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Reduction of Total Fat Intake Does Not Significantly Reduce the Risk of Cardiovascular Disease

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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