Asthma and diet
There is no special asthma diet, or specific foods recommended for people with asthma. In some cases, if specific foods are known to trigger asthma symptoms through allergic reactions, individual recommendations may be made.
Eating a healthy balanced diet is an important part of an overall asthma management plan, along with regular exercise.
Obesity is associated with more severe asthma, so managing weight can be important.
Asthma and nutrition
Asthma UK says that researchers looking at the diets of children and adults have shown that people who eat the most fruit and vegetables have the healthiest lung function. The charity says vitamin C and E are thought to help reduce the severity of inflammation in the lungs.
A healthy diet also plays a role in maintaining the immune system - the body's defences. This can help protect against infections like colds and flu that can make asthma symptoms worse.
A US study found that teenagers with asthma who ate poor diets were more likely to have asthma symptoms. Lung function was worse among those who did not eat enough fruit, foods providing vitamins C and E, and omega-3 fatty acids.
A 2007 study found that children who grew up eating a Mediterranean-style diet, rich in nuts, vegetables and healthy fats, were less likely to have asthma-like symptoms.
Attempts to improve asthma by using specific vitamins and mineral supplements have not been successful.
Some experts think the interaction of different naturally occurring vitamins, minerals and antioxidants in food help the most rather than supplements.
What should I eat?
Given the unclear evidence for a link between asthma and nutrition, here are some basic tips:
Eat plenty of fruit and vegetables. It is still not known which fruits and vegetables might have an effect on asthma, so eat a variety of different coloured fruits and vegetables as part of your 5-a-day.
Include foods that provide omega-3 fatty acids in your diet. The UK 'Eatwell guide' recommends a portion of oily fish weekly to provide us with essential omega-3 fats. Oily fish include salmon, fresh tuna, and sardines. Omega-3 fats are also found in some plant sources like rapeseed oil, flaxseed and flaxseed oils, but these are thought to have a less powerful effect in the body than the fish oil type of omega-3 fats.
Will this dietary advice help your asthma symptoms? No-one can be sure. However, while it may not be known what specific vitamins, minerals and antioxidants might help with asthma - if any - there is no downside to eating more fruit and vegetables and (in moderation) healthy fats.
What else affects symptoms?
Nutrition, good or bad, is not the only way that asthma might be affected by diet. Here are some examples:
Diets high in calories: If you eat more calories than you burn through daily life or exercise, weight can creep up. People who are obese are more likely to have more severe asthma symptoms, need more medication and miss more days of work than people who maintain a healthy weight.