When Nut Consumption Goes Up, Cholesterol Level Goes
Down, Heart Health Improves
Blood cholesterol levels improve after eating nuts:
bad cholesterol drops 7.4%, ratio improves 8.3%, 5.1% drop in total
May 10, 2010 A new study reported today in the
Archives of Internal Medicine, one of the JAMA/Archives journals,
further confirms previous research findings that eating nuts improves
blood cholesterol levels, which reduces the risk of coronary heart
disease. A large Penn State study in 2001 (reported below) reached the same
conclusion, as have many other studies in recent years.
Participants in the 25 trials providing data for
this analysis consumed an average of 67 grams (about 2.4 ounces) of nuts
This was associated with an average
► 5.1 percent reduction in total cholesterol concentration,
► 7.4 percent reduction in low-density lipoprotein (LDL, or "bad"
► 8.3 percent change in ratio of LDL cholesterol to high-density
lipoprotein (HDL, or "good" cholesterol).
In addition, triglyceride levels declined by 10.2
percent among individuals with high triglyceride levels (at least 150
milligrams per deciliter), although not among those with lower levels.
"Dietary interventions to lower blood cholesterol
concentrations and to modify blood lipoprotein levels are the
cornerstone of prevention and treatment plans for coronary heart
disease," the authors note as background information in their report.
"Recently, consumption of nuts has been the focus
of intense research because of their potential to reduce coronary heart
disease risk and to lower blood lipid (fat and cholesterol) levels based
on their unique nutritional attributes."
Nuts are a nutrient-dense food rich in plant
protein (10%-25%) and fat (50%-75%), mostly unsaturated fatty acids.
They are a rich source of additional nutrients, dietary fiber, minerals
(eg, copper, magnesium, and potassium), vitamins (eg, folic acid,
niacin, vitamin E, and vitamin B6), and other bioactive constituents
such as phenolic antioxidants and phytosterols.
Joan Sabatι, M.D., Dr.P.H., of Loma Linda
University, Loma Linda, Calif., and colleagues pooled primary data from
25 nut consumption trials conducted in seven countries and involving 583
women and men with high cholesterol or normal cholesterol levels. All
the studies compared a control group to a group assigned to consume
nuts; participants were not taking lipid-lowering medications.
"The effects of nut consumption were dose related,
and different types of nuts had similar effects on blood lipid levels,"
the authors write.
"The effects of nut consumption were significantly
modified by LDL-C, body mass index and diet type: the lipid-lowering
effects of nut consumption were greatest among subjects with high
baseline LDL-C and with low body mass index and among those consuming
The results support the inclusion of nuts in
therapeutic dietary interventions for improving blood cholesterol
levels, they conclude.
"Nuts are a whole food that have been consumed by
humans throughout history. Increasing the 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."
This research was partially funded by a grant from
the McLean Research Fund of the Department of Nutrition, Loma Linda
University, and by the International Tree Nut Council Nutrition Research
and Education Foundation.
Comprehensive Study in 2001 Concluded Nuts Cut
Coronary Heart Disease Risk
A comprehensive review of the available
epidemiological and clinical evidence led Penn State researchers to
release a report in 2001 that concluded eating tree nuts or peanuts has
a strong protective effect against coronary heart disease. Dr. Penny
Kris-Etherton, distinguished professor of nutrition and lead author of
the review, said, "To date, five large epidemiologic studies and 11
clinical studies have demonstrated that frequent consumption of nuts
decreases the risk of coronary heart disease."
The most improvement came with adding very small
amounts of nuts an ounce, or about three to four tablespoons, five or
more times a week.
Kris-Etherton said, "You have to replace some of
the calories you usually consume with nuts and substitute the
unsaturated fat in nuts for some of the saturated fat in your diet."
The study was published in the May 8, 2001 issue of
the journal, Nutrition Reviews.
The researcher's review of the existing published
epidemiologic studies shows that consuming 1 ounce of nuts more than 5
times/week can result in a 25 to 39 percent reduction in coronary heart
disease risk among people whose characteristics match those of the
general adult U.S. population.
Among the nuts consumed by the people who took part
in the epidemiologic studies were almonds, brazil nuts, cashews,
hazelnuts, macademia nuts, pecans, pistachios, and walnuts, as well as
peanuts. However, the effects of specific nuts on coronary heart disease
risk were not evaluated in these studies due to difficulties in
classifying consumption patterns of specific nuts and because of the
small number of cases in each category. In typical American diets,
peanuts account for approximately half of all nuts consumed.
Nuts studied in clinical investigations included
walnuts, almonds, macadamia nuts, pecans, pistachio nuts and peanuts.
The 11 clinical studies reviewed by the Penn State
researchers focused on the blood cholesterol-lowering effects of nuts.
Collectively, these studies showed that including nuts in a blood
cholesterol-lowering diet has favorable effects. However, the
researchers write, "Whether the inclusion of nuts evokes a greater
cholesterol-lowering response than would be expected from a typical
lipid-lowering diet remains to be resolved."
Nuts are a rich source of unsaturated fatty acids,
the "good" fats, and are low in saturated fatty acids, the "bad" fats.
However, the researchers concluded that the fatty acid profile of nuts
contributes to only part of the total reduction in coronary heart
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