To test the efficacy of different vitamin D delivery methods on serum 25(OH)D. Participants randomly assigned to one of seven groups - three placebo groups and 4 active supplement groups receiving 100,000IU vitamin D3

Various delivery methods of vitamin D supplementation are available to consumers but there have been no studies providing evidence of whether one delivery method is superior to others. The researchers wanted to compare the delivery of 100,000IU vitamin D3 by three methods on serum 25(OH)D levels. Two methods of oral supplementation (pill [prolonged release] and liquid [immediate release]), and delivery through the skin (with and without a penetrator enhancer. Placebo groups were pill, oral liquid and skin applied oil

Inclusion Criteria:

• healthy, female

Exclusion Criteria:

• any participant that was taking vitamin supplementation, had a skin condition that would prevent them from applying oil to their skin or were taking, or had been taking in the past 6-months, oestrogen based contraception