Association between fish and shellfish consumption, n-3 polyunsaturated fatty acids, and gastric cancer risk: the Japan Public Health Center-based Prospective Study.

PURPOSE: Fish and shellfish consumption is suggested to be a cancer-protective factor. However, studies investigating this association for gastric cancer, especially considering Helicobacter pylori (H. pylori) and atrophic gastritis (AG), are limited. We investigated gastric cancer risk associated with fish, shellfish, and n-3 polyunsaturated fatty acids (n-3 PUFAs) consumption among Japanese adults. METHODS: 90,504 subjects enrolled in the Japan Public Health Center-based Prospective Study (JPHC Study) were followed until December 2013. Dietary intake data were collected using a food frequency questionnaire. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated for gastric cancer risk associated with fish and shellfish consumption and marine n-3 PUFAs (sum of eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA)) using Cox proportional hazards models. Among those with avaliable data, we conducted a subgroup analysis taking H. pylori infection and AG status  into consideration. RESULTS: There were 2,701 gastric cancer cases during an average of 15 years of follow-up. We observed an increased gastric cancer risk for salted fish consumption for men [HR for fifth quintile versus first quintile 1.43 (95% CI 1.18-1.75)] and for women [HR 1.33 (95% CI 1.00-1.77)]. We observed a weak risk reduction trend for women as the intake of marine n-3 PUFAs increased (p-trend:0.07). When we included H. pylori infection and atrophic gastritis status in the analysis, the associations diminished. CONCLUSION: Our results suggest that salted fish increases gastric cancer risk for men and women, while marine n-3 PUFAs marginally decreases this risk among women in Japan.

Validity of the Intake of Sugars, Amino Acids, and Fatty Acids Estimated Using a Self-administered Food Frequency Questionnaire in Middle-aged and Elderly Japanese: The Japan Public Health Center-based Prospective Study for the Next Generation (JPHC-NEXT) Protocol Area.

BACKGROUND: The Japanese database of food composition was revised in 2020, during which both the number of food items and the number of food items measured for sugars, amino acids, and fatty acids were increased. We evaluated the validity of estimated intakes of sugars, amino acids and fatty acids using a long food frequency questionnaire (long-FFQ) among middle-aged and elderly Japanese. METHODS: From 2012 to 2013, 240 men and women aged 40-74 years from five areas in the JPHC-NEXT protocol were asked to respond to the long-FFQ and provide a 12-day weighed food record (WFR) as reference. The long-FFQ, which included 172 food and beverage items and 11 seasonings, was compared with a 3-day WFR, completed during each distinct season, and validity was assessed using Spearman's correlation coefficients. RESULTS: Percentage differences based on the long-FFQ with the 12-day WFR in men and women varied from -84.4% to 419.6%, and from -75.8% to 623.1% for sugars, -17.5% to 3.8% and -5.8% to 19.6% for amino acids, and -58.5% to 78.8% and -43.4% to 129.3% for fatty acids, respectively. Median values of correlation coefficients for the long-FFQ in men and women were 0.52 and 0.42 for sugars, 0.38 and 0.37 for amino acids, and 0.42 and 0.42 for fatty acids, respectively. CONCLUSION: The long-FFQ provided reasonable validity in estimating the intakes of sugars, amino acids, and fatty acids in middle-aged and elderly Japanese. Although caution is warranted for some nutrients, these results may be used in future epidemiological studies.