Eating a poor-quality diet high in fat, refined sugar and processed foods can worsen asthma symptoms, a study has shown.

University of Newcastle nutritional biochemist Lisa Wood and her colleagues made the finding after studying the diets of 99 people with asthma and 61 healthy people.

The researchers scored the study participants' diets based on their potential to either cause inflammation, linked to overactivity in the immune system, or protect against it.

Inflammatory foods include those high in saturated fat and refined sugar, while anti-inflammatory foods include fruit and vegetables and those high in soluble fibre such as oat bran and lentils.

Dr Wood said people with asthma who took part in the study were more likely to eat inflammatory diets than those without the disease.

She said previous research had shown that eating a single high-fat meal could cause inflammation in the airways of people with asthma.

The body responded to an excess of dietary fat in the same way it would an invading pathogen, she said, and "if you chronically eat like that, your immune system will be chronically activated".

She said it was particularly important for people who already had asthma to eat a diet high in fruit and vegetables, and low in saturated fat and takeaway foods.