Exercise and diet improved cholesterol levels in high-risk adults
ACP J Club. 1999 Jan-Feb;130:16. doi:10.7326/ACPJC-1999-130-1-016
Stefanick ML, Mackey S, Sheehan M, et al. Effects of diet and exercise in men and postmenopausal women with low levels of HDL cholesterol and high levels of LDL cholesterol. N Engl J Med. 1998 Jul 2;339:12-20.
Can diet (National Cholesterol Education Program [NCEP] recommended diet), exercise, or both reduce low-density lipoprotein (LDL) cholesterol levels and increase high-density lipoprotein (HDL) cholesterol levels in adults with low levels of HDL cholesterol and high levels of LDL cholesterol?
Randomized controlled trial with 1 year of follow-up (Diet and Exercise for Elevated Risk trial).
A community study in California, USA.
180 postmenopausal women and 197 men. Women were 45 to 64 years of age, had HDL cholesterol levels < 1.55 mmol/L (60 mg/dL), and had LDL cholesterol levels between 3.23 and 5.42 mmol/L (125 to 209 mg/dL). Men were 30 to 64 years of age, had HDL cholesterol levels < 1.14 mmol/L (45 mg/dL), and had LDL cholesterol levels between 3.23 and 4.90 mmol/L 125 to 189 mg/dL). Exclusion criteria were history of cardiovascular disease, diabetes, or other severe illness; hypertension; treatment with insulin, cardiac medications, or cholesterol- or blood pressure-lowering drugs; smoking; high alcohol consumption; high blood glucose or triglyceride levels; or high body mass index. Follow-up was 97%.
The diet program was the NCEP step 2 diet (< 30% of calories from total fat, < 7% of calories from saturated fat, and < 200 mg of cholesterol/d) using an individual session and 8 group sessions during a 6-week adoption phase and monthly follow-up. The aerobic exercise program included an individual session and group sessions during a 6-week adoption phase and a 7- to 8-month maintenance phase. Exercise 3 times/wk was equivalent to brisk walking or jogging for 16 km/wk. Participants were allocated to diet alone (47 women and 49 men), exercise alone (44 women, and 50 men), diet and exercise (44 women and 50 men), or neither (43 women and 51 men).
Main outcome measures
Change in diet and lipoprotein levels.
The diet and diet-plus-exercise groups had reduced intake of calories; total, saturated, and monounsaturated fat; and cholesterol, with increased intake of carbohydrates. Body weight and waist-to-hip ratio were reduced in both diet groups. Exercise capacity was improved in both exercise groups. Total cholesterol and LDL cholesterol levels were reduced in the diet-plus-exercise group but not in the diet-alone or exercise-alone groups in both women and men. The changes in HDL cholesterol and triglyceride levels were not statistically significant in any group.
Diet plus exercise was effective at reducing total and LDL cholesterol levels in women and men with low HDL cholesterol levels and high LDL cholesterol levels at baseline. Neither the NCEP step 2 diet alone nor exercise alone improved the overall lipid profile.
Source of funding: National Heart, Lung, and Blood Institute.
For correspondence: Dr. M.L. Stefanick, 730 Welch Road, Suite B, Palo Alto, CA 94304-1583, USA. FAX 650-723-7018.
The dictum has long been that diet and exercise are the cornerstones of managing hyperlipidemia. As with many things that we "know," the picture is more complex than expected. Diet alone lowers LDL cholesterol levels but may also lower HDL cholesterol levels. Exercise alone raises HDL but does little to lower LDL cholesterol levels. This issue is important, because the risks resulting from lowering HDL cholesterol levels by diet might offset the gains resulting from lowering LDL cholesterol levels. Stefanick and colleagues address the important clinical benefits and risks of diet, exercise, and the combination of both. Several questions are worth examining.
1. Did the participants actually adhere to the interventions? The authors carefully document changes in caloric intake, metabolic expenditure, and conditioning, showing that the diet groups changed their diets and the exercise groups were more active.
2. Did the interventions work? Of note, diet alone and exercise alone had little effect on the lipid profile. The combination of diet and exercise, however, improved nearly all parts of the lipid profile. Thus, patients probably need to change their habits with respect to both physical activity and diet.
3. Will my patients adhere to this intervention? The intervention was intense. Nutritional counseling included 9 sessions and monthly follow-up. Both exercise groups attended supervised training 3 times/wk. The effects in practice are likely to be smaller.
4. What can I do in my busy practice? Adapting a model used for smoking cessation, you should do 4 things. First, ask the patient about nutrition and exercise habits. Second, advise about diet, exercise, and weight management. Third, assist in developing a diet and exercise plan. Finally, arrange follow-up to review progress and mutually solve problems. To save time, use instructional handouts, involve other health professionals (such as nutritionists, physiatrists, and kinesiotherapists), and have patients monitor their diet and exercise with a log, a strategy that has proven to be very effective.
Scott E. Sherman, MD, MPH
Veterans Affairs for the Study of Healthcare Provider BehaviorSepulveda, California, USA