Joan Sabaté, MD, DrPH, and colleagues from Loma Linda University in California, pooled data from 25 studies on nut consumption in seven countries, looking at 583 men and women with various cholesterol levels. None was on cholesterol-lowering medications. Nuts evaluated included almonds, hazelnuts, pecans, pistachios, walnuts, macadamia nuts, and peanuts.
Patients in the trials ate an average of 67 grams, or about 2.4 ounces, of nuts daily.
This dietary practice resulted in an average 5.1% reduction in total cholesterol concentration, a 7.4% reduction in LDL or bad cholesterol, and an 8.3% reduction in the ratio of LDL to HDL (“good” cholesterol) levels.
In addition, triglyceride measurements declined by 10.2%, but only among people with initially elevated triglyceride readings. The cholesterol effects of nut consumption were similar in men and women, and were dose related.
Different types of nuts had similar effects on bloodcholesterol levels, according to the authors. However, “effects of nut consumption were significantly modified by LDL, body mass index, and diet type: the lipid-lowering effects of nut consumption were greatest among subjects with high baseline LDL and with low body mass index and among those consuming Western diets.”
The findings support the inclusion of nuts in therapeutic dietary interventions for improving cholesterol levels, the authors say.
“Increasing consumption of nuts as part of an otherwise prudent diet can be expected to favorably affect blood lipid levels (at least in the short term), and have the potential to lower coronary heart disease risk,” the authors write.
Nevertheless, moderation is key. Although eating nuts on a regular basis appears to have significant health benefits, nut consumption should be limited to no more than 3 ounces per day because of their high calorie density.
Sabaté and fellow author Emilio Ros, MD, PhD, disclose receiving research funding from the California Walnut Commission, the Almond Board of California, the National Peanut Board, and the International Tree Nut Council. Sabaté has also received an honorarium as a member of the Pistachio Scientific Advisory Board.
The study is published in the May 10 issue of Archives of Internal Medicine.