Soy Isoflavones

Soy Isoflavones

Soy isoflavones are major bioflavonoids found in soybeans, miso, tofu, soy milk, and other soy-based foods. They belong to a class of plant-based compounds called phytoestrogens, so-called because they resemble both the structure and function of the female sex hormone estrogen. Soy contains many individual isoflavones, but the most predominant and beneficial of them all are genistein and daidzein.

Benefits of Soy Isoflavones

By mimicking estrogen at certain sites in the body, soy isoflavones offer immense benefits that help you achieve optimal health and well-being.

Prevents Cancer

Epidemiological studies have shown that the incidences of cancers are much higher in the United States compared to Asian countries such as Japan and China.^[1] The reason behind this is that Japanese and Chinese people consume a traditional diet high in soy products compared to the Americans. Additionally, there are growing body of experimental evidence that show that genistein may actually prevent the progression of five human breast cancer cell lines by inhibiting its growth and reproduction.^[2] This clearly shows that genistein can be a promising therapeutic agent for various types of cancer.

Improves Cardiovascular Health

A higher intake of soy-based foods is actually good for the heart. In fact, one study proved that consuming 60 mg of soy protein isoflavones reduces the levels of various clinical markers of cardiovascular disease in normal post-menopausal women.^[3]

Prevents Hot Flushes Associated with Menopause

Hot flushes are the most common symptoms of menopause. During a hot flush, you may experience a sudden feeling of warmth spreading through your upper body and face at anytime of the day. Since the age-related decline in estrogen is the most common cause of hot flushes and other menopausal symptoms, researchers suggest that supplementation of phytoestrogens in menopausal women can be beneficial. In one study, postmenopausal women who took 50 mg of genistin and daidzein per day experienced significant reductions in the incidence and severity of hot flushes 2 weeks after the treatment compared to placebo group.^[4]

Maintains Healthy Skeletal Frame

Soy isoflavones help in the preservation of bone mineral density (BMD) and lower one’s risk for osteoporosis and fractures. Evidence suggests that soy isoflavone supplementation in postmenopausal women with low initial bone mass have a significant, independent effect on the maintenance of bone mineral content of the hip.^[5] In another study, postmenopausal Japanese women who consumed higher amounts of soy products experienced a significant increase in bone mass.^[6] 

Lowers High Cholesterol

A recent meta-analysis of randomized controlled trials found that intake of soy-based products for one month to one year significantly reduced the levels of circulating triglycerides, total cholesterol, and low density lipoprotein (bad cholesterol) and increased the levels of high density lipoprotein (good cholesterol).^[7]  

Boosts Cognitive Function

Numerous clinical trials show that soy isoflavones may safely improve cognitive function especially in the older population. Studies found that postmenopausal women who took 60 mg/day of soy isoflavones for 6 to 12 weeks performed better on a series of memory and mental flexibility tests.^[8-9] 

References:

1. Sarkar FH, Li Y. Soy isoflavones and cancer prevention. Cancer Invest. 2003;21(5):744-57.
2. Peterson G, Barnes S. Genistein inhibits both estrogen and growth factor-stimulated proliferation of human breast cancer cells. Cell Growth Differ. 1996;7(10):1345-51.
3. Scheiber MD, Liu JH, Subbiah MT, Rebar RW, Setchell KD. Dietary inclusion of whole soy foods results in significant reductions in clinical risk factors for osteoporosis and cardiovascular disease in normal postmenopausal women. Menopause. 2001;8(5):384-92.
4. Upmalis DH, Lobo R, Bradley L, Warren M, Cone FL, Lamia CA. Vasomotor symptom relief by soy isoflavone extract tablets in postmenopausal women: a multicenter, double-blind, randomized, placebo-controlled study. Menopause. 2000;7(4):236-42.
5. Chen YM, Ho SC, Lam SS, Ho SS, Woo JL. Soy isoflavones have a favorable effect on bone loss in Chinese postmenopausal women with lower bone mass: a double-blind, randomized, controlled trial. J Clin Endocrinol Metab. 2003;88(10):4740-7.
6. Somekawa Y, Chiguchi M, Ishibashi T, Aso T. Soy intake related to menopausal symptoms, serum lipids, and bone mineral density in postmenopausal Japanese women. Obstet Gynecol. 2001;97(1):109-15.
7. Tokede OA, Onabanjo TA, Yansane A, Gaziano JM, Djousse L. Soya products and serum lipids: a meta-analysis of randomised controlled trials. Br J Nutr. 2015;114(6):831-843.
8. Duffy R, Wiseman H, File SE. Improved cognitive function in postmenopausal women after 12 weeks of consumption of a soya extract containing isoflavones. Pharmacol Biochem Behav. 2003;75(3):721-729.
9. File SE, Hartley DE, Elsabagh S, Duffy R, Wiseman H. Cognitive improvement after 6 weeks of soy supplements in postmenopausal women is limited to frontal lobe function. Menopause. 2005;12(2):193-201.