Asthma patients who suffer from severe attacks, or exacerbations, were at a lower risk of having an attack and less likely to need hospital treatment if they had been taking regular doses of the vitamin, trials carried out by a Cochrane Review showed.
They were also less likely to need treatment with steroid tablets.
Asthma is a chronic respiratory disease that affects around 300 million people worldwide, causing wheezing, coughing, chest tightness and shortage of breath.
Vitamin D in children and adults has been linked to lowering the risk of asthma attacks. Evidence suggests it may help prevent respiratory infections, such as the common cold, which can lead to exacerbations in patients.
The trials were organised by Cochrane, a not-for-profit network of health professionals, after experts noticed a link between low levels of the vitamin in asthmatics and an increased risk of attacks.
Speaking at a review of the research at London's Science Media Centre on Monday, lead research author Professor Adrian Martineau said: "Asthma is a rising problem in the UK, with one out of 11 people receiving treatment for it every day.
"Vitamin D, or the sunshine vitamin, as well as enhancing bone development, helps the development of at least 35 other tissues and white blood cells. This can boost immunity against other illnesses and dampen down inflammation."
The investigation involved nine trials with 1093 people with different levels of asthma. The patients, from a range of ethnic backgrounds, were given different dosages over six to 12-month periods.
The results also showed that the vitamin supplements did not increase the risk of side effects, but did not improve lung function or day-to-day asthma symptoms in patients either.
"We don't know whether these heightened dosages will benefit all asthma patients or just those who already have low levels of vitamin D. Also, about three quarters of asthma patients do not suffer from exacerbations, and we need to do further trials to discover whether the supplements can benefit other groups," Prof Martineau said.
Dr Imran Rafi, chair of clinical innovation and research at the Royal College of GPs, shared his support for the research and the impact that further investigation could have for treating asthma.
He said: "More work still needs to be done in gathering the evidence, particularly around effectiveness for young people and children."
