Many runners have an intolerance to a certain type of food that often does not become apparent until they start training. These intolerances can lead to side effects which can end up ruining many a training session or race.

Food intolerance v food allergy

A food intolerance is not to be confused with a food allergy. Allergies, such as an allergy to nuts, can be much more serious and can even lead to death in some cases, whereas an intolerance generally just has a mild effect but can nevertheless be very inconvenient. Typical food intolerances include: yeast and dairy, which can wreak havoc with your digestive system and your running.

It is not uncommon for runners to suffer from the infamous ' runner's trots ', the symptoms of which probably don't require spelling out. Diarrhoea can ruin some of the best laid training plans, after all you're never meeting your training targets if you are continually having to cut short your training sessions or spending part of your time squatting in a field or behind a bush!

It is also common for many runners to dismiss runner's trots as being due to a specific meal or the alcohol you drank last night, but you could actually be suffering from intolerance to a particular food group that over a period of time (and often as you get fitter) exhibits itself in the most frustrating way.

Identifying a food intolerance

So how can you find out if you have a problem? One way is to visit your doctor and obtain details of a specialist in this area. You can do various tests during which intolerances can be identified.

An alternative is to go on a detox program. This involves drinking a prune juice based liquid for a few days or taking a series of plant extract pills to cleanse your system. You then slowly start to add back various foods into your diet until one of them causes a reaction.

It is surprising how many people actually do have an intolerance, whether it’s lactose, yeast or even fruit, which is generally not identified or even a real problem until they begin running. By identifying your intolerance, and not just dismissing it as something that happens occasionally, can really help you focus solely on your running and therefore help you perform better.