Taking extra vitamin D can protect against colds, flu and other respiratory infections, said a study Thursday which reopened a debate on the usefulness of over-the-counter supplements.
A review of 25 clinical trials in 14 countries, some with conflicting results, yielded “the first definitive evidence” of a link between vitamin D and flu prevention, researchers claimed in The BMJ medical journal.
The effects were strongest for people with very low levels of the nutrient which is found in some foods and can be synthesised by the body when the skin is exposed to ultraviolet light.
Many people, especially in grey, cloudy climes, do not have enough vitamin D.