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Originally Published NO April 2010
Over the past decade, soy has retained its place on the cusp of mainstream American eating. Withstanding fringe-group connotations of hippies and vegans, and myths linking it to breast cancer and male breast enlargement, soy has often endured an ill-deserved reputation. But a look at the broader scope of soy science tells a different story: the story that warrants soy's 10-year Food and Drug Administration (FDA) health claim, its wide use in the nutrition bar industry, and a bright potential for expansion into wider food markets.
The following are a few health sectors where soy continues to impress.
Soy's recognition as a heart-healthy food kicked off in 1999, when FDA awarded soy a heart-health claim stating that soy foods "may reduce risk of coronary heart disease by lowering blood cholesterol levels." Soy's heart-health benefits have been officially observed in other countries as well, including Korea, Japan, the United Kingdom, South Africa, and Brazil.
FDA reopened soy protein health claims for public comment in 2008. Arline McDonald, PhD, an adjunct assistant professor for the department of preventive medicine at Northwestern University, submitted to FDA a review of 35 studies published from 1998 to 2008 on soy and heart health. Her review provided a wealth of evidence that low-density lipoprotein (LDL, or "bad cholesterol") levels can experience 4 to 6% reductions with a soy intake from a range of 20 to 50 g daily.
DIGESTING PROTEIN'S BENEFITS
By Nena Dockery, scientific and regulatory affairs manager, National Enzyme Co.
EVEN BEFORE the U.S. Department of Agriculture established the first food pyramid in 1992, a focus had begun to evolve on the relative proportions of the three major macronutrients-proteins, carbohydrates, and fat-in supporting and maintaining optimal health. When the first food pyramid was designed, it was recognized that the preponderance of calories should come from carbohydrates, with lesser amounts coming from fats and protein. However, this simplified guidance failed to fully elucidate how these nutrients were utilized by the body.
More recently, the benefits of protein in a well-balanced diet have become better understood. Moreover, several nutritional disadvantages of high dietary carbohydrates, in which the quality of those carbohydrates is not stipulated, have been researched. It has now been demonstrated that the consumption of excess carbohydrates, especially refined carbohydrates and those that increase the glycemic index, may play an equal, if not bigger, role in the development of obesity and heart disease than dietary fat intake. In addition, the development of type 2 diabetes may be directly related in part to the ingestion of excess refined carbohydrates.
With the exception of the more-extreme weight-loss diets, current popular diet plans espouse a nutrient proportion that is more balanced and, in many ways, more individualized. Most of these diets advocate higher consumption of protein and substantially fewer carbohydrates. In addition, recommendations for specific persons-in particular, the aging population and individuals involved in regular athletic endeavors-include increasing the consumption of high-quality protein.
As a result of the changing perspective on protein consumption, high-protein supplements in the form of drinks and food bars have become a mainstay in the diets of many individuals. From the serious bodybuilder to the postmenopausal woman and the vegan who must ensure adequate protein consumption from non-animal sources, diverse groups of health-conscious people are looking for ways to realize the benefits associated with protein. Soy- and whey-based powdered drink supplements line the shelves of not only the health food and nutritional supplement stores, but also the corner grocery store and large discount outlet.
Increasing protein intake can result in various digestive challenges, however. Some proteins are more difficult to digest than others, most often due to our body's own deficiencies in the appropriate digestive enzymes necessary to completely break down the protein. Soy- and dairy-based protein supplements in particular can cause excess gas, bloating, and intestinal discomfort for many people.
For other individuals, digestive problems can be the result of a large quantity of protein consumed at one time. Many people simply cannot break down excess amounts of protein fast enough. Protein fragments that remain undigested and are not absorbed in the small intestine can be fermented by colonic bacteria. This fermentation process can produce gas and cramping temporarily, and the byproducts of this breakdown include thiols, phenols, amines, ammonia, indoles, and branched-chain fatty acids, which are all potentially toxic to the body.
To ensure the greatest benefit from high-protein supplements, meal replacements, protein bars, and even conventional food protein sources, it is essential that the protein be completely and efficiently broken down. Many of today's protein supplements are either partially or completely hydrolyzed, but the products are frequently more expensive, often result in an unpleasant flavor, and may not completely eliminate the digestive problems.
One approach in providing a natural way to assist in protein digestion is a protein-digesting enzyme product that is designed to be taken in conjunction with a protein food source or supplement. These enzyme blends can be made in the form of encapsulated or tableted product containing several protein-digesting enzymes (proteases). Alternately, they can be offered as select protease blends that can be added to the protein drink mix itself. These drink mixes are typically mixed with a liquid such as water or milk, and are meant to be consumed immediately.
Getting the maximum benefit from consuming extra dietary protein is the goal of many health-conscious individuals. Ensuring that protein is completely digested will help ensure that goal is met.
Larger LDL reductions were found in subjects with higher LDL and total cholesterol levels, says McDonald. The results came from studies on a variety of populations, including premenopausal and postmenopausal women, young adults, middle-aged adults, and adults ages 60 or older.
"It's particularly important to recognize that soy is lower in saturated fats and cholesterol than its animal protein alternative," says Nancy Chapman, RD, MPH, executive director of the Soyfoods Association of North America.
Experts believe that soy's ability to ward off dangerous cholesterol could also make soy foods a potential method for eradicating type 2 diabetes, a disease often caused by factors such as obesity and high cholesterol.
The existing science on soy and type 2 diabetes is growing. One epidemiological study published this year by the Journal of Nutrition involved 25,872 Japanese men and 33,919 Japanese women with no history of diabetes. The subjects submitted food-intake questionnaires over five years. At the end of the study, 1114 subjects self-reported having developed diabetes. Overweight women with higher intakes of soy products were found to have a lower incidence of diabetes. Several other studies published this year also bode well for soy and diabetes.
Epidemiological studies should not be relied upon, of course-especially since green tea and fatty fish, two foods believed to have cardiovascular benefits, are generally in high intake in Asian cultures. However, the positive news may also be what many studies haven't found in subjects: "What is reassuring about these studies is that soy has no negative effect," says Chapman.
Perhaps the most debated of soy's characteristics is its similar chemical structure to estrogen, and the proposed effect this might have on both men and women with high soy intake.
Regarding women, past studies have raised concern that some isoflavone compounds in soy could have inhibitory effects on the body's natural-born killers of breast cancer. Rumor has even circulated that soy could have a detrimental effect on tamoxifen, a common drug treatment for breast cancer patients. Cancer Research published a study in 2002 concluding that "caution is warranted for postmenopausal women consuming dietary genistein (a soy isoflavone) while on [tamoxifen]."
But again, consider what has not been discovered. Recent studies have consistently concluded that soy has no negative effect on breast cancer risk or tamoxifen efficiency.
Furthermore, large-scale epidemiological studies are suggesting that soy intake may actually induce lower rates of mortality and new cases of breast cancer. In the last year alone, such studies were printed in the Journal of Nutrition, the Journal of the American Medical Association, and the American Journal of Clinical Nutrition.
The Journal of Nutrition's multisite, randomized, double-blinded, placebo-controlled study in May 2009 placed 406 menopausal women on 80 to 120 mg of soy isoflavone or placebo, daily, for two years. The patients took three mammograms over that time, and of the 358 women who did take mammograms, researchers concluded that "isoflavone supplements did not modify breast density in menopausal women."
In the American Journal of Clinical Nutrition's study involving 73,223 women, soy food consumption was measured by soy protein isoflavone intake, with breast cancer incidents measured by Cox regression analyses. In this case, scientists concluded that soy intake "was inversely associated with premenopausal breast cancer, and that association was highly significant."
Fear not, ladies; soy looks safe.
Soy's similarities to estrogen have perhaps created more negative assumptions about soy for men's health than women's. Mainstream press has sometimes alleged that high soy intake could physically feminize the male body. The rumors often contrived about soy are deep, even infiltrating magazines such as Men's Health. However, the story that's largely untold on the muscle market is that soy is actually full of benefits for men.
Dave Ellis is a veteran sports dietitian with more than 25 years of experience working with Major League Baseball, Olympic hockey, and Division 1 collegiate football. What his athletes all have in common is that, regardless of soy's supposed "feminizing" qualities, Ellis feeds them all soy.
"They say that every bite of soy has some potential estrogenic outcome," says Ellis. "But the reality is that we have a bunch of males who tend to overdo their animal protein consumption, whether it's from animal tissues or from dairy products." Ellis says that he prefers that players focus on getting protein from a well-rounded range of sources, including soy.
Plus, he says, vegan proteins offer a number of benefits that animal proteins don't-for instance, where fat is concerned. That, combined with soy's heart health benefits, makes soy a protein of choice in his eyes. "For example, there is concern about NFL athletes. We're very worried about high blood pressure, enlarged hearts, some of the acute coronary events that we've seen in this population under certain stress periods, and the short lifespan that these athletes have. It would be nice to give something back to them on a cardiovascular level" in the form of soy protein, he says.
SOY: A NEW SOURCE OF OMEGA-3
ACCORDING TOSoyfoods: the U.S. Market 2009, retail sales of soyfood products have exceeded $4 billion for the first time in history.
And as if soy's future wasn't strong enough, Monsanto Co. and Solae LLC, leading soy manufacturers in the United States, are finally seeing the light of their search for an omega-3 soy market. The two companies agreed to invest in developing a soy omega-3 market in 2007, and just last year, the Food and Drug Administration awarded their stearidonic acid (SDA) omega-3 soy oil with generally recognized as safe (GRAS) status.
"Consumers are increasingly looking for ways to improve health through better nutrition," says Al Gallegos, marketing and sales director for Solae. "One approach food companies are taking is incorporating omega-3 into food and beverage products. The development of this new, plant-based omega-3 soybean oil can play an important role in helping food companies achieve this objective."
A soy source for omega-3 could have the potential to bring omega-3 fortification to areas of food production that aren't well positioned for using fish or algae omega sources.
The hype keeping men from increasing their soy intakes stems from a soy compound called equol, which can block some of the actions of testosterone.
"The story being pitched to males is that 100% of every gram of soy they consume elicits this equol response," says Ellis, "In reality, 25% of non-vegans elicit some kind of equol expression after they eat soy isoflavones. It's a matter of how an individual processes it. Of the equol that is produced, the bioactivity in males is sketchy, at best."
In fact, last year, the journal Fertility and Sterility published a soy review of 32 reports on soy studies in which the review authors concluded soy to have no significant effect on testosterone levels in men.
Beyond the estrogen theories, soy contributes some otherwise hard-to-find amino acids to the body, which can be key in maintaining peak athletic form. Arginine and glutamine, two amino acids key in repairing damaged muscle tissues, can be found in higher amounts in soy than in other standard sports proteins, like whey. Arginine is also believed to enhance blood vessel function and a stronger immune system.
One area of soy research that has seen a negative hit is bone health. Soy is often said to aid bone resorption in postmenopausal women, but several studies have surfaced reporting that soy did not have an effect on bone health of postmenopausal women and other populations. All in all, soy's effect on bone mineral density is inconclusive, but "high amounts of calcium and vitamin D in fortified soy milk make soy a reliable method for delivering calcium" says Chapman-especially for those who rely on plant-based diets.