Do maternal dietary vitamin D intake and sunlight exposure affect the vitamin D status of exclusively breastfed infants?

Abstract

AIM: Exclusively breastfed infants are dependent upon their mothers for their vitamin D intake. In New Zealand (NZ), vitamin D supplementation is not routinely recommended for exclusively breastfed infants. We aimed to determine the association of exogenous maternal vitamin D intake and sunlight exposure with serum 25â hydroxyvitamin D [25(OH)D] concentration in exclusively breastfed infants aged 2â 3 months. METHODS: We enrolled a convenience sample of women and their exclusively breastfed infants. Maternal dietary and supplemental vitamin D intake was determined from an interviewerâ administered semiâ quantitative food frequency questionnaire. Sunlight exposure was determined from reported time spent outdoors. Associations of vitamin D intake and sunlight exposure with infant serum 25(OH)D concentration at age 2â 3 months were determined using multivariable linear regression. RESULTS: Sixtyâ three motherâ infant pairs, 73% of whom were European, and their exclusively breastfed infants completed the study. Mean (SD) serum 25(OH)D concentration was 52â nmol/L (30), with 28% of infants being vitamin D deficient (25(OH)D < 50â nmol/L). Estimated median maternal dietary vitamin D intake from food was 158â IU/day. Thirty (48%) mothers consumed vitamin D supplements. Nonâ European ethnicity (P = 0.01) and measurement of 25(OH)D during winter (P < 0.001) were independently associated with infant serum 25(OH)D concentration. Maternal dietary vitamin D intake (P = 0.62), supplement use (P = 0.32) and sunlight exposure (P = 0.72) were not independently associated with infant serum 25(OH)D concentration. CONCLUSIONS: Serum 25(OH)D concentrations in exclusively breastfed infants in NZ are independent of current maternal vitamin D intake and sunlight exposure practices. Consideration needs to be given for vitamin D supplementation of exclusively breastfed infants during winter.