by Megan Crockart
Soy beans are getting some bad press – there seems to be confusion whether they are healthy to eat or pose possible health concerns.
Soy beans have been around many years, the Chinese started farming them around 1100BC! In the 1940’s America’s soy farming took off. Soybean meal is the most widely used feed for livestock.
One of the main concerns with soy is whether it is genetically modified and there is a fair amount of soy that is genetically modified (especially in America). In the 1990’s there were scientific advances “improving” soy so that it could withstand herbicides sprayed directly on the plants without the herbicides killing the plants. This soy is not the type you want to eat and needs to be avoided. Choosing certified organic soy products is a must.
Another main concern surrounding soy is the fact that it is a “phyto-oestrogen”. It is given this name as it possesses a particular structural similarity to the oestrogen molecule which can allow the phyto-oestrogen to bind to oestrogen receptor sites. What does need to be emphasised is that there are two oestrogen receptors – oestrogen receptor alpha (ER-α) and oestrogen receptor beta (ER-β). ER-α and oestrogen is responsible for growth of hormone-sensitive tissues and is key in the female menstrual cycle and pregnancy. Over-activation of ER-α is related to hormonal cancers such as breast, endometrial and prostate as well as being related to osteoporosis.
Most phyto-oestrogens, especially isoflavones, bind to and activate ER-β rather than ER-α which can give oppositional effects and can have a balancing effect. Therefore activating ER-β with soy isoflavones protects tissues from excessive oestrogenic effects. These positive effects can be reduced menopausal symptoms, decreased risk of developing breast and endometrial cancers, beneficial changes to bone density and can help reduce cholesterol and other cardiovascular risks.
There are over 2,000 soy-related papers published annually and most studies show that there are health benefits for humans consuming soy foods. Majority of the negative information on soy has been those conducted on mice. Some studies involve injecting high amounts of the isoflavones into mice that you would never be able to obtain through food. How soy isoflavones impact your body also has a lot to do with human digestion, which can’t be compared with mice studies who digest soy differently from humans.
There is also evidence of Asian cultures having lower rates of breast cancer and menopausal symptoms than the western world attributable to their soy intake.
Did you know linseeds are also high in phyto-oestrogens. They are safe to consume.
Soy protein is a complete protein (similar to meat). Soy is high in fibre, low saturated fat, high in vitamins E, B6, calcium and lecithin. Fermented soy products such as miso, tempeh and fermented tofu have more nutrients and are the best forms of soy to eat – making sure they are organic.
If in doubt, leave soy out, but I feel there is more proof that soy has health benefits than detriments!
*References available upon request
Megan will follow on with this topic in her next article addressing the manufacture of soy products and whether this may be of concern to consumers. Stay tuned…
Megan Crockart is a qualified nutritionist who specilises in digestive problems, food allergy and intolerances – preparing individualised eating plans.
by Megan Crockart