Adding soy isoflavones into products such as bread, bars and beverages may allow processors to target specific markets. Examples include older women going through menopause, younger females looking to avoid breast cancer and men worried about prostate cancer. Processors should proceed cautiously, however. Research results on soy isoflavones keep coming in, and debate on their potential health benefits continues.
Genistein, a predominant isoflavone in soybeans, is considered a phytoestrogen, said Dr. Elizabeth A. Droke, associate professor in the department of nutrition, food science and hospitality at South Dakota State University, Brookings.
"This means it is a plant-derived compound that possesses estrogen-like biological activity," she said. "It is important because it can have both estrogenic and anti-estrogenic activities within the body as well as functioning as an antioxidant. Thus, these functions of genistein are behind its purported health benefits for cardiovascular disease, cancer prevention and bone health."
Because they are phytoestrogens, isoflavones research has focused predominantly on women, she said. French Meadow Bakery, Minneapolis, even targets women with its Woman’s Bread variety that includes soy isoflavones. The company said the bread provides support for women’s changing needs throughout the premenstrual syndrome, menopause and postmenopausal years. One slice provides 40 mg of phytoestrogen, according to French Meadow Bakery, while two slices provide the essential daily supply of natural soy isoflavones.
Archer Daniels Midland Co., Decatur, Ill., offers a Novasoy isoflavone product line. Formulators need to add enough isoflavones into a product for it to have an effect on menopause symptoms, said Liza Pepple, product manager for the ADM Health and Nutrition division.
"In a critical review of hot flash research it was found that interventions that included at least 15 mg of genistein were consistently effective in reducing the frequency and severity of hot flashes," she said.
Isoflavones also may have an effect on breast cancer. According to the American Cancer Society, "Substances in soy called isoflavones, such as genistein, may be able to lower natural estrogen levels. This may, in turn, lower the risk of breast cancer. While it is an attractive theory, the evidence to support it remains mixed."
Intake of genistein may reduce the risk of breast cancer when taken at a young age, said Dr. William Helferich, a professor of food science and human nutrition at the University of Illinois in Urbana-Champaign. Exposure to genistein before puberty causes mammary gland differentiation, he said.
"A differentiated cell undergoes less proliferation and therefore is less likely to progress through the cancer process," he said.
However, older women with breast cancer may need to be more cautious with isoflavone intake. Dietary genistein may stimulate the growth of estrogen-responsive tumors and interfere with treatments that target estrogen receptors in breast tumors, he said.
According to the American Cancer Society, "Soy may even be harmful in certain groups of people. For example, in women with breast cancer or a history of breast cancer, isoflavones may actually act as weak estrogens, increasing the risk of the cancer growing or coming back."
Ms. Droke added, "Isoflavones may have different effects depending on the age, sex and circumstance of the consumer. Emerging data suggests soy intake during adolescence may reduce the risk of breast cancer to a greater extent than does the amount of soy intake as an adult.
"Soy and its associated isoflavones may help decrease the risk for heart disease, but it is not clear whether soy should be recommended for breast cancer patients. Thus, there is a lot we still need to learn regarding when intake of soy and its isoflavones may be the most beneficial."
Ongoing research at South Dakota State University is investigating the ability of soy isoflavone consumption to decrease the risk of developing complications associated with obesity, she said.
"There is evidence suggesting that soy protein and soy isoflavones may have an anti-obesity effect by decreasing body weight and deposition of fat," Ms. Droke said.
Men may benefit from isoflavones, too. The consumption of soy and its isoflavones may decrease the risk of developing prostate cancer by altering hormone levels and decreasing androgen receptor expression in prostate tissue, Ms. Droke said.
Determining a healthy dose
A Food and Drug Administration health claim exists for soy but not for its isoflavones.
"Because of current controversy over the safety and efficacy of soy isoflavones, I do not think we will see specific dietary recommendations for isoflavones within the next five years," Ms. Droke said. "We need to know much more about their safety and efficacy before specific recommendations can be made."
Soy offers more healthy substances than just isoflavones, she said. The F.D.A. health claim says, "Twenty-five grams of soy protein a day, as part of a diet low in saturated fat and cholesterol, may reduce the risk of coronary heart disease."
Ms. Droke added, "When talking about making dietary recommendations, you need to consider that by consuming soy or soy-containing foods, you are not only getting the potential health benefits of the isoflavones, but also benefits from the other healthy components of soy such as fiber, higher polyunsaturated fatty acids and low saturated fatty acids.
"So in terms of a healthy diet that may decrease the risk of chronic diseases, focusing on the whole food may be better than focusing on isolated compounds from the food."
Mr. Helferich said he believes the whole soybean is healthier than many of its individual chemical parts.
ADM increased its presence in the soy isoflavone arena when it acquired the global soy isoflavone business of The Solae Co., St. Louis, in 2005. Novasoy brand isoflavones from ADM are available in a variety of forms. Because formulators need to use a small quantity, or about 25 to 50 mg per serving, there is no off taste when including soy isoflavones like Novasoy to food or beverage formulations, Ms. Pepple said. Soy isoflavones may work well in many different foods, she said. Novasoy is generally recognized as safe in healthy beverages, healthy bars, and adult meal replacements.
Findings on isoflavones
Three recent studies examined the health effects of soy isoflavone consumption. The results include:
• High doses of dietary soy isoflavonoids had minimal effects on reproductive tissues in a postmenopausal primate model in study results published in the September 2006 issue of Biology of Reproduction. The results suggest it is unlikely high isoflavonoid intake may promote development of uterine and breast cancers. Thirty adult female monkeys randomly received one of three diets: a control diet, a diet with 509 mg per day of the soy isoflavones genistein and daidzein, and a diet with 1.2 grams per day of racemic equol, an isoflavone. The study involved researchers from the Wake Forest University School of Medicine in Winston-Salem, N.C.; the Cancer Research Center of Hawaii in Honolulu; and the Division of Biochemical Toxicology, National Center for Toxocological Research, U.S. Food and Drug Administration, in Jefferson, Ark.
• A review of 11 previously published studies examined how isoflavone supplement intake may affect hot flash symptoms. The review’s results appeared in the September/October 2006 issue of Menopause. In 5 of the 11 studies, more than 15 mg of genistein, an isoflavone, were provided per treatment. Each of the five studies consistently reported a statistically significant decrease in hot flash symptoms. In the other six studies, less than 15 mg of genistein were provided per treatment. Only one of these six studies reported a statistically significant decrease in hot flash symptoms.
• Soy isoflavones significantly reduced serum total and L.D.L. (bad) cholesterol but did not change H.D.L. (good) cholesterol and triacylglycerol in meta-analysis results that were published in the April 2007 issue of The American Journal of Clinical Nutrition. Soy protein that contained enriched or depleted isoflavones also significantly improved lipid profiles. The work involved researchers from the National Institute of Health and Nutrition in Tokyo.
This article can also be found in the digital edition of Food Business News, July 24, 2007, starting on Page 77. Click