Soy

Parts used

Bean

Main constituents

• Proteins; oil: mixture of monounsaturated and polyunsaturated fatty acids (linolenic, linoleic, oleic, stearic, and palmitic acids); lecithin (mixture of phospholipids); phytoestrogens: isoflavones (daidzein, genistein, glycitein), and coumestrol.

Major therapeutic interest

• Reducing bad blood cholesterol (LDL) levels (proteins, isoflavones);
• Alleviating vasomotor symptoms associated with menopause: hot flashes, heavy perspiration, night sweats (isoflavones);
• Preventing osteoporosis (proteins, isoflavones).

Other therapeutic interest / Traditional Use

• Reducing the risk of developing prostate cancer (protein);
• Reducing the risk of developing thyroid cancer (protein);
• Reducing blood pressure (protein);
• Improving cognitive functions, treating memory disorders (phospholipids);
• Helping protect against kidney disease in diabetic subjects (protein);
• Used in parenteral nutrition (phospholipids).

Cons-indications

• Soy protein allergies;
• Caution in cases of allergic rhinitis (hay fever) and asthma;
• People suffering from urolithiasis;
• In children who are allergic to cow’s milk, soy is not recommended as an alternative, because it may lead to sensitivity to soy protein.

As a supplement

It should be noted that moderate consumption of various soy products as part of a normal diet is safe for these groups.

• Breast cancer, ovarian cancer, and endometrial cancer, or if there is a history of hormone-dependent cancer in close relatives. Soy phytoestrogens may directly stimulate the growth of estrogen-dependent tumors. With high doses over a prolonged period (over 150 mg of isoflavones a day for several years), there is a risk of developing endometrial hyperplasia;
• Pregnancy;
• Breastfeeding: Safety has not yet been established;
• Hypothyroidism: Soy isoflavones may inhibit thyroid hormone synthesis.

Important Notice

• Phytoestrogen and cancer research findings are sometimes contradictory. The preventive effects of soy are therefore considered hypothetical at present. Discussions are currently underway to determine the recommended quantity, source, and duration of use. The FDA recommendation is 25 to 50 grams of soy protein a day from food. The American Nutraceutical Association recommends a daily dietary intake of 50 mg of isoflavones. As a reference, 21 grams of soy flour contains 44 mg, 100 grams of tofu contains 22 to 30 mg, 250 ml of soy milk contains 20 mg, and 50 grams of roasted soybeans contain 64 mg of isoflavones.

Drug Interactions

Known human interactions

• With Coumadin, heightens risk of bleeding.

Suspected interactions

• With antibiotics, may reduce the beneficial effects of isoflavones;
• May reduce the effect of hormone replacement therapy (Premarine, Evista, etc.) and tamoxifen (Tamofen).

Other names

Glycine max