HEALTH NEWS

PROTECTING BONES WITH SOY PROTEIN

By Rajen M.

Scientific research continues to demonstrate that adding soy protein to the diet can lead to beneficial health effects in menopause. It has been shown to help reduce cholesterol level and, reducing coronary heart disease risk. There is ongoing clinical research on soy protein in the protection of bones.

One group of soy components under investigation by researchers are isoflavones. These are a type of phytoestrogen (estrogen-like plant substances). They behave like hormones in some but not all ways. They bind very weakly to hormone receptors.

In so doing, they can mimic some of the hormonal effects and, in the process, reduce some distress that might result from the drop in hormones seen in menopause.

Plant hormones

Researchers are becoming fascinated by phytoestrogens' potential as cancer preventatives and as non-hormone approach in helping with menopausal symptoms and osteoporosis.

There is doubt as to whether estrogen replacement therapies can treat menopausal symptoms or prevent health problems such as breast and endometrial cancers as well as osteoporosis.

Many women are reluctant to take estrogenic drugs because of side-effects such as resumption of menstrual bleeding, breast tenderness, and weight gain.

Categories of women who may benefit most from consuming soy protein with isoflavones include:

• women at high risk of heart disease;
• women who cannot or do not wish to take hormone replacement therapy;
• women who are concerned about bone health; and
• women experiencing menopausal symptoms

Heart disease

The association between protein intake and the development of heart disease is not new information.

The use of isolated soy protein with its native isoflavones may be a therapeutic tool that has a number of advantages over commonly prescribed cholesterol-lowering medications. In addition to decreasing elevated levels of blood cholesterol, isolated soy protein may decrease oxidation of LDL-cholesterol.

This may prevent the formation of artery-blocking blood clots, improve response in arteries already exhibiting plaque formation, reduce collapse of the artery after balloon angioplasty, and generally decrease atherosclerosis. It is critical that studies be conducted to confirm these findings in humans.

Researchers recently presented the results of a study showing that regular intake of soy protein may help the cardiovascular health of post-menopausal women.

The findings of the study, which were presented last week by Dr Robert DuBroff and Dr P. Decker at the annual meeting of the North American Menopause Society in New York City, add to the mounting data supporting the cardiovascular benefits of soy protein with naturally occurring isoflavones.

The research shows that daily consumption of soy protein with naturally occurring isoflavones can result in significant improvement in endothelial function, an important marker of vascular function. Endothelial dysfunction is associated with a higher risk of cardiovascular disease.

According to the results presented, women who consumed 40g of soy protein that contained 88mg of naturally occurring isoflavones daily experienced a statistically significant increase improvement in endothelial function measured by brachial artery ultra-sound.

This study is extremely relevant, considering the dramatic increase in the incidence of cardiovascular disease in women following the onset of menopause, which scientists attribute to the loss of estrogen and the subsequent onset of endothelial dysfunction.

Recent studies have shown that endothelial dysfunction in post-menopausal women can be reduced with estrogen. However, soy protein rich in isoflavones may be a viable alternative.

Bone disease

It is estimated that more than half of all women and about a third of men will have fractures caused by osteoporosis during their lives. There is increasing interest in the possible role of soy protein in the prevention of osteoporosis, a chronic disease characterised by a loss of normal bone density.

Osteoporosis typically occurs in women and is primarily related to ageing and hormone deficiency. Additionally, the isoflavones in soy may inhibit the reabsorption of bone.

A drug that is effective in decreasing bone loss is similar in structure to soy bean isoflavones. Soy protein may confer protection against osteoporosis and fracture risk by promoting a more optimal calcium balance.

Soy protein with isoflavones has been shown to increase both bone mineral content and bone mineral density in the lumbar spine. (Alekel, D.L.,A.S. Germain, et al. Isoflavone-rich soy protein isolate attentuates bone loss in the lumbar spine of perimenopausal women. Am J Clin Nutr 2000; 72)

Also, calcium in soy foods is highly available and is only slightly less-easily absorbed by the body than the calcium contained in cheese and milk.

Source

Studies show that pure isoflavone alone does not seem to help. It needs to be occurring together with soy protein.

Specific isoflavones found almost exclusively in soy exist in three families which are based on the chemical structure of genistein, daidzein and glycitein.

Isoflavone levels and ratios in soy protein based foods vary depending on the variety of soy beans used, growing conditions and soil, as well as how the soy protein is processed. Isoflavones are an excellent biomarker to indicate the content of bioactive components in soy protein.

These phytoestrogens occur at levels of 50-300mg per 100g in soy beans, and in lower levels in soy products such as miso, soy milk, and tofu.

To have high isoflavone content, the soy must be minimally processed. Soy milk and tofu are quite low in isoflavones as it is highly processed. Tempeh, which is fermented soy, is a good (and tasty) source. Soy protein isolates that have been cold water extracted are also rich in isoflavone content. These powders could be easily incorporated into any beverage.

Consuming 40-90mg of isoflavones has been shown to be of help in calming irritating hot flushes. The doses have been clinically documented to help bone and heart health.

Source: The Star, 29 July 2001