Glycine max, Isoflavones
- Indications with possible efficacy:
- Indications with possible, but poorly documented efficacy :
Hot flashes related to menopause (popular use)
- Other indications with no proof of efficacy:
Breast cancer prevention
Cyclical breast pain
Prostate cancer prevention
- Risk of Drug Interactions: Low
- Adverse Effects: Not Frequent
Part of the plant used: beans
Soy is a legume cultivated in most parts of the world. In fact, it is one of the most cultivated plants in the world. Soy is an important source of plant protein, and plays a more and more important role in the human diet. Tofu, tempeh, soy milk and beans are some of the main dietary sources of soy. The protein content of various soy products can considerably vary.
Soy contains several active compounds: choline, lecithin and isoflavones. Soy proteins should be used preferably, because soy extracts do not appear to be very effective. One gram of soy protein contains 1 to 3 mg of isoflavones. Those isoflavones are considered phytoestrogens.
Direction of use
Replacing animal protein by soy protein in one's diet may lower total cholesterol, "bad" cholesterol and triglyceride levels in people with hypercholesterolemia.
Recommended intake: 20 to 50 grams daily of soy protein
- Breast cancer prevention:
Eating soy protein during childhood and teenage years may lower the risk of breast cancer later in life.
- Hot flashes related to menopause:
May reduce the frequency and intensity of hot flashes related to menopause. A 2-week period may be necessary before noticing the beneficial effects.
Recommended intake: 20 to 60 g of soy proteins (providing 34 to 76 mg of isoflavones) daily
May lower the risk of osteoporosis in menopausal women. A 6-month period may be necessary before noticing the beneficial effects.
Recommended intake: 40 g of isoflavone-rich (2-2,5 mg/g) soy protein
Amount of isoflavones found in food:
250 ml of soy beverage - 20 mg
50 g of roasted soy beans - 64 mg
There is insufficient reliable information to conclude that this plant is effective in any other indication.
- Side effects
Soy sometimes causes constipation, bloating and nausea.
It is contraindicated if you have a history of breast cancer and use it with caution if you have kidney stones. People with allergic rhinitis, asthma, and cow milk allergies are more at risk of being allergic to soy. Soymilk is contraindicated in children with cystic fibrosis.
- Pregnancy and breastfeeding
Dietary amounts of soy are safe during pregnancy and while breast-feeding. However, pregnant women should not eat large amounts of soy proteins.
Soy can reduce the effects of tamoxifen and hormone replacement therapy. It can however increase the effects of oral anticoagulant such as CoumadinTM. The risk of bleeding could increase. Before taking flaxseeds, check with your pharmacist to make sure that there are no interactions with your regular medication.
- Seventy percent (70%) of the soy produced in the United-States was genetically modified.
In 2004, Canada adopted new regulations that control the manufacturing, packaging, labeling and importing of natural health products. The new regulations also include an adverse reaction reporting system. Products that conform to the regulation's criteria are identified with a natural product number (NPN) and can be legally sold in Canada. This number indicates that the product meets specific criteria for safety and purity, not that it is effective for any indication.
Medicinal plant contents vary naturally from plant to plant - just as fruits from the same package may vary in taste and texture. There is no standard to measure the active content of each plant. Thus, efficacy of natural products should be expected to vary from brand to brand as well as from bottle to bottle of the same brand.
For more information about the Natural Health Products Regulations, or to check if a product has been assessed, visit the Health Canada website at www.hc-sc.gc.ca/dhp-mps/prodnatur/index-eng.php.
- Natural Medicines Comprehensive Database, 3rd edition, Therapeutic Research Faculty, 2010
- Passeportsanté.net. Protéines et isoflavones de soya. www.passeportsante.net
- Kotecha N. and Lockwood B. Soy - relieving the symptoms of menopause and fighting osteoporosis. The Pharmaceutical Journal, 15 October 2005
- Natural Therapeutics Pocket Guide, 2000-2001
- The Review of Natural Products, 6th Edition, 2010
- Health Canada, Natural Products Database
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The patient information leaflets are provided by Vigilance Santé Inc. This content is for information purposes only and does not in any manner whatsoever replace the opinion or advice of your health care professional. Always consult a health care professional before making a decision about your medication or treatment.