Along with diet, regular exercise is an essential ingredient for improving an unhealthy cholesterol profile. Exercise can lower “bad” low-density lipoprotein (LDL) cholesterol and triglycerides, and raise levels of high-density lipoprotein (HDL) – the “good” cholesterol. Plus, exercise is a crucial element in any weight-control program, and the National Cholesterol Education Program’s (NCEP) guidelines for therapeutic lifestyle changes emphasize weight control as an important component of treatment.

Almost as important, exercise can overcome the unfortunate tendency of a low-fat, lower-calorie diet to reduce levels of HDL, particularly in women. In one classic study, called the Stanford Weight Control Project, women on a low-fat diet saw their HDL levels drop 7% during a year of dieting. But women who combined diet and exercise — about eight miles of brisk walking or jogging a week — increased their HDL levels in addition to losing weight and lowering their levels of total and LDL cholesterol. For men, a low-fat diet alone didn’t change HDL levels, but diet plus exercise substantially increased them.

Even if you’re already somewhat active, the more exercise you get, the better. A landmark study of 17,000 Harvard alumni suggested that men who burn an extra 700 or so calories a week by walking, playing sports, or doing some other form of exercise live longer than those who aren’t active. The health benefits continue to increase up to about 2,000 calories a week, and then seem to level off from there. Information from a long-term study of female nurses shows similar trends for women.

The list below shows you activities that will burn 150 calories. If you undertake any of these activities five times a week, you’ll burn 750 calories, enough to start realizing health benefits. If you do two of these activities every day of the week, you’ll burn a little over 2,000 calories per week and reap a health bonanza. (These figures are based on a body weight of 150 pounds. If you weigh less than 150 pounds, it’ll take you longer to burn the same amount of calories. The opposite is true if you weigh more than 150 pounds.)

• Biking, 6 mph (38 minutes)
• Biking, 12 mph (22 minutes)
• Jogging, 5.5 mph (12 minutes)
• Running, 10 mph (7 minutes)
• Walking, 2 mph (38 minutes)
• Walking, 4.5 mph (20 minutes)
• Tennis, singles (23 minutes)
• Gardening (30–45 minutes)
• Washing windows or floors (60 minutes)
• Water aerobics (35 minutes)
• Swimming, 25 yards/minute (33 minutes)
• Raking leaves (35 minutes)
• Shooting baskets (35 minutes)

For more information on how to manage your cholesterol, order our special health report, What To Do About High Cholesterol. www.health.harvard.edu/HC.

Q: I’ve been taking Prilosec for esophageal reflux. My doctor says I may need to take it indefinitely. Is that safe?

A: Prilosec (generic name omeprazole) is a member of a class of drugs called proton pump inhibitors (PPIs) that has revolutionized the treatment of gastroesophageal reflux disease (GERD). PPIs work by shutting down the “proton pump,” an enzyme involved in the production of stomach acid. Although acid is necessary for digestion, acidic stomach contents can damage the esophagus, the tube that carries food from the mouth to the stomach.

GERD occurs when the lower esophageal sphincter (a valve-like muscle at the bottom of the esophagus) fails to close properly, and stomach contents flow back or “reflux” into the esophagus. When refluxed stomach acid strikes the esophagus, it causes the burning sensation, better known as “heartburn,” that you feel in your chest and throat.

Prilosec and other PPIs — esomeprazole (Nexium), lansoprazole (Prevacid), pantoprazole (Protonix), and rabeprazole (Aciphex) — are the most effective drugs for treating GERD. Since the condition is chronic, many people will need to take a PPI indefinitely because symptoms often return if the medicine is stopped.

Since PPIs have only been in widespread use since the 1990s, we don’t have much information about their long-term effects. Studies of patients taking omeprazole for up to 15 years have shown no significant adverse effects. Biopsies of stomach tissue have shown increases in certain kinds of cells and in stomach polyps, but neither of these changes is considered dangerous.

Even when drugs control symptoms, anyone with GERD should be regularly checked for complications of the condition, such as bleeding or ulcers in the esophagus. Also, scarring can narrow the esophagus and make swallowing difficult. Some people with GERD develop Barrett’s esophagus, a condition in which the cells lining the esophagus change and, over time, become cancerous.

Proton pump inhibitors are most effective when taken before a meal. Although PPIs have few drug interactions, if you’re taking other medications, you should check with your pharmacist or doctor.

Celeste Robb-Nicholson, M.D., is Editor in Chief of Harvard Women’s Health Watch (www.health.harvard.edu/women)