Home

Soya research

Read the scientific evidence for yourself...
We cannot reproduce the full text of these studies but we do provide concluding or relevant comments.

Soya isoflavones attenuated (reduced) bone loss from the lumbar spine in perimenopausal women. The perimenopuase is the time period before the menopause and may begin up to six years before the menopause.
Alekel, D.L., St Germain, A., Peterson, C.T., Hanson, K.B., Stewart, J.W. and
Toshiya, T. 2000. Isoflavone-rich soy protein isolate attenuates bone loss in the lumbar spine of perimenopausal women. American Journal of Clinical Nutrition. 72, 844-852.   

Soya protein isolate added daily to the diet substantially reduced the frequency of menopausal hot flushes.
Albertazzi, P., Pansini, F., Bonaccorsi, G., Zanotti, L., Forini, E. and De
Aloysio, D. 1998. The effect of dietary soy supplementation on hot flushes. Obstetrics and Gynecology. 91 (1) 6-11.

The consumption of soya protein, rather than animal protein, significantly decreased blood levels of total cholesterol and LDL (‘bad') cholesterol without affecting blood levels of HDL (‘good') cholesterol.
Anderson, J.W., Johnstone, B.M. and Cook-Newell, M.E. 1995. Metaanalysis of the effects of soy protein intake on serum lipids. New England Journal of Medicine. 333, 276-282.

12 weeks' partial substitution of omnivorous postmenopausal women with phytoestrogen-rich foods (tofu, soya milk, miso and flax seeds) increased their blood levels of sex hormone-binding globulin (a protein that binds oestrogen) and so may alleviate menopausal symptoms such as hot flushes.  
Brzezinski, A., Adlercreutz, H., Shaoul, R., Rösler, A., Shmueli, A., Tanos V. and Schenker J.G. 1997. Short-term effects of phytoestrogen-rich diet on postmenopausal women. Menopause. 4, 89-94.

The exposure of vegetarians to phytoestrogens is comparable to that of the general population.  
Clarke, D.B., Barnes, K.A., Castle, L., Rose, M., Wilson, L.A., Baxter, M.J.,
Price, K.R. and DuPont, M.S. 2003. Levels of phytoestrogens, inorganic trace-elements, natural toxicants and nitrate in vegetarian duplicate diets. Food Chemistry. 81 (2) 287-300.

The oestrogenic potency of a range of compounds (including synthetic oestrogens and phytoestrogens) was measured. Synthetic oestrogens were among the most potent comparable with oestrogen while the phytoestrogens were several orders of magnitude less potent than oestrogen.  
Coldham, N.G., Dave M., Sivapathasundaram S., McDonnell D.P., Connor C. and Sauer M.J. 1997. Evaluation of a recombinant yeast cell estrogen screening assay. Environmental Health Perspectives. 105 (7) 734-742.

The Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT) reported that only one single study has specifically examined the long-term health effects of soya-based infant formula feeding on sexual development and fertility in humans. The Working Group of COT considered that these data do not provide definite evidence for adverse clinical effects on sexual development or reproductive health.
 COT, 2003. Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment. Phytoestrogens and Health. London: The Food Standards Agency, FSA/0826/0503.

Significant cognitive improvements in postmenopausal women were gained from 12 weeks of consumption of a supplement containing soya isoflavones.
Duffy, R., Wiseman, H. and File, S.E. 2003. Improved cognitive function in postmenopausal women after 12 weeks of consumption of a soya extract containing isoflavones. Pharmacology Biochemistry and Behaviour. 75 (3) 721-729.

Soya isoflavone extracts may help to reduce the frequency of hot flushes in climacteric (menopausal) women and provide an attractive addition to the choices available for the relief of hot flushes.
Faure, E.D., Chantre, P. and Mares, P. 2002. Effects of a standardized soy extract on hot flushes: a multicentre, double-blind, randomized, placebo-controlled study. Menopause. 9 (5) 329-334.

Significant cognitive improvements can arise from a high soya diet.
File, S.E., Jarrett, N., Fluck, E., Duffy, R., Casey, K. and Wiseman, H. 2001.
Eating soya improves human memory. Psychopharmacology (Berl). 157 (4)
430-436.

Six weeks of treatment with a soya supplement produced significantly better performance in the two tests of frontal lobe function, those of mental flexibility and of planning ability.  
File, S.E., Hartley, D.E., Elsabagh, S., Duffy, R. and Wiseman, H. 2005. Cognitive improvement after 6 weeks of soy supplements in postmenopausal women is limited to frontal lobe function. Menopause. 12 (2) 193-201.

Increased consumption of animal-derived food (meat and dairy) may have adverse effects on the development of hormone-dependent cancers.  We are most concerned with milk and dairy products, because the milk we drink today is produced from pregnant cows, in which oestrogen and progesterone levels are markedly elevated.
Ganmaa, D. and Sato, A. 2005. The possible role of female sex hormones in milk from pregnant cows in the development of breast, ovarian and corpus uteri cancers. Medical Hypotheses. 65 (6) 1028-1037.

Most (80 per cent) of the world's soya production is fed to the livestock industry. Increasing demand for soya animal feed is driving the expansion of agriculture into the Amazon rainforest. Europe buys half the soya exported from the Amazon state of Mato Grosso, where 90 per cent of rainforest soya is grown. Meat reared on rainforest soya is found in supermarkets and fast food outlets across Europe.
Greenpeace. 2006. Eating up the Amazon [online]. Available at:
www.greenpeace.org.uk/MultimediaFiles/Live/FullReport/7555.pdf  [Accessed
November 1 2006].

In the 1920s Hill and Stuart recommended soya-based infant formula (SBIF) for infantile eczema and the first commercial SBIF was introduced in 1929.
Hill, L.W. and Stuart H.C. 1929. A soya bean food preparation for feeding infants with milk idiosyncrasy. Journal of the American Medical Association. 93, 985-987.

Growth is normal and no changes in the timing of puberty or in fertility rates have been reported in humans who consumed soya-based infant formulas as infants. Consequently, soya-based infant formulas continue to be a safe, nutritionally complete feeding option for most infants.
Klein, K.O. 1998. Isoflavones, soy-based infant formulas, and relevance to endocrine function. Nutrition Review. 56 (7) 193-204.

The results of this trial do not support the hypothesis that soya isoflavones have beneficial effects on cognitive function, bone mineral density (BMD) or plasma lipids in older postmenopausal women. The timing of supplementation may be the reason why soya did not have an effect here; the most pronounced effects of oestrogen on cognitive function have been reported in perimenopausal women (women approaching the menopause) and not in late postmenopausal women. It has also been suggested that it is easier to prevent changes in bone mineral density or bone loss after menopause than reverse them when they have already taken place. Our findings appear to support this hypothesis; in women who were recently menopausal, our intervention improved BMD while in the late menopausal women such effect was absent.  
Kreijkamp-Kaspers, S., Kok, L., Grobbee, D.E., de Haan, E.H., Aleman, A.,
Lampe, J.W. and van der Schouw, Y.T. 2004. Effect of soy protein containing isoflavones on cognitive function, bone mineral density, and plasma lipids in postmenopausal women: a randomized controlled trial. Journal of the American Medical Association. 292 (1) 65-74.

Soya consumption appears to exert modest hormonal effects in both premenopausal and postmenopausal women. The effects are generally in the direction of providing health benefits.
Kurzer, M.S. 2002. Hormonal effects of soy isoflavones: studies in premenopausal and postmenopausal women. Journal of Nutrition. 130 (3) 660S-661S.

This study demonstrated similar growth in the first year of life among infants fed cow's milk formula or soya-based infant formula.
Lasekan, J.B., Ostrom, K.M., Jacobs, J.R., Blatter, M.M., Ndife, L.I., Gooch,
W.M. 3rd and Cho, S. 1999. Growth of newborn, term infants fed soy formulas for one year. Clinical Pediatrics. 38 (10) 563-571.

This study showed that daily intake of two glasses of soya milk prevented lumbar spine bone loss in postmenopausal women.
Lydeking-Olsen, E., Beck-Jensen, J.E., Setchell, K.D. and Holm-Jensen, T. 2004.
Soymilk or progesterone for prevention of bone loss--a 2 year randomized, placebo controlled trial. European Journal of Nutrition. 4: 246-57.

Soya protein (regardless of isoflavone content) modulated serum lipid ratios (the balance of fats in the blood) in a direction beneficial for cardiovascular disease risk in healthy young men.
McVeigh, B.L., Dillingham, B.L., Lampe, J.W. and Duncan, A.M. 2006.
Effect of soy protein varying in isoflavone content on serum lipids in healthy young men. American Journal of Clinical Nutrition. 83 (2) 244-251.

Postmenopausal women with a high intake of soya isoflavones are associated with higher bone mineral density (BMD) values at both the spine and hip region.
Mei, J., Yeung, S.S.C. and Kung, A.W.C. 2001. High dietary phytoestrogen intake is associated with higher bone mineral density in postmenopausal but not premenopausal women. Journal of Clinical Endocrinology and Metabolism. 86:5217-5221.

Collectively the findings provide little evidence that for the vast majority of people (with normal thyroid function who get enough iodine in the diet) soya foods or isoflavones adversely affect thyroid function.
Messina, M. and Redmond, G. 2006. Effects of soy protein and soybean isoflavones on thyroid function in healthy adults and hypothyroid patients: a review of the relevant literature. Thyroid. 16 (3) 249-258.

Viewed in its entirety, the current literature supports the safety of isoflavones as typically consumed in diets based on soya or containing soya products.
Munro, I.C., Harwood, M., Hlywka, J.J., Stephen, A.M., Doull, J., Flamm,
W.G. and Adlercreutz, H. 2003. Soy isoflavones: a safety review. Nutrition Review. 61 (1) 1-33.

Hot flushes significantly decreased in the soya and wheat flour groups (40% and 25% reduction respectively) with a significant rapid response in the soya flour group in six weeks that continued.
Murkies, A.L., Lombard, C., Strauss, B.J.G., Wilcox, G., Burger, H.G. and
Morton. M.S. 1995. Dietary flour supplementation decreases postmenopausal
hot flushes: effect of soy and wheat. Maturitas. 21, 189-195.

These data suggest that the consumption of soya products has a protective effect against menopausal hot flushes.
Nagata, C., Takatsuka, N., Kawakami, N. and Shimizu, H. 2001. Soy product intake and hot flashes in Japanese women: results from a community-based prospective study. American Journal of Epidemiology. 153
(8) 790-793.

Soya isoflavones may decrease the risk factors associated with cardiovascular disease in postmenopausal women. The higher isoflavone-containing products also protected against spinal bone loss.
Potter, S.M., Baum, J.A., Teng, H., Stillman, R.J., Shay, N.F. and Erdman,
J.W. Jr. 1998. Soy protein and isoflavones: their effects on blood lipids and bone density in postmenopausal women. American Journal of Clinical Nutrition. 68 (suppl) 1375S–1379S.

Both nutritional status and growth were normal in infants fed either soya formula or hydrolysed whey formula.
Seppo, L., Korpela, R, Lonnerdal, B., Metsaniitty, L., Juntunen-Backman, K.,
Klemola, T., Paganus, A. and Vanto, T. 2005. A follow-up study of nutrient intake, nutritional status, and growth in infants with cow milk allergy fed either a soy formula or an extensively hydrolyzed whey formula. American Journal of Clinical Nutrition. 82 (1) 140-145.

The collective data suggest that diets rich in phytoestrogens have bone-sparing (protective) effects in the long term.
Setchell, K.D. and Lydeking-Olsen, E. 2003. Dietary phytoestrogens and their effect on bone: evidence from in vitro and vivo, human observational, and dietary intervention studies. American Journal of Clinical Nutrition. 78 (supplement) 593S-609S.

The mouse, rat and monkey metabolize soya isoflavones differently from humans. The only appropriate model for postnatal human reproductive development is the human infant.
Setchell, K.D. 2006. Assessing risks and benefits of genistein and soy. Environmental Health Perspectives. 114 (6) A332-A333.

High consumption of soya products is associated with increased bone mass in postmenopausal women.
Somekawa, Y., Chiguchi, M., Ishibashi, T., and Aso, T. 2001. Soy intake related to menopausal symptoms, serum lipids, and bone mineral density in postmenopausal Japanese women. Obstetrics and Gynecology. 97:109-115.

This study suggests that high soya intake during adolescence may reduce the risk of breast cancer in later life.
Shu, X.O., Jin, F., Dai, Q., Wen, W., Potter, J.D., Kushi, L.H., Ruan, Z., Gao, Y.T. and Zheng, W. 2001. Soyfood intake during adolescence and subsequent risk of breast cancer among Chinese women. Cancer Epidemiology Biomarkers and Prevention. 10 (5) 483-488.

Exposure to soya-based infant formula does not appear to lead to different general health or reproductive outcomes than exposure to cow's milk formula. Although the few positive findings should be explored in future studies, our findings are reassuring about the safety of infant soya formula.
Strom, B.L., Schinnar, R., Ziegler, E.E., Barnhart, K.T., Sammel, M.D.,
Macones, G.A., Stallings, V.A., Drulis, J.M., Nelson, S.E. and Hanson, S.A.
2001. Exposure to soy-based formula in infancy and endocrinological and reproductive outcomes in young adulthood. Journal of the Medical Association. 286 (7) 807-814.

Soya intake may be associated with a small reduction in breast cancer risk. The author states that this result should be interpreted with caution and recommendations for high-dose isoflavone supplementation to prevent breast cancer or prevent its recurrence would be premature.
Trock, B.J., Hilakivi-Clarke, L. and Clarke, R. 2006. Meta-analysis of soy intake and breast cancer risk. Journal of the National Cancer Institute. 98 (7) 459-471.

This study showed that high soya intake in childhood in Asian-Americans is associated with reduced breast cancer risk and that risk may be further reduced by intake as an adult.
Wu, A.H., Wan, P., Hankin, J., Tseng, C.C., Yu, M.C. and Pike, M.C. 2002.
Adolescent and adult soy intake and risk of breast cancer in Asian- Americans. Carcinogenesis. 23 (9) 1491-1496.

Soya isoflavones attenuated (reduced) bone loss at the spine and femoral neck in non-obese postmenopausal Chinese women.
Ye, Y.B., Tang, X.Y., Verbruggen, M.A. and Su, Y.X. 2006. Soy isoflavones attenuate bone loss in early postmenopausal Chinese women : A single-blind randomized, placebo-controlled trial. European Journal of Nutrition. 45 (6) 327-334.

Soya isoflavones significantly reduced total cholesterol, LDL 'bad' cholesterol, and significantly increased HDL ‘good' cholesterol.
Zhan, S. and Ho, S.C. 2005. Meta-analysis of the effects of soy protein containing isoflavones on the lipid profile. American Journal of Clinical Nutrition. 81 (2) 397-408.

 

 

 

Resources:

The Safety of Soya
Read our fully-referenced soya fact sheet
Download the pdf
Buy the factsheet

Soya-Based Infant Formula
A safe alternative to cow's milk formula
Download the pdf

The Soya Saga
Should we be running scared or welcoming this little bean into our hearts and stew pots?
Read this article on soya from VeggieHealth issue 4

Myth-Busting
The VVF examines the soya scare-mongering stories and investigates what, if any, scientific basis there is behind them

Soya and the Environment
Soya farming is devastating the Amazon, but where does all the soya go? It's not for human consumption…

FAQs
What worries you most? Read some of our most frequently asked nutritional enquiries

Soya research
Read the scientific evidence for yourself…

Vegetarian & Vegan Foundation
Top Suite, 8 York Court, Wilder Street, Bristol, BS2 8QH, UK
T: 0117 970 5190 W: www.vegetarian.org.uk E: info@vegetarian.org.uk