Ronny Terry is a Swindon-based personal trainer. He has previously worked as Performance Analyst with Swindon Town FC and on obesity initiatives with the NHS. Tweet your questions to @SWITCHFITUK or visit www.switchfituk.co.uk

FOOD allergies are immune system responses to food or drink the body considers harmful. Coughing, sneezing, rashes and itching are some of the milder symptoms, but some reactions can require medical attention, like anaphylaxis.

Anaphylaxis is when the eyes, lips, hands and tongue swell up and airways become restricted, causing breathing difficulties. While symptoms usually show minutes after consumption, they can be delayed by hours. Anaphylaxis should always be treated as a medical emergency. Nuts, shellfish and milk are common culprits, although any food could potentially cause anaphylaxis.

While only two per cent of people have a genuine food allergy, intolerances are more common. Caused by the body’s inability to produce specific enzymes to help digest certain foods, they are not life-threatening but can cause misery with symptoms like diarrhoea, stomach cramps and gas.

People can be either intolerant or allergic to milk. An inability to properly digest lactose, the sugar in milk, affects around one in five people and causes much digestive discomfort. Meanwhile, an allergic reaction to the protein component of milk can trigger an immune system response causing rashes, wheezing, coughing and a runny nose.

Coeliac disease affects around one per cent of people and is neither an intolerance nor an allergy. It is actually an immune system response caused by an adverse reaction to gluten, which is found in wheat, barley and rye. Common traits include diarrhoea, stomach cramps, fatigue and weight loss, and it can damage the bowls, hindering the absorption of nutrients and causing malnourishment. There is no cure for coeliac disease but a gluten-free diet can minimise bowel damage.

If certain foods appear to be causing problems, try excluding them from your diet. Alternatively, contact your GP who may test you for coeliac disease or refer you to a dietician specialising in food intolerances.