A low intake of vitamins A and C could raise the risk of asthma, a team which reviewed 40 studies carried out over the past 30 years has said.A Nottingham University-led team found people with a low intake of vitamin C had a 12% increased risk of asthma, the Thorax journal reported.For vitamin A the raised risk was less clear cut, the team said, but there was still a significant association.Asthma UK and the Medical Research Council said more research was needed.There has been a lot of confusion over the link between vitamins and the condition, which affects five million people in the UK.Previous studies have come up with a variety of conclusions.In this study, the researchers analysed the relevant reports on both children and adults published since 1980.They found no link for vitamin E, but said the associations for A and C were significant.They concluded low levels of vitamin C - found in fruit and vegetables - increased the risk of asthma by 12%.They were unable to put an exact figure on vitamin A - found in cheese, eggs and oily fish - but noted that those with severe asthma consumed on average half of the recommended intake of the vitamin.Lead researcher Dr Jo Leonardi-Bee said: "Our findings indicate that low levels of vitamin C intake and to a lesser extent vitamin A are consistently associated with asthma risk to a degree that, if causal, would be sufficient to be clinically relevant."He said it was now important to carry out larger-scale studies to clarify the link and to see if there was a direct cause between vitamin intake and asthma.Other factorsExperts agreed more research was needed, but warned other factors would also play a significant role.Glenys Jones, a nutritionist with the Medical Research Council, said: "The data provided is interesting, but inconclusive."There are many factors such as smoking, physical activity and socio-economic status that have not been taken into account."Therefore more research is required to investigate a causal relationship."Leanne Male, assistant director of research at Asthma UK, added: "The jury is still out as to how exactly vitamin intake and asthma are related."Source:BBC