Oestrogen-containing contraceptive pills increase vitamin D levels, study finds

Taking oestrogen-containing oral contraceptives is associated with increased vitamin D levels, a large US follow-up study has shown.1

Previous small studies have found that taking oestrogen in hormone replacement therapy or oral contraception may be associated with increases in serum levels of 25 hydroxyvitamin D (25[OH]D), which is the widely accepted clinical biomarker of vitamin D status. But it has been unclear whether this was a causative effect or due to other lifestyle factors.

Researchers investigated the …