A large cohort study shows sticking to a diet heavy on fruits, vegetables, legumes, whole grains, fish, and poultry reduced mortality risk.

by Todd Neale, Staff Writer, MedPage Today 

BOSTON, June 23 — Sticking to a diet heavy on fruits, vegetables, legumes, whole grains, fish, and poultry reduced mortality risk, a large cohort study showed.

Action Points 
Explain to interested patients that this study found that women adhering closely to a healthy overall dietary pattern tended to live longer than those who ate a “Western” diet.

Women who most closely followed this “prudent” diet had a 17% reduced risk of dying from any cause and a 28% lower risk of cardiovascular mortality compared with those who were least likely to make those food choices (P<0.001 for both), Frank Hu, M.D., Ph.D., of Harvard School of Public Health, and colleagues reported online in Circulation: Journal of the American Heart Association.

On the other hand, a diet rich in red meat, processed meat, refined grains, french fries, and sweets — the so-called Western diet — was associated with increased risks of dying from any cause (21%, P<0.001), cardiovascular disease (22%, P=0.009), and cancer (16%, P=0.004).

“Nutritional recommendations to prevent chronic diseases and promote longevity may need to focus on overall dietary patterns rather than individual nutrients,” the researchers said.

Few studies have evaluated the influence of overall dietary patterns on mortality risk, they said, with most focusing on single nutrients or foods.

So the researchers turned to the Nurses’ Health Study, which prospectively followed 72,113 women ages 30 to 55 (97% white) who had been trained as registered nurses. All were free from cardiovascular disease and cancer at baseline.

The researchers identified and scored adherence to the two major dietary patterns — prudent and Western — using food frequency questionnaires collected every two to four years. The questionnaires documented the consumption of 116 food items.

During follow-up from 1984 through 2002, 6,011 participants died, including 1,154 from cardiovascular disease and 3,139 from cancer.

After adjusting for several variables, participants in the highest quintile of adherence to the prudent diet had reduced risks of dying from cardiovascular disease (RR 0.72, 95% CI 0.60 to 0.87), other causes (RR 0.70, 95% CI 0.60 to 0.81), and any cause (RR 0.83, 95% CI 0.76 to 0.90) (P<0.001 for all) compared with those in the lowest quintile.

There was no significant association with cancer mortality (P=0.97), which the researchers said was not surprising because previous studies had found that the prudent diet was not significantly related to risk of postmenopausal breast cancer, colorectal cancer, and pancreatic cancer — among the main causes of cancer mortality in women.

In contrast, participants who were most likely to eat the Western diet had increased risks of dying from cardiovascular disease (RR 1.22, 95% CI 1.01 to 1.48, P=0.009), cancer (RR 1.16, 95% CI 1.03 to 1.30, P=0.004), other causes (RR 1.31, 95% CI 1.12 to 1.52, P<0.001), and any cause (RR 1.21, 95% CI 1.12 to 1.32, P<0.001) compared with those in the lowest quintile.

There were no significant interactions between the dietary patterns and age, physical activity level, smoking status, or weight for cause-specific or all-cause mortality.

The authors acknowledged that the study was limited because it compared the dietary patterns of the participants, which were not necessarily the optimal diets with the greatest influence on mortality.

Also, they said, the selection of the food items and of the dietary patterns were subjective.

The researchers could not rule out residual confounding because of the observational nature of the study.

Finally, they said, the study population was homogeneous, which may limit the generalizability of the results.

The study was supported by grants from the National Institutes of Health. One of Dr. Hu’s co-authors was supported by fellowships from the German Academic Exchange Service and the Hans & Eugenia Juetting-Foundation. Another co-author is supported by a discretionary grant by Beth Israel Deaconess Medical Center. The authors made no disclosures.

Primary source: Circulation: Journal of the American Heart Association

Source reference: Heidemann C, et al “Dietary patterns and risk of mortality from cardiovascular disease, cancer, and all causes in a prospective cohort of women” Circulation 2008; DOI: 10.1161/CIRCULATIONAHA.108.771881.

Reviewed by Dori F. Zaleznik, MD; Associate Clinical Professor of Medicine, Harvard Medical School, Boston.

Published: June 23, 2008

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