Soy

Common Name(s)

soy

Scientific Name(s)

Glycine max

General Information

Soy, a plant in the pea family, has been common in Asian diets for thousands of years. It is found in modern American diets as a food or food additive. Soybeans, the high-protein seeds of the soy plant, contain isoflavones – compounds similar to the female hormone estrogen. The following information highlights what is known about soy when used by adults for health purposes.

How is this product usually used?

Soy is available in dietary supplements, in forms such as tablets and capsules. Soy supplements may contain isoflavones or soy protein or both.

Soybeans can be cooked and eaten or used to make tofu, soy milk, and other foods. Also, soy is sometimes used as an additive in various processed foods, including baked goods, cheese, and pasta.

Your health care provider may have recommended this product for other conditions. Contact a health care provider if you have questions.

What is this product used for?

People use soy products as traditional or folk remedies to prevent or treat menopausal symptoms (such as hot flashes and/or night sweats) or prevent osteoporosis when taken with an adequate dose of calcium and vitamin D.

Soy products should be taken for at least 2 weeks for treating menopausal symptoms or at least 6 months for preventing osteoporosis. Consult your health care provider if you plan to take soy products for longer than 1 year.

Your health care provider may have recommended this product for other conditions. Contact a health care provider if you have questions.

What else should I be aware of?

There is limited evidence to support the use of soy protein for:

• increasing muscle strength
• preventing breast cancer
• reducing blood pressure
• reducing cholesterol levels
• reducing hot flashes related to menopause
• reducing the risk of osteoporosis in post-menopausal people
• reducing the risk of type 2 diabetes
• reducing urine protein in those who have chronic kidney disease
• treating diarrhea in infants

There is not enough scientific evidence to determine whether soy supplements are effective for any other health uses.

Soy is considered safe for most people when used as a food or when taken for short periods as a dietary supplement.

Minor stomach and bowel problems such as nausea, bloating, diarrhea, and constipation are possible.

Allergic reactions such as breathing problems and rash can occur in rare cases.

Soy products may interact with the following medications:

• anticoagulants (e.g., apixaban, warfarin)
• antiplatelets (e.g., acetylsalicylic acid (ASA), clopidogrel)
• blood-pressure lowering medications (e.g., amlodipine, ramipril)
• diabetes medications (e.g., metformin, sitagliptin)
• caffeine
• diuretics (e.g., furosemide, hydrochlorothiazide)
• estrogens
• monoamine oxidase inhibitors (e.g., phenelzine, selegiline)
• progesterone
• tamoxifen
• thyroid hormone replacements (e.g., levothyroxine)

Avoid taking soy products if you have a history of breast cancer or a family history of it. If you are taking soy products and are experiencing breast pain, discomfort or tenderness, or are experiencing spotting, let your health care provider know.

If you develop any signs of liver damage such as abdominal pain, yellowing of the skin or eyes, or darkening of the urine, let your health care provider know.

Ask your doctor before taking soy products if you have:

• a history of bladder cancer
• a history of hormone related disorders such as ovarian cancer, endometriosis, or uterine fibroids
• a history of kidney problems such as kidney failure or kidney stones
• a history of liver problems
• an allergy to milk products
• an allergy to soy or other products in the Fabaceae family (e.g., peanuts, soybeans)
• low thyroid hormone levels

Before taking any new medications, including natural health products, speak to your physician, pharmacist, or other health care provider. Tell your health care provider about any natural health products you may be taking.

Source(s)

1. Health Canada. Natural Health Product Ingredients Database. Monograph: Soybean Extracts and Isolates. Available at: https://webprod.hc-sc.gc.ca/nhpid-bdipsn/atReq.do?atid=soy_extra_isolate&lang=eng.
2. Natural Medicines Comprehensive Database. Soy.