There are a number of reasons why hair loss can occur in patents with Crohn’s and other inflammatory bowel disorders:
High levels of cortisol – Increased levels of cortisol are common in patients with Crohn’s disease . Whilst cortisol is a powerful moderator of the inflammation, it is a catabolic hormone and when cortisol levels are consistently high normal metabolism and growth will be suppressed.
Cortisol leads to the breakdown of the collagenous stricture that supports the hair follicle. When collagen is broken down, the hair fibre will be less firmly anchored and the keratin cells within the hair fibre will go through a shorter hair growth phase leading to shorter hair that sheds prematurely.
Nutrition – Patients with Crohn’s often develop anemia due to impaired vitamin absorption. Many patients have low B12, folate, iron deficiency or anemia of chronic disease. This could be due to inflammation leading to high levels of hepcidin inhibiting iron uptake, lack of B12 binding with intrinsic factor needed for absorption and inflammation of the duodenum and jejunum leading to low folate uptake. Vitamin D and zinc levels are also often affected.
The keratin cells within a growing hair fibre require a number of vitamins and minerals to mature and grow. A restriction in vitamins and minerals will give rise to weaker hair that may feel dry and brittle or break easily.
Gut bacteria imbalance – Patients with Crohn’s often have an imbalanced gut bacteria population. A number of studies have linked Crohn’s with reduced gut bacteria diversity. In active disease states, there is a definite and specific alteration in gut bacteria population. In active disease there are a larger number of members belonging to Enterococus, Desulfovibrio, Fusobacterium, Haemphilus, Megasphaera, and Campylobacter. When the disease is inactive, there are higher members of Roseburi, Christensenellaceae, Oscillibacter and Odoribacter.
Gut bacteria are responsible for many vital physiological processes such as protection against invading bacteria, the harvest of energy and the development of host immunity. One study linked the gut bacteria to poor sulphur metabolism due to an increased levels of sulphate reliant bacteria using sulphur for metabolism producing hydrogen disulphide as a toxic metabolic byproduct.
As sulphur is needed for extensive disulphide linkages in the growing hair shaft this can affect the quality of the linkages responsible for the strength of the hair fibre. The increase of hydrogen sulphide in the inhibits the production of Acyl-COA dehydrogenase with is needed for butyrate oxidation. Butyrate is a preferred energy source for the epithelial cells of the gut, it reduces inflammation, strengthens gut cell walls and lowers cholesterol .
The dysregulation of sulphur metabolism explains why most Crohn’ patients cannot tolerate foods such as raw onions and garlic. The metabolism of sulphur containing amino acids needed for keratin production within keratin cells (cysteine and methionine) was also shown to be affected negatively when disease is active.
Medication side affects – Immunosuppressants that are prescribed for Crohn’s can interfere with hair growth as they are designed to slow down cell multiplication to deal with the inflammation in the bowel. If you think your hair loss may be due to medication, you can talk with your doctor about potentially changing your medication to one where hair loss is a less common side effect.