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© 2002 American Public Health Association
LETTER |
Correspondence: Requests for reprints should be sent to Rebecca Din, MD, MPH, PhD, Morehouse School of Medicine, Social Epidemiology Research Division, 720 Westview Dr SW, Atlanta GA 30310-1495 (e-mail: rebecca_din{at}msm.edu).
I read with great interest "A Motivational Interviewing Intervention to Increase Fruit and Vegetable Intake Through Black Churches: Results of the Eat for Life Trial," by Resnicow and colleagues.1 Modifying lifestyle risk factors has proven beneficial in preventing or controlling chronic diseases (cardiovascular disease and cancer) and decreasing mortality.2,3 Resnicow et al. found a significant difference in fruit and vegetable intake among participants from urban Black churches who underwent 3 motivational phone interviews in addition to receiving culturally sensitive self-help materials and usual educational material, compared with participants who received the latter 2 (group 2) or just the latter (group 1).
Several additional points can be made. First, this study proves once again the importance of Black churches as a venue for recruiting and retaining African Americans from a wide range of age and socioeconomic groups. However, the investigators could have put their results into perspective by relating the amount of change to the degree of prevention of disease or risk factor modification. Indeed, the magnitude of effect, though statistically significant, may appear small.
During the 1-year follow-up, participants in group 3 consumed, on average, 0.7 more servings of fruit per day than participants in group 1 and 0.6 more servings per day than participants in group 2. The increase in vegetable intake was 0.5 and 0.4 servings for the same group comparisons. Interestingly, prospective studies do show a beneficial effect of a similar magnitude of combined fruit and vegetable intake on the incidence of coronary heart disease,3 nonfatal myocardial infarction, stroke, coronary surgical procedures, and cardiovascular disease–related death (Table 1
).4–7
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Second, a 1-year follow-up, even if it is associated with positive outcomes, seems short in the disease course. Hence the methodological choices are either to perform longer studies or to monitor intermediate end points associated with hard end points, such as weight or subclinical disease.8,9 It would also have been interesting to see whether the method had different effects depending on participants' initial health status. Finally, we need more work on how to recruit out-of-the mainstream participants who have different sets of additional contextual risk factors and who also deserve to have their risk factor profiles modified.
Dietary behavior modification will continue to be an important issue in the prevention and management of cardiovascular disease. Thus, this encouraging study calls for more investigations that involve (1) intensifying the intervention from "brief" to "full-blown" motivational study, as suggested by Resnicow et al., to assess whether the magnitude of change is greater; (2) adding some measurable intermediate end points that have been related to hard pathological end points; and (3) adding a time-series dimension with a longer follow-up period to determine the minimal maintenance period of behavioral change. This study illustrates that achieving even small differences can make a difference in cardiovascular outcomes for high-disparity populations.
References
1.
Resnicow K, Jackson A, Wang T, et al. A motivational interviewing intervention to increase fruit and vegetable intake through black churches: results of the Eat for Life trial. Am J Public Health.2001;91:1686–1693.
2.
Ness AR, Powles JW. Fruit and vegetables, and cardiovascular disease: a review. Int J Epidemiol.1997;26:1–13.
3. Cronin KA. Evaluating the impact of population changes in diet, physical activity, and weight status on population risk for colon cancer (United States). Cancer Causes Control.2001;12:305–316.[Medline]
4.
Joshipura KJ, Hu FB, Manson JE, et al. The effect of fruit and vegetable intake on risk for coronary heart disease. Ann Intern Med.2001;134:1106–1114.
5.
Liu S, Manson JE, Lee IM, et al. Fruit and vegetable intake and risk of cardiovascular disease: the Women's Health Study. Am J Clin Nutr.2000;72:922–928.
6.
Joshipura KJ, Ascherio A, Manson JE, et al. Fruit and vegetable intake in relation to risk of ischemic stroke. JAMA.1999;282:1233–1239.
7.
Gillman MW, Cupples LA, Gagnon D, et al. Protective effect of fruits and vegetables on development of stroke in men. JAMA.1995;273:1113–1117.
8. Khaw KT, Bingham S, Welch A, et al. Relation between plasma ascorbic acid and mortality in men and women in EPIC-Norfolk prospective study: a prospective population study. Lancet.2001;357:657–663.[Medline]
9.
Dwyer JH, Navab M, Dwyer KM, et al. Oxygenated carotenoid lutein and progression of early atherosclerosis: the Los Angeles atherosclerosis study. Circulation.2001;103:2922–2927.
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