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Update From the Medical Journals: October 2008
October 31, 2008  By Mary Pickett, M.D.
Harvard Medical School What's the latest news in the medical journals this month? Find out what your doctor is reading. Government Issues New Physical Activity Guidelines The U.S. Department of Health and Human Services published new recommendations for physical activity on October 7. The guidelines recommend 2 1/2 hours of moderate to vigorous physical activity a week for most Americans. There are special recommendations for people who don't exercise regularly, children, pregnant women, older adults and people with chronic illnesses. Here is how you can satisfy the guidelines: - Children and adolescents – Do at least one hour of moderate to vigorous exercise per day: Include vigorous activity (such as biking, running, or field sports), muscle-strengthening exercises (such as climbing), and weight-bearing (bone-strengthening) activities (such as running or jumping rope) on at least three days of the week.
- Adults – Spend at least 2 and ½ hours per week doing moderately intensive aerobic exercise (such as brisk walking or gardening). If you prefer, you can exercise vigorously (for example running, swimming laps) for 1 hour and 15 minutes per week. Ideally, to get the maximum health benefits from exercise, increase the time to five hours per week of moderate-intensity aerobic exercise or 2 ½ hours of vigorous exercise. Include muscle-strengthening exercises (weight training, sit-ups, pushups, carrying heavy loads) on at least 2 days of the week.
- Older adults – Keep exercising like other adults as long as you can sustain that level of exercise. If you have a history of falls or have balance concerns, include exercises like tai chi, other martial arts or yoga.
- Pregnant women – Spread 2 1/2 hours of moderate-intensity aerobic activity through the week. If a woman was vigorously active prior to getting pregnant, vigorous activity can be continued through the pregnancy. Continue exercise after delivery.
- People with chronic conditions – In general, exercise recommendations are the same as for well people. However, it is recommended that people with chronic illnesses discuss their exercise plans with their doctors.
Most Americans exercise less than is recommended. Regular exercise habits have been shown to lower the risk for premature death, heart attack, stroke, high blood pressure, diabetes, colon cancer, breast cancer, bone thinning, dementia and depression. Back to top Depression Adds to Heart-Disease Risk The American Heart Association (AHA) says that doctors should check to see if their patients with heart disease also have depression. The AHA released the recommendation September 29 online. It was published in Circulation on October 21. There's evidence that being depressed adds to your risk from heart disease. Depression is three times more common in people who survive a heart attack or go into the hospital with heart problems, compared with usual rates of depression in the community. The idea that depression puts people at added risk for heart events is not new. Forty years ago, a study showed that middle-aged widowers had a 40% higher death rate during the first six months after a wife's death. More than half of these deaths were from heart attacks or rhythm changes. Many experts blame depression for the added heart events. Stress can also trigger heart events. After the terrorist attacks of 9/11, cardiologists who track heart rhythm recordings from automatic implantable cardioverter defibrillators (AICDs) noted that the rate of life-threatening rhythm changes had doubled in several cities. The rate returned to expected levels in later months. Doctors don't know why emotional stress may contribute to heart risk. Changes in brain hormones occur with stress or depression. Some experts think this may affect the flexibility of blood vessels and the way the heart responds to stress. Some doctors wonder whether heart disease or depression comes first. Heart disease can certainly make life more difficult, and depression more likely. When doctors interview patients diagnosed with a heart attack, about 15% to 20% of the patients have major depression. We don't know for sure whether successful treatment for depression can lower the risk a person faces from existing heart disease. Heart and psychiatry specialists suspect that it can. At a minimum, identifying and treating depression is likely to improve depression symptoms. Back to top Fruits and Vegetables Offer Major Protection Against Heart Attack Chew on this: Experts have demonstrated in a multi-nation study that 30% of heart attack risk could be due to bad eating habits. Blame it on eating too few fruits and vegetables, and too many fried foods, salty food snacks, eggs and meat that together make up the typical "Western" diet. This was the conclusion after researchers analyzed diet data from the "INTERHEART" study, which was based on the habits of 16,407 people from 52 countries. The report was published online by the journal Circulation on October 20. Study participants included 5,761 people who had had a previous heart attack. The other participants had no heart attack history but were similar in age. This allowed the researchers to compare habits and histories of both groups and identify heart risks. The researchers used a survey to collect information about people's eating habits. They also collected data about known heart disease risks, such as smoking, high blood pressure and family history. Using sophisticated math, researchers were able to separate the effect of eating habits from other known risk factors. The participants were divided into three groups based on eating patterns: - Western diet, containing a lot of fried foods, salty snack foods, eggs and meat
- Prudent diet, containing lots of fruits and vegetables
- Oriental diet, containing soy and tofu proteins, soy sauces and Asian seasonings
People with a strongly "Western" style of eating had a somewhat higher-than-average heart attack risk. People who ate an Oriental diet had no obvious heart risk from their diet. The prudent diet was by far the best way to avoid heart disease — eating raw vegetables, green leafy vegetables, other cooked vegetables, and fruits offered definite protection against heart risk. If everyone in this study had eaten a highly "prudent" diet, the researchers calculated that about 30% of the heart attacks that occurred in the study participants could have been prevented. The participants in this study were generally very healthy. They were only enrolled in the study if they did not have high cholesterol, did not have diabetes, did not have a long history of chest pain (angina) leading up to their heart attack, and did not have a diagnosis of hypertension (high blood pressure). Choosing participants so carefully allowed the researchers to avoid some confusion when they analyzed their results. We can’t accurately predict, based on this study, whether diet is even more important for people who have diabetes, hypertension, high cholesterol or another heart risk. But it is "prudent" to suggest that it is. More News in Brief - Vitamin D Supplements Are Recommended For Most Kids. Children need twice as much vitamin D as previously recommended, according to a new guideline released October 13 at a meeting of the National Conference and Exhibition of the American Academy of Pediatrics (AAP) in Boston. The report and a news release were also published on the AAP website. Newborns, infants, children, and teens should get 400 units (also called international units, "IU") of vitamin D daily. A portion of vitamin D comes from vitamin-fortified milk (100 IU of vitamin D per 8-ounce serving). Most children do not drink four servings each day, so most will need a supplement to provide the 400 IU of vitamin D. This is in addition to the vitamin D that children get by exposure to sunlight. Even kids who spend a lot of time outdoors need the 400 units. Research shows that 400 IU can treat poor bone health in children who have poor growth or rickets (demineralized bone due to low vitamin D levels). Adequate vitamin D is also associated with a lower risk for cancer and diabetes, and improved recovery from infections in adults.
- Colon Cancer Screening Can Stop At Age 75. The U.S. Preventive Services Task Force (USPSTF) released new guidelines online on October 7 that colon cancer screening can stop at age 75. The recommendation is based on the limited life expectancy after age 75, which reduces the value of detecting cancer in an early stage. The USPSTF reviews tests, analyzes evidence and provides updates to doctors and patients about which tests are sensible for preventive health care, and which tests are not. The new guidelines will be published in the November 4 issue of the Annals of Internal Medicine.
Back to top Mary Pickett, M.D. is an Associate professor at Oregon Health & Science University where she is a primary care doctor for adults. She supervises and educates residents in the field of Internal Medicine, for outpatient and hospital care. She is a Lecturer for Harvard Medical School and a Senior Medical Editor for Harvard Health Publications.
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