Which nutrient malabsorption is most affected in CF due to pancreatic enzyme deficiency?

• A. Carbohydrates only
• B. Fats and fat-soluble vitamins
• C. Proteins only
• D. Water-soluble vitamins only

Answer: (B)

In this scenario, the important concept is that pancreatic enzymes are essential for fat digestion. Cystic fibrosis often causes exocrine pancreatic insufficiency because thick secretions block the pancreatic ducts, so lipase—the enzyme that hydrolyzes dietary fats—is markedly reduced reaching the intestine. Without enough lipase, fats aren’t broken down effectively, leading to severe fat malabsorption. Since fat digestion is closely tied to the absorption of fat-soluble vitamins (A, D, E, and K), those vitamins are also poorly absorbed when pancreatic enzymes are deficient.

Carbohydrate and protein digestion can still occur with the help of other enzymes and intestinal mechanisms, so their malabsorption is not as pronounced as that of fats in this context. Water-soluble vitamins may be affected to some degree only indirectly, but the hallmark of pancreatic enzyme deficiency in CF is the prominent impairment of fat absorption and fat-soluble vitamin uptake. This explains why pancreatic enzyme replacement therapy and fat-soluble vitamin supplementation are central to management, to improve fat absorption and prevent related deficiencies.