Vitamins and minerals

People with IBD are at risk of vitamin deficiencies, particularly if they have Crohn’s Disease and have trouble absorbing nutrients due to inflammation in the small intestine. It may be necessary to take a vitamin supplement - your doctor or IBD nurse will tell you if this is the case.

Iron deficiency is common among people with IBD. This can be caused by a number of factors - such as lack of iron in the diet, blood loss, or difficulties absorbing iron. Lack of iron can lead to anaemia - where there are fewer red blood cells to carry oxygen around the body. Anaemia can cause tiredness and fatigue, shortness of breath, headaches and general weakness. It can be treated by iron supplements, either as tablets, or as intravenous iron which is given by an injection or by infusion through a drip. Intravenous iron is often better tolerated than oral iron in people with IBD. It may also help to eat iron rich foods such as red meat, eggs, dark green vegetables such as spinach and broccoli, pulses such as peas, beans and lentils, and fortified breakfast cereals. Iron from non-meat sources is absorbed more easily when it is taken with vitamin C. Try, for example, having a glass of orange juice with your fortified breakfast cereals.

People who have had their ileum (the last part of the small intestine) removed, or who have inflammation in that area, may have vitamin B12 deficiency. This can also lead to a form of anaemia called ‘vitamin B12 deficiency anaemia’. For more information, see the section on Eating after surgery.

Vitamin D is another common deficiency amongst people with IBD. Vitamin D is formed by the action of sunlight on the skin, and can also be found in foods such as eggs and oily fish. It is important for the immune system, and is also needed for healthy bones. Some studies suggest that low vitamin D levels may lead to an increased risk of surgery and hospitalisations, particularly in people with Crohn’s. Another study found that giving vitamin D supplements to people with Crohn’s reduced the risk of having a flare-up.

Some people with IBD may be calcium deficient. This may be due to inflammation in the small intestine reducing absorption, but may also be down to lack of calcium in the diet. Calcium is important to maintain healthy strong bones and is found in foods such as dairy products, fortified breakfast cereals and some green leafy vegetables, such as spinach. However, some people with IBD cannot tolerate dairy products (for more information see Lactose intolerance below). If this is the case with you, your doctor may suggest you take a calcium supplement. Your doctor may also suggest calcium supplements if you are on steroid medication, because steroids can increase the risk of having weak bones. See our information sheet Bones and IBD for more information.