Click on the different areas of the male or female body to learn about the effects of soy.

Heart

Cardiovascular disease (CVD) is the leading cause of death in American men, killing more than 450,000 men in 1997 (most recent statistics available). Death rates from CVD are much lower in Japanese than in American men—186 in Japan versus 389 (deaths per 100,000 population)in the United States. One difference between Japanese and American men is the high intake of soyfoods in the traditional Japanese diet, compared to a very low soyfood intake in the United States. This has led researchers to investigate ways in which soy protein may help lower the risk of CVD.

Atherosclerosis —the development of plaque in the inner lining of arteries—is the process underlying most CVD. The level of Low-Density Lipoprotein-cholesterol (LDL-cholesterol) in your blood that has undergone a damaging chemical reaction called oxidation is a major factor in the development of artery-clogging plaque.

Consumption of soy protein instead of animal protein reduces blood levels of LDL-cholesterol. Although some studies suggest that the isoflavones naturally occurring in soy may be responsible for its cholesterol-lowering effect, research has shown that purified isoflavone "pills" don't lower cholesterol. These findings suggest either that isoflavones are effective only when consumed in their natural state as combined with soy protein or that some other biologically active component of soy protein is responsible for its cholesterol-lowering effect. There also is evidence that soy protein retaining its isoflavones and other naturally occurring phytochemicals may—

• improve artery health
• reduce the amount of atherosclerotic plaque in arteries
• protect against oxidation of LDL-cholesterol
• reduce the tendency to form blood clots, which can complete the blocking of narrowed arteries

In October 1999 the U.S. Food and Drug Administration (FDA) authorized the use of a Health Claim stating that consuming 25 grams of soy protein per day, as part of a diet low in saturated fat and cholesterol, may lower the risk of coronary heart disease.

For more information, go to Cardiovascular Disease.

References
1. AHA (American Heart Association). 2000 Heart and Stroke Statistical Update. Dallas (TX):American Heart Association, 1999.

2. Anderson JW, Johnstone BM, Cook-Newell ME. Meta-analysis of the effects of soy protein intake on serum lipids. New England Journal of Medicine 1995;333:276-282.

3. Crouse JR III, Morgan T, Terry JG, et al. A randomized trial comparing the effect of casein with that of soy protein containing varying amounts of isoflavones on plasma concentrations of lipids and lipoproteins. Archives of Internal Medicine 1999;159:2070-2076.

4. Nestel PJ, Yamashita T, Sasahara T, et al. Soy isoflavones improve systemic arterial compliance but not plasma lipids in menopausal and perimenopausal women. Arteriosclerosis, Thrombosis, and Vascular Biology 1997;17:3392-3398.

5. Kapiotis S, Hermann M, Held I, et al. Genistein, the dietary-derived angiogenesis inhibitor, prevents LDL oxidation and protects endothelial cells from damage by atherogenic LDL. Arteriosclerosis, Thrombosis, and Vascular Biology 1997;17:2868-2874.

6. Honoré EK, Williams JK, Anthony MS, Clarkson TB. Soy isoflavones enhance coronary vascular reactivity in atherosclerotic female macaques. Fertility and Sterility 1997;67:148-154.

7. Wilcox JN, Blumenthal BF. Thrombotic mechanisms in atherosclerosis: potential impact of soy proteins. Journal of Nutrition 1995;125(suppl): 631S-638S.

8. Anthony MS, Clarkson TB, Bullock BC, Wagner JD. Soy protein versus soy phytoestrogens in the prevention of diet-induced coronary artery atherosclerosis of male cynomolgus monkeys. Arteriosclerosis, Thrombosis, and Vascular Biology 1997;17:2524-2531.

 

 

 

 

Bones

Although women are more likely than men to develop osteoporosis, 20% of the 28 million Americans who either have osteoporosis or who are at increased risk of developing this disabling disease are men. One major factor for developing the weak bones characteristic of osteoporosis is insufficient calcium intake and availability particularly early in life. A diet high in animal protein, such as is common in the United States, increases calcium excretion in urine leaving less for the body to use. However, research has shown that soy protein doesn't increase calcium excretion.

Soy protein with its naturally occurring isoflavones has been shown to have a positive effect on bone health in women. This is thought to be due in large part to the fact that isoflavones have some activities similar to the hormone estrogen, which helps protect against excessive breakdown of bone. Research suggests that estrogen plays a more important role than testosterone in maintaining bone density in older men. Therefore, it is possible that soy protein with isoflavones may also help protect bone health in men.

For more information, go to Bone Health.

References
1. NIH (National Institutes of Health). Osteoporosis overview. Accessed 6/2000.

2. Breslau NA, Brinkley L, Hill KD, Pak CYC. Relationship of animal protein-rich diet to kidney stone formation and calcium metabolism. Journal of Clinical Endocrinology and Metabolism 1988;66:140-146.

3. Potter SM, Baum JA, Teng H, et al. Soy protein and isoflavones: their effects on blood lipids and bone density in postmenopausal women. American Journal of Clinical Nutrition 1998;68(suppl):1375S-1379S.

4. Ongphiphadhanakul B, RajatanavinR, Chanprasertyothin S, et al. Serum oestradiol and oestrogen-receptor gene polymorphism are associated with bone mineral density independently of serum testosterone in normal males. Clinical Endocrinology 1998;49:803-809.

 

 

 

 

Prostate

Prostate cancer is the second leading cause of cancer death in men and is expected to account for almost 32,000 deaths in 2000. Death rates (deaths per 100,000 population) from prostate cancer differ around the world. For example, the death rate for prostate cancer in Japan is 5.1, compared with 15.9 in the United States.

Studies have found the frequencies of tiny latent (inactive) prostate cancers to be somewhat similar in different countries. However, the presence of both larger latent tumors and clinical (symptomatic) prostate cancer is much higher in Europeans than in Asian men. Research has shown that enlargement of a tumor depends on angiogenesis, the development of tiny blood vessels to provide oxygen and nutrients needed for growth.

Consuming soyfoods is associated with lower mortality from prostate cancer. A study in Seventh Day Adventist men suggested that the consumption of soymilk was associated with a reduced risk of prostate cancer. Genistein , the major isoflavone in soy, decreased the growth of prostate cancer cells in the laboratory. In addition, genistein has been shown to be an antiangiogenic agent, inhibiting the growth of the tiny vessels needed to nourish a tumor. It has been suggested that genistein's antiangiogenic activity may help explain the fact that Asian men have so many more prostate tumors that remain very tiny rather than becoming larger or symptomatic.

For more information, go to Cancer.

References

1. ACS (American Cancer Society. Cancer Facts & Figures 2000. Atlanta (GA):American Cancer Society, 2000.

2. Breslow N, Chan CW, Dhom G, et al. Latent carcinoma of prostate at autopsy in seven areas. The International Agency for Research on Cancer, Lyons, France. International Journal of Cancer 1977;20:680-688.

3. Furusato M, Wakui S, Sasaki H, et al. Tumour angiogenesis in latent prostatic carcinoma. British Journal of Cancer 1994;70:1244-1246.

4. Hebert JR, Hurley TG, Olendzki BC, et al. Nutritional and socioeconomic factors in relation to prostate cancer mortality: a cross-national study. Journal of the National Cancer Institute 1998;90:1637-1647.

5. Jacobsen JK, Knutsen SF, Fraser GE. Does high soy milk intake reduce prostate cancer incidence? The Adventist Health Study (United States). Cancer Causes and Control 1998;9:553-557.

6. Geller J, Sionit L, Partido C, et al. Genistein inhibits the growth of human-patient BPH and prostate cancer in histoculture. The Prostate 1998;34: 75-79.

7. Fotsis T, Pepper M, Adlercreutz H, et al. Genistein, a dietary-derived inhibitor of in vitro angiogenesis. Proceedings of the National Academy of Science USA 1993;90:2690-2694.

 

 

 

 

Colon & Rectum

Colorectal cancer—cancer of the colon and/or rectum — is the third leading cause of cancer death in American men. It is estimated that colorectal cancer will kill 27,800 men in 2000.

A high-fiber diet is known to decrease the risk of colorectal cancer. This includes those soyfoods that retain their fiber, such as soybeans and soynuts. In addition, research has suggested an antioxidant effect for phytates such as are found in soy, making these substances potential anticancer agents. Although studies have shown soy isoflavones to be protective in several types of cancer, the evidence supporting a role for isoflavones in reducing the risk of colorectal cancer currently is limited.

For more information, go to Cancer.

References

1. ACS (American Cancer Society. Cancer Facts & Figures 2000. Atlanta (GA):American Cancer Society, 2000.

2. Segasothy M, Phillips PA. Vegetarian diet: panacea for modern lifestyle diseases? Quarterly Journal of Medicine 1999;92:531-544.

3. Graf E, Eaton JW. Suppression of colonic cancer by dietary phytic acid. Nutrition and Cancer 1993;19:11-19.

4. Messina M, Bennink M. Soyfoods, isoflavones and risk of colonic cancer: a review of the in vitro and in vivo data. Baillière's Clinical Endocrinology and Metabolism 1998;12:707-728.

 

 

 

 

Kidney

Kidney disorders affect more than 3 million Americans. Renal damage is most often a result of diabetes or high blood pressure. In addition, high blood levels of cholesterol and triglycerides can injure kidneys. Most people with chronic kidney disorders are prescribed a low-protein diet in order to decrease the workload of their kidneys and slow the progress of renal disease.

Some long-term studies have shown that consuming soy protein protects kidneys, while excessive amounts of animal protein harm them. In people with chronic kidney disease, a diet based on soy protein appears to have the same effect on kidney function as a low-protein diet of primarily animal protein, but with the important benefit of providing a higher amount of high-quality protein. In addition, substituting soy protein for animal protein has been shown to lower blood levels of cholesterol and triglycerides.

References
1. NIDDK (National Institute of Diabetes and Digestive and Kidney Diseases). Kidney and urologic diseases statistics for the United States. Accessed 6/00.

2. Anderson JW, Smith BM, Washnock CS. Cardiovascular and renal benefits of dry bean and soy intake. American Journal of Clinical Nutrition 1999;70(suppl):464S-474S.

3. Kontessis P, Jones S, Dodds R. et al. Renal, metabolic and hormonal responses to ingestion of animal and vegetable proteins. Kidney International 1990;38:136-144.

4. Anderson JW, Johnstone BM, Cook-Newell ME. Meta-analysis of the effects of soy protein intake on serum lipids. New England Journal of Medicine 1995;333:276-282.