The WHI was a 15-year research program designed to investigate the most common causes of death, disability and poor quality of life for postmenopausal women including cardiovascular disease, cancer and osteoporosis. The initiative was launched in 1991 and involved the clinical observation of 161,808 women. Clinical trials were focused on postmenopausal hormone therapy, dietary modification, and calcium and vitamin D supplementation of heart disease, fractures, and breast and colorectal cancer. The WHI was established by the National Institutes of Health (NIH), and the National Heart, Lung and Blood Institute (NHLB).
Formulators of dietary needs for postmenopausal women seek ways of improving cardiovascular markers, as cardiovascular disease is a leading killer of this population in the U.S.
Low-fat Diet ShockerAccording to a new study from the WHI, a low-fat diet does not lower the risk of certain cancers or heart disease (Journal of the American Medical Association, vol. 295, pp. 629-642). The study involved 48,835 postmenopausal women and lasted eight years, yet certain design flaws allowed for what many call questionable conclusions. For example, the intervention group was supposed to consume a diet with 20% fat, but by year six, the average was up to 29%, and the researchers admitted that very few of the women in the intervention group actually met the nutritional targets. In spite of its flaws, mainstream media outlets published stories based on the study's results suggesting a low-fat diet does not reduce the risk of certain diseases. For instance, theSan Francisco Chroniclepublished a story entitled “O.K., So Don't Hold the Fries,” and CBS News ran the story “Study: Low-fat Diets Big Letdown.” So, what is the truth about low-fat diets, and how do these dietary recommendations affect women concerned with cardiovascular disease?
Soy and Isoflavones Provide InsightA new study published in the journalNutrition(vol. 22, pp.104-113) shed some possible insight into the dietary prevention of cardiovascular disease. This study reported that a low-glycemic diet supplemented with 30g of soy protein (containing 34mg of isoflavones) and 4g of phytosterols resulted in significant improvements in cholesterol in comparison to people following the low-fat, high-carbohydrate diet recommended by the American Heart Association (AHA). After 12 weeks of the diet, the group on the low-glycemic diet showed significant decreases in total cholesterol (15.8%), low-density lipoprotein (LDL) cholesterol (14.8%) and triacylglycerols (44.8%), whereas the AHA group showed no significant decrease in either total cholesterol or LDL cholesterol. Perhaps a healthy diet with known functional ingredients, such as soy and isoflavones, provides the best solution for both men and women who seek a heart-healthy diet.
According to another study, daily isoflavone reduces bone loss in early postmenopausal women. However, the effect was not dependent on the dose. In this study, the bone density and bone-mineral content were measured after one year of supplementation with tablets of 125mg soy protein extracts (containing 50mg isoflavones—35.5mg genistein and 14.5mg of daidzein). The bone-mineral density (of the lumbar vertebrae) and bone mineral content (of the thigh bone) in the 100mg isoflavone group increased significantly. However, the 200mg isoflavone group showed no additional benefit (J Nutr Biochem. 2006 Feb 3; [Epub ahead of print]). This may be good news for the convenience and efficacy of functional foods, in that it indicates that (for certain ingredients) people do not need to “megadose,” as they often do with vitamins and minerals to get the optimal clinical benefit.
Dietary FibersDespite the depth of scientific substantiation of fiber, and even the health claims permissible for promoting fiber-containing products, consumers still consume only about half of the recommended daily amount (RDA) of 28g for women and 35g for men. However, a recent study by HealthFocus International (on behalf of an innovative starch supplier) found fiber consumption would increase if its intake was linked to health benefits, such as energy management, weight management, digestive health and blood sugar. Specifically, the phrase “helps maintain healthy blood sugar levels” was perceived as important to over two-thirds of those surveyed, even though they had never seen this printed on food labels. Shoppers were not even aware of blood sugar's link to dietary health when asked about it in 2002. Thus, its importance has skyrocketed from being so low that it was not even included in the previous study, to being one of the more important benefits that consumers seek.
The WHI also has provided some interesting insight into the use of dietary fiber for women's health. The practice of consuming fiber as a means of reducing the risk of colorectal cancer has been clarified, with recent research showing men who have diets high in fiber are 29% more likely to be protected from colorectal cancer than women. This data comes from a new study in the American Journal of Clinical Nutrition (vol. 83, pp. 343-349) and may explain some of the conflicting results from other studies reported in the past. However, some questions were raised once again as to the validity of the results due to the study's design and poor compliance among participants.
Calcium and Vitamin DOnly an estimated 10% of girls and 30% of boys are getting the recommended daily intake (RDI) of calcium, according to a new study published inPediatrics(vol. 117, pp. 578-585). This is troubling news considering osteoporosis affects 55% of the over-50 population and 80% of these sufferers are women. Another study, which appeared in theJournal of Nutrition(vol. 135, pp. 2362-2366), showed that calcium supplementation of women aged 20 to 25 had no measurable effect on bone density, thereby suggesting teenage years are the most important to calcium supplementation and reducing risk of osteoporosis. The authors of the Pediatrics study suggested that a low intake of calcium may be related to the substitution of soft drinks for milk, and the belief among young women that dairy products are fattening. These attitudes also provide an opportunity for food formulators to design functional drinks that are more appealing to adolescents who are in need of better calcium supplementation.
Again, published research from the WHI calls into question our beliefs about calcium and vitamin D supplementation. In this research, the combination of vitamin D and calcium, which has been recommended for reducing the risk of bone fracture for older people (particularly from osteoporosis), may be less beneficial than originally thought. In this study, published by the New England Journal of Medicine (vol. 354, pp. 669-683), the WHI conducted a trial that showed that a combination of vitamin D and calcium did not reduce the risk of fractures in postmenopausal women. After seven years of follow-up with the participants, calcium and vitamin D supplementation resulted in a small but significant improvement in hipbone density, but the incidences of bone fracture remained unaffected. Once again, the study's results may be misleading, as only 59% of the participants actually adhered to the supplementation recommendations, although the results among this group were favorable.
Certain studies also have supported the use of vitamin D and calcium supplementation in older women. For example, a double-blind, randomized, placebo-controlled study, published in the Archives of Internal Medicine (vol. 166, pp.424-430) “supplemented the diets of 199 men and 246 women [age 65 or older] with 700IU of cholocalciferol (vitamin D3) plus 500mg of calcium in the form of calcium citrate malate, or placebo.” Daily supplementation cut the rate of falls among elderly women by 50%, but not men. The researchers noted that earlier studies linked vitamin D and calcium supplements to fewer falls, as well as a lower risk of osteoporosis and osteoporotic fractures.
Folic AcidA new study shows that despite eating folic acid-fortified foods, pregnant women who do not supplement their diets with additional folic acid are eight times more likely to have low serum folate values (American Journal of Obstetrics and Gynecology, vol. 194, pp. 203-210). This study shows that although all cereals and grains are fortified in the U.S., this strategy may not be sufficient. The results of this study suggest more market opportunities exist for the development of folic acid-fortified foods and the promotion of folic acid supplements.
The National Council for Folic Acid is promoting supplement use among Hispanic women, who are almost twice as likely to give birth to children with birth defects (see Website Resources). Hispanic women consume the least amount of folic acid of any ethnic group. Although all of the cereal-based foods in the U.S. must be fortified with folic acid, many staple foods, such as corn-based products, have little folic acid and are not subject to the fortification rule. Perhaps the fortification of corn-based products such as tortillas can better reach this ethnic population in the U.S. Hispanic-Americans represent a large potential market for food processors, because they will become the nation's largest ethnic minority in the early 21st century.
ProbioticsThe probiotics market has grown, as evidenced by new product innovations and an increase in research and development activity. For instance, Danone has teamed up with the Pasteur Institute to discover new probiotic strains and to gain a better understanding of the mechanisms behind probiotics. Danone has reported growth in the drinkable yogurt market, with its own probiotic brand ACTIVIA showing 30% growth in the third quarter of last year. Probiotic cultures have been growing at a rate of around 15% in North America, which has led to many innovations in the yogurt market. Probiotics are beginning to appear in other beverages, confectionery products and spreads. ChocoMed™ (a subsidiary of House of Brussels Chocolates) launched its first functional chocolates under the ChocoMed Pure Chocolate label at the end of 2005.
Certain probiotic benefits extend beyond gut health, as they may be especially helpful in preventing and treating vaginal infections (World Journal of Urology, vol. 31, pp. 1-5). As more research is conducted and the correct strains are identified, perhaps the use of functional foods such as yogurts specifically targeted toward women will provide more comprehensive women's benefits. Research also is extending into the benefits that probiotics—consumed by the mother—may provide her newborn baby (Canadian Family Physician, vol. 51, pp. 1477-1479).
As research continues in many areas of nutritional health, there seem to be ever-increasing opportunities for providing consumers with well-substantiated functional food products. Every so often, information that seems to contradict what “we thought we knew” comes along, and is picked up by the mainstream media and considered very newsworthy. What kind of impact this has on consumers' dietary and health behavior is a concern. Thus, it is important that we look at new science—good or bad—with a critical eye. Stephen Daniells, a food science reporter, calls the recent media focus on low-fat diets from the WHI “the cost of bad research.” Indeed, figuring out how to interpret and use the results from the WHI as well as other ongoing clinical investigative work on women's nutrition will be up to nutritionists and food formulators alike.
Website Resources:www.nhlbi.nih.gov/whi/ — National Institutes of Health, Women's Health Initiative
www.whi.org/ — Website with information for participants in the WHI study
http://drcranton.com/hrt/HRT_benefits.pdf — Site that lists supporting documentation for hormone replacement benefits
http://archinte.ama-assn.org/cgi/content/abstract/ 166/4/424 — An abstract of the study on vitamin D and calcium supplementation and the prevention of falls
www.nutraingredients-usa.com/news/ng.asp?id=64867 — Hispanic women and lack of folic acid
Sidebar: Harbingers of HealthThe Centers for Disease Control (CDC) released some heavy statistics from its National Health and Nutrition Examination Survey (NHANES), which collects data from actual in-person height and weight measurements. Data from 3,958 children and adolescents (2 to 19 years in age) and 4,431 adults (20 and over) were obtained in 2003-2004 and compared to 1999-2000 data. The results show obesity rates in one subgroup—adult women—have not increased. An Associated Press release notes “…some experts think the leveling off in women could signal a turning point in the nation's obesity epidemic.” It quotes William Dietz, director of the CDC's Division of Nutrition and Physical Activity, as saying, “Women have always been more responsible about health than the general population…I'd like to think this shows women are leading the way in recognizing obesity as a health threat."
—Claudia D. O'Donnell, Chief Editor