we know that high cholesterol is one of the major risk factors for atherosclerosis. in the may 10th edition of archives of internal medicine researchers found that eating nuts improves blood lipid levels which may help stave off heart disease. in a pooled analysis of 25 intervention trials eating an average of 67 grams of nuts a day (2. 4 ounces) reduced total cholesterol by 5. 9% and ldl cholesterol by 7. 4% (p<0. 001 for both) according to joan sabaté md drph of loma linda university in california and colleagues. in 2003 the fda allowed a qualified health claim that evidence suggests – but does not prove - that eating 1. 5 ounces (43 grams) of nuts per day as part of a diet low in saturated fat and cholesterol reduces coronary heart disease risk. the government allows the claim on dietary labeling for specific nuts including almonds hazelnuts pecans pistachios walnuts peanuts and some pine nuts. walnuts and almonds have been most comprehensively studied. epidemiological studies have linked nut consumption with a reduced risk of coronary heart disease and many dietary intervention trials have studied the effects of nut consumption on blood lipid levels. most clinical trials evaluating the impact of nuts on lipid profiles have been small scale (10-49 participants). ldl-c (the bad cholesterol) reduction has been consistently shown in these small-scale studies typically in the range of 12-13%. though less consistent triglyceride reduction was shown. however hdl-c (the good cholesterol) generally remained unchanged. one must always remember that these studies are far too small to establish any guidelines and there certainly is not one ounce of level one outcome data regarding the effect on cardiovascular morbidity and mortality. the american dietetics association evidence library concludes “consumption of 50-113 grams (1/2 cup to 1 cup) of nuts daily with a diet low in saturated fat and cholesterol decreased total cholesterol by 4-21% and ldl-c by 6-29% when weight was not gained. ” although the decrease in ldl cholesterol in the current analysis is modest compared with that seen with statins “the value of regular nut consumption for coronary heart disease prevention is unlikely due to the blood cholesterol-lowering effect alone ” sabaté and his colleagues wrote. the authors of the current study felt that “nut consumption exerts beneficial effects by improving endothelial function lowering oxidative stress and reducing lipoprotein(a) level. ” i have previously written about lipoprotein(a). aside from the fatty acid composition of nuts other components such as arginine plant sterols and phenolic components may play a favorable role in the lowering of lipid levels for those who eat nuts as a regular part of their diet. in the current study the researchers performed a pooled analysis of raw data from 25 intervention trials conducted in seven countries that included 583 men and women with normolipidemia or hypercholesterolemia. none of the participants was taking lipid-lowering medications. sample size ranged from 10 to 49. all of the dietary interventions were exclusively nuts – mostly almonds and walnuts – and ranged in duration from three to eight weeks. quantities ranged from 23 to 132 grams per day with a mean of 67 grams. the interventions resulted in the following mean reductions (with percentage changes) regardless of the type of nut used (p<0. 001 for all): total cholesterol: 10. 9 mg/dl (5. 1%) ldl cholesterol: 10. 2 mg/dl (7. 4%) ratio of ldl to hdl cholesterol: 0. 22 (8. 3%) ratio of total to hdl cholesterol: 0. 24 (5. 6%)
how do nuts work in a heart-healthy diet?