Something to Chew On
A balanced and-sometimes-supplemented diet during pivotal points in life can protect your health.by Monika Guttman
Call it age-related eating, the notion that consuming certain foods can slow the aging process.
Tailoring a diet for future health is not a new concept. It is widely accepted that eating lean meats while young leads to leaner bodies and less atherosclerosis in middle age-and that a diet heavy in fruits and vegetables can ward off many diseases.
"But there has been no direct evidence that a healthy diet in the 20s will have a better outcome than starting a good diet later in life," says Howard Hodis, M.D., director of the USC Atherosclerosis Research Unit. He also suggests that drawing conclusions from published nutritional studies be done carefully and in consultation with a health professional.
What are the new facts about food? Extensive research into what we eat-particularly vegetables and fruits-is revealing much about the role of vitamins and minerals such as the "antioxidant" vitamins C and E that may boost immunity. A study in the Journal of the National Cancer Institute found that men who consume vitamins C and E reduce risk of prostate cancer, but Hodis cautions that several studies "show increased risk of cancer in smokers who use supplements and multivitamins."
Science is just beginning to understand the potential benefits of "phytochemicals," compounds produced by plants to protect themselves against disease. A study in the American Journal of Clinical Nutrition reports that the lutein in broccoli, dark-green leafy vegetables and orange vegetables may protect against cancers.
As the research advances, nutritionists and others say the best diets should not rely heavily on nutrients or supplements. Rather, good diets should include a variety of foods and a "colorful plate"-a variety of fruits and vegetables in a spectrum of dark green, light green, yellow, red and orange. "This is an old concept, but it helps to think of a balanced diet in those terms," says Sally Rauch, R.D., M.S., a nutritionist in the USC division of internal medicine. "We're learning that components of foods work together in the body to produce beneficial effects."
Evidence mounts that a moderate daily multivitamin dose may be beneficial-particularly for those whose diets are not well balanced. The American Dietetic Association (ADA) strongly recommends that daily nutritional needs be met through a varied diet, but supports vitamin supplementation up to the Dietary Reference Intake limits (formerly Recommended Daily Allowances). Hodis suggests that, lacking evidence to specify optimal dosages, multivitamins should only be taken up to these limits to avoid potential side effects.
"There's only slight evidence to support higher-level vitamin supplements," Hodis says. And he cautions: "People say, 'Vitamins can't hurt you.' But we don't know that for sure. There is some evidence that certain supplements may be harmful." A controversial Finnish study found an 18 percent increase in lung cancer deaths in smokers who took 20 mg. supplements of betacarotene daily.
Trace elements as supplements are also getting attention. At the USC Department of Urology researchers are investigating whether selenium, a trace element found in meat, fish, grains and nuts, helps reduce prostate cancer in men at high risk.
One supplement widely approved is calcium, because most Americans, especially women, do not get enough of it. According to the ADA, Americans on average consume calcium in amounts well below the recommended 1,000 mg. daily minimum. As a result, one in two women and one in eight men over age 50 will have an osteoporosis-related bone fracture in their lifetime, according to the National Osteoporosis Foundation.
"From age 12 on, women can compensate pretty well-until they hit 35," says Donna Shoupe, M.D., professor of obstetrics and gynecology at the Keck School of Medicine. "After that, there is bone loss and risk of osteoporosis increases." Shoupe and others recommend calcium supplements, particularly for those whose diets do not include adequate amounts of dairy products, tofu or dark-green leafy vegetables. There is some evidence that calcium may protect more than bones: a study led by Robert Haile, M.D., professor of preventive medicine at the Keck School of Medicine, showed taking calcium supplements may help ward off colorectal cancer as well.
Diet can't do the job alone, notes Loren Lipson, M.D., chief of geriatric medicine at the Keck School. "One of the most important factors is exercise," he says. "With it, the body functions better and is usually leaner. Without it, the body does not maintain muscle mass, and that becomes a serious problem as you age." Other important lifestyle factors: screening for health risks, such as heart disease, high blood pressure, diabetes and breast, colorectal, prostate and lung cancers-and not smoking.
Diet remains central to good health. Here are the latest views from science and medicine on what to eat-and when-to help achieve a sound, healthy future:
Infancy
Popular diets can harm infants. Pediatricians do not recommend a low-fat diet for children under age 2 because certain fatty acids are essential for rapid growth at this stage of life.
Many infants lack essential nutrients like iron because they do not eat foods rich in iron, such as meat. Low iron intake in the first year of life can retard brain development, so pediatricians test iron levels at about eight months of age. Parents can use iron-fortified infant food and formulas, or pediatricians can prescribe iron supplements made specifically for babies.
Childhood
According to the ADA, one of four American children is overweight. Studies like those by USC's Michael Goran, Ph.D., associate director of the Institute for Prevention Research, have shown that obesity in children leads to obesity in adulthood with all its inherent risks.
But the ADA warns that growing children should not restrict calories to achieve a healthy weight, because "restricting calories and nutrients can retard or stunt growth and impair learning." Hodis recommends that children exercise regularly and eat appropriate amounts of a variety of foods.
By age 5, a child's eating style should conform to dietary guidelines for older children and adults. Fat should be limited to 30 percent of total calories, and saturated fat to no more than 10 percent of total calories.
Teens
After age 11 there is an increase in the percentage of youth and adolescents whose diets do not meet the established levels of vitamins and minerals, particularly iron zinc and calcium, the ADA says.
A Purdue University study showed that calcium absorption is greatest in the teen years. By age 14, teens reach 91 percent of their total bone density; the rest by age 22. "Ideally you want adequate calcium intake from the beginning of life and then maintain that throughout life," says Hodis. "If you miss this window of opportunity for bolstering bone density, it could lead to problems." The National Institutes of Health recommends that from age 12, young women get 1,200 to 1,500 mg. of calcium daily, dropping down to 1,000 mg. daily after age 20.
Menarche-the beginning of menstruation-is a nutritional flash point that may lead to anemia if sufficient iron levels are not maintained, says Shoupe. When a young woman begins menstruating, it is time to measure iron levels and supplement if necessary.
20s & 30s
When young adults begin creating independent lives it is crucial that they continue the healthful eating habits they should have established earlier-or adopt good habits, says Hodis.
The current Food Guide Pyramid from the U.S. Department of Agriculture suggests that for optimal protection against many types of cancer, young adults should consume more than the usual five servings of fruits and vegetables every day. Eight servings of fruits and vegetables daily, the new recommendation, supply approximately 27 grams of fiber-close to the suggested 25-35 grams. Whole grains, which provide fiber, folate, vitamins B6 and E and other nutrients, are also emphasized.
Pregnancy
Substantial evidence recommends that women take folic acid before conception and through the first few months of embryonic development. This can prevent such disastrous outcomes as spina bifida and neural tube defects. Each year about 2,500 babies in the United States are born with neural-tube defects, but perhaps up to 75 percent could be prevented with folic acid supplements.
Although folic acid can be obtained by eating fortified foods like breads, pasta, rice and breakfast cereals, many physicians suggest taking a prenatal vitamin containing folic acid.
Calcium is also important during pregnancy, "because the baby's skeleton is built from the mother's calcium," says Lipson. "If she doesn't have adequate calcium intake to replace the loss to the baby, her risk of getting osteoporosis increases." Lipson recommends tofu, spinach and canned salmon as excellent sources of calcium, along with milk and dairy products. The NIH recommends 1,000 mg. of calcium per day for pregnant and lactating women 18 years of age and over, and 1,300 mg. for those under 18.
40s & 50s
Consider age 40 a time to change bad habits and pay more attention to diet and exercise, says Hodis. From then on, every bite counts more because metabolism begins to slow down, meaning fewer calories are required to maintain the same energy level. "This is when you should focus on quality, not quantity," he says.
After age 30, the body starts losing muscle mass, says Rauch. "And because muscle tissue burns calories more efficiently than fat tissue and many people are less active as they age, they fulfill a formula for gaining weight."
Rauch notes that nutritional recommendations are the same for 20- and 45-year-olds. But at 45, she says, caloric intake should probably be reduced by 100-200 calories a day. Other tips include choosing reduced-fat and fat-free foods and participating in physical activity for at least 30 minutes each day.
"Starting in the 40s," Hodis says, "we don't absorb nutrients as effectively. That is probably the time to start taking a multivitamin supplement, even though we still need this backed up by scientific evidence."
Menopause
Women can lose up to 20 percent of bone mass in the first five to seven years following menopause, making them more susceptible to osteoporosis. But how much to supplement with multivitamins for maximum benefit remains open to discussion, says Shoupe. "If you do estrogen replacement therapy, you probably need about the same amount of multivitamins-about 1,000 mg. a day-because the ERT helps you absorb them normally." According to the NIH, women who do not take estrogen should probably take at least 1,500 mg. of multivitamins per day.
Iron supplements are not needed after menopause. Women are often iron deficient when menstruating, says Shoupe, but after menopause too much iron can form deposits in the liver and lead to cirrhosis or liver failure. Many vitamin supplements tailored for seniors drop the iron completely or reduce it significantly.
60, 70s, & Older
As people age, the need to monitor for specific nutrients increases. For example, the elderly have a difficult time producing vitamin D-which in turn is essential for calcium absorption. "The skin makes vitamin D when exposed to the sun, and many frail elderly just don't get outside," says Lipson. Those in their 70s produce only 40 percent of the vitamin D they produced at age 8. The NIH recommends gradually increasing vitamin D dosage from 200 IU to 600 IU by age 60.
Lipson says that the elderly often have vitamin deficiencies because they can't get to the store for fresh produce, or they may have a decreased appetite. He suggests adding a nutritional supplement like Ensure.
That advice is even more important for the frail elderly, says Lipson. "Their nutritional requirements are about the same as teenagers, because their bodies are under so much stress." In addition to supplements, he says, it is even more vital that meals contain a variety of colors for the vitamin benefit.
While it is best to start age-related eating as early in life as possible, the good news is that even a youth spent devouring pizza and fast food can be overcome. "What has been shown in studies is that improving diet at any stage in life leads to both immediate and long-term benefits," says Hodis. "Exercise is vital as well. It's never too late to start a newer, healthier lifestyle."
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