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I soy.

  • 10-07-2019 11:14am
    Registered Users Posts: 4,497 ✭✭✭

    There is significant evidence that eating moderate amounts (one to two servings per day) of traditional soy foods, whether fermented or not, can reduce the risk of prostate cancer and can lower LDL cholesterol.

    Everyone who eats soy should make sure they are getting enough iodine.

    Many clinical studies have found that soy increases cognition.

    A 2009 meta-analysis on soy and prostate cancer found that soy, in the highest versus lowest intake categories, was associated with a statistically significant, 26% reduction in prostate cancer risk.

    A 2009 paper from the 8th International Symposium on the Role of Soy in Health Promotion and Chronic Disease Prevention and Treatment reported that soy isoflavone supplements containing at least 15 mg of genistein per day have been consistently effective at reducing hot flashes.

    The vast majority of the evidence is that soy is either neutral or protective against breast cancer, including for women previously diagnosed with estrogen receptor positive breast cancer (tumors stimulated by estrogen contact). This evidence is mostly limited to amounts of two servings per day or less.

    There is growing evidence that eating traditional soy foods such as tofu, tempeh, edamame, miso, and soymilk may lower the risk of breast cancer, especially among Asian women. Soy foods are excellent sources of protein, especially when they replace other, less healthy foods such as animal fats and red or processed meats. Soy foods have been linked to lower rates of heart disease and may even help lower cholesterol.
    Women in the top one-third of soy intake during childhood, adolescence, and adulthood had a lower risk of breast cancer than those in the lowest one-third, with the strongest, most consistent effect being for childhood intake.

    The American Academy of Pediatrics and the National Toxicology Program considers soy formula safe for term infants.
    It is best to choose a soy formula with DHA. Soy-formula is not intended for pre-term infants.

     A longitudinal study found tempeh to be associated with improved cognition.
    The authors suggested that tempeh might be good for memory because the bacteria used in the tempeh starter, Rhizopus oligosporus, produce folate which is thought to protect memory.
    A cross-sectional study of 151 men and women (most from the previous report) over the age of 56. Both immediate and delayed recall were tested. Median and mean tempeh and tofu consumption was seven times a week, ranging from never to three times a day. Before adjusting for age, sex, and education, tempeh and tofu were associated with better immediate recall; after adjusting, the associations were no longer significant. In the group younger than 73 years, higher tofu consumption was significantly associated with better immediate recall even after the adjustments.
    In a 1993 study of California Seventh-day Adventists (SDA) ages 65 and over, those who hadn’t eaten meat in the previous 30 years were about one-third as likely to develop dementia as their regular meat-eating counterparts (58).

    There is little evidence to determine whether the hexane residues in some processed soy meats are safe over the long term, though hexane processing can be harmful to workers and the environment. It seems prudent to buy most of your processed soy from companies that do not use hexane extraction.
    Hexane is sometimes used by the soy industry to separate the oil from the protein in soybeans. The protein is then used for soy meats and other products that contain soy protein extract. This process inevitably leaves some hexane residues in the products.

    Luckily, there are soy meats available that do not use hexane such as Tofurky, Field Roast, Wildwood, Amy’s Kitchen, and some (though not all) Boca products (link). Foods certified as “USDA Organic” are produced without using hexane extraction.

    Three studies on adults (99, 100, 101) have shown calcium to be absorbed from soy at rates comparable to that of cow’s milk.
    A study from Victoria University (2010) found calcium absorption to be the same from fortified soymilk as from cow’s milk in post-menopausal women.

    There is a plethora of evidence that soy does not harm bones; including a cross-sectional study from the Chinese University of Hong Kong (2003) which found that women who ate the most soy (10 g/day of soy protein or more) had greater bone mineral density than those in the lower intake groups (104).

     Iron from plant foods is generally not absorbed as well as iron from meat. But a type of iron in soy, ferritin iron, is absorbed at about 30% among people with low iron stores, and this is a high rate of absorption. Ferritin iron makes up a large percentage of the iron found in soybeans; up to 90% (127). Some soy foods have a decent amount of iron, including extra firm tofu (3.35 mg per 1/2 cup), edamame (1.75 mg per 1/2 cup), and soy nuts (1.7 mg per 1/4 cup). There is no reason to worry that moderate amounts of soy might cause iron deficiency.

    Also note that adding vitamin C to a meal (in a dose of about 100 mg) has been shown to significantly increase absorption of the iron in plant foods in numerous studies. I found no studies on vitamin C’s effect on iron absorption from soy foods in adults, but two showed that it significantly increased iron absorption from soy formula in infants (114, 115).

    It requires twelve servings of soy (and probably much more for most men) to have any sort of noticeable feminizing effects. While one epidemiological study raised concerns about soy and sperm quantity (14), two clinical studies have shown no effects of soy on sperm quality or quantity (15, 126).

    A 2009 meta-analysis of five retrospective and two prospective studies found that participants with a higher soy intake (roughly one serving per day) had a reduced risk for endometrial cancer and ovarian cancer, when compared with lower soy intakes.


  • Registered Users Posts: 755 ✭✭✭davidjtaylor

    I decided to take a year off of any soy whatsoever, just to see what happens. I'm not allergic to it, I just like little experiments like this.

    I think - it's only a think, I didn't get tested - my iron levels dropped; general lethargy and lack of stamina set in. I've been borderline anaemic my entire life (even pre-vegetarian, before the 1990s) so in some ways it's not surprising. I now top up with FloraVital once or twice a week and feel that my iron levels are ok.

    BUT! the most surprising and annoying thing is not the difficulty with food variety but the sheer ubiquity of soy. I could wander round any shop and pick up any notionally vegan product and put it down again because of soy-this or soy-that. Why the feck is it so necessary in bread or chocolate?