Many people with cystic fibrosis have problems releasing digestive enzymes. This can disrupt the absorption of nutrients from food, causing a vitamin deficiency.

Vitamins support several metabolic processes. They are essential for the function of the human body.

People with cystic fibrosis (CF) may have problems with pancreatic function, which can impair the release of digestive enzymes necessary for nutrient breakdown and absorption. This can potentially lead to vitamin deficiencies.

This article reviews vitamin deficiency in people with CF, its causes, common deficiencies in people with CF, and how to manage a deficiency.

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People with CF have trouble absorbing fat-soluble nutrients, such as vitamins A, D, E, and K.

In some cases, people with CF may also have issues absorbing water-soluble vitamins, such as vitamin C and B vitamins.

Poor vitamin absorption can happen when the pancreas does not release enzymes necessary for proper digestion, leading to deficiencies. Doctors refer to this as pancreatic insufficiency.

About 85% of people with CF have pancreatic insufficiency. People typically develop it at birth. However, some people may develop pancreatic insufficiency later in life.

People with CF have problems absorbing fat-soluble and water-soluble vitamins, including:

Vitamin A

Vitamin A is essential for repairing and maintaining the lining inside the lungs. Vitamin A also helps keep the immune system healthy by protecting cell membranes.

Additionally, it plays a role in helping the eyes adjust to the dark, preventing nighttime blindness.

Vitamin D

Vitamin D helps the body absorb calcium, which is essential for maintaining healthy teeth and bones.

This vitamin also helps keep the immune system healthy and reduces inflammation. Vitamin D is also important for muscle, digestive, and lung function.

Vitamin D is vital in managing health conditions in people with CF.

In people with CF, low vitamin D levels can increase the risk of:

  • impaired bone mineralization
  • decrease bone mass over time
  • lung infection
  • decreased lung function
  • inflammation
  • developing autoimmune conditions
  • poor gut health
  • diabetes

About 7% of people with CF still experience vitamin D deficiency after receiving appropriate treatment.

Vitamin C

Vitamin C has several important roles in the human body, including:

  • fighting free radicals that can damage cells
  • supporting collagen production
  • protecting the linings of the blood vessels
  • reducing inflammation in the body

B vitamins

B vitamins help support several important bodily processes, including:

  • energy production
  • maintaining skin, heart, and nervous system health
  • tissue repair
  • red blood cell production
  • cell growth and division
  • fat metabolization

Low levels of vitamin B-complex can lead to nervous system and heart problems, causing symptoms such as:

  • weakness
  • heart palpitations
  • fatigue

Vitamin E

Vitamin E protects the nervous and immune systems. It also helps produce red blood cells.

This vitamin also has an antioxidant effect.

Vitamin K

Vitamin K helps keep the bones strong. It is also essential for blood clotting.

Low levels of vitamin K can cause a person to bleed and bruise easily, even after a minor trauma.

Eating a diet rich in nutrient-dense foods and periodically monitoring vitamin levels can help people with CF manage vitamin deficiencies.

Doctors often recommend pancreatic enzyme replacement therapy (PERT) to help people with CF absorb more nutrients from food. About 80–90% of people with CF need PERT.

PERT contains several enzymes, such as:

  • protease
  • amylase
  • lipase

Lipase is an enzyme that improves the absorption of fat-soluble vitamins, which can help treat vitamin A, D, E, and K deficiencies.

A person must take PERT before eating since enzymes usually work for about 45–60 minutes after being taken.

Because CF can cause problems with nutrient absorption, people with the condition may develop vitamin deficiencies.

People with CF often require vitamin supplementation to treat their deficiencies and prevent CF-related complications. A doctor can provide tailored advice and prescribe the right treatment.