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February 6, 2006
By:
Sahar Bedrood and Asher
Kimchi M.D.
Hyattsville, MD - Many
epidemiological studies has shown a healthy diet to
include low intake of saturated and trans fat,
cholesterol and a high intake of fruits, vegetables
and grains. A study done by Barbara V. Howard PhD et
al from the MedStar Research Institute in
Hyattsville, MD found a dietary intervention that
reduced total fat intake and increased intakes of
vegetables, fruits and grains did not significantly
reduce the risk of congestive Heart Disease (CHD),
stroke, or cardiovascular disease (CVD) in
postmenopausal women. The study was published in the
February 8, 2006 issue of the Journal of the
American Medical Association.
The primary aim of The Women’s Health
Initiative Randomized Controlled Dietary Modification Trial was
to assess whether behavioral intervention consisting of low
total fat intake and increased intakes of fruit, vegetables and
grains would decrease the incidence of breast and colorectal
cancer in postmenopausal women. A secondary aim was to assess
such dietary changes on the effect of CVD risk reduction.
The study was a randomized controlled trial of
48,835 post-menopausal women aged 50 to 79 years who were
assigned to either dietary intervention or a comparison group
who did not follow the dietary changes. The intervention was
originally designed to reduce intake of total fat to 20% of
energy intake by increasing intake of fruits and vegetables to
at least 5 servings daily and of grains to at least 6 servings
daily.
By the sixth year of the trial, mean fat
intake was actually decreased by 8.2% of energy intake in the
intervention group. Increased intakes of vegetables/fruits (1.1
servings/day) and grains (0.5 serving/day) occurred in the
intervention group as well. Low-density lipoprotein cholesterol
levels, diastolic blood pressure and factor V11c levels were
significantly reduced by 3.55 mg/dL, 0.31 mmHg and 4.29%,
respectively. The numbers who developed CHD, stroke,
and CVD (annualized incidence rates) were 1000 (0.63%), 434
(0.28%), and 1357 (0.86%) in the intervention and 1549
(0.65%), 642 (0.27%), and 2088 (0.88%) in the
comparison group. The diet had no significant effects
on incidence of CHD (hazard ratio [HR], 0.97; 95%
confidence interval [CI], 0.90-1.06), stroke (HR,
1.02; 95% CI, 0.90-1.15), or CVD (HR, 0.98; 95% CI, 0.92-1.05).
Excluding participants with baseline CVD (3.4%), the HRs
(95% CIs) for CHD and stroke were 0.94 (0.86-1.02)
and 1.02 (0.90-1.17), respectively. Trends toward
greater reductions in CHD risk were observed in those
with lower intakes of saturated fat or trans
fat or higher intakes of vegetables/fruits.
Over the mean 8.1 years of this study, a
dietary intervention that reduced total fat intake and
moderately increased intakes of vegetables, fruits and grains
did not significantly reduce the risk of CHD, stroke or CVD in
postmenopausal women. The study suggests that more focused diet
and lifestyle intervention may be needed to improve risk factors
and reduce CVD risk.
Coauthors: Barbara V. Howard, PhD; Linda Van Horn, PhD;
Judith Hsia, MD; JoAnn E. Manson, MD; Marcia L. Stefanick, PhD;
Sylvia Wassertheil-Smoller, PhD; Lewis H. Kuller, MD; Andrea Z.
LaCroix, PhD; Robert D. Langer, MD; Norman L. Lasser, MD; Cora
E. Lewis, MD; Marian C. Limacher, MD; Karen L. Margolis, MD; W.
Jerry Mysiw, MD; Judith K. Ockene, PhD; Linda M. Parker, DSc;
Michael G. Perri, PhD; Lawrence Phillips, MD; Ross L. Prentice,
PhD; John Robbins, MD; Jacques E. Rossouw, MD; Gloria E. Sarto,
MD; Irwin J. Schatz, MD; Linda G. Snetselaar, PhD; Victor J.
Stevens, PhD; Lesley F. Tinker, PhD; Maurizio Trevisan, MD; Mara
Z. Vitolins, DrPH; Garnet L. Anderson, PhD; Annlouise R. Assaf,
PhD; Tamsen Bassford, MD; Shirley A. A. Beresford, PhD; Henry R.
Black, MD; Robert L. Brunner, PhD; Robert G. Brzyski, MD; Bette
Caan, DrPH; Rowan T. Chlebowski, MD; Margery Gass, MD; Iris
Granek, MD; Philip Greenland, MD; Jennifer Hays, PhD; David
Heber, MD; Gerardo Heiss, MD; Susan L. Hendrix, DO; F. Allan
Hubbell, MD; Karen C. Johnson, MD; Jane Morley Kotchen, MD
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