Soya

Jun 14, 20153 min read

Alternative names/Derivatives

Edamame - immature soya beans
Tofu - curdled soya milk (soak beans, grind, boil and strain)
Miso – soya beans fermented with fungus Aspergillus oryzae & salt
Soy sauce - liquid derivative from making miso
Vegetable oil

It is estimated that in excess of 70% of supermarket food contains soya and most fast food outlets use it. Soya is fibrous, therefore bulking out foods. It is cheap. The oil it produces is the most consumed vegetable oil in the world. Soya oil acts as a great emulsifier (binding water with fat) for baking products. 90% of the 200 milion tonnes of soya produced around the world each year is fed to animals.

What are the benefits and concerns relating to soya, as expressed by the media over the years?

I have listed the main pros and cons below under the headings “Benefits of Soya” & “Concerns Relating to Soya”, as expresses by the media (e.g. http://www.theguardian.com/lifeandstyle/2004/nov/07/foodanddrink.features7). This does not mean that these have been verified. In fact, when experts in their field compare all the studies, & remove the ones that are not valid, outdated or unsubstantiated, you get a more balanced and up-to-date view. This is exactly what David Tchilingirian & Deborah Norman have done and I have provided extracts from their findings (below) for you to read.

David Tchilingirian BSc hons. Registered public health nutritionist working for NHS & local government, delivering public health nutrition interventions & policy
Deborah Norman Bsc hons pgdip, registered dietician. Worked for NHS in clinical, public health for >20yrs.t is articles such as the following that brings these concerns and benefits to the public attention:

Benefits of Soya

May assist memory in later life
May assist recovery of patients with breast cancer
May reduce occurrence of breast cancer in pre-menopausal women – Shanghai Women’s Health Study (2)
May help reduction in LDL (bad) cholesterol and therefore reducing the risk of coronary heart disease – claim by US Food and Drug Administration in 2003 (3) & British Food Standards Agency. Reviewed and seen as having less of an impact on heart health (4)
May assist in maintaining bone density and reducing fractures in post-menopausal women with osteoporosis. Sharif et al (2009)
May reduce menopausal symptoms

Concerns relating to soya

May cause negative effect on Thyroid gland
May promote memory loss in later life, due to introducing higher levels of oestrogen into females as their natural levels drop. Based on study written up in 2009 concerning women with Japanese ancestry living in Hawaii. (1)
Eaten by men may reduce sperm activity
Eaten by women during pregnancy may result in abnormal brain and reproductive tract development in foetus
Drunk by babies may increase oestrogen levels sufficient to cause harm
Phyto oestrogens in soya may increase breast cancer risk in healthy women
Deforestation in favour of soya plantations in Argentina (and to lesser extent Brazil, Paraguay & Bolivia) if continued at current rate may leave Argentina completely bereft of forest in just 5 years.
In order to have cholesterol reducing effects 25-50g of soya would need to be eaten daily (i.e. 4-8 large glasses of soya milk daily!), which may induce the oestrogen related problems above.

Findings Consolidated by David Tchilingirian & Deborah Norman in 2011

Menopause

Cholesterol

Cancer

Bone Strength in Osteoporosis

References

1. White, L.R., et al., Brain aging and midlife tofu consumption. J Am Coll Nutr, 2000. 19(2): p. 242-55

2. Lee, S.A., et al., Adolescent and adult soy food intake and breast cancer risk: results from the Shanghai Women’s Health Study. Am J Clin Nutr, 2009. 89(6): p. 1920-6

3. Code of Federal Regulations. Health claims: Soy protein and risk of coronary heart disease. 21CFR101.82. 2001.

4. Sacks, F.M., et al., Soy protein, isoflavones, and cardiovascular health: an American Heart Association Science Advisory for professionals from the Nutrition Committee. Circulation, 2006. 113(7): p. 1034-44.