evidence of efficacy and safety is clear it makes little sense to take action. Your links are broken below, but I found the studies anyway.

ZYX wrote: »

Selenium and vitamin E: cell type- and intervention-specific tissue effects in prostate cancer.J Natl Cancer Inst. 2009 Mar 4;101(5):283-5.

That's a good study, but it looks only at prostate cancer patients. I think we're agreed that vitamin supplements can benefit ill people, I'm interested in data on normal people.

ZYX wrote: »

Nutrition and depressive symptoms in community-dwelling elderly persons in Japan.[URL="javascript:AL_get(this, 'jour', 'Acta Med Okayama.');"]Acta Med Okayama.[/URL] 2009 Feb;63(1):9-17.

This isn't a great study overall- it's a randomised mail-out questionnaire-based study with no specific control or treatment groups. They don't detail how they randomised either, which is probably not a great sign. Of course, all honest data has value. But this study doesn't examine food supplements, just food-based nutrient intake. So it really doesn't support the use of supplements at all (nor does the study even mention them), though it could be used as weak evidence that diet can affect depression.

ZYX wrote: »

Folate and one-carbon metabolism nutrients from supplements and diet in relation to breast cancer risk.[URL="javascript:AL_get(this, 'jour', 'Am J Clin Nutr.');"]Am J Clin Nutr.[/URL] 2009 Feb;89(2):624-33. Epub 2008 Dec 30

This is a bit more like it, a large-scale cohort study. Unfortunately I can't get full access to the trial even through my university pubmed access. So, I'll have to base my judgement of this one on the abstract for now. The conclusion of the study is suitably cautious and suggests that high folate intake may be protective against breast cancers in a population of normal women. So I'm not sure it really backs you up all that well.

They report a relative risk ratio of 0.78, and then state that this represents a 20% reduction in cancer rates. Numbers like this are a bit tricky for reasons I've blogged about. If you found only 5 cases out of a million without treatment and 4 cases per million with treatement, you'd get RR=0.80 and a "20% reduction" as well- essentially the same numbers- but that would not be compelling data at all. Without seeing the raw numbers it's quite hard to judge their findings. I'll try to work out some of what's in the abstract- and if there are any medics or epidemiologists about please feel free to set me straight.

They say that the total number of cases of breast cancer diagnosed was 743 out of a total of 35,023 participants. So, if we assume there is only two groups and that they're roughly equal in size (and I can't be sure of either), reversing the RR calculations gives us something like:

326 cases in the high folate group and 417 cases in the low folate group. That's a difference of 52 cases of breast cancer per 10,000 people. So, as I understand it, this means that a high intake of folate reduces a given woman's breast cancer risk from and absolute level of about 2% over 6 years to about 1.5%. If you take lots of folate then, you may reduce your absolute chance of getting breast cancer by 0.5%. The confidence intervals they present seem rather wide to me (as a total non-expert), and I suspect that's why they're being cautious about the results. There's also some haziness in how they collected the folate level data, looks like it was self-reported by the participants for the 10 years up to baseline and I'm not clear on how the study proceeded beyond baseline. Most critically, since I can't be clear on whether the folate intake was randomised (it certainly wasn't placebo controlled) we also run into issues of causality and the danger of confounding variables. It looks as if the study just watches women's normal folate intake, which could mean the real reason for the (very small) cancer rate differences is something that impacts on women's eating habits including folate intake.

So you've got one study there which might support the regular use of multivitamins by normal people. But it's not a very strong or compelling one. The beauty of meta-analyses is that these sorts of ambiguous studies can all be combine and re-analysed to give a clear picture. But I've yet to see a meta analysis that gives the thumbs-up to supplements, though that doesn't mean they don't exist.

Bottle_of_Smoke

AtomicHorror wrote: »

That's a recommendation for women planning a pregnancy, not a general recommendation for women of childbearing age. I'm saying that the second case is of questionable benefit.

In fairness how many pregnancies are planned compared to unplanned? Although I don't think a multivitamin is neccesary I do think every girl should take folic acid once they've hit puberty\sexually active as they can fall pregnant at any time. Folic acid is only beneficial to the foetus if its taken before pregnancy/in early pregnancy, early to the point a lot of people wouldn't actually realise they're pregnant.

ZYX

AtomicHorror wrote: »

That's a recommendation for women planning a pregnancy, not a general recommendation for women of childbearing age. I'm saying that the second case is of questionable benefit.

As Bottle_of_smoke said

AtomicHorror wrote: »

Did they compare poorly with the normal doses in a multivitamin pill?

Yes

AtomicHorror wrote: »

So you've got one study there which might support the regular use of multivitamins by normal people. But it's not a very strong or compelling one. The beauty of meta-analyses is that these sorts of ambiguous studies can all be combine and re-analysed to give a clear picture. But I've yet to see a meta analysis that gives the thumbs-up to supplements, though that doesn't mean they don't exist.

I picked these 3 articles simply beacause they were the first 3 I came accross. No other reason. There are thousands of articles on the benefits of multi-vitamins. It may all be nonsense or it may not. The evidence for folic acid preventing neural tibe defects is beyond doubt. A friend of mine is a cardiologist and he takes a multivitamin every day. He believes it may prevent heart disease. He may be wrong, I may be wrong but as I have said there is enough evidence that we may be right and you may be wrong. For a cost of €15 a year, taking a multivitamin, a single capsule a day, may improve your life expectancy while doing very little if any harm. I am not expecting to convince you, but I think you may be confusing multivitamins for megadose vitamins that some people push. I am simply saying there are clear recommended daily allowances of vitamins and minerals. You cannot always be sure you get all 30 or so every day. A multivitamin helps you reach that recommended level.

Locamon

Going back to the OP from personal experience some the vitamins can give you a little kick and I found sleeping a problem after taking them, so morning only for me. No reports to back this up just personal experience.
Don't see how taking them at lunch time would hurt.

DrIndy

Now here's a proper debate brewing! (unlike bloody vaccinations)

Keep it coming!

anotherlostie

I think diet is the primary factor here. More and more people are leading a slovenly lifestyle, unable to cook, and relying on the chipper, chinese and microwave for their main meal (and Cadbury's and Coke for the rest...) If you live this lifestyle, you will not be getting enough vitamins, and taking a supplement fills the gap. If you're someone that eats three square meals a day, then of course you shouldn't need vitamins, but in my book telling someone like the above to start to cook healthily is like telling an alcoholic to stop drinking. Such as this lot (and sorry that I'm veering O/T)

http://www.telegraph.co.uk/news/newstopics/howaboutthat/5004431/Family-who-are-too-fat-to-work-say-22000-worth-of-benefits-is-not-enough.html

nesf

ZYX wrote: »

As Bottle_of_smoke said





Yes




I picked these 3 articles simply beacause they were the first 3 I came accross. No other reason. There are thousands of articles on the benefits of multi-vitamins. It may all be nonsense or it may not. The evidence for folic acid preventing neural tibe defects is beyond doubt. A friend of mine is a cardiologist and he takes a multivitamin every day. He believes it may prevent heart disease. He may be wrong, I may be wrong but as I have said there is enough evidence that we may be right and you may be wrong. For a cost of €15 a year, taking a multivitamin, a single capsule a day, may improve your life expectancy while doing very little if any harm. I am not expecting to convince you, but I think you may be confusing multivitamins for megadose vitamins that some people push. I am simply saying there are clear recommended daily allowances of vitamins and minerals. You cannot always be sure you get all 30 or so every day. A multivitamin helps you reach that recommended level.

The problem though in this debate, and I've only skimmed a few papers on this so I'm not thoroughly informed, the answer seems to be murky. If you're elderly, chronically ill or pregnant multivitamins seem to have a positive effect. If you're not, they don't seem to produce anything other than the occasional study that looks "promising".

On one hand, it's harmless if normal multivitamins are taken as indicated and it might be beneficial to your health. On the other it's a snake oil industry profiting from people's willingness to think a pill can fix something.

What I find amusing is that the some of the people who rant about statin's effectiveness tend to push multivitamins without any qualms.

Capt'n Midnight

AtomicHorror wrote: »

Vitamins don't really stick around for long though, do they? We can't store them, so we use them or excrete/egest them.

As long as you don't go crazy on suppliments there should be no chance of Hypervitaminosis but A, D ,E and K are fat soluble so they could accumulate in rare circumstances. Eating polar bear liver could give you fatal levels of vitamin A, then again getting a polar bear to part with it's liver isn't risk free either.

There was the story of a guy who got carrot juice posioning. He was drinking a 8 pints of carrot juice a day AND taking massive amounts of vitamin suppliments AND continued to do so after turning yellow and being told by his doctor and a specialist to stop. Haven't found a definitive link for it though.

Lack of vitamins is also rare since some foods have to have them added, mostly cereals. Corn Flakes are fortified by vitamins because it's the law.

AtomicHorror

ZYX wrote:

AtomicHorror wrote:

Did they compare poorly with the normal doses in a multivitamin pill?

Yes

Again, you're not even trying to back up what you're saying. Look, compare them to Quest Multivitamins and the doses don't look that odd to me:

beta carotene: trial range = 1.2 to 50.0 mg (mean, 17.8 mg), Quest = 3 mg
vitamin E: trial range = 10 to 5000 IU, Quest = 15 IU
vitamin A: trial range = 1333 to 200 000 IU (400-60,000 ug), Quest = 750 ug
vitamin C: trial range = 60 to 2000 mg, Quest = 150 mg
selenium: trial range = 20 to 200 µg , Quest = 13 ug

So basically they cover a range of doses from below standard to above standard. Which is what they should do. So the normal dose is examined. And it's not like they're going to compare dissimilar doses.

ZYX wrote: »

I picked these 3 articles simply beacause they were the first 3 I came accross. No other reason.

Well what was the point of that? I was asking you to show me evidence that backs up your position and you give me papers based on keywords?

ZYX wrote: »

There are thousands of articles on the benefits of multi-vitamins. It may all be nonsense or it may not.

This is just an argument from ignorance. It's meaningless. Do your doubt your capacity to assess the evidence? There are peer-reviewed reviews and meta-analyses that make the process much easier. If you're going to take a position, for goodness sake have a reason.

ZYX wrote: »

The evidence for folic acid preventing neural tibe defects is beyond doubt.

You keep saying that and I keep agreeing. We only differ on whether it makes sense to recommend folic acid to women who are not planning to have children. I say it probably doesn't, since folic acid is not retained for long enough for the neural tube issue to be relevant. The NHS quote you provided seems to back that up.

ZYX wrote: »

A friend of mine is a cardiologist and he takes a multivitamin every day. He believes it may prevent heart disease. He may be wrong, I may be wrong but as I have said there is enough evidence that we may be right and you may be wrong.

The personal opinions of cardiologists or anyone at all means nothing to me unless they have hard data to back it up. Again, appealing to the lack of clarity in the evidence is not a justification for taking an affirmative position. Appealing to the authority of a medic is pointless too. Scientific decision making is not based on authority opinions.

ZYX wrote: »

For a cost of €15 a year, taking a multivitamin, a single capsule a day, may improve your life expectancy while doing very little if any harm. I am not expecting to convince you, but I think you may be confusing multivitamins for megadose vitamins that some people push. I am simply saying there are clear recommended daily allowances of vitamins and minerals. You cannot always be sure you get all 30 or so every day. A multivitamin helps you reach that recommended level.

If that's the logic you want to go with then knock yourself out. The fact of the matter is this. If you are going to argue that multivitamins have some significant benefit that we have not yet detected by testing then it is equally likely that they can do significant harm that we have not detected. In all likelihood, neither is the case.

Until money is put into research we will not know, and until then this is not an industry that I think should be supported by anyone. If the drugs companies tried this we'd be all out crying about the evils of Big Pharma, but for some reason you'll let the "alternative" away with telling you literally nothing and expecting you to pay for it.

The likes of Gillian McKeith and Patrick Holford have made their fortunes because they know that some people, in the absence of evidence, will happily take the attitude that the unknown can either help or do nothing. I don't think that is right. Slap a label like "natural" on something and the concept of harm seems to vanish from people's minds. That is an illusion and is totally irrational. In the absence of evidence on the benefit or harm (or efficacy) of an action the sensible thing to do is nothing. If you cannot understand the logic of that then by all means continue as you are. Personally I intend to go on pointing out that multivitamins are proven to do squat until I am shown otherwise.

AtomicHorror

nesf wrote: »

The problem though in this debate, and I've only skimmed a few papers on this so I'm not thoroughly informed, the answer seems to be murky. If you're elderly, chronically ill or pregnant multivitamins seem to have a positive effect. If you're not, they don't seem to produce anything other than the occasional study that looks "promising".

Check out the Cochrane Library and do a search on vitamins or supplements and you'll get meta-analyses. These are systematic reviews of all comparable studies on a given topic. That tends to de-murkify things nicely. As far as I know the full texts of these papers are free and most seem to contain a good sort of "layperson's conclusion" as well as the in depth stuff.

anotherlostie wrote: »

I think diet is the primary factor here. More and more people are leading a slovenly lifestyle, unable to cook, and relying on the chipper, chinese and microwave for their main meal (and Cadbury's and Coke for the rest...) If you live this lifestyle, you will not be getting enough vitamins, and taking a supplement fills the gap. If you're someone that eats three square meals a day, then of course you shouldn't need vitamins, but in my book telling someone like the above to start to cook healthily is like telling an alcoholic to stop drinking. Such as this lot (and sorry that I'm veering O/T)

http://www.telegraph.co.uk/news/newstopics/howaboutthat/5004431/Family-who-are-too-fat-to-work-say-22000-worth-of-benefits-is-not-enough.html

But my point before is that it's unlikely you could convince people who care so little about their health to bother with regular supplements. And if you can get them to care about their health then you'd probably be doing them no favours to cause them to rely on a stop gap. Let's face it, alcohol abuse, smoking and a lack of exercise are probably the real deal breakers here in terms of lifespan and quality of life. There's just no quick fix for this, and supplements create the illusion that there is.

It has just not been shown that supplements confer a benefit even over that totally crappy lifestyle, let alone over the lifestyle of the average person.

Bottle_of_Smoke wrote: »

In fairness how many pregnancies are planned compared to unplanned? Although I don't think a multivitamin is neccesary I do think every girl should take folic acid once they've hit puberty\sexually active as they can fall pregnant at any time. Folic acid is only beneficial to the foetus if its taken before pregnancy/in early pregnancy, early to the point a lot of people wouldn't actually realise they're pregnant.

I take your point but that brings us to the question of whether the average woman really is so deficient in folic acid that it demands that they all start taking a pill every day to fix it? I fear we're starting to medicalise some pretty mundane stuff these days. Can't we just recommend a balanced diet that accounts for this instead? I think that would be a lot more responsible, and as likely to be heeded.

ZYX

AtomicHorror wrote: »

You keep saying that and I keep agreeing. We only differ on whether it makes sense to recommend folic acid to women who are not planning to have children. I say it probably doesn't, since folic acid is not retained for long enough for the neural tube issue to be relevant. The NHS quote you provided seems to back that up.

AtomicHorror I am not going to convince you so for my last post on this. You do not agree that preconception is necessary. Most obstetricians disagree. So much so that many countries are starting to fortify bread with folic acid. The FSA has recommended doing this in the UK and the Irish government are considering similar proposals. Irealnd has one of the highest rates of neural tube defects in the world. We have about 80 cases a year. Just to put that in context this is roughly the same number who die of cervical cancer every year. In addition the very high levels in Ireland also indicate a possible high level of folic acid deficiency in the entire population.

Nicotinic acid has been shown to Increase HDL cholesterol so much so that it is recommended by many/most US cardiologists.
B Complex and Lutein are also used for treatment of macular degeneration and may prevent it. You disagree, many ophthalmologists agree.
The point is the evidence may not prove their effectiveness beyond any doubt but it is enough to convince many experts in the field. Everything does not need metaanalysis.


Dietary Iron deficency anaemia is very common in Ireland as is Non-Anaemic iron deficiency. Obviously a multivitamin/mineral would prevent this. Vitamin B12 deficiency that responds to oral B12 is increasing rapidly in this country. Certainly I can never remember seeing it 20 years ago. Now most practices have a few. (many don't investigate and treat with injections, hence the number of young women on B12 injections.) Again a vitamin supplement would stop this.

Perhaps you should remember that old saying:
"An absence of evidence of an effect is not evidence of the absence of an effect"

You constantly say that a proper diet is better. I am not denying that, but the fact is most people do not have a proper diet and are at risk of vitamin deficiency. I presume you work in a hospital. So tomorrow go to the canteen and see the food choices people are making. Look at the levels of obesity among doctors, nurses and other paramedics. These are the people most highly educated re nutrition. Look at the diets they have, and then guess what Joe Soap is eating. Yes, convincing everyone to eat their 10 portions of fruit and veg would be fantastic. Get them eating their oily fish twice a week, yes, but, if doctors cannot be convinced after 6 years in medical school what chance does anyone else. I cannot see how you can see people with poor diets and not make the connection that they may be lacking in some vitamins & minerals. If they are not going to get it from their food where are they going to get it?

AtomicHorror

ZYX wrote: »

AtomicHorror I am not going to convince you so for my last post on this. You do not agree that preconception is necessary.

That's not what I'm saying. I'm questioning the wisdom of advising it for all women of childbearing age. Is that an actual recommendation made by any of the medical authorities?

ZYX wrote: »

Most obstetricians disagree. So much so that many countries are starting to fortify bread with folic acid. The FSA has recommended doing this in the UK and the Irish government are considering similar proposals. Irealnd has one of the highest rates of neural tube defects in the world. We have about 80 cases a year. Just to put that in context this is roughly the same number who die of cervical cancer every year. In addition the very high levels in Ireland also indicate a possible high level of folic acid deficiency in the entire population.

If the evidence is there to justify it and it is safe, then I am fully on board.

ZYX wrote: »

Nicotinic acid has been shown to Increase HDL cholesterol so much so that it is recommended by many/most US cardiologists.

Again, if there's good evidence of this then I would be in favour of recommending supplements of nicotinic acid or it's introduction into some common food.

ZYX wrote: »

B Complex and Lutein are also used for treatment of macular degeneration and may prevent it. You disagree, many ophthalmologists agree.
The point is the evidence may not prove their effectiveness beyond any doubt but it is enough to convince many experts in the field. Everything does not need metaanalysis.

If the evidence does not prove their effectiveness then the opinions of the experts betray them. The experts ought to base their recommendations on the best available information.

ZYX wrote: »

Dietary Iron deficency anaemia is very common in Ireland as is Non-Anaemic iron deficiency. Obviously a multivitamin/mineral would prevent this.

That's a specific deficiency. Obviously a deficiency in some mineral or vitamin should be treated. But not with a scattergun approach, with the appropriate mineral. We're not talking about treating deficiencies though, we're talking about the use of multivitamin supplements by people who have no diagnosed deficiency.

ZYX wrote: »

Vitamin B12 deficiency that responds to oral B12 is increasing rapidly in this country. Certainly I can never remember seeing it 20 years ago. Now most practices have a few. (many don't investigate and treat with injections, hence the number of young women on B12 injections.) Again a vitamin supplement would stop this.

And again this is a specific ailment which is not the topic of the discussion. If it's a very widespread problem then perhaps it should be dealt with in a similar manner to the folic acid issue. I don't see how throwing vitamins A, C and E at a B12 deficiency is helping unless the patient also has those deficiencies.

ZYX wrote: »

Perhaps you should remember that old saying:
"An absence of evidence of an effect is not evidence of the absence of an effect"

Given that "effect" can equal benefit or harm that's not an argument in your favour. At any rate it's just the same as "absence of proof is not proof of absence", an argument I generally only hear from creationists with regard to God. It's a logical fallacy, an argument from ignorance.

ZYX wrote: »

You constantly say that a proper diet is better. I am not denying that, but the fact is most people do not have a proper diet and are at risk of vitamin deficiency. I presume you work in a hospital. So tomorrow go to the canteen and see the food choices people are making. Look at the levels of obesity among doctors, nurses and other paramedics. These are the people most highly educated re nutrition. Look at the diets they have, and then guess what Joe Soap is eating. Yes, convincing everyone to eat their 10 portions of fruit and veg would be fantastic. Get them eating their oily fish twice a week, yes, but, if doctors cannot be convinced after 6 years in medical school what chance does anyone else. I cannot see how you can see people with poor diets and not make the connection that they may be lacking in some vitamins & minerals. If they are not going to get it from their food where are they going to get it?

I don't have an answer to that one. I don't know how you convince people either to eat better or to take supplements, so it's rather a moot point. It seems like they won't do either. I suspect that what underlies that is nothing to do with either food or pills, though that's just my hunch. By and large these people aren't the ones buying the supplements regularly. Ironically, the people who eat well, excercise and limit their alcohol intake are. The rest is useless fad purchases to accompany equally useless detox diets.

nesf

ZYX wrote: »

In addition the very high levels in Ireland also indicate a possible high level of folic acid deficiency in the entire population.

Really? I thought it was believed to be some genetic anomaly given our diets being relatively similar to those in the UK?

Not that I oppose folic acid fortification of food stuffs or anything like that, one of my cousins was severely physically and mentally handicapped due to spina bifida. That it is (to an extent) preventable through fortification of foodstuffs with something as "benign" as folic acid is wonderful.

ZYX

AtomicHorror wrote: »

If the evidence does not prove their effectiveness then the opinions of the experts betray them. The experts ought to base their recommendations on the best available information.

I know I said I would not comment anymore so for a definitely final comment. The fact is, the evidence is there. It does not convince you. It does convince many experts. They are basing their opinion on the best available information, probably more information than you have. The fact that they have come to a different conclusion to you does not make them wrong. I am not sure of your opinion of Bandolier but they say:

http://www.medicine.ox.ac.uk/bandolier/band123/b123-2.html#Heading5


"All of this has to be interpreted with caution. What we have are straws in the wind. But for those people with macular degeneration, or who want to avoid it, these straws are worth having. A good diet, rich in antioxidants, and perhaps with some antioxidant supplementation, is the first thing to go for. Apart from anything else, it has benefits in terms of hearts, bones, and against cancer.

The second thing is to increase intake of lutein and zeaxanthin. The amount found in a normal western diet is said to be between 1 and 3 mg lutein and zeaxanthin a day. Even those of us with relatively good diets might find that hard to manage,"

Multivitamins and lutein may work. More importantly there is nothing else to offer to prevent macular degeneration. So you tell people now not to take multivitamins. In 10 years time if their effect is proven what happens then. Oh sorry you have macular degeneration. Nothing we can do for you now but you should have been taking multivitamins and lutein for last 10 years. Me Bad.

AtomicHorror wrote: »

Given that "effect" can equal benefit or harm that's not an argument in your favour. At any rate it's just the same as "absence of proof is not proof of absence", an argument I generally only hear from creationists with regard to God. It's a logical fallacy, an argument from ignorance.

The argument the it may harm as much as do good is very unlikely. Up to 20% of people already take multivitamin/minerals. Many foods are already fortified such as cereals, milk and bread.

The situation we are in is, there is a tablet that will cost about €15 a year. It almost certainly does no harm. It may reduce your risk of having a child with a neural tube defect, prevent macular degeneration, improve your lipid profile, reduce risk of heart disease, improve fertility, prevent iron deficiency (esp in women), may reduce depression symptoms and reduce risk of dementia.
On top of all this it will cost the state nothing, (will actually benefit the cofers with VAT), and may reduce costs to the state in the future.
Yes I accept it may be proven that multi vitamins do nothing but there is enough evidence that they might.
A look at the risks/benefits and costs make taking a multi vitamin a reasonable thing to do. If it works in only one of these areas then it is definitely worth taking.

AtomicHorror

ZYX wrote: »

I know I said I would not comment anymore so for a definitely final comment. The fact is, the evidence is there. It does not convince you. It does convince many experts.

I'm not sure that it does, to be honest. As far as I'm aware "normal people should regularly take multivitamin supplements" is not the consensus opinion of either medics or life scientists in general. If there are any medics here who can set me straight on that with a decent reference then I'll gladly withdraw that.

ZYX wrote: »

They are basing their opinion on the best available information, probably more information than you have. The fact that they have come to a different conclusion to you does not make them wrong. I am not sure of your opinion of Bandolier but they say:

http://www.medicine.ox.ac.uk/bandolier/band123/b123-2.html#Heading5

I don't see a recommendation in there for normal people to regularly take multivitamin supplements...

ZYX wrote: »

"All of this has to be interpreted with caution. What we have are straws in the wind. But for those people with macular degeneration, or who want to avoid it, these straws are worth having. A good diet, rich in antioxidants, and perhaps with some antioxidant supplementation, is the first thing to go for. Apart from anything else, it has benefits in terms of hearts, bones, and against cancer.

Once again, this is a recommendation (and a cautious one at that) being made to people with a specific ailment. And once again, I repeat that I am not denying the potential benefit in such cases.

ZYX wrote: »

The second thing is to increase intake of lutein and zeaxanthin. The amount found in a normal western diet is said to be between 1 and 3 mg lutein and zeaxanthin a day. Even those of us with relatively good diets might find that hard to manage,"

You left out their concluding line on that: "The strength of that evidence, though, is not known." They don't seem to be all that confident to stand by their word without caveats. Of course, that tends to be the way even with the best of evidence. It's notable though, that the main review they are working off of here (this one) looks at 7 randomised controlled trials, of which only 3 show a therapeutic benefit for nutritional supplementation. Of those 3, the authors expressed confidence only in 1. Their conclusions were suitably cautious, suggesting further research but not, so far as I can see, recommending regular supplementation for all.

ZYX wrote: »

Multivitamins and lutein may work. More importantly there is nothing else to offer to prevent macular degeneration. So you tell people now not to take multivitamins. In 10 years time if their effect is proven what happens then. Oh sorry you have macular degeneration. Nothing we can do for you now but you should have been taking multivitamins and lutein for last 10 years. Me Bad.

And similarly, if there's no discernible effect or if some detectable harm is done, what then? I can guarantee you one thing; the pill manufacturers will walk away untouched. They're very careful about the claims they make, to the point of making no solid claims of therapeutic efficacy at all. They make functional claims. Vitamin X is involved in function Y. But never "this supplement will help prevent prostate cancer".

ZYX wrote: »

The argument the it may harm as much as do good is very unlikely. Up to 20% of people already take multivitamin/minerals. Many foods are already fortified such as cereals, milk and bread.

The evidence is split both ways, so on what basis can you be confident that we're failing to detect benefit that is there but failing to detect harm because it isn't there? How does that make sense?

ZYX wrote: »

The situation we are in is, there is a tablet that will cost about €15 a year. It almost certainly does no harm. It may reduce your risk of having a child with a neural tube defect, prevent macular degeneration, improve your lipid profile, reduce risk of heart disease, improve fertility, prevent iron deficiency (esp in women), may reduce depression symptoms and reduce risk of dementia.

Yeah, a lot of "mays". So long as we don't confuse them for anything real or accountable.

ZYX wrote: »

On top of all this it will cost the state nothing, (will actually benefit the cofers with VAT), and may reduce costs to the state in the future. Yes I accept it may be proven that multi vitamins do nothing but there is enough evidence that they might.
A look at the risks/benefits and costs make taking a multi vitamin a reasonable thing to do. If it works in only one of these areas then it is definitely worth taking.

And what exactly does the risk:benefit analysis say? Does it take into account the more general harm done by promoting a culture in which we make health decisions in an evidence vacuum?

Bottle_of_Smoke

AtomicHorror wrote: »

I take your point but that brings us to the question of whether the average woman really is so deficient in folic acid that it demands that they all start taking a pill every day to fix it? I fear we're starting to medicalise some pretty mundane stuff these days. Can't we just recommend a balanced diet that accounts for this instead? I think that would be a lot more responsible, and as likely to be heeded.

To rule out spina bofida the average woman needs to be taking more than she currently does. I think you're right about the last bit though - would probably be best to fortify breads and other common foods with it.

ZYX

AtomicHorror wrote: »

I'm not sure that it does, to be honest. As far as I'm aware "normal people should regularly take multivitamin supplements" is not the consensus opinion of either medics or life scientists in general. If there are any medics here who can set me straight on that with a decent reference then I'll gladly withdraw that.

The aforementioned Bandolier says in its advice for a healthy lifestyle to "help avoid seeing a doctor about heart disease or cancer based on good quality information"

http://www.medicine.ox.ac.uk/bandolier/booth/hliving/10steps.html

"Take a multivitamin tablet every day, but be sure that it is one with at least 200 micrograms of folate. The evidence is that this can substantially reduce chances of heart disease in some individuals, and it has been shown to reduce colon cancer by over 85%. It may also reduce the likelihood of developing dementia. Folate is essential in any woman contemplating pregnancy because it will reduce the chance of some birth defects."


Also in the Journal of the American Medical Association in 2002

"Reversing a longstanding policy on vitamin supplements, the Journal of the American Medical Association announced last month that it will begin advising all adults to take at least one multivitamin pill each day (1). The last time the journal made a comprehensive review of vitamins, about twenty years ago, it concluded that normal people shouldn't take multivitamins. Most people, it was believed, could obtain adequate amounts of these nutrients from their diet. "

AtomicHorror wrote: »

Once again, this is a recommendation (and a cautious one at that) being made to people with a specific ailment. And once again, I repeat that I am not denying the potential benefit in such cases.

It was for "those people with macular degeneration, or who want to avoid it,"

AtomicHorror

I'm starting to come round to the folate argument for women. It certainly seems to be a bit more convincing than the general vitamin supplement argument. The regular supplementation question is still hazy though, as is the fortification issue.

Here's a nice review of that folate/pregnancy thing which seems to have been updated this year:

http://mrw.interscience.wiley.com/cochrane/clsysrev/articles/CD001056/pdf_fs.html

Results: relative risk 0.28, 95% confidence interval 0.13 to 0.58. Which is fairly compelling stuff. But they do conclude: "The benefits and risks of fortifying basic food stuffs, such as flour, with added folate remain unresolved."

They also mention:

"Evidence on the effectiveness of multivitamins in preventing recurrent
neural tube defects is available from two trials only. There
was no statistically significant reduction when multivitamins alone
were compared with placebo RR 0.61(95% CI 0.26,1.45)."

I doubt there's any real reason to suppose that multivitamins will somehow reduce the benefit of folate, but the data is fuzzy there. If we're generous, the above justifies regular folate supplementation in women. But multivitamin supplmentation is still of questionable benefit, especially when we consider the data on Vit C, D and E which don't seem to demonstrate any benefit unless you're diagnosable as deficient.

Capt'n Midnight

I like the old victorian myth that if you eat the right foods you will live forever. But it's never as simple as that. Are the problems associated with food allergies worth the benefits of extra vitamins in the very young ?
Or are multivitamins a symptom of overprotection that leads to a poorer immune system.

Early infant multivitamin supplementation is associated with increased risk for food allergy and asthma.
http://www.ncbi.nlm.nih.gov/pubmed/15231904

RESULTS: There were >8000 total patients in the study.
The overall incidence of asthma was 10.5% and of food allergy was 4.9%. In univariate analysis, male gender, smoker in the household, child care, prematurity (<37 weeks), being black, no history of breastfeeding, lower income, and lower education were associated with higher risk for asthma.

Child care, higher levels of education, income, and history of breastfeeding were associated with a higher risk for food allergies. In multivariate logistic analyses, a history of vitamin use within the first 6 months of life was associated with a higher risk for asthma in black infants (odds ratio [OR]: 1.27; 95% confidence interval [CI]: 1.04-1.56).

Early vitamin use was also associated with a higher risk for food allergies in the exclusively formula-fed population (OR: 1.63; 95% CI: 1.21-2.20).

Vitamin use at 3 years of age was associated with increased risk for food allergies but not asthma in both breastfed (OR: 1.62; 95% CI: 1.19-2.21) and exclusively formula-fed infants (OR: 1.39; 95% CI: 1.03-1.88).

CONCLUSIONS:
Early vitamin supplementation is associated with increased risk for asthma in black children and food allergies in exclusively formula-fed children. Additional study is warranted to examine which components most strongly contribute to this risk.

Kevster

If you're a vegetarian, then you might want to take a Vitamin K supplement, as this is the only vitamin that is only found in meat-sources. That said, I don't think that a general vitamin supplement is needed. Why do you think you need it? - Media pressure got to you?

ZYX

Kevster wrote: »

If you're a vegetarian, then you might want to take a Vitamin K supplement, as this is the only vitamin that is only found in meat-sources. That said, I don't think that a general vitamin supplement is needed. Why do you think you need it? - Media pressure got to you?

Vitamin K comes mainly from green leafy vegetables ie spinach, cabbage etc.

Media pressure generally says not to take a multi vitamin. It is the kind of thing Gerry Ryan and Pat Kenny advise. As per my previous post the American Medical Association said via their Journal JAMA that a multivitamin may help. Bandolier, which is by various medical based scientists at Oxford University and Hospitals, recommends everyone should take a multivitamin every day for good health.

Kevster

Arrrgh! - What am I thinking! You are of course correct. The vitamin that I was referring to was Vitamin B12 (Cyanocobalamin). It is only found in meat.

Anyway, I won't be listening to the American Medical Association because, as others have even mentioned here, evidence for/against taking vitamin supplements has never been concrete. I have heard reports, for example, that taking too much of certain vitamins can induce cancer. My opinion is that the apparent benefits they bring are mostly due to the 'feel-good' mental factor, like a placebo in a certain sense.

Also, media pressure does generally encourage us to take them. Do you not watch TV?

angeldelight

As a pharmacy graduate with absolutely no intentions of getting pregnant anytime in the next 3 years, I'm taking folic acid supplements. This is due to the large amount of evidence I was exposed to at all stages of my degree about how important folic acid is pre-conception and during the first 12 weeks post-conception. Unfortunately I threw out all my notes upon graduation but even a quick look shows some evidence to back it up
Recommendation 3:
http://www.sogc.org/guidelines/public/138E-CPG-November2003.pdf

http://www.cdc.gov/Features/FolicAcid/

Any woman of child-bearing age who is sexually active and hence may become pregnant should ideally be taking folic acid 400mcg daily