Am J Epidemiol 2003; 157:85-86.
Copyright © 2003 by Johns
Hopkins Bloomberg School of Public Health
LETTERS TO THE EDITOR |
THREE AUTHORS REPLY
Department of Preventive Medicine, University of Southern California/Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033-0800
We thank Dr. Alonso et al. for their comments (1) on our paper (2) on dietary fish/shellfish intake and myocardial infarction mortality in middle-aged and older men in Shanghai, China. They raised the possibility of residual confounding in our observed association of fish consumption with fatal myocardial infarction, noting that our food questionnaire included only 45 food items. We would like to point out that the relatively few number of food items in the Shanghai Cohort Study questionnaire (compared with usually 120–160 food items in a validated food questionnaire for western populations) reflected the limited food choices available to residents of the People’s Republic of China until the late 1980s. In fact, foods rich in protein, such as meat, fish, eggs, and milk, were rationed in China between the 1950s and 1970s. At the time of our cohort accrual, only warm-water fish were commonly available in Shanghai. The three fish items listed in the study questionnaire—fresh fish, salted fish, and shellfish— captured all seafoods commonly available in Shanghai. The inverse association between seafood (or marine n-3 fatty acid) intake and myocardial infarction mortality remained materially the same after adjustment for various other food items and nutrients as well as for the ratio of serum total cholesterol to high density lipoprotein cholesterol concentrations (a diet-related, established risk factor for coronary heart disease). Therefore, it seems unlikely that residual confounding is the explanation for our observed association between fish and myocardial infarction mortality.
Dr. Alonso et al. pointed out (1) that high levels of consumption of fish/shellfish and n-3 fatty acid might also protect against the development of nonfatal myocardial infarction based on observations from two recent case-control studies in Italy and Spain (3, 4). In both studies, dietary intake information was collected from patients after their disease diagnosis; therefore, the possibility of recall bias and/or dietary change following manifestation of clinical symptoms cannot be ruled out. On the other hand, the Shanghai Cohort Study collected dietary information from apparently healthy subjects, thus ruling out the possibility of recall bias. Six prospective studies have examined the relation of fish/shellfish (or marine n-3 fatty acid) intake with the risk of fatal myocardial infarction (2, 5–9). Four found a statistically significant, inverse association (2, 5–7), while the other two failed to detect an association (8, 9). On the other hand, four prospective studies have examined the association between seafood (or marine n-3 fatty acid) intake and the risk of nonfatal myocardial infarction. All four failed to find an inverse association (5, 9–11). Furthermore, two large intervention trials, one conducted in Britain and the other in Italy, demonstrated that increased consumption of fish or dietary supplementation with marine n-3 fatty acids significantly reduced the risk of fatal myocardial infarction but had little effect on the incidence of nonfatal reinfarction in patients who had experienced myocardial infarction (12, 13). Therefore, current data from prospective epidemiologic studies and intervention trials do not support the hypothesis that fish or marine n-3 fatty acids play a protective role in the development of nonfatal myocardial infarction.
REFERENCES
- Alonso A, Fernández-Jarne E, Serrano-Martínez M, et al. Re: "Fish and shellfish consumption in relation to death from myocardial infarction among men in Shanghai, China. (Letter). Am J Epidemiol 2003;157:85.[CrossRef][Medline]
- Yuan JM, Ross RK, Gao YT, et al. Fish and shellfish consumption in relation to death from myocardial infarction among men in Shanghai, China. Am J Epidemiol 2001;154:809–16.
[Abstract/Free Full Text] - Tavani A, Pelucchi C, Negri E, et al. n-3 polyunsaturated fatty acids, fish, and nonfatal acute myocardial infarction. Circulation 2001;104:2269–72.
[Abstract/Free Full Text] - Fernández-Jarne E, Alegre F, Alonso A, et al. Dietary intake of n-3 fatty acids and the risk of acute myocardial infarction: a case-control study (Ingesta de ácidos grasos omega-3 y riesgo de infarto de miocardio: un estudio de casos y controles). (In Spanish). Med Clin (Barc) 2002;118:121–5.
- Albert CM, Hennekens CH, O’Donnell CJ, et al. Fish consumption and risk of sudden cardiac death. JAMA 1998;279:23–8.
[Abstract/Free Full Text] - Daviglus ML, Stamler J, Orencia AJ, et al. Fish consumption and the 30-year risk of fatal myocardial infarction. N Engl J Med 1997;336:1046–53.
[Abstract/Free Full Text] - Norell SE, Ahlbom A, Feychting M, et al. Fish consumption and mortality from coronary heart disease. BMJ (Clin Res Ed) 1986;293:426.[ISI][Medline]
- Vollset SE, Heuch I, Bjelke E. Fish consumption and mortality from coronary heart disease. (Letter). N Engl J Med 1985;313:820–1.[Medline]
- Ascherio A, Rimm EB, Stampfer MJ, et al. Dietary intake of marine n-3 fatty acids, fish intake, and the risk of coronary disease among men. N Engl J Med 1995;332:977–82.
[Abstract/Free Full Text] - Fraser GE, Sabate J, Beeson WL, et al. A possible protective effect of nut consumption on risk of coronary heart disease. The Adventist Health Study. Arch Intern Med 1992;152:1416–24.[Abstract]
- Salonen JT, Seppanen K, Nyyssonen K, et al. Intake of mercury from fish, lipid peroxidation, and the risk of myocardial infarction and coronary, cardiovascular, and any death in eastern Finnish men. Circulation 1995;91:645–55.
[Abstract/Free Full Text] - Burr ML, Fehily AM, Gilbert JF, et al. Effects of changes in fat, fish, and fibre intakes on death and myocardial reinfarction: diet and reinfarction trial (DART). Lancet 1989;2:757–61.[ISI][Medline]
- Dietary supplementation with n-3 polyunsaturated fatty acids and vitamin E after myocardial infarction: results of the GISSI-Prevenzione trial. Gruppo Italiano per lo Studio della Sopravvivenza nell’Infarto miocardico. Lancet 1999;354:447–55.[CrossRef][ISI][Medline]
CiteULike 
Connotea 
Del.icio.us What's this?
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||