The sunshine nutrient made by the skin in sunlight also reduced by nearly a third the number of asthmatics needing steroids after suffering breathing difficulties.
It adds further evidence the nutrient also found in oily fish such as salmon, sardines, herring, mackerel and fresh tuna, red meat, liver, egg yolks and fortified foods such as most fat spreads and some breakfast cereals boosted the body’s defences.
The incurable long-term condition affects around 5.4 million Britons – one in every 12 adults and one in every 11 children.
Yet it kills three people die every day but two in three asthma deaths are preventable - writesgolifehacks.info.
The attacks are commonly triggered by viral upper respiratory infections.