Change in plasma levels of vitamin D after consumption of cod-liver and fresh cod-liver oil as part of the traditional north Norwegian fish dish “Molje”

Abstract

Objective. To assess changes in plasma 25-hydroxy vitamin D (25(OH)D) concentrations after ingestion of «Mølje», a traditional north Norwegian fish dish rich in vitamin D.Methods. Thirty-three volunteers all living in the city of Tromsø, located in northern Norway (latitude 69°), were served a “Mølje” meal consisting of cod, hard roe, cod liver, and fresh cod-liver oil. The amounts of liver, and cod-liver oil consumed were weighed and recorded. Blood samples were collected before the meal, and at 4 hours, 12 hours and 5 days after it. The cod liver and cod-liver oil were analysed for vitamin D content and the plasma samples for the metabolite 25(OH)D. Trends in plasma 25(OH)D levels during the five-day observation period were analysed. The study was conducted at the beginning of April of 2000. Results. Among the 33 participating subjects, 69.7% had baseline plasma 25(OH)D concentrations below 50 nmol/l and for one-quarter of the subjects, they were < 37.5 nmol/l. The participants who acknowledged taking cod-liver oil supplements had significantly higher aseline 25(OH)D plasma levels at the outset of the study compared to those reporting not doing so (p=0.02). Changes in plasma 25(OH)D levels relative to baseline concentrations were significantly associated with the body mass index (p<0.01).Conclusion. Vitamin D status in populations living in circumpolar areas needs more research to investigate to what degree people living in the Arctic areas are at increased risk for vitamin D insufficiency and to determine the role of the traditional diet in preventing such deficiency.