Sex, Adiposity, and Hypertension Status Modify the Inverse Effect of Marine Food Intake on Blood Pressure in Alaska Native (Yup'ik) People.

BACKGROUND: Alaska Native people currently have a higher prevalence of hypertension than do nonnative Alaskans, although in the 1950s hypertension was rare among Alaska Native people. A novel biomarker of marine foods, the nitrogen isotope ratio (δ¹5N) in RBCs was shown to be negatively associated with systolic and diastolic blood pressure. Few studies have examined how individual characteristics modify the association of marine food intake with blood pressure. OBJECTIVE: This exploratory analysis examined whether sex, adiposity, and hypertension modify the inverse association between marine food intake and blood pressure. METHODS: We used covariate-adjusted linear models to describe the association between δ¹5N and blood pressure in 873 adult Alaska Native (Yup'ik) people who resided in 8 communities in southwest Alaska. We separately stratified by sex, body mass index (BMI) group, abdominal obesity, and hypertension status and assessed the interaction between δ¹5N and participant characteristics on blood pressure via likelihood ratio tests. RESULTS: The association between δ¹5N and systolic blood pressure was modified by sex, BMI status, and abdominal obesity, with the inverse association observed only in the male (ß = -1.5; 95% CI: -2.4, -0.6 : , nonobese BMI (ß = -1.7; 95% CI: -2.5, -1.0), and non-abdominally obese (ß = -1.6; 95% CI: -2.4, -0.9) strata (all P-interaction < 0.0001). A reduction in diastolic blood pressure associated with δ¹5N was observed in the nonobese BMI (ß = -1.1; 95% CI: -1.7, -0.5) and non-abdominally obese (ß = -1.1; 95% CI: -1.7, -0.5) strata, although only the interaction between BMI group and δ¹5N with diastolic blood pressure was significant. The inverse association between δ¹5N and both systolic and diastolic blood pressure was observed in nonhypertensive individuals, although the comparison had limited power. The results were consistent with those identified by using combined RBC concentrations of eicosapentaenoic acid and docosahexaenoic acid as the biomarker of marine food intake, although the associations identified by using δ¹5N were larger. CONCLUSIONS: Obesity status modified the inverse association between marine food intake and both systolic and diastolic blood pressure in adult Alaska Native (Yup'ik) people. The inverse association between δ¹5N and systolic blood pressure was also modified by sex.

Associations between toenail arsenic concentration and dietary factors in a New Hampshire population.

BACKGROUND: Dietary factors such as folate, vitamin B12, protein, and methionine are important for the excretion of arsenic via one-carbon metabolism in undernourished populations exposed to high levels of arsenic via drinking water. However, the effects of dietary factors on toenail arsenic concentrations in well-nourished populations exposed to relatively low levels of water arsenic are unknown. METHODS: As part of a population-based case-control study of skin and bladder cancer from the USA, we evaluated relationships between consumption of dietary factors and arsenic concentrations in toenail clippings. Consumption of each dietary factor was determined from a validated food frequency questionnaire. We used general linear models to examine the associations between toenail arsenic and each dietary factor, taking into account potentially confounding effects. RESULTS: As expected, we found an inverse association between ln-transformed toenail arsenic and consumption of vitamin B12 (excluding supplements) and animal protein. Unexpectedly, there were also inverse associations with numerous dietary lipids (e.g., total fat, total animal fat, total vegetable fat, total monounsaturated fat, total polyunsaturated fat, and total saturated fat). Finally, increased toenail arsenic concentrations were associated with increased consumption of long chain n-3 fatty acids. CONCLUSION: In a relatively well-nourished population exposed to relatively low levels of arsenic via water, consumption of certain dietary lipids may decrease toenail arsenic concentration, while long chain n-3 fatty acids may increase toenail arsenic concentration, possibly due to their association with arsenolipids in fish tissue.