Nutritional consequences of IBD
By: Naomi Joseph, Dietitian BSc RD
The effects of Inflammatory Bowel Disease (IBD) on the body’s nutritional status can be quite significant and in some cases fairly extreme. The body relies on an efficient digestion and absorption system to acquire sufficient nutrition for health, and in children, growth and development.
Unfortunately, with IBD, many of the body’s mechanisms for digestion and absorption of nutrition are compromised. Therefore malnutrition is a key focus factor in the treatment of IBD.
The following is a summary of the most common nutritional issues which need to be addressed for patients with Crohn’s or Colitis.
- Maintaining a healthy weight and BMI.
Typically patients will have lost weight at the point of diagnosis as the condition will often be identified by a combination of weight loss and other medical parameters. Once treatment begins, weight and BMI are measured regularly as part of the monitoring process. Usually, increase or maintenance of weight is seen as a sign of good response to treatment. Weight can fluctuate during the courses of treatment, particularly during a relapse.
- Calcium, vitamin D and bone health
For children with IBD, development of bone health is an important aspect of their treatment as their peak bone development will be attained by adolescence.
- Micronutrients – vitamins and minerals
Previous studies have shown that vitamin and mineral levels in the body can often tend to be low or less than the recommended amount, in IBD. Virtually all vitamins and minerals are typically suboptimal, but in particular vitamins A,E, D and C and zinc, selenium and copper. B vitamins can tend to be low as well.
This is usually due to a combination of poor dietary intake, decreased absorption, and high intestinal losses. Often vitamin supplementation will be necessary if deficiencies are identified.
There are different types of anaemia and in order to treat it correctly, the type and origin of the anaemia must be correctly determined. Patients with IBD will have monitoring of iron, iron stores, iron transfer proteins, and vitamin B12, at different stages of the disease process to ensure the monitoring and interpretation is correct. The two main types of anaemia are iron deficiency anaemia, (more common in children), and chronic disease anaemia (more common in adults). The anaemia is treated with supplementation, either with oral iron supplements, or intravenous iron infusions. Patients who have had bowel resections of their terminal ileum will usually require B12 supplementation for life.
- Fibre and residue
The body’s ability to break down roughage and fibre is most often weakened in an IBD flare up, and actually can make symptoms worse, because there is more chance the fibres will irritate the already sore and ulcerated inside of the bowel. Therefore, most patients experiencing a flare up of their IBD are put on low fibre and low residue diets. In some cases even solid food is too difficult to tolerate and a liquid diet is needed for a period of time to give the bowel rest and time to heal.
To summarise, there are a number of nutritional factors which require attention in order to avoid or treat IBD associated malnutrition – poor dietary intake, increased energy requirements, and metabolism, malabsorption, and increased losses. There are also biochemical inflammatory processes that can affect bone health, and growth and development in children.
In an acute attack, appetite is often poor, or the diet has to be modified to liquid form or reduced fibre, so the range of nutrients available to the body might be limited.
Therefore careful attention to nutrition status and good nutrition support is an important part of the patient’s overall IBD treatment and management.