Scientific Update
By Reed Mangels, PhD, RD
Don't Want Cataracts? Eat More Kale!
Cataracts are a common eye problem in older adults. While they can be treated, prevention of cataracts would certainly reduce health care costs and could improve quality of life for many older people. A number of dietary antioxidants have been examined as possible preventive agents, including vitamin C, vitamin A, and various carotenoids.
Researchers recently examined the association between carotenoid intake and cataract removal in more than 77,000 women and 36,000 men. Carotenoids are substances like beta-carotene which are found in foods. After controlling for factors like age and smoking, subjects with the highest intakes of two carotenoids, lutein and zeaxanthin, had the lowest risk of having had cataracts removed. Women with the highest intakes of these carotenoids had a 22% lower risk of requiring cataract removal compared with those who had the lowest intakes of these carotenoids; men had a 19% lower risk. Among specific foods, for women, spinach and kale were associated with decreased risk of cataracts; for men, broccoli and spinach were associated with decreased risk.
The authors recommend daily use of vegetables and fruits high in carotenoids. Foods which are especially high in lutein and zeaxanthin include kale, collard greens, spinach, Swiss chard, mustard greens, beet greens, okra, and romaine lettuce.
Willett, W.C., Seddon, J.M., Stampfer, M.J., et al. 1999. A prospective study of carotenoid and vitamin A intakes and risk of cataract extraction in US women. Am J Clin Nutr 70:509-516.
Brown, L., Rimm, E.B., Seddon, J.M., et al. 1999. A prospective study of carotenoid intake and risk of cataract extraction in US men. Am J Clin Nutr 70:517- 524.
Are US Adults Eating Enough Fruits and Vegetables?
We've all seen the slogan "Strive for Five!" We are being encouraged to eat more fruits and vegetables, at least 5 servings a day. The typical US adult does not reach these goals. A study of more than 15,000 adults found an average daily intake of 3.6 servings of fruits and vegetables. Less than 1/5 of those surveyed ate 5 or more servings of fruits and vegetables per day. People typically ate fewer vegetables than fruits. Older people consumed more fruits and vegetables than either middle aged or younger people. College graduates ate more fruits and vegetables than did those with less education.
Frequent use of fruits and vegetables has been associated with all sorts of health benefits, including lower rates of some kinds of cancer. It would seem that vegetarians would eat more fruits and vegetables than the general population, but we don't know this for sure. What about you? Do you eat five or more servings daily?
Thompson, B., Demark-Wahnefried, W., Taylor, G., et al. 1999. Baseline fruit and vegetable intake among adults in seven 5 A Day study centers located in diverse geographic areas. J Am Diet Assoc 99:1241-1248.
FDA Approves Health Claim for Soy Protein and Heart Disease
Besides providing information about ingredients and amounts of fat and protein in a food, food labels can also make health claims if these claims are approved by the Food and Drug Administration (FDA). On October 26, 1999, the FDA approved a health claim for soy protein and heart disease. This means that the FDA has looked at the scientific studies examining soy protein's role in reducing risk of developing heart disease and has concluded that soy protein included in a diet low in saturated fat and cholesterol may reduce the risk of heart disease by lowering blood cholesterol levels.
Labels of products like soy beverages, tofu, tempeh, soy-based meat analogues, and possibly some baked goods may contain a statement like, "Diets low in saturated fat and cholesterol that include 25 grams of soy protein a day may reduce the risk of heart disease.
One serving of (name of food) provides ____ grams of soy protein." Foods which have this statement on their label must also be low in fat, low in saturated fat, and have a low cholesterol content. Foods made with the whole soybean may also qualify for the health claim if they contain no fat in addition to that present in the whole soybean. Foods must also contain at least 6.25 grams of soy protein per serving, one quarter of the level of soy protein which has been shown to have a cholesterol lowering effect.
Federal Register 64 (206):57699-57733 (October 26, 1999).
FDA Issues Standards to Enhance Safety of Sprouts
Raw bean sprouts have been associated with more than 1,000 cases of foodborne illness (food poisoning). In July 1999, the US Food and Drug Administration warned all consumers to avoid eating raw bean sprouts. Sprouts can be contaminated with Salmonella and E. coli. These bacteria appear to be present in the seeds which are being sprouted. When the moist seeds are held at warm temperature, part of the sprouting process, bacterial growth is stimulated.
To protect consumers, the FDA recently issued guidelines for sprout producers and seed suppliers. These guidelines include recommendations to cultivate seeds to be used for sprouting using sanitary conditions, to disinfect seeds (with solutions such as calcium hypo-chlorite), and to test used irrigation water from each batch of sprouts to determine whether Salmonella and E. coli are present. For more information see <http://www.cfsan.fda.gov/~lrd/hhsprout.html>.
Federal Register Notice and Guidance Documents (October 27, 1999).
Raw Food Diets
Raw food diets are those which are composed mainly or exclusively of unheated foods, mainly of plant origin. Fruits and vegetables make up the bulk of food consumed. Little is known of the effects of these diets on long-term health. A study of more than 500 German adults who used raw food diets found that adoption of this diet led to a rather large decrease in body weight. Study participants frequently (25% of women) had very low body weights, with those subjects whose diets were almost entirely raw foods having the lowest weights. Vegans following raw food diets were no more likely to be underweight than were vegetarians or meat eaters. Close to one out of three women under 45 years of age had partial to complete amenorrhea (absence of menstrual periods). Amenorrhea can lead to impaired fertility and increase the risk of osteoporosis and heart disease. Excessively low body weights can also be harmful. The researchers who conducted this study do not recommend use of a strict raw food diet containing more than 90% of food in the raw state because of the risk of amenorrhea and excessive weight loss.
Koebnick, C., Strassner, C., Hoffmann, I., Leitzmann, C. 1999. Consequences of a long-term raw food diet on body weight and menstruation: results of a questionnaire survey. Ann Nutr Metab 43:69-79.
