Zinc in cystic fibrosis: why is it so important?

Zinc is essential for many metabolic processes and is a component of some enzymes. In cystic fibrosis, zinc deficiency is a risk for exclusively breastfed infants, so after 6 months, consideration should be given to introducing foods rich in this micronutrient.

Young children who consume excessive amounts of soy-based beverages may have lower zinc bioavailability due to the presence of phytate. Zinc deficiency can occur in the setting of diarrhea, including steatorrhea caused by untreated or undertreated pancreatic insufficiency. Zinc deficiency has been associated with growth retardation and reduced growth velocity.

In a study of 30 infants with cystic fibrosis diagnosed by newborn screening, plasma zinc was significantly lower in one-third of the infants and improved after initiation of enzyme replacement therapy. In adults with cystic fibrosis, low zinc levels have been associated with adverse clinical outcomes.

Zinc measurements (red blood cell or plasma zinc levels) do not necessarily reflect zinc status. In 62 children with cystic fibrosis, plasma zinc did not correlate with growth and pulmonary status. Empirical trials of zinc supplementation for 6 months are recommended in infants younger than 2 years of age with unexplained growth failure despite adequate caloric intake.

However, studies have also failed to demonstrate improvement in growth with zinc supplementation. In a double-blind, placebo-controlled trial, 26 children with cystic fibrosis received 30 mg of zinc daily for 1 year, thereby reducing the need for oral antibiotics for the treatment of pulmonary infections.

The effect of zinc supplementation was greater in children who initially had low plasma zinc levels compared with children who initially had higher levels.

Long-term high doses of zinc can lead to copper deficiency and should be carefully monitored. Serum zinc levels are not sensitive in the early stages of deficiency, and lower levels are seen in cases of prolonged and severe zinc deficiency.

Zinc plays an important role in the following processes:

• antioxidant and anti-inflammatory activity
• metabolic processes
• immune function
• affects growth and development
• protein and DNA synthesis
• wound healing
• oxidation and cellular immune responses
• eye health
• blood clotting
•  Zn is a component of nearly 300 enzymes.

Deficiency of this trace element can cause serious health disorders.

• Plasma zinc levels may not reflect deficiency.
• Consider empirical supplementation if deficiency is suspected or if persistent poor weight gain is observed despite adequate caloric intake and supplementation.
• Patients with an ileostomy are at increased risk of zinc deficiency.
• Patients at risk of zinc deficiency can be empirically treated with supplementation for 6 months.

There is no consensus on the regular intake of zinc. Dosage: infants up to 2 years old receive 1 mg/kg/day, children – 15 mg/day, adults – 25 mg/day. Like many other trace elements, zinc is not stored in the body, so it is important to consume it daily.

List of foods richest in zinc:

• Seafood
• Beef
• Beef jerky (about 2 g of zinc in a 30 g serving)
• Legumes
• Lentils, beans and chickpeas (about 2.5 mg of zinc in a glass of cooked lentils)
• Canned beans and canned tuna (1 can of tuna weighing 150 g contains almost 1 mg of zinc)
• Nuts and seeds
• Chocolate (preferably dark. A 30 g serving contains 1 mg of zinc)
• Whole grains – oatmeal, quinoa, rice, wheat.

Remember, you don’t have to spend all your free time on making a special diet. It is enough to make a salad with tuna, avocado and greens, add a sandwich with nut butter. Or a portion of whole grain cereals, seasoned with nut butter can be a side dish for boiled meat or seafood. For a snack – snacks from dried beef or a little chocolate. For breakfast, granola from oatmeal, a handful of nuts and seeds.

Such dishes will become not only a source of Zn, but also a source of dietary fiber, iron, magnesium, vitamins, proteins and Omega-3 fats. The information in the article is not intended to establish a diagnosis. It is for informational purposes only. Consult your doctor about diagnosing Zn control and treating identified problems.