The present study was designed to evaluate the relationship between different seafood meals and marine omega-3 fatty acid (eicosapentaenoic acid and docosahexaenoic acid) biomarkers. The study cohort, the Multi-Ethnic Study of Atherosclerosis (MESA), included white, Chinese-American, black, and Hispanic participants. Dietary intake from a food frequency questionnaire and plasma phospholipid fatty acids were determined for 900 MESA participants who were not taking any fish oil supplements. Simultaneously adjusting for all seafood groups, concentrations of eicosapentaenoic acid and docosahexaenoic acid in plasma phospholipids were found to be positively associated with nonfried fish consumption in all four ethnic groups (r = 0.24–0.46; P < 0.01) but not with fried shellfish, fried fish, or fish in mixed dishes. This correlation was reduced by up to 67% when type of seafood was not taken into account. After further adjusting for demographic characteristics and other dietary characteristics, the association of plasma marine omega-3 fatty acid levels with nonfried fish consumption remained significant (P-trend < 0.001). The data were suggestive of a plateau effect at a nonfried fish intake of approximately two times per week. The association of nonfried fish consumption was not modified by intake of (n-6) polyunsaturated fatty acids or α-linolenic acid. The authors conclude that this study highlights the importance of cooking methods (i.e., nonfried versus fried fish), types of seafood (fish versus shellfish), and overall seafood consumption when assessing the health effects of long-chain (n-3) fatty acids of seafood consumption.

The present study was designed to develop a quantitative method to analyze the net risk/benefit of individual fish species based on their methylmercury (MeHg) and omega-3 fatty acid contents. Fish consumption advice remains controversial. Concerns have been raised that negative messages concerning mercury and other contaminants will steer people away from fish and the benefits of omega-3 fatty acid consumption. One approach is to give advice for individual species that points out beneficial fish while cautioning against riskier fish. The authors identified dose–response relationships for MeHg and omega-3 fatty acid effects on coronary heart disease and neurodevelopment. Estimated omega-3 fatty acid benefits were found to outweigh methylmercury risks for some fish species (e.g., farmed salmon, herring, and trout); however, the risks outweighed the benefits for others (swordfish, shark). Other fish species were found to be associated with a small net benefit (canned light tuna, flounder) or a small net risk (canned white tuna, halibut). The results were used to place fish into one of four recommended meal frequency categories, with the advice tentative because of shortcomings in the underlying dose–response information. The authors conclude that this research develops a framework for fish consumption risk/benefit analysis by species that can be used to develop categories of consumption advice ranging from “do not eat” to “unlimited,” with the caveat that unlimited may need to be tempered for some fish (e.g., farm-raised salmon) because of other contaminants and risks (e.g., cancer risk).

The current prospective study evaluated the association between total fish intake (as well as the fat content and preparation method of the fish) and the risk of breast cancer among postmenopausal women. The study also investigated the effect of fish intake with regard to estrogen receptor (ER) expression of breast cancer. 23,693 postmenopausal women from the Diet, Cancer and Health study were included; 424 women were diagnosed with breast cancer during the follow-up period. The overall incidence rate ratio (IRR) and 95% confidence interval (CI) per each additional 25 g of average daily intake of fish were found to be 1.13 (CI, 1.03–1.23). For fatty fish the IRR was 1.11 (CI, 0.91–1.34), for lean fish the IRR was 1.13 (CI, 0.99–1.29). When fish intake was divided by preparation method, the IRR was found to be 1.09 (CI, 0.95–1.25) for fried fish, 1.09 (CI, 0.85–1.42) for boiled fish, and 1.12 (CI, 0.93–1.34) for processed fish. The IRR for each additional 25 g of average daily intake of fish for estrogen receptor–positive (ER+) breast cancer was 1.14 (CI, 1.03–1.26) whereas it was 1.00 (CI, 0.81–1.24) for estrogen receptor–negative (ER-) breast cancer. The authors conclude that higher intakes of fish were significantly associated with higher incidence rates of ER+ breast cancer.

The current case-control study investigated the association between intake of omega-3 and other fatty acids and the omega-3/omega-6 polyunsaturated fatty acid ratio and breast cancer risk. Combining the data from two related Connecticut case-control studies resulted in a study group consisting of 1119 women (565 cases and 554 controls). A food-frequency questionnaire was used to gather information on dietary intake. No significant trends for any macronutrient or fatty acid were observed in the overall study population when comparing the highest to the lowest quartile of intake. However, for the premenopausal women considered alone, consumption of the highest compared with the lowest quartile of the omega-3/omega-6 ratio was associated with a nonsignificant lower risk of breast cancer [odds ratio = 0.59, 95% confidence interval 0.29-1.19, P for trend = 0.09]. The authors conclude that these results are consistent with the hypothesis that a higher omega-3/omega-6 ratio may reduce the risk of breast cancer, especially in premenopausal women.