To measure the trends in traditional marine food intake and serum vitamin D levels in Alaska Native women of childbearing age (20–29 years old) from the 1960s to the present.

We measured a biomarker of traditional food intake, the δ15N value, and vitamin D level, as 25-hydroxycholecalciferol (25(OH)D3) concentration, in 100 serum samples from 20–29-year-old women archived in the Alaska Area Specimen Bank, selecting twenty-five per decade from the 1960s to the 1990s. We compared these with measurements of red-blood-cell δ15N values and serum 25(OH)D3 concentrations from 20–29-year-old women from the same region collected during the 2000s and 2010s in a Center for Alaska Native Health Research study.

The Yukon Kuskokwim Delta region of south-west Alaska.

Alaska Native women (n 319) aged 20–29 years at the time of specimen collection.

Intake of traditional marine foods, as measured by serum δ15N values, decreased significantly each decade from the 1960s through the 1990s, then remained constant from the 1990s through the present (F5,306=77·4, P<0·0001). Serum vitamin D concentrations also decreased from the 1960s to the present (F4,162=26·1, P<0·0001).

Consumption of traditional marine foods by young Alaska Native women dropped significantly between the 1960s and the 1990s and was associated with a significant decline in serum vitamin D concentrations. Studies are needed to evaluate the promotion of traditional marine foods and routine vitamin D supplementation during pregnancy for this population.

To determine the vitamin D status of middle-aged women living in the Norwegian arctic and its relationship with vitamin D intake and exposure to ultraviolet (UV) radiation.

Cross-sectional study.

This study is based on measurements of 25-hydroxyvitamin D (25(OH)D) levels in a sub-sample of the Norwegian component of the EPIC biological bank, which consists of blood samples from a random selection of participants in the Norwegian Women and Cancer Study. From November 2001 until June 2002, 309 blood samples were collected from a total of 443 invited middle-aged women (44–59 years) in northern Norway (65–71°N) (crude response rate, 69.8%). Questionnaire data provided information on dietary sources of vitamin D and UV exposure.

Median plasma 25(OH)D concentration for the whole group was 55.0 nmol l−1 (range 8.1–142.8 nmol l−1). Vitamin D intake was a significant predictor of 25(OH)D status (P = 0.0003). The time of the year when the blood sample was collected significantly predicted plasma 25(OH)D level (P = 0.005). Levels of 25(OH)D were positively associated (P = 0.0002) with estimated hours per day of exposure to UV-B radiation. Residing in northern Norway during the summer prior to blood sampling was negatively associated with 25(OH)D concentration (P = 0.001). The prevalence of moderate hypovitaminosis D was highest in January–February, when a quarter of the participants had 25(OH)D concentrations ≤37.5 nmol l−1.

Increased ingestion of marine food items that provide vitamin D should be promoted and further studies should be carried out to investigate vitamin D status in arctic populations in relation to both UV exposure and traditional food sources.