Soy and Your Health
by Claudia Jones, Wellness Director, Samahita Retreat
One of the questions I get asked most often is, 'should I eat soy?' Naturally, people are concerned as soy has received so much media attention in recent years, both positive and negative. It has been promoted as the cure all for a number of health issues such as cardiovascular diseases, breast cancer, menopausal symptoms, even promoted as a wonder food for weight loss. At the same time it has been maligned as one of the causes of thyroid dysfunction, various cancers, immune issues in babies and so on. As with many foods, it would be fair to say that we don't yet know enough about it's actions on the body to take a clear line. So what should we do?
Let's first be clear on what soy is. Soy is a bean, composed of around 40% protein , 20% oil, 35% carbohydrate and 5% ash. So it's a high protein food and considered by some a complete protein as it contains all of the essential amino acids, hence it is very popular with vegetarians as a meat alternative. The soy bean is very versatile and can be prepared in a number of different ways for consumption, from the immature pod cooked and served with salt - edamame, to tofu and various fermented forms such a miso, tempeh and natto and dairy-like products such as soy milk, yogurt and cheese, imitation meat products made of textured vegetable protein (TVP) often used in soy burgers and of course soy sauce.
Since being promoted as a health food, it has also been marketed as a health supplement and added to some foods for its health benefits. This has raised concerns among some soy experts about overconsumption. Soy has been a component of the Asian diet for centuries, in forms such as tofu, tempeh and miso and it is believed that soy bean foods had health giving properties, including a lowering of breast cancer risk (incidence is lower in these countires), however, the amounts consumed in a average Asian diet are small, and soy products are not eaten as a primary source of protein. The western diet, particularly for vegetarians may be considerably higher in soy intake, with people consuming up to three times more soy products than in a typical Asian diet. Eaten in these amounts, It is possible that overconsumption may be contributing to health problems.
Another factor to consider is the genetic engineering of soy which may be to blame for the bad press soy has received. Again, the Asian diet has typically included non-GM soy foods, whereas most of the soy eaten is the US for example has been genetically modified. Eating soy from the right source is important, always choose organic and non-GM.
What the research says
There is some evidence to suggest that consumption of soy products may reduce the risk of breast cancer in women and prostate cancer in men as well as other types of cancers. It may also help as a treatment for menopause, osteoporosis and cardiovascular disease by reducing cholesterol levels, however, the supportive evidence that soy can help with any of these issues is limited.
On the negative side, soy may have an anti-thyroid action contributing to hypothyroidism, however, some researchers say that it is more likely that soy products interfere with the medication used to treat this condition. Over consumption of isoflavones, the phytoestrogens found in soy that are thought to reduce the incidence of breast cancer may actually contribute to the onset of the disease in those at high risk, including post-menopausal women.
There is not yet enough evidence to recommend soy for use as part of a weight reduction program.
Despite hundreds of studies on soy consumption and its effects on our health, meta-analysis (which compiles the results of numerous studies and examines the quality of the trials and the validity of the results ) shows that there is a lack of evidence to clearly support suggestions that soy has strong beneficial or detrimental effects on health. Although there are many individual papers that support both the health benefit claims as well evidence that supports the negative health effects meta-analysis shows that many of the research papers on soy and its effects on health do not stand up to rigorous scrutiny, and for those that do, the proof is marginal.
So, should we eat soy or not?
- From the research to date it would seem that soy can be a nutritious component of a healthy diet consisting mainly of whole foods. However, as with any food, it is important to eat it in moderation.
- Those at high risk from breast cancer or with thyroid issues should probably avoid its intake.
- Soy is also an allergy triggering food, causing reactions such as acne, swelling, blocked nose, diarrhea, stomach pains, heart palpitations and itching among others, so anyone who experiences this type of reaction after eating soy products should also avoid it.
- Some people find soy hard to digest; soy contains the sugars raffinose and stachyose which cause gas and discomfort in some people, for this reason, eating the food in its fermented form could be easier on the system.
- If you are vegetarian, soy products can be a good source of complete protein, however, it should only form part of a varied diet which should be rich in fresh fruits and vegetables, whole grains, nuts, seeds and legumes.
Claudia is the Wellness Director at Samahita Retreat. Claudia offers support and advice to guests on our detox programs and teaches detox & wellness retreats at Samahita Retreat throughout the year.
References and Resources
1. Meta-Analysis of the Effects of Soy Protein Intake on Serum Lipids
James W. Anderson, M.D., Bryan M. Johnstone, Ph.D., and Margaret E. Cook-Newell, M.S., R.D.
N Engl J Med 1995; 333:276-282 August 3, 1995
2. Meta-Analysis of Soy Intake and Breast Cancer Risk
Bruce J. Trock, Leena Hilakivi-Clarke and Robert Clarke
3. The Cochrane Collaboration -
4. The Cochrane Library -