Incorporating more nut and
nut-containing foods into the diet at the expense of foods
full of saturated fats could reduce cholesterol levels by
six per cent, suggests a new study with macadamia nuts.
The ratio of total cholesterol to HDL cholesterol,
reported to be the most specific lipid risk factor for
cardiovascular disease (CVD), decreased by 0.29 after
consuming a macadamia-rich diet for five weeks, according
to the randomised, crossover, controlled feeding study
with 25 healthy participants.
The study, published in this month's issue of the Journal
of Nutrition, adds to an ever-growing body of science,
particularly epidemiological studies, linking nut
consumption to improvements in markers of cardiovascular
health. Previously, researchers have reported benefits for
both almonds and walnuts.
Researchers from Pennsylvania State University and the
University of Guelph compared blood cholesterol levels
after consuming a typical American diet or a macadamia
nut-rich diet. They note that the nuts are a rich source
of both polyunsaturated fatty acids (PUFA) and
monounsaturated fatty acids (MUFA)
Adds nuts
Lead author of the study Amy Griel reports that the 15
women and 10 men were randomly assigned to five weeks of
consuming either an average American diet (AAD) consisting
of 33 per cent total fat, 13 per cent saturated fatty
acids (SFA), 11 per cent MUFA, and five per cent PUFA, or
the macadamia nut-rich diet (42.5 grams of nuts),
providing 33 per cent total fat, seven per cent SFA, 18
per cent MUFA, and five per cent PUFA.
The subjects were all classed as mildly
hypercholesterolemic. High cholesterol levels,
hypercholesterolaemia, have a long association with many
diseases, particularly CVD.
Griel and co-workers report that total cholesterol and LDL
cholesterol levels decreased after consuming the macadamia
nut-rich diet. Indeed, levels were 4.94 and 3.14 mmol/L,
respectively, compared to 5.45 and 3.44 mmol/L after
consuming the average American diet.
Furthermore, the ratio of total cholesterol to HDL
cholesterol and LDL to HDL decreased after five weeks of
eating the nut-rich diet. The former ratio was 4.60,
compared to 4.89 following the average American diet,
while the latter ratio was 2.91 after the nut-rich diet,
compared to 3.09 following the average American diet.
"Thus, macadamia nuts can be included in a heart-healthy
dietary pattern that reduces lipid/lipoprotein CVD risk
factors," wrote Griel.
"Nuts as an isocaloric substitute for high SFA foods
increase the proportion of unsaturated fatty acids and
decrease SFA, thereby lowering CVD risk," she added.
An alternative to statins?
The new research could be significant in reducing the
incidence of high cholesterol as health care professionals
are increasingly recommending a dietary approach to
controlling cholesterol over prescription drugs such as
statins, which may have serious side effects.
CVD causes almost 50 per cent of deaths in Europe, and is
reported to cost the EU economy an estimated €169bn
($202bn) per year. According to the American Heart
Association, 34.2 per cent of Americans (70.1m people)
suffered from some form of cardiovascular disease (CVD) in
2002.
Beyond lowering cholesterol, PUFA-MUFA balance has also
been linked with prevention of Parkinson's disease. In
2005 a Dutch study published in Neurology (2005; Vol. 64,
pp. 2040-2045) indicated that higher consumption of both
types of unsaturated fat may help stave off the
degenerative disease.
Source: Journal of Nutrition
2008, Volume 138, Pages 761-767
"A Macadamia Nut-Rich Diet Reduces Total and
LDL-Cholesterol in Mildly Hypercholesterolemic Men and
Women"
Authors: A.E. Griel, Y. Cao, D.D. Bagshaw, A.M. Cifelli,
B.Holub, P.M. Kris-Etherton |
