You can lower your cholesterol with a low-fat diet. But you get twice the bang for your buck if you eat lots of vegetables, fruits, and whole grains.

For years, Americans were told to avoid fats. But it's not enough to avoid unhealthy foods. New dietary guidelines stress the value of eating plenty of healthy foods: vegetables, fruits, whole grains, and beans.

How much better is the new advice? At least twice as good, find Stanford researcher Christopher Gardner, PhD, and colleagues. Gardner's team finds that people who eat a low-fat diet lower their cholesterol. But those who eat just as few fats and eat lots of plant-based foods double the diet's cholesterol-lowering power.

"The effect of diet on lowering cholesterol has been really minimized and undermined by a lot of clinicians and researchers saying, 'Yes, it has an effect but it is really trivial. It would be better to put you on drugs to control your cholesterol,'" Gardner says in a news release. "We weren't really giving diet a fair shake. We were so focused on the negative — just what to avoid — and not what to include."

The plant-food-enhanced diet isn't strictly vegetarian. It's simply rich in foods known to lower cholesterol. These include soy-based foods, garlic, soluble fiber (provided by food like oats, barley, psyllium and beans), whole grains, and nuts.

Two Low-Fat Diets

So what's more important — simply avoiding fat or eating lots of good foods? Gardner's team asked 120 people to help answer this question. These 30- to 65-year-olds had moderately high LDL "bad" cholesterol, ranging from 130 to 190 mg/dL. None was obese, and all were in generally good health.

For four weeks, half the volunteers adopted the old-fashioned low-fat diet and half stuck to a low-fat, plant-based diet. To minimize cheating, the researchers fed them dinner every weekday and gave them a cooler filled with foods for the rest of the time.

The diets were fat and calorie balanced so that nobody gained or lost weight. Some of the study participants were, indeed, overweight. Losing weight is a good way to cut your cholesterol. But the study was designed to look at the effects of diet and not weight loss.

Exactly what did they eat? Here's a sample menu for each group:

Low-fat diet:

— Breakfast: frozen waffles, butter, syrup, apple juice, coffee, and low-fat milk

— Morning snack: apple-grape juice and nonfat raspberry yogurt

— Lunch: turkey-bologna sandwich, light potato chips, caffeine-free Diet Coke

— Afternoon snack: lemon cake pudding and low-fat milk

— Dinner: garden lasagna, iceberg lettuce salad, French dinner roll, margarine, coffee

Low-fat "plus" diet:

— Breakfast: whole-wheat bread, sunflower-seed butter, smoothie, plain yogurt, tea, grapes

— Morning snack: soy nuts, sun-dried raisins

— Lunch: tempeh burger with vegetables and cheddar cheese on whole-wheat bread

— Afternoon snack: black licorice

— Dinner: parsley pesto and soba noodles, garlic butter, spinach and mandarin salad with sesame, egg, Odwalla Superfood juice, and tea

LDL Results After the Diets

After four weeks, those in the low-fat group cut their LDL "bad" cholesterol levels by 4.6 percent. Those in the low-fat-plus group got an extra 4.7 percent reduction, for a total LDL cholesterol drop of 9.3 percent. The findings appear in the May 3 issue of Annals of Internal Medicine.

People who take the powerful cholesterol-lowering drugs known as statins get about a 25 percent to 35 percent drop in LDL cholesterol.

Diet can have just as powerful an effect, write David J.A. Jenkins, MD, PhD, DSc, and colleagues in an editorial accompanying the Gardner study. In earlier studies, Jenkins' team has reported powerful cholesterol-lowering effects for diets containing a "portfolio" of cholesterol-lowering foods.

"The plant-based diet studied by Gardner and colleagues occupies an intermediate, bridging position between conventional diets low in saturated fat ... and drug therapy," Jenkins and colleagues write. "Gardner and colleagues' study also points to the advantage of combining several plant-based dietary strategies and forms a link with diets using more concentrated sources of the plant food components."

Jenkins and colleagues note that plant-based cholesterol-lowering diets could be used in combination with cholesterol-lowering drugs — both to achieve maximum cholesterol-lowering effects and to avoid the side effects of high drug doses.

By Daniel J. DeNoon, reviewed by Brunilda Nazario, MD

SOURCES: Gardner, C. Annals of Internal Medicine, May 3, 2005; vol 142: pp 725-733. Jenkins, D. Annals of Internal Medicine, May 3, 2005; vol 142: pp 793-795. News release, Stanford University. WebMD Feature: "Portfolio Diet: Recipe for Lower Cholesterol."