The soya bean has been part of the human diet for thousands of years and, thanks to a protein profile nutritionally equivalent to meat, it has made its way into the spotlight as a suitable alternative. Soya was considered by the Ancient Chinese to be one of the five sacred grains vital for life (alongside rice, wheat, barley and millet), but it is still met with its fair share of controversy.
So, what is the verdict? Is soya a suitable meat replacement, are there dangers of long-term soya intake, and what do the experts have to say on the issue? Fry’s Vegetarian Foods has long been hailed as SA’s best producer of tasty soya alternatives to meat, and when putting this question to them I was of course hoping for a positive outcome – I’m not ready to part with my delicious faux-chicken nuggets just yet!
Dietitian Caryn Davies gives us the run-down:
(Please note that I’ve summarised her text for easy reading, and you are welcome to read the full article here.)
First we need to acknowledge different sources of soya and, therefore, their different potential health implications. Genetic modification of agricultural soya (much of our SA soya options) has been associated with negative health and environmental consequences. This, however, is not true for soya that has been naturally farmed.
Finding valid research
The next point is identifying which sources of information (both for or against soya) are valuable and credible. It is often unfounded claims that cement themselves in the minds of readers, inaccurately portraying different foods and their properties. which makes research so complex, is that not all sources of information are equally credible. There are also areas in which different studies (on the same topic) give conflicting results, as well as areas where not enough research has been done to provide reliable answers.
We’ve looked at position statements of the American Dietetic Association, the FDA, and the US National Library of Medicine (amongst other sources) to gather our research.
Soya health benefits
Soya is suggested to benefit: heart disease, reduction of menopausal symptoms, prevention of hormone dependent cancers (breast, prostate and endometrial) and bone health. It contains healthy phytochemicals (plant compounds) called isoflavones. There are various types of isoflavones, but two specifically (genistein and diadzen) have been studied closely and found to be very similar in structure to the hormone oestrogen, which thus mimic the activities of oestrogen in the body.
These so-called ‘plant hormones’ are much weaker than true hormones, yet seem to have a positive influence on oestrogen balancing in the body and lowering LDL cholesterol. Phytoestrogens found in soya foods also act as antioxidants, carcinogen blockers or tumor suppressors and may exert a protective effect against hormone related cancers by binding at oestrogen receptor sites. Further studies suggest that plant based estrogens may reduce the incidence of vasomotor symptoms (hot flashes) of menopause and lastly that they may protect women against osteoporosis by the action of genestein, which stimulates osteoblasts (bone forming cells).
Exploring side effects
As long as you are choosing good quality soya products, that have not been genetically modified, there is very little reason to avoid soya with the obvious exception being soya allergy.
There have been references to limiting soya in order to combat gout. All protein foods contain substances called purines, which yield uric acid as a by-product of metabolism, and could thus supposedly aggravate acid build up and the symptoms of gout. However, avoiding soya would warrant avoiding meat protein, which is usually higher in purine. It is also worth noting that improvements in the efficacy of gout medication have largely replaced the need for rigid dietary restriction of purines in recent times.
There is a big difference between soya based foods and soya supplements, which contain a much higher concentration of isoflavones, and unfortunately there is not enough accurate scientific evidence to support the use of soya supplements. As with many healthful nutritional ingredients, more is not necessarily better – a balanced diet remains the professional prescription for optimal health.
The only specific recommendation available is from the FDA, which advises 25g soya protein per day for adults to potentially reduce the risk of heart disease.
Caryn Davies RD(SA)
So, no need to turf out those faux-chicken nuggets then! Want to learn more? Here are additional articles that offer sound research promoting soya.
Doctor addresses misinformation on soy – http://freefromharm.org/health-nutrition/vegan-doctor-addresses-soy-myths-and-misinformation/
American Institute for Cancer Research’s position on soya – http://www.aicr.org/foods-that-fight-cancer/soy.html
Harvard School of Public Health – Straight talk about soya – http://www.hsph.harvard.edu/nutritionsource/2014/02/12/straight-talk-about-soy/