Scope: Fish liver, fish liver oil, oily fish and seagull eggs have been major sources of vitamin D for the coastal population of Norway. They also provide dioxin and polychlorinated dioxin-like compounds (dl-compounds), which may interfere with vitamin D homeostasis. We investigated whether serum 25-hydroxyvitamin D (25(OH)D) might be compromised by concomitant intake of dl-compounds.
Methods and results: We studied 182 adults participating in the Norwegian Fish and Game Study. Participants who consumed fish liver and/or seagull eggs had higher dl-compound intake and blood concentrations than non-consumers (p < 0.001). Vitamin D intake was higher (p < 0.001), whereas serum 25(OH)D was lower (p = 0.029) in consumers than in non-consumers. Among non-consumers, vitamin D intake was associated with serum 25(OH)D (β=1.06; 95% CI: 0.48, 1.63). This association was weaker among consumers (β = 0.52; 95% CI: -0.05, 1.08), but strengthened when adjusted for retinol intake (β = 0.66; 95% CI: 0.12, 1.21). The association between vitamin D intake and serum 25(OH)D did not seem to be compromised by intake of dl-compounds.
Conclusion: To secure adequate vitamin D status while keeping the intake of dioxins and dl-polychlorinated biphenyls low, a healthy diet should include both supplemental vitamin D and oily fish. Despite high nutrient content, dietary fish liver and seagull eggs should be restricted, due to dl-compounds and possible vitamin A-D antagonism.
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