Some studies have revealed that the biological compounds in soy such as isoflavones and phyto-oestrogens are useful for health. The other researches which have studied certain aspects of phyto-oestrogens show that in some cases these compounds can be harmful.
The advantages of soy
Isoflavones which are also known as bioflavonoids are very beneficial for health:
1. They lower the raised blood cholesterol levels and prevent from heart disease. If you consume 25-50 grams of soy per day your LDL (“bad” cholesterol levels) will decrease by up to 10%.
2. Improve the prostate health and protect from prostate cancer. They act as oestrogen-like agonists and prevent testosterone from stimulating prostate tumour growth.
3. They reduce the risks of breast cancer. Also they are beneficial for increasing the length of the menstrual cycle which is necessary for protecting your body against breast cancer. Also in the predmenopausal period they are helpful in decreasing the levels of FSH (follicle stimulating hormone) and LH (luteinising hormone).
4. They are necessary for improving the menopausal symptoms and prevent from hot flushes and other negative symptoms.
5. The expansion of blood vessels is improved which is beneficial for avoiding the risks of heart failure, hypertension and narrowing of the arteries in diabetes and heart disease.
6. Increase the density of bones and protect against osteoporosis. Example: Asian women that follow diets rich in soy have lower incidence of osteoporosis as western women.
The disadvantages of soy
If you consume too much soy and get exceeding amount of phytochemicals it may lead to dangerous health problems.
1. It has been found that infants that consumed soy-based formulas have high levels of circulating phyto-oestrogens (13 000 to 22 000 times higher than would normally be the case). Such overexposure to phyto-oestrogens can create hormone imbalances and competition with enzymes that metabolise steroids, drugs and other biological compounds. It may also lead to problems with the future reproductive function of the person.
2. Today a working group of the Independent Scientific Committee on Toxicity in the UK tries to find out if the phyto-oestrogens in soy foods can have a bad influence on hypothyroidism.
3. Phyto-oestrogens in soy perform the actions of both oestrogen agonists and antagonists. They have the abilities to stimulate cells in the body sensitive to oestrogen or block the effect of oestrogen. However it hasn’t been proved that the consumption of soy and phyto-oestrogens is safe for women who already suffer from breast cancer, particularly those that have oestrogen-sensitive tumours.
It is useful to complement your diet with soy and products containing soy, for example you can take tempeh and bean curd, textured vegetable protein and soy protein foods. You are able to take these products regularly but you mustn’t go overboard.
People suffering from heart disease or vasoconstriction should consume 25g of soy protein per day. In order to decrease negative menopausal symptoms phyto-oestrogens can be taken by women who do not have a family or personal history of breast cancer.
People with hypothyroidism or oestrogen-dependent breast cancer shouldn’t take soy in large quantities and avoid phyto-oestrogensū