Zinc is an essential trace element, which is absorbed in the small intestine and serves as a cofactor for numerous enzymes involved in growth, immune function, and tissue repair. Zinc deficiency is rare in the general population. In contrast, 15 – 40 % of patients with Inflammatory Bowel Disease (IBD, Crohn’s and Colitis) may have zinc deficiency.
Lower Zinc Levels – Higher Risk of Complications?
A recent University of Chicago database analysis of 773 patients with Crohn’s disease and 223 with ulcerative colitis showed that zinc deficiency was associated with an increased risk of subsequent hospitalizations, surgeries, and disease-related complications in patients with both Inflammatory Bowel Diseases.[i] This is very interesting; however, it is known that zinc deficiency is more likely found in patients with severe disease and that patients with severe disease have more complications. Indeed, the authors acknowledge that “a major limitation of this study is that we were unable to directly assess disease activity at the time of zinc measurement.” Still, the researchers did control for CRP and albumin levels that indirectly reflect disease activity. Perhaps their research will attract funding for a future controlled interventional study.
Should I run out and get Zinc supplements?
While it seems to make sense to measure zinc levels, and if low, replace zinc, the management of zinc and other mineral and vitamin deficiencies in Inflammatory Bowel Disease is not straightforward, requires lots of thought, and should be supervised by a gastroenterologist or nutritionist. Here is why:
- Plasma zinc concentrations are affected by many factors, including inflammation, fasting or eating, pregnancy, oral contraceptive use and diurnal rhythm. That means a borderline low level on one day may be normal when measured again and may therefore not indicate a true deficiency state.[ii]
- High-dose and long-tern supplementation with zinc should be used with caution. The upper limit (highest daily intake above which side effects or toxicity may occur) for this mineral is set to 40 mg/d, and zinc can interfere with iron and copper absorption, exacerbating their potential deficiencies. In turn, supplementation with calcium or folate and can reduce zinc absorption.[iii]
What is the take home message?
Vitamin and mineral deficiencies are common among inflammatory bowel disease (IBD) patients and may warrant supplementation to restore recommended values if true deficiencies exist. Zinc is only one of many micronutrients that may be affected, and overzealous replacement can have undesirable consequences.
Further reading: NIH Office of Dietary Supplements Zinc Fact Sheet for Health Professionals
[i] Siva S, Rubin DT, Gulotta G, Wroblewski K, Pekow J. Zinc deficiency is associated with poor clinical outcomes in patients with inflammatory bowel disease. Inflammatory bowel diseases. 2017 Jan 1;23(1):152-7.
[ii] Kruis W, Nguyen GP. Iron Deficiency, Zinc, Magnesium, Vitamin Deficiencies in Crohn’s Disease: Substitute or Not?. Digestive Diseases. 2016;34(1-2):105-11.
[iii] Ghishan FK, Kiela PR. Vitamins and Minerals in Inflammatory Bowel Disease. Gastroenterology Clinics of North America. 2017 Oct 3.