Counseling patients to consume specific cholesterol-lowering foods was more successful at reducing low-density lipoprotein cholesterol levels than was standard advice to follow a diet low in saturated fat, according to a study in the Aug. 24 JAMA.
In a study of 351 adults with hyperlipidemia, a dietary intervention that encouraged a high intake of foods rich in viscous fiber, plant sterols, soy protein, and nuts – "foods denoted by the U.S. [Food and Drug Administration] to have a heart health benefit" – decreased LDL cholesterol by 13% after 6 months, compared with a 3% reduction associated with a standard low-fat diet.
It is not yet known whether this cholesterol reduction will translate into decreased coronary heart disease mortality. But the 13% drop in cholesterol is approximately half of that achieved in early statin trials, which corresponded to a 20% decrease in CHD mortality, said Dr. David J.A. Jenkins of the clinical nutrition and risk factor modification center of St. Michael’s Hospital, Toronto, and his associates.
In this study, the 137 men and 214 postmenopausal women with hyperlipidemia who were recruited at four medical centers across Canada were randomly assigned to follow one of three diets.
The first was a standard low-fat diet that emphasized high fiber, whole grains, fruits, and vegetables (the control diet). Subjects met with dietitians at baseline, 3 months, and 6 months.
The second was a "routine" intervention diet that specifically promoted plant sterol ester–enriched margarine, oats, barley, psyllium, soy milk, tofu, soy meat analogues, nuts, peas, beans, and lentils, in which subjects similarly met with dietitians at baseline, 3 months, and 6 months.
The third was an "intense" intervention diet in which the food components were identical to those in the routine diet, but subjects also met with dietitians at baseline, 2 weeks, and for monthly visits thereafter for 6 months.
Outcomes were similar between the routine and the intense intervention diets, so the more frequent visits with a dietitian did not confer added benefit. In all three groups, subjects lost a similar amount of weight (1.2-1.7 kg).
The average decrease in LDL cholesterol was 3% with the control diet, compared with 13% with the routine intervention diet and 14% with the intense intervention diet, the investigators said (JAMA 2011;306:831-9).
There were no serious adverse events in any of the three study groups; food allergies were a problem for two participants in the intervention arm.
The dropout rate was deemed "high" at 23%. Such attrition is common in studies in which diets are restricted to this degree, Dr. Jenkins and his colleagues said.
A major limitation of this study was the fact that nearly all the subjects were white, had a low body mass index, and were at low to intermediate risk of CV disease. "The generalizability of this clinical trial to higher-risk, more overweight, or obese patient populations is unknown," the researchers noted.
Moreover, these study subjects "were already consuming an acceptable background diet low in saturated fat and cholesterol," so it is possible that they were better able to adhere to the intervention diets than members of the general population would be.
However, this also means that the effectiveness of the intervention diets would be even more pronounced in the general population, Dr. Jenkins and his associates added.
This study was funded primarily by the Canadian Institutes of Health Research. Loblaw Brands, Solae, and Unilever also provided supplementary funding. Dr. Jenkins and his associates reported ties to Unilever, Santarium, the California Strawberry Commission, Loblaw Supermarket, Herbal Life International, Advanced Foods and Materials Network, Nutritional Fundamental for Health, Pacific Health Laboratories, Metagenics, Bayer Consumer Care, Orafti, Dean Foods, Kellogg’s, Quaker Oats, Procter & Gamble, Coca-Cola, Abbott, Pulse Canada, Saskatchewan Pulse Growers, Canola Council of Canada, Almond Board of California, International Tree Nut Council, Barilla, Solae, Oldways, Haine Celestial, Alpro Foundation, Peanut Institute, Danone, Enzymotec, Viterra Food Processing, and Glycemic Index Laboratories.