Trends in Modern Nutrition
Author: Winston Craig, MPH, PhD, RD.
An estimated 180,000 new cases of breast cancer will be diagnosed in the United States in 2007, with 40,900 deaths expected from breast cancer, the most common cancer in women. While heredity, reproductive/hormonal factors are involved, diet and other lifestyle factors are also determinants of breast cancer. Obesity and use of alcohol are risk factors for breast cancer, while fruits and vegetables rich in fiber, phytochemicals and antioxidant vitamins protect against breast cancer. Low serum vitamin B12 levels (below a certain threshold) have recently been shown to increase the risk of breast cancer among postmenopausal women. Death rates in the United States from breast cancer are highest in the northeastern states and lowest in the sunny southwest and Hawaii. Recent studies suggest that a decreased vitamin D and calcium intake are associated with an increased risk of breast cancer.
In 2007, an estimated 112,340 Americans will be diagnosed with colon cancer and another 41,420 with rectal cancer. Within 10 years, 55 percent are expected to die. Avoiding excess weight, increasing physical activity, and eating more fruits and vegetables and less meat are recommended as significant ways to lower one's risk of colorectal cancer. Data from the CDC shows that obesity triples the risk of developing colon cancer.
Rates of diabetes worldwide are expected to double in the next 10 years. Type 2 or adult-onset diabetes is now showing up in adolescents. Studies suggest that over 80 percent of diabetes is due to overweight and obesity. Worldwide obesity rates are soaring and in the United States obesity has increased 30 percent over the past 10-15 years. Physical activity, whole-grain foods, and high fiber fruits and vegetables can reduce the risk of diabetes. Studies have shown all these to be protective factors.
Two new cholesterol-lowering margarines (Benecol and Take Promise) are hot items on the market right now. These margarines are fortified with plant sterols which block cholesterol absorption. Various studies show they can lower elevated blood cholesterol levels by as much as 10 percent. However, new research shows that persons using these margarines experienced a 25-30 percent drop in their blood levels of beta-carotene, a change that may result in reduced protection against cancer and heart disease. Plant sterols are naturally found in legumes, nuts and seeds.
The FDA has decided to require nutrition labeling that clearly states how much trans fat a product contains. Crackers, cookies, doughnuts, french fries and margarine all contain trans fat, a fat that raises the risk of heart disease by raising LDL cholesterol and lowering HDL cholesterol levels.
Low-fat diets have become very popular since the media has pushed the notion that all fat is bad for your health. However, low-fat diets are not considered ideal by some scientists because they can increase blood triglyceride levels and lower HDL cholesterol levels. A diet that contains 30 - 35 percent fat does not seem to be detrimental and actually improves cardiovascular risk factors as long as the fat comes from monounsaturated fat, such as nuts, avocado, olives and olive oil. In a recent report, 22 healthy men and women, aged 21 to 54 years, with a mean cholesterol level of only 188 mg/dl, were fed a diet rich in monounsaturated fat, derived from peanuts and peanut butter. On this diet they experienced a 14 percent drop in LDL cholesterol levels and a 13 percent drop in blood triglycerides while their HDL cholesterol levels were unchanged.
Stroke kills over 150,000 Americans a year, making it the number 3 killer. But there is some good news from research at Harvard. Men who consumed an average of 5 servings/day and women who consumed an average of 6 servings/day of fruit and vegetables experienced a 30 percent lower risk of stroke compared to those consuming less than 3 servings a day. Cruciferous vegetables (broccoli, cauliflower, cabbage), green, leafy vegetables, citrus fruits and citrus juices, but not potatoes or legumes, contributed the most to the protective effect of fruit and vegetables.
It is anticipated that research will continue to validate the value of using whole-grain foods in our diet, rather than refined grains. In a recent study from northern Italy, researchers found that those who had the highest consumption of refined cereals (pasta, breads, or rice) experienced a 30 to 60 percent higher incidence of cancer of the gastrointestinal tract (mouth, esophagus, stomach, colon, and rectum) compared with those who had the lowest intake of refined grains. In the Nurses' Health Study, women who consumed an average of 2.7 servings of whole grain breads/cereals/rice/and bran had a risk of heart disease that was 33 percent lower than those women who had little, if any, whole grain products.
Studies on soy, rich in isoflavones, continues to show its effectiveness in reducing the risk of breast and prostate cancers, osteoporosis, and heart disease. Recently, when researchers from Wake Forest Univer-sity fed soy protein to 156 subjects for 2 months they observed significant drops in blood lipids, especially in those with initially elevated cholesterol levels. In such persons blood cholesterol and LDL cholesterol levels fell 9 and 10 percent, respectively. Low-fat choices may not provide these beneficial effects since low-fat soy milk and low-fat tofu are low in the health-promoting isoflavones. Furthermore, the use of antibiotics has a negative effect on isoflavone metabolism, so that a regular use of antibiotics may negate the positive effect of soy in the diet.
There is a surge of interest in functional foods, that is, those foods that are rich in health-promoting phytochemicals. In a new study from the University of Wisconsin, grape juice was shown to improve blood flow by 6.4 percent and protect LDL from oxidation by 35.4 percent. Earlier research revealed that the flavonoids in grape juice decreased the tendency of blood clots to form. Together, these results suggest that the regular use of grape juice (rich in phytochemicals) will help reduce the risk of cardiovascular disease. Grape juice is certainly a safer way to achieve protection against heart disease than wine.
Dietary antioxidants play a role in preventing age-related cataracts by preventing the oxidation of proteins and lipids within the lens. Spinach, kale, broccoli, and other leafy vegetables rich in the carotenoid lutein, reduce the risk of developing cataracts. In the Nurses' Health Study, women who ate spinach and other greens at least twice a week had an 18 percent lower risk of cataract surgery than women who consumed them less than once a month. In the Health Professionals' Study, men who ate broccoli more than twice a week had a 23 percent lower risk of cataract surgery than men who consumed broccoli less than once a month.
Obesity continues to increase in this country at a rapid pace. Many studies highlight the value of regular exercise for good health. In a study of 11,000 Germans, aged 50-69 years, moderate exercise improved health and helped with weight management. Those who exercised only 30 minutes to 2 hours a week experienced 2 percent reduction in blood pressure, a 3 percent drop in resting heart rate, and a 3 percent drop in body weight. These changes could be achieved by walking or cycling 5 times a week.
Women who regularly exercise may reduce their risk of breast cancer. In the Nurses' Health Study in Boston, those women who exercised an average of 7 hours a week had a 20 percent lower risk of developing breast cancer than in women who led a more sedentary life. Women exercising an average of 30 minutes a day experienced about a 10-15 percent reduction in risk of breast cancer. Researchers found that brisk walking or bike riding could reduce the risk of breast cancer as effectively as more vigorous exercise.
Food-borne illnesses continue to be a menacing health threat. The deadly food-borne pathogen, E. coli 0157: H7, which causes fever, lethargy, bloody diarrhea, and dehydration, is much more prevalent in the American meat supply than was previously thought. The E coli may be present in 50 percent of all cattle carcasses. This winter, egg cartons will carry a label warning consumers to thoroughly cook their eggs to avoid Salmonella poisoning, a leading cause of food-borne illness in the United States. For the second time in less than a year the FDA has issued an advisory warning against the consumption of raw sprouts (alfalfa, clover and radish sprouts). Three outbreaks of Salmonella have been associated with eating raw sprouts this year, affecting over 150 people. Contaminated water at the sprout facilities is to blame for these food-borne illnesses.
Inappropriate, and often unsafe, high-protein diets, such as the Zone diet and the Atkins' diet, continue to be promoted everywhere. People also continue to be attracted to strange health practices such as colonic cleansing. Chronic overuse of the "cleansing agents" can often produce dehydration, fainting and electrolyte disorders, or eventually they may compromise colonic function. Nevertheless, some people have the notion that they periodically need an internal cleansing to purge the gastrointestinal tract. It is their belief that pollutants and toxins build up in the colon and cause a range of diseases. Laxatives, herbal and fiber capsules and teas are commonly used to "sweep debris from the colon". In reality, the body has its own self-cleansing system. The cells of the gastrointestinal tract regenerate every 3 days.
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Soy, garlic, and purple grapes have antithrombotic effects, while monounsaturated-fat-rich plant foods may also have a protective role in blood clotting.