Vitamin D3 can be taken anytime; however, it is a fat-soluble vitamin meaning it absorbs better in the presence of fat. Taking vitamin D3 with a meal or snack is preferable. Follow the product’s packaging directions or as instructed by your healthcare provider. Vitamin D3 can be taken anytime; however, it is a fat-soluble vitamin meaning it absorbs better in the presence of fat. Taking vitamin D3 with a meal or snack is preferable. Follow the product’s packaging directions or as instructed by your healthcare provider.