We learned that vitamin D is good for many things, but may not help with colds.

In a New Zealand study of healthy adults over 18 months, half of the participants were given large, monthly doses of Vitamin D3 – the form of vitamin D the body produces when exposed to sunlight – and half were given placebo pills. 

During the 18-month period, which included two severe cold and flu seasons, 593 of the people who took the vitamin D supplements contracted an upper respiratory tract infection (URTI) while 611 of the people who took placebos contracted a URTI.

Scientists concluded that the discrepancy between the vitamin D and placebo group is not statistically significant enough to say that vitamin D did anything to prevent the infections.