tryptophan and depression

ronbyrne2005

i was reading that a high protein diet can stop much of the amino acid tryptophan from getting into the brain where it is needed to form serotonin,any views? i have heard insulin can help tryptophan get into the brain ,how could you ensure you get enough tryptophan into brain ?

DrIndy

I'm not quite sure what you mean by this question.

Do you mean how is tryptophan related to serotonin? How is it absorbed? How does serotonin function in depression?

Where have you heard that insulin enhances tryptophan absorption?

ronbyrne2005

does anyone know if a high protein diet decreases tryptophan entering brain?

i read on a website that insulin causes competing amino acids in blood to be cleared into skeletal muscle leaving tryptophan to enter blood brain barrier on carrier protein which it cant do when there are high levels of competing amino acids like phenayline tyrosine etc which are far more abundant in foods.

DrIndy

Can you provide a link to that website?

Both myself (and I am sure John2) and others would be interested in reading the information as it is new to me. We can also tell you if the information they propose is based on good evidence and try to give you an answer.

John

ronbyrne2005 wrote:

does anyone know if a high protein diet decreases tryptophan entering brain?

I've never heard of this but upon going on to PubMed there seems to be a bit about it. In aggressive behaviour, strategies that increase levels of serotonin reduce the severity of the aggressive behaviour (such as antidepressant treatment). Adding tryptophan to a high-protein diet or by giving a low-protein diet seems to reduce aggression in dogs (deNapoli et al., 2000). That's one study that seems to suggest that tryptophan uptake is reduced in a high-protein diet.

As for insulin, I found a few papers that link diabetes with depression (Musselman et al., 2003 being one). Another paper had a bit in the abstract (I can't access the full articles from home) about how indeed insulin plays a part in tryptophan uptake into the CNS (Salazar, 2000). Another small article from the BMJ points out why I haven't really heard of all this, it's not very well researched and what research that has been done has lead to controversial results (Timonen et al., 2005). You should all be able to follow the links for this last article to a free PDF version.

Basically I think it'll be a few years before we have any real idea what's going on. This will all have to go with all the other models of depression (already a very complicated issue) but it is very interesting to say the least.

DrIndy

may I further cloud the issue by suggesting to you, John2, that insulin may not play a role in depression in diabetics, but that a diagnosis of diabetes causes depression?

ronbyrne2005

http://www.serendipity.li/dmt/eros.html

John

DrIndy wrote:

may I further cloud the issue by suggesting to you, John2, that insulin may not play a role in depression in diabetics, but that a diagnosis of diabetes causes depression?

Oh yes, it could very well be like that. And right now I'm too tired to make any sort of meaningful response to it. To be continued!