Relations between the Consumption of Fatty or Lean Fish and Risk of Cardiovascular Disease and All-Cause Mortality: A Systematic Review and Meta-Analysis

Fish consumption is associated with a reduced risk of cardiovascular diseases (CVDs) partly ascribed to the high content of long-chain (LC) n-3 PUFAs; however, not all fish types are equally rich in these components. To date, it is not clear whether the beneficial effects of fish consumption are shared by fatty and lean fish. Therefore, the aim of this meta-analysis was to synthesize knowledge regarding the relation between the intake of fatty fish or lean fish and the risk of cardiovascular events and all-cause mortality. We conducted a systematic search in PubMed, Web of Science, and Embase until May 2021 for full text with a prospective design involving humans providing data for the highest compared with the lowest fish consumption categories. Summary risk ratios (RRs) and 95% CIs were estimated using a random-effects model. Out of 1902 articles retrieved from the literature search, 19 reports met the criteria for inclusion in the meta-analysis. Altogether, studies on fatty fish comprised 1,320,596 person-years of follow-up, 20,531 incident coronary heart disease (CHD) cases, 9256 incident CVD cases, and 104,763 total deaths. Studies on lean fish comprised 937,362 person-years of follow-up, 21,636 incident CHD cases, 7315 incident CVD cases, and 16,831 total deaths. An inverse association was present for fatty fish with CHD incidence (RR: 0.92; 95% CI: 0.86, 0.97), CHD mortality (RR: 0.83; 95% CI: 0.70, 0.98), and total mortality (RR: 0.97; 95% CI: 0.94, 0.99). This was not the case for lean fish. The summary estimates for CVD incidence and mortality did not show significant association with both fatty fish and lean fish consumption. The study findings are innovative in highlighting that the health benefits so far linked to fish consumption are, in fact, driven by fatty fish.

How the Seven Countries Study contributed to the launch and development of cardiovascular epidemiology in Italy. A historical perspective

The Italian research group of the Seven Countries Study of Cardiovascular Diseases (SCS), through the independent use of the national cohorts and data, had the lucky opportunity, starting in the early 1960, to launch the Italian research in epidemiology of cardiovascular diseases (CVD). In this way, the Italian Section of that international study became the first investigation with baseline measurements in various cohorts, subsequent re-examinations, systematic search for morbid events, and follow-up for mortality up to 50 years. A large number of scientific aspects has been tackled including estimates of morbidity and mortality rates, the association of risk factors with cardiovascular events and total mortality, the role of risk factor changes, the use of multivariable models, the role of lifestyle behavior, the determinants of all-cause mortality including risk factors rarely measured in other studies, the identification of characteristics of a condition called Heart Disease of Uncertain Etiology (HDUE), the production of predictive tools for practical use and several other issues. All this has been enhanced by the availability of extremely long follow-up data rarely found in other studies. Field work organization, measurement techniques, diagnostic criteria, data handling and computing had the limitations and difficulties typical of those times, the mid of last century, when CVD epidemiology was at its beginning. All this represented anyhow the start of CVD epidemiology research in the country and was the stimulus to the start of other studies and a valuable collaboration with some of them.