A food intolerance is different to a food allergy. If you are intolerant to a food, you may find that small amounts can be eaten without problems but larger amounts cause pain or irritable bowel symptoms. Some of the foods most likely to cause problems are a special group of carbohydrates, sometimes called FODMAP foods. Common foods that include large amounts of FODMAPs include:
- lactose milk, yoghurt and icecream (if digesting lactose is a problem for you)
- wheat products (bread, pasta, pizza)
- onions and garlic
- corn syrup
- apples
- artificial sweeteners, especially sorbitol
While many of the foods we eat are absorbed quite quickly from the ‘small bowel’ (small intestine), FODMAP foods are digested slowly. While in the small bowel, they pull water into the bowel making the contents more liquid. The small amounts of FODMAP foods that reach the ‘large bowel’ (large intestine) are fermented by bacteria to form gas and irritating substances causing pain, diarrhoea, constipation or bloating. This isn’t a problem in most people. They pass wind from time to time but don’t have pain.
Some people absorb FODMAP foods even more slowly than usual. Even more water is pulled into the small bowel, and even more gas is made. If the bowel is otherwise healthy, they may make more wind than other people but still not have pain.
However, if the large bowel is sensitive (as it is in many people with pelvic pain), then eating these foods is likely to cause pain. The bowel doesn’t like the extra wind and water and let’s you know there is a problem by causing pain or bloating. Your bowels might vary from day to day – sometimes with diarrhoea, sometimes with constipation and sometimes with a mix of both.
This means that while your friends may be able to eat any food and feel fine, your bowel will be painful unless you are careful.
Should I just go ‘gluten-free’?
A gluten free diet is a special diet for people with Coeliac Disease. People with coeliac disease need to be on a strict ‘gluten free’ diet for the rest of their life.
People with an irritable bowel often feel much better on a ‘gluten free’ diet, because by cutting out gluten they are also cutting out wheat, a major FODMAP food. They do not have a problem with gluten and may be able to tolerate small amounts of wheat.
Before you change your diet, ask your doctor for a blood test that checks for coeliac disease. This test isn’t reliable if you have already cut out wheat from your diet, so it’s much easier to get it done first.
Are there other problem foods?
Yes, definitely, but everyone is different. You might have a problem with rich or fatty foods (cream, takeaway, animal fats), alcohol, coffee, fizzy drinks, and spicy food.
A low fat, low salt diet is good for everyone, but even more important if you have bowel problems.
If you find it all too hard to work out, a dietitian may be able to help.