The benefits of soy

The soybean is a legume.  A staple in Asian diets for centuries, soy foods include traditional Asian foods like soy milk, tofu, tempeh and miso.

Interest in the health benefits of soy first emerged when scientists observed that Asian populations consuming their traditional diets have much lower rates of heart disease and some cancers compared to people in Western populations.

With all the research and knowledge on soy’s health benefits, there are now even more soy foods for us to choose from, like yoghurts, cheese, breads, breakfast cereals and meat alternatives like burger patties, soy sausages and sandwich slices.

Why is soy so nutritious?

High quality protein

Protein helps to support the growth and repair of your body’s cells. Amino acids are the building blocks of protein and while your body can make some of them, there are nine amino acids that need to come from your diet. Soy protein contains all of the nine essential amino acids and is therefore called a high quality protein.

High in fibre

Like all legumes, soy beans are high in fibre. In fact, just a cup (200g) of cooked soy beans has more than 14 grams of fibre, which is half the recommended daily intake!

Protective phytoestrogens

Phytoestrogens are natural occurring substances found in plant foods. Different types of phytoestrogens are found in wholegrains, vegetables, legumes, fruits, nuts and seeds.

While phytoestrogen molecules are similar in shape and size to the human body’s oestrogen, they're not the same and act differently in the body. The benefits of phytoestrogens include:

  • important antioxidant and anti-inflammatory properties
  • mimicing some of the positive effects of oestrogens, like reducing cholesterol and hot flushes
  • acting in opposition to the harmful effects of oestrogen like increasing heart disease risk and weight gain.

The main type of phytoestrogens found in soy are isoflavones. It's the isoflavones in soy that give soy foods their many protective health benefits.

The health benefits of soy

Soy foods are a great choice for good health. The body of scientific evidence from many thousands of research papers suggests many health protective benefits of consuming soy beans and soy foods.

Soy for healthy hearts

Soy foods are great for protecting your heart.

The soy protein, fibre and isoflavones present in soybeans can help to:

  • lower your blood cholesterol

  • lower your blood pressure

  • help to keep your blood vessels flexible as you age.

Did you know?
Research shows that soy protein can lower LDL or ‘bad’ cholesterol by 5.5%.

Soy can protect against cancer

Research shows that soy can protect against cancers of the breast, prostate and bowel. In fact, recent studies have shown that women who have between 1-1½ servings of soy a day when they were children and adolescents can reduce their risk of breast cancer later in life by up to 60%.

For women who have breast cancer, research shows that those with the highest isoflavone intake from soy foods had a 17% lower risk of death and were 25% less likely to have their breast cancer return than women who did not eat soy foods.

Soy relieves the symptoms of menopause

For women in Asian countries who regularly eat soy as part of their traditional diets, hot flushes are rare.  A review of studies in this area has shown that the isoflavones in soy can help to reduce the frequency and severity of hot flushes by more than 20%. In fact, soy beans and tofu are recommended by the North American Menopause Society to help reduce menopausal symptoms.

Soy for healthy bones

While more research is needed in this area, there's evidence that the isoflavones in soy foods may help to strengthen bones by increasing bone formation and mineral density.

How much should I consume?

While traditional Asian cultures include up to three serves of soy foods each day, if you include just one serve a day you can obtain nutritional and health benefits.

One serving of soy is:

  • one cup of soy milk

  • one cup of cooked soy beans, or

  • 170 g tofu.

Tips to include more soy

One of the easiest ways to include more soy in your diet is to swap dairy milk with soy milk. Along with its important isoflavones, a calcium-enriched soy beverage provides you with as much calcium as regular dairy milk but with no cholesterol, animal fat or lactose.

Along with the simple milk swap, soy yoghurts, breads and cereals are all great ways to boost your soy intake.

You could also try:

  • Soy beans - in soups, pasta sauces or stews

  • Edamame - soybeans in their pod that you can enjoy warm or tossed through a salad

  • Tofu – try it firm, smoked or marinated in stir-fries, curries or on the BBQ

  • Tempeh – slice and grill, barbeque or panfry and add to stir-fries or salads

  • Miso –  add to soups, sauces and marinades in place of regular stock

  • Soy-nuts – a tasty snack of roasted soy beans

  • Soy burgers, sausages and slices - a great meat alternative that is tasty, low saturated fat

  • TVP – also known as textured vegetable protein, can be used as an alternative to mince in pasta sauces or casseroles

For more information on soy and its benefits, go to The Facts About Soy website.

References

  1. Michelfelder AJ. Soy: a complete source of protein. Am Fam Physician 2009;79(1):43-47.

  2. Anderson JW, Baird P, Davis RH, et al. Health benefits of dietary fiber. Nutr Rev 2009;67(4):188-205.

  3. Dietitians Association of Australia. Fibre. [Internet] 2016 [cited 2016 June 21]; available from: http://daa.asn.au/for-the-public/smart-eating-for-you/nutrition-a-z/fibre/

  4. Sirotkin AV, Harrath AH. Phytoestrogens and their effects. Euro J Pharmacology 2014;741:230-236.

  5. Messina M, Messina VL. Exploring the soyfood controversy. Food Nutr 2013;48(2):68-75.

  6. Anderson JW, Bush HM. Soy protein effects on serum lipoproteins: a quality assessment and meta-analysis of randomised, controlled studies. J Am Col Nutr 2011;30(2):79-91.

  7. Van Die D, Bone KM, Williams SG, and Pirotta MV. Soy and soy isoflavones in prostate cancer: a systematic review and meta-analysis of randomised controlled trials. BJU International 2014;113(5b):E119-E130.

  8. Tse G, Eslick GD. Soy and isoflavone consumption and risk of gastrointestinal cancer: a systematic review and meta-analysis. Eur J Nutr 2016;55(1):63-73.

  9. Rock CL, Doyle C, Demark-Wahnefried W, et al. Nutrition and physical activity guidelines for cancer survivors. Cancer J Clin 2012;62(4):242-274.

  10. Nechuta SJ, Caan BJ, Chen WY, et al. Soy food intake after diagnosis of breast cancer and survival: an in-depth analysis of combined evidence from cohort studies of US and Chinese women. Am J Clin Nutr 2012;96:123-132.

  11. Taku K, Melby MK, Kronenberg F, et al. Extracted or synthesized soybean isoflavones reduce menopausal hot flash frequency and severity: a systematic review and meta-analysis of randomised controlled trials. Menopause 2012;19(7):776-790.

  12. The North American Menopause Society. Integrative medicine. [Internet] 2016 [cited 2016 June 20]; available from: http://www.menopause.org/publications/clinical-care-recommendations/chapter-6-complementary-and-alternative-medicine

  13. Lanou AJ. Soy foods: are they useful for optimal bone health? Ther Adv Musculoskel Dis 2011;3(6):293-300.

  14. Academy of Nutrition and Dietetics. Vegetarian Nutrition. Safety of soyfoods. [Internet] 2012 [cited 2016 June 20]; available from: http://vegetariannutrition.net/docs/Soy-Safety.pdf

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