To assess vitamin D status and the influence of risk factors such as skin pigmentation and time spent outdoors on hypovitaminosis D among Guatemalan Kekchi and Garifuna adolescents.

Cross-sectional study, with convenient sampling design. Blood samples, anthropometric and behavioural data were all collected during the dry season. Serum 25-hydroxyvitamin D (25(OH)D) concentrations were measured by RIA.

Communities of Rio Dulce and Livingston, Izabal Province, Caribbean coast of Guatemala, with latitude and longitude of 15°49′N and 88°45′W for Livingston and 15°46′N and 88°49′W for Rio Dulce, respectively.

Eighty-six adolescents, divided evenly by sex and ethnicity, with mean age of 14 years.

Mean (sd) 25(OH)D value was 27·8 (7·2) ng/ml for the total group, with 25·8 (5·9) and 29·8 (7·9) ng/ml, respectively, in Kekchis and Garifunas (P=0·01). Use of vitamin D supplementation, clothing practices and sun protection were not statistically different between groups. Skin area exposed on the day of data collection ranged from 20·0 % minimum to 49·4 % maximum, with mean (sd) exposure of 32·0 (8.5) %. With univariate regression analysis, age (P=0·034), sex (P=0·044), ethnicity (P=0·010), time spent outdoors (P=0·006) and percentage skin area exposed (P=0·001) were predictive. However, multivariate analysis indicated that only sex (P=0·034) and percentage skin area exposed (P=0·044) remained as predictors of 25(OH)D.

Despite residing in an optimal geographic location for sunlight exposure, nearly 65 % of study adolescents were either insufficient or deficient in vitamin D. Correction and long-term prevention of this nutritional problem may be instrumental in avoiding adverse effects in adulthood attributed to low 25(OH)D during adolescence.