Soy is an excellent source of plant-based protein that can benefit those concerned about their heart and bone health, as well as their breast and prostate health.
Heart health benefits of soy: A meta-analysis of 38 studies indicates that consuming protein from soy foods is linked to retaining normal cholesterol levels. Another study suggests that soy protein may have antioxidant properties that helps protect bad(LDL) cholesterol from oxidizing.
Beyond the potential of soy protein to positively impact the cholesterol that travels through arteries, soy isoflavones may also support the healthy function of the arteries themselves. One study showed that menopausal women taking soy protein supplements (rich in isoflavones) experienced a significant improvement in elasticity of their arteries.
This elasticity has been shown to decline with age, a change that is viewed as a risk factor for cardiovascular health. Some scientists are predicting that these isoflavone effects may prove to be as valuable in supporting heart-healthy aging as their potential to retain normal cholesterol levels.
The American Cancer Society has created guidelines for a healthy diet: Choose most of the foods you eat from plant sources. Eat five or more servings of fruits and vegetables each day. Eat other foods from plant sources, such as breads, cereals, grain products, rice, pasta, or beans several times each day.
Limit your intake of high-fat foods, particularly from animal sources. Choose foods low in fat. Limit consumption of meats, especially those high in fat. Be physically active: achieve and maintain a healthy weight.
Be at least moderately active for 30 minutes or more each day. Stay within your healthy weight range. Limit consumption of alcoholic beverages, if you drink at all. For people who already drink alcoholic beverages, limit intake to two drinks a day for men and one drink per day for women. Soy foods fit guidelines 1 and 2 for a health-promoting diet.
Soy and bone health: Americans typically think of dairy products as the best source of calcium, but there are many other good sources of calcium. In fact, soy protein is an excellent source of dietary calcium, providing 50% of the daily value of this important nutrient per serving.
Soy protein may also offer bone-health advantages by replacing sources of animal protein in the diet. For long-term bone health, calcium intake is only part of the story. Urinary calcium loss is another factor that contributes to a negative calcium balance. High consumption of animal proteins, which are high in sulfur amino acids, appear to be responsible for this effect.
Soy protein, which has less sulfur amino acids relative to meat and other animal protein sources, may result in less calcium being lost in the urine and help keep calcium in the skeleton. In one study, calcium excretion was found to be 30% lower when dietary protein from soy sources was compared to equal amounts of protein from beef, fish, and chicken in healthy adults consuming a constant amount of calcium.
The isoflavones in soy foods may also help support healthy bones. A recent study showed that dietary intake of soy products containing isoflavones had a significant positive impact on bone turnover in healthy postmenopausal women.
Soy and breast and prostate health: It has long been known that many soy-consuming Asian populations have better rates of breast and prostate health than do Western populations. There are many factors involved in prostate health, but a recent, large-scale population-health study suggests soy intake as one of those factors.
In this study, men who reported frequently consuming soy milk (which contains isoflavones) were 70% more likely to maintain prostate health during a follow-up period, compared to the men who had little or no soy in their diet. A recent population-health study conducted in China investigated the relationship between soy intake during adolescence and breast health later in life.
After adjustments for known risk factors, higher soy food intakes reported during the teen years were associated with significantly better breast health when these women reached their pre-and post-menopausal adult years. Researchers believe that soy intake starting at a young age and continued throughout life is linked to maintaining breast health.
Another way that soy may promote heart, breast, and prostate health is by providing protection against oxidation damage. The soy isoflavone, genistein, has been shown to have antioxidant properties.
NOTE: While the totality of evidence suggests health benefits for soy protein , scientific opinion is not uniform on the appropriate use of soy by women with a history of breast cancer. I recommend that women with this history discuss the option of soy intake with their physician.
Soy protein and menopause: Cross-cultural studies of menopausal women have found that women in Japan experience a smoother transitional period than women in the West. Eleven soy foods are commonly consumed in Asian countries, providing an estimated 45 mg of isoflavones per day for the average person.
For the menopausal woman, soy protein has particular interest, as it is studied for both its apparent beneficial effect during menopause as well as for bone-building and helping to retain normal cholesterol levels.
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