Adding cholesterol-lowering foods to your diet

A study in The Journal of the American Medical Association (Aug.24/31, 2011) found that a vegetarian diet emphasizing a "portfolio" of cholesterol-lowering foods did a better job of reducing low-density lipoprotein — the so-called "bad" cholesterol — than a low-saturated-fat vegetarian diet. All participants in the study followed a heart-healthy diet rich in fruits, vegetables, and whole grains. Those in the portfolio group were told to emphasize four specific types of cholesterol-lowering foods in their diets — soluble fiber, nuts, soy protein, and margarines enriched with plant sterols — while those in the low-saturated fat group were told to avoid these foods.

For someone eating 2,000 calories per day, a portfolio diet would aim to provide the following amounts of these cholesterol-lowering foods:

• Soluble fiber: 18 grams per day of fiber from foods such as oatmeal, oat bran, barley, peas, beans, lentils, psyllium, and vegetables such as okra and eggplant
• Nuts: one ounce, or about one handful, per day
• Soy protein: 42.8 grams per day from soy-based foods such as soy milk, tofu, and soy meat substitutes (four ounces of tofu contains 9.4 grams of soy protein; eight ounces of regular soy milk contains six grams of soy protein)
• Plant-sterol-enriched margarine: 1.8 grams per day (1 to 2 tablespoons, depending on the product)

Below is a representative diet followed by participants in the portfolio group:

The study. Researchers at the University of Toronto enrolled 351 women and men with hyperlipidemia (high levels of fats in the blood), including an LDL level that averaged 171 milligrams per deciliter, or mg/dL. (Optimal LDL is less than 100 mg/dL). None of the participants were taking cholesterol-lowering drugs. All were instructed to follow weight-maintaining, largely vegetarian diets. Some were assigned to incorporate a "portfolio" of cholesterol-lowering foods into their diet. These foods included soluble fibers such as oatmeal, barley, psyllium-enriched cereals, okra, and eggplant; nuts; soy protein (soy milk, tofu, and soy meat substitutes); and margarines enriched with plant sterols. The control group was advised to focus on eating low-fat dairy, whole grains, fruits, and vegetables and to avoid the portfolio foods.

The results. After six months, LDL levels dropped an average of 13% to 14% in the portfolio group, compared with 3% — a nonsignificant drop, meaning it could have been due to chance — in the group eating the low-saturated-fat diet. The portfolio group also had an 11% reduction in their calculated 10-year risk of having a heart attack (based on the Framingham Heart Study risk assessment tool). On the other hand, the control group had a nonsignificant 0.5% drop in calculated risk.

Limitations and implications. Results showed that a diet high in cholesterol-lowering foods can lower LDL levels even in people who are already following a heart-healthy diet. But this brief study doesn't tell us whether this results in fewer heart attacks or other cardiovascular events down the road. Also, the study did not determine the LDL-lowering impact of the individual portfolio foods, though the combination may be important, because each lowers cholesterol in different ways. The study had a high overall dropout rate (22.6%) — a common problem in intensive dietary studies. Also, participants were mostly white with an average body mass index of 27, so it's unknown whether the results would generalize to more diverse or more overweight or obese populations. Nonetheless, the findings offer evidence of the value of adding cholesterol-lowering foods to your diet.