What vitamin deficiency is relatively common in people with CF?

October 8, 2025 •

4 min read

Approximately 85% to 90% of people with cystic fibrosis (CF) suffer from pancreatic insufficiency, which leads to poor fat digestion and malabsorption. This creates a high risk for deficiencies in fat-soluble vitamins, prompting the question: What vitamin deficiency is relatively common in people with CF?.

Quick Summary

Fat-soluble vitamin deficiencies (A, D, E, K) are widespread in people with cystic fibrosis due to fat malabsorption caused by pancreatic insufficiency. Deficiencies must be managed with high-potency supplements and careful monitoring.

Key Points

Fat-Soluble Vitamin Group: All fat-soluble vitamins (A, D, E, and K) are commonly deficient in CF patients due to fat malabsorption.
Pancreatic Insufficiency: The root cause of the malabsorption is pancreatic insufficiency, which affects most people with CF and prevents the release of necessary digestive enzymes.
High Prevalence of Vitamin D Deficiency: Vitamin D deficiency is a major concern in CF patients, with high rates reported even with supplementation, impacting bone health and immune function.
Consequences of Deficiencies: Each deficiency carries specific risks, including night blindness (A), bone disease (D, K), and nerve damage (E), which can worsen CF symptoms.
Specialized Supplementation: Due to poor absorption, CF patients require specialized, high-potency multivitamin supplements that are often water-miscible or micellized to improve bioavailability.
Importance of Monitoring: Regular blood tests are crucial for monitoring vitamin levels to ensure effective supplementation and prevent toxicity.
CFTR Modulators' Impact: Newer modulator therapies may improve fat absorption and potentially impact vitamin status, though nutritional vigilance remains essential.

Understanding Cystic Fibrosis and Fat Malabsorption

Cystic Fibrosis (CF) is a genetic disorder caused by a faulty cystic fibrosis transmembrane conductance regulator (CFTR) protein. This protein is important for the movement of salt and water, and its malfunction leads to thick, sticky mucus in organs like the lungs and pancreas. The mucus blocks pancreatic ducts, preventing the release of digestive enzymes needed for breaking down food, resulting in pancreatic insufficiency.

Fat-soluble vitamins (A, D, E, and K) require dietary fat for absorption. When fat digestion is impaired due to pancreatic insufficiency, the absorption of these vitamins is also significantly reduced. This makes deficiencies in fat-soluble vitamins very common in people with CF, affecting up to 90% of those with pancreatic insufficiency.

The Critical Role of Fat-Soluble Vitamins

Each fat-soluble vitamin plays a crucial role in maintaining health. Deficiencies can lead to serious complications for CF patients, requiring proactive nutritional management.

Vitamin D

Vitamin D deficiency is particularly common and impactful in CF. It is essential for absorbing calcium and maintaining bone health, and deficiency can contribute to bone loss and increased fracture risk. Vitamin D also supports immune function, and low levels have been linked to more frequent lung infections in CF.

Vitamin A

Vitamin A is important for vision, immune function, and the health of linings in the respiratory, urinary, and intestinal tracts. Severe deficiency can cause night blindness and other eye problems. It also supports growth and a healthy immune system, which is vital for children with CF.

Vitamin E

Vitamin E is an antioxidant that protects cells from damage caused by chronic inflammation, a key feature of CF. Deficiency can lead to neurological issues like nerve damage, muscle weakness, and problems with coordination. It may also affect cognitive function and, in children, can cause a type of anemia.

Vitamin K

Vitamin K is necessary for blood clotting and bone health. It helps produce proteins needed for clotting, though severe bleeding due to deficiency is uncommon, while milder deficiency is frequent. Vitamin K also plays a role in bone mineralization with vitamin D and can worsen CF-related bone disease if deficient. Long-term antibiotic use, common in CF, can also reduce the body's production of vitamin K.

Management and Supplementation Strategies

Managing fat-soluble vitamin deficiencies is a critical part of CF care. This includes:

Pancreatic Enzyme Replacement Therapy (PERT): Most CF patients with pancreatic insufficiency take PERT with food to improve digestion and absorption of fats, proteins, carbohydrates, and fat-soluble vitamins.
Specialized Multivitamins: Standard multivitamins are usually insufficient. CF patients need high-potency, CF-specific multivitamins, often formulated for better absorption with technologies like water-miscible or micellized forms.
Monitoring: Regular blood tests to check vitamin levels are vital to ensure adequate supplementation and prevent potential toxicity. A CF care team, including a dietitian, manages this.

Comparison of Fat-Soluble Vitamin Deficiencies in CF


Feature	Vitamin A	Vitamin D	Vitamin E	Vitamin K
Function	Vision, immune function, epithelial health	Calcium absorption, bone health, immune modulation	Antioxidant, nerve function, immune health	Blood clotting, bone formation
Main Deficiency Sign	Night blindness, epithelial issues	Osteoporosis, fractures, weakened immunity	Neuropathy, muscle weakness	Impaired blood clotting, bone issues
Absorption Issue	Poor fat absorption	Poor fat absorption, limited sun exposure	Poor fat absorption	Poor fat absorption, antibiotic effects
Commonality in CF	Relatively common, needs monitoring	Very common, often despite supplementation	Common, can worsen oxidative stress	Common, especially subclinical deficiency
Primary Management	CF-specific multivitamin with beta-carotene	High-dose D3 supplementation, annual monitoring	Water-soluble or micellized E supplementation	Daily K1 supplementation, especially with liver issues

How CFTR Modulators Affect Vitamin Status

CFTR modulator therapies can improve CFTR protein function in some patients, potentially leading to better fat absorption and nutritional status. For individuals who respond well, adjustments to pancreatic enzymes and vitamin supplements might be possible. However, ongoing nutritional management remains crucial, and the long-term effects of these modulators on vitamin requirements are still being studied.

Conclusion

Deficiencies in fat-soluble vitamins (A, D, E, K) are a significant nutritional issue for people with cystic fibrosis, primarily due to fat malabsorption caused by pancreatic insufficiency. To answer the question What vitamin deficiency is relatively common in people with CF?, all four are common, with vitamin D deficiency being particularly widespread even with routine treatment. Effective management involves pancreatic enzyme replacement, high-potency CF-specific vitamin supplements, and regular monitoring to prevent serious health complications. While CFTR modulators offer potential improvements in nutritional status, personalized care and monitoring are still essential for the best outcomes.

External Resource

For further information on CF nutrition, consult the Cystic Fibrosis Foundation: Cystic Fibrosis Foundation Nutrition Guidelines

Frequently Asked Questions

Fat-soluble vitamins (A, D, E, and K) dissolve in fat and are absorbed with dietary fat. For people with CF and pancreatic insufficiency, the malabsorption of fat prevents the absorption of these vitamins, leading to deficiencies.

While pancreatic enzyme replacement therapy (PERT) significantly aids in digestion, it does not always completely normalize fat absorption. As a result, CF patients still need specific, high-potency vitamin supplements to ensure adequate levels.

Vitamin D is vital for calcium absorption and bone health. Its deficiency significantly increases the risk of bone disease, including osteopenia and osteoporosis, which are already common in CF.

CF-specific multivitamins contain higher concentrations of fat-soluble vitamins than standard options and are often formulated for better absorption, such as in water-miscible or micellized forms.

Yes, excessive intake of fat-soluble vitamins, particularly vitamin A, can lead to toxicity, which can damage the liver and bones. This is why regular monitoring of vitamin levels is necessary.

Not necessarily. While CFTR modulators can improve fat absorption for some patients, nutritional management is still essential. The impact on vitamin status is variable, and patients should continue to follow their CF care team's recommendations.

Initial symptoms can be subtle, but may include night blindness (A), frequent infections (A, D), poor bone mineral density (D, K), or signs of nerve damage (E). Regular monitoring is key to catching deficiencies early.