Current issues of ACP Journal Club are published in Annals of Internal Medicine


Etiology

Frequent nut eating lowered the risk for coronary heart disease among white Seventh-Day Adventists

ACP J Club. 1992 Nov-Dec;117:90. doi:10.7326/ACPJC-1992-117-3-090


Source Citation

Fraser GE, Sabaté J, Beeson WL, Strahan TM. A possible protective effect of nut consumption on risk of coronary heart disease. The Adventist Health Study. Arch Intern Med. 1992 Jul:152:1416-24.


Abstract

Objective

To investigate dietary factors in the risk for coronary heart disease among white Seventh-Day Adventists.

Design

A cohort was followed from 1976 through 1982.

Setting

Community study of all Adventist households in California.

Participants

The 1974 census identified 59 081 Adventists aged ≥ 25 years. Among those who returned a 1976 life-style questionnaire, 26 473 non-Hispanic white persons without a history of heart disease or diabetes entered the study. Follow-up was complete for 97% of participants.

Assessment of risk factors

At baseline participants were asked to report on how often they consumed 65 different foods, beverages, and vitamin supplements on an 8-point scale ranging from "never consume" to "more than once per day." Validity of the food questionnaire was checked against 24-hour dietary recall in a separate study. Information on vegetarianism, height, weight, smoking, blood pressure, and exercise habits was collected.

Main outcome measures

Fatal or nonfatal myocardial infarction and other fatal coronary heart disease. Events were ascertained from electrocardiograms, cardiac-enzyme levels, and other medical records and autopsies of participants. Death certificate classifications alone were used for "all coronary deaths."

Main results

134 definite nonfatal myocardial infarctions (0.5%), 260 definite cases of fatal coronary heart disease (1%), and a total of 463 coronary deaths ascertained from death certificates (2%) occurred. Among the multiple comparisons made after adjustment for age, sex, weight, smoking, exercise, hypertension, and 7 other foods, consumption of nuts ≥ 5 times/wk compared with negligible nut-eating was associated with a lower risk for nonfatal myocardial infarction (relative risk [RR] 0.49, 95% CI 0.28 to 0.85), definite fatal coronary heart disease (RR 0.52, CI 0.36 to 0.76), and all coronary deaths (RR 0.59, CI 0.45 to 0.78). Whole-wheat bread eaters had a lower risk for nonfatal myocardial infarction (RR 0.56, CI 0.35 to 0.89), but coronary events were not consistently influenced by consumption of cheese, beef, fish, coffee, legumes, or fruit. Men but not women who ate beef ≥ 3 times/wk had a higher risk for definite fatal coronary heart disease (RR 2.31, CI 1.11 to 4.78).

Conclusion

Frequent nut eating was associated with a lower risk for myocardial infarction and fatal coronary heart disease among white Seventh-Day Adventists.

Source of funding: National Institutes of Health.

For article reprint: Dr. G.E. Fraser, Center for Health Research, School of Public Health, Nichol Hall, Loma Linda University, Loma Linda, CA 92350, USA.


Commentary

Foods are complex, and most foods contain both health-promoting and health-degrading factors. Thus, when nuts, high in both fiber and fat, are reported to have a protective effect on coronary heart disease, the information is hard to interpret.

Fraser and colleagues show a consistent and dose-related reduction of coronary heart disease in nut eaters. The authors did a fine job of statistically controlling for multiple confounding effects of other foods and of risk factors for coronary heart disease. The validity of the questionnaires was checked, and the 97% follow-up of over 26 000 subjects is impressive.

These findings, however, may not necessarily be applicable to the general population. This is a very select and healthy group of subjects (1% to 2% smokers, 60% exercisers, 40% vegetarian, < 2% incidence of coronary heart disease) and includes only non-Hispanic, white Adventists. In addition, there is reduced consistency in dose-response between nut consumption and coronary heart disease in hypertensive persons, previous smokers, and less intense exercisers.

The categories of nut, cheese, and beef consumption do not appear equivalent. It would be helpful if the authors made an attempt to quantify the meaning of "frequent nut eating" in terms of important food components such as fiber, cholesterol, and fat to see if these factors, known to be related to coronary heart disease, could explain the effect (1).

At worst this study could falsely encourage people to add another high-fat food to their diet. At best it could serve as icing on the coronary-free cake (whole wheat, of course) for those who are already doing all the right things. Further studies will be needed to determine which is the case.

Wayne B. Jonas, MD
Walter Reed Army Institute of ResearchWashington, DC, USA

Wayne B. Jonas, MD
Walter Reed Army Institute of Research
Washington, DC, USA


Reference

1. Castelli WP. Concerning the possibility of a nut . . . [Editorial]. Arch Intern Med. 1992;152:1371-2.