Soy and Disease

More and more the research on soy foods is showing that they may provide an important number of health benefits- heart disease, cancer, osteoporosis, menopause relief are a few.

Soy protein vs. animal protein and hyperlipidemia - people with very high cholesterol who switch to soy protein over beef and poultry lower their elevated levels of triglycerides and LDL (low density lipoproteins) and maintain their HDL.

Foods that contain 6.25 grams of soy protein per serving are allowed to make the claim that they reduce the risk for heart disease. In order to see any significant difference in cholesterol levels you would have to eat 25 grams/day or 4 daily servings of such foods.

Breast and Uterine Cancer- Asian women who consume soyfoods have a lower incidence of hormonal cancers than American women do.

Hot Flashes - Asian women seem to suffer less from hot flashes or other uncomfortable menopausal symptoms. (There is no term for "hot flashes" in Japanese)

Prostate Cancer- Asian men have a lower incidence of prostate cancer than American men do.

The magic of soy lies in the isoflavones or "phytoestrogens". These phytochemicals mimic the action of estrogen but are much weaker- this way you get the benefits without its harmful effects.

For example the phytoestrogens in soy attach to some the estrogen receptors in human breast tissue-blocking the entrance of human estrogen into breast cells. That's important because estrogen can encourage the growth of cancerous breast tumors. Likewise phytestrogens in men can block some of the effects of testosterone, which can hasten the progression of prostate cancer.

A word of caution for women with breast cancer or a family history- there are mixed reviews on soyfood and women with breast cancer or a family history. While it may protect in most women in this population it may promote carcinogenesis. For now eat soy in moderation and do not supplement (see Breast Cancer on this website under Diet and Disease).

Soy's cholesterol lowering properties seems to depend on a combination of soy protein and isoflavones. Looking at isoflavones alone there have been no cardiac benefits, the combination of both seems to do the trick. Some say 30 mgs/day of isoflavones/day and or 50-70 grams soy protein/week might be protective for the general population. For those at high risk for heart disease 110-140 grams of soy protein week might be protective. For those diagnosed with heart disease even higher 170-210 grams/ week is suggested.

The problem is that we can measure the grams of protein in most foods, but the isoflavones or phytoestrogens are more elusive and not usually listed. Listed below are some soyfood

Soy Food	Isoflavones (mgs)	Protein (gms)
Mature soybeans 1/2C	170	34
Soy nuts (rst soybeans) 1/2C	167	30
Green Soy Beans ½ C	70	21
Tempeh 4oz	61	19
TVP 1oz	57	26
Soy milk 8oz	20	10

See Protein under Macronutrients on this website for a description of some of the soyfood listed above.

Soy and Calcium

The calcium in fortified soy beverages is not as well absorbed as that in cow's milk.

In a recent study it was reported that the amount absorbed was typically 25% less than the amount absorbed from cow's milk. Researchers believe there are substances in soy that causes a partial absorption block. They think this shortcoming can be overcome if manufacturers add about 500-mg calcium per cup. Advice to the consumer is to drink more soymilk or supplement.

Soy foods: tofu, tempeh, soymilk appears to confer bone health. The amino acid composition of soy protects against calcium excretion. In addition, the isoflavones- phytochemicals in soy protect against bone breakdown. For more information on soyfood and your health in general log onto www.soyfoods.com

Donna Tinnerello, MS, RD, CD/N is a registered dietitian, living in Manhattan, with more than 10 years experience in HIV and nutrition. Her subspecialties are cardiovascular, renal, gastrointestinal disease, diabetes and weight management.
Donna is available for private consultation by referral only. Ms.Tinnerello has donated time and articles to our web site at always your choice and we sincerely appreciate her contributions.