Taking vitamin D supplements may lower blood pressure and boost exercise performance, Scots research has shown.
Volunteers given the vitamin daily for two weeks saw fitness improvements that allowed them to cycle longer with less exertion.
Their blood pressure and levels of the stress hormone cortisol were also lower compared with another group taking a dummy pill.
The Edinburgh research emerged two months after the independent Scientific Advisory Body on Nutrition (SACN) advisory group recommended all Scots should take vitamin D supplements because of the health implications of a lack of bright sunshine.
The body set up by the UK Government said the bleak British weather is stopping much of the population from receiving healthy amounts of the essential vitamin from sunlight – and natural food sources alone are not enough to boost levels.
It made the recommendation after studying the links between vitamin D levels and a range of health problems, including musculoskeletal health, heart disease, type 1 diabetes, cancer and multiple sclerosis.
More than one million people in Scotland are deficient in vitamin D, which is chiefly obtained from the action of sunlight on the skin.
Previous studies have indicated that vitamin D blocks the action of an enzyme needed to make cortisol.
Large amounts of the hormone are thought to raise blood pressure by narrowing blood vessels and to stimulate the kidneys to retain water.
The findings were presented at the annual meeting of the Society for Endocrinology in Edinburgh.
Study lead author Dr Emad Al-Dujaili, also from Queen Margaret University, said: ‘Vitamin D deficiency is a silent syndrome linked to insulin resistance, diabetes, rheumatoid arthritis, and a higher risk for certain cancers.
‘Our study adds to the body of evidence showing the importance of tackling this widespread problem.’