To ensure tests for Vitamin D deficiency are priced so they are affordable for everyone, the Ministry of Health is being urged.

A deficiency of the vitamin contributes to the risk of respiratory infections, a University of Harvard study of more than 900 New Zealand children found.

Respiratory infection bronchiolitis in New Zealand is about twice that of the United States.

Lead scientist Carlos Camargo says for all-round good health, everyone needs an adequate supply of Vitamin D.

Vitamin D comes mainly from sunlight but the answer lies in taking a supplement as Dr Camargo says that New Zealand has a world leading rate of melanoma also known as skin cancer.

A test to see how much they actually need should be taken by everyone as overdosing of the sunshine vitamin can have dire consequences and he would like to see the Health Ministry facilitate that.

With a test Dr Camargo says it can not be stated how much sunshine someone should get.

He added, "Going outside, even in the winter in New Zealand, you're not going to make any Vitamin D - you need to get it from something else.”

Because of small amounts of the vitamin present in food, food is not a very good way of getting it. So you take the supplements.