From the Guidelines
Vitamin A supplementation should be tailored to individual needs based on serum values, with a target of achieving normal serum retinol concentrations, and careful consideration of the supplement form to avoid toxicity. The recommended approach for Vitamin A supplementation, especially in populations like those with cystic fibrosis, emphasizes the importance of assessing vitamin A intake and blood levels before conception or early in pregnancy, and adjusting supplementation to achieve the normal range of serum retinol concentrations for healthy people, as advised by the laboratory performing the assay 1.
Key Considerations for Vitamin A Supplementation
- For individuals with cystic fibrosis, vitamin A deficiency is common and can lead to poorer clinical status, impaired lung function, and increased pulmonary exacerbations, making adequate supplementation crucial 1.
- The potential toxicity of vitamin A is a significant concern, particularly with water-miscible and water-soluble forms, highlighting the need for careful dosing to avoid harmful effects 1.
- Special consideration should be given to the dose during pregnancy, as both hyper- and hypovitaminosis A can cause harm to the mother and her fetus, with water-soluble forms being safer for pregnant women 1.
Guidelines for Supplementation
- Retinol (preformed) supplementation should start low and adapt rapidly to target the normal serum reference range.
- Beta carotene (provitamin A) supplementation is recommended at 1 mg/kg/day (maximum 50 mg/day) for 12 weeks, followed by a maintenance dose (maximum 10 mg/day), as outlined in the guidelines for pancreatic insufficient patients with CF 1.
Importance of Monitoring
- Serum reference values and monitoring frequency are crucial for adjusting supplementation, with recommendations to monitor annually and 3-6 months after a dosage change, or when pregnancy is considered 1.
Dietary Sources and Essential Functions
- Vitamin A is essential for vision, immune function, and cell growth, with good dietary sources including liver, fish oils, dairy, eggs, leafy greens, and orange/yellow vegetables 1.
- Deficiency can cause night blindness and compromised immunity, while excess can lead to headaches, nausea, and even liver damage, emphasizing the need for balanced intake and careful supplementation 1.
From the Research
Recommended Dietary Allowances for Vitamin A
- The recommended dietary intake of vitamin A is approximately 700 micrograms for men and 600 micrograms for women, as suggested by a study published in 1987 2.
- These values are based on the amount of vitamin A required to maintain an adequate body pool, which is defined as a total-body pool that provides adequate vitamin A to meet all known physiological needs and a reserve for 4 months on low intakes or during stress.
Food-Based Approaches to Increase Vitamin A Intake
- Food-based approaches, such as introducing orange-fleshed sweet potatoes, can increase vitamin A intake and serum retinol concentrations in young children, as shown in a study conducted in rural Mozambique in 2007 3.
- Other plant sources of vitamin A, such as Indian spinach (Basella alba), can also have a positive effect on total-body vitamin A stores, as demonstrated in a study published in 2004 4.
- Animal sources of vitamin A, such as eggs and liver, are also important, but their consumption may be low in some populations, as reported in a study conducted in rural Jammu in 2017 5.
Supplementation Guidelines for Vitamin A
- While food-based approaches are preferred, supplementation may be necessary in some cases, especially in populations with limited access to vitamin A-rich foods.
- However, it is essential to note that the toxicity of vitamin A in early pregnancy is a concern, and a safe intake level is not known, as highlighted in a study published in 1987 2.
- Therefore, supplementation guidelines for vitamin A should be carefully considered, and individuals should consult with healthcare professionals before taking any supplements.
Dietary Deficiency of Vitamin A
- Dietary deficiency of vitamin A is a significant public health problem in many parts of the world, particularly in rural areas, as reported in a study conducted in rural Jammu in 2017 5.
- The prevalence of subclinical vitamin A deficiency may be high, even in areas where overt vitamin A deficiency has been controlled, as noted in a study published in 2017 5.
- Faulty diets, improper breastfeeding practices, low coverage of vitamin A supplementation, and high prevalence of undernutrition may contribute to the observed subclinical deficiency, as suggested in a study published in 2017 5.