Jama
Study Finds Plant-Based Diet Leads to Weight Loss, Reduced Cholesterol
Overweight
individuals who ate a low-calorie, low-carbohydrate diet high in
plant-based proteins for four weeks lost weight and experienced
improvements in blood cholesterol levels and other heart disease
risk factors, according to a report in the June 8 issue of Archives
of Internal Medicine, one of the JAMA/Archives journals. A high-carbohydrate,
low-fat vegetarian diet also resulted in weight loss but without
the additional cardiovascular benefits.
"There
is a dilemma relating to the proportion and source of fat, protein
and carbohydrate that constitutes the optimal weight loss and cholesterol-lowering
diet," the authors write as background information in the article.
Newer dietary approaches for the prevention and treatment of chronic
disease emphasize increased fruit and vegetable intake and reduced
meat consumption.
However,
low-carbohydrate diets with increased meat consumption have also
been promoted for body weight reduction and the prevention and treatment
of diabetes and coronary heart disease. These diets have been shown
to be effective in inducing weight loss, reducing insulin resistance,
lowering blood fats known as triglycerides and raising high-density
lipoprotein cholesterol (HDL-C, or "good" cholesterol)
levels, but have tended to increase low-density lipoprotein cholesterol
(LDL-C, or "bad" cholesterol) levels. "This lack
of a benefit for LDL-C control is a major disadvantage in using
this dietary strategy in those already at increased risk of coronary
heart disease," the authors write.
David
J.A. Jenkins, M.D., of St. Michael's Hospital and the University
of Toronto, Ontario, Canada, and colleagues tested the effects of
a low-carbohydrate diet high in vegetable proteins from gluten,
soy, nuts, fruits, vegetables, cereals and vegetable oils among
overweight men and women with high LDL cholesterol levels. A total
of 25 participants were randomly assigned to consume this dietthe
"Eco-Atkins" dietfor four weeks, while an additional
25 participants ate a control diet that was high-carbohydrate, lacto-ovo
vegetarian and based on low-fat dairy and whole grain products.
Study food was provided to participants at 60 percent of their estimated
calorie requirements.
Of
the 47 participants who began the study, 44 (22 in each group) completed
the four-week period. Weight loss was similarabout 4 kilograms
or 8.8 poundsin both groups. However, reductions in LDL-C
levels and improvements in the ratios between total cholesterol
and HDL-C were greater for the low-carbohydrate diet compared with
the high-carbohydrate diet. The low-carbohydrate diet also appeared
to produce beneficial changes in levels and ratios of apolipoproteins,
proteins that bind to fats. In addition, small but significantly
greater reductions were seen in both systolic (top number) and diastolic
(bottom number) blood pressure for the low-carbohydrate vs. the
high-carbohydrate group.
Pending
answers to important questions, including whether further reducing
carbohydrate intake would produce additional benefits, "a plant-based
low-carbohydrate diet high in vegetable proteins and oils may be
an effective option in treating those with dyslipidemia for whom
both weight loss and lower LDL-C concentrations are treatment goals,"
the authors conclude.
(Arch
Intern Med. 2009;169[11]:1046-1054. Available pre-embargo to the
media at www.jamamedia.org.)
Editor's
Note: This study was supported by Solae, LLC, Loblaw Companies Limited
and the Canadian Research Chair Program of the Federal Government
of Canada. Co-author Ms. Wong is a recipient of a Canadian Institutes
of Health Research Doctoral Research Award. Please see the article
for additional information, including other authors, author contributions
and affiliations, financial disclosures, funding and support, etc.
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