Habitual salt intake and risk of gastric cancer: a meta-analysis of prospective studies

Background & aims: Systematic reviews of case-control studies evaluating the relationship between dietary salt intake and gastric cancer showed a positive association, however a quantitative analysis of longitudinal cohort studies is lacking. Therefore, we carried out a meta-analysis to assess the association between habitual salt intake and risk of gastric cancer in prospective studies.

Methods: We performed a systematic search of published articles (1966-2010). Criteria for inclusion were: original articles, prospective adult population studies, assessment of salt intake as baseline exposure and of gastric cancer as outcome, follow-up of at least 4 years, indication of number of participants exposed and events across different salt intake categories.

Results: Seven studies (10 cohorts) met the inclusion criteria (268 718 participants, 1474 events, follow-up 6-15 years). In the pooled analysis, "high" and "moderately high" vs "low" salt intake were both associated with increased risk of gastric cancer (RR = 1.68 [95% C.I. 1.17-2.41], p = 0.005 and respectively 1.41 [1.03-1.93], p = 0.032), with no evidence of publication bias. The association was stronger in the Japanese population and higher consumption of selected salt-rich foods was also associated with greater risk. Meta-regression analyses did not detect specific sources of heterogeneity.

Conclusions: Dietary salt intake was directly associated with risk of gastric cancer in prospective population studies, with progressively increasing risk across consumption levels.