From the Guidelines
Vitamin A deficiency is a serious public health problem that can lead to increased susceptibility to infections, impairment of intestinal immune and barrier function, and potentially blindness, and thus requires prompt identification and treatment. The effects of Vitamin A deficiency can be severe and far-reaching, impacting not only vision but also the immune system and overall health [ 1 ].
Key Effects of Vitamin A Deficiency
- Increased susceptibility to infections, especially of the respiratory tract
- Impairment of the intestinal immune and barrier function
- Night blindness due to insufficient rhodopsin synthesis
- Bitot spots - grey/white, foamy appearance on the conjunctiva
- Xerophthalmia - maceration of the cornea, secondary infection, and potentially blindness
At-Risk Populations
Vitamin A deficiency should be sought in individuals with:
- Liver disease, as patients with chronic liver disease show a high prevalence of vitamin A deficiency [ 1 ]
- Chronic alcohol consumption, which results in a depletion of vitamin A liver stores
- Chronic kidney disease, where high retinol serum levels may be observed but can lead to a vitamin A deficiency if liver stores become depleted
- Short bowel syndrome, cystic fibrosis, coeliac disease, and chronic diarrhea, due to the risk of reduced fat absorption
- Obesity, as RBP shows a positive correlation with BMI, visceral fat tissue, and insulin resistance, leading to a low retinol-RBP ratio
Treatment and Prevention
In cases of very low serum retinol levels, IV administration of retinol palmitate may be proposed, but current data are insufficient to make this a standard recommendation [ 1 ]. Maintaining adequate vitamin A levels through diet is essential, and individuals at risk should consume foods rich in preformed vitamin A and provitamin A carotenoids. Regular monitoring of vitamin A status is crucial for those at risk, including malnourished individuals and those with fat malabsorption conditions [ 1 ].
From the Research
Effects of Vitamin A Deficiency
- Vitamin A deficiency is a serious problem throughout the developing world, affecting an estimated 25-50 million children and causing increased risk of diarrhea, respiratory disease, and death 2.
- Mild vitamin A deficiency has been associated with a 14- to 10-fold increase in mortality, while controlled field trials have demonstrated that vitamin A supplementation can reduce childhood death rates by 30%-70% 2.
- Health consequences of vitamin A deficiency include mild to severe systemic effects on innate and acquired mechanisms of host resistance to infection and growth, increased burden of infectious morbidity, mild to severe (blinding) stages of xerophthalmia, and increased risk of mortality 3.
- Vitamin A deficiency impairs innate immunity by impeding normal regeneration of mucosal barriers damaged by infection, and by diminishing the function of neutrophils, macrophages, and natural killer cells 4.
- Vitamin A deficiency also diminishes antibody-mediated responses directed by Th2 cells, although some aspects of Th1-mediated immunity are also diminished 4.
Prevalence and Target Groups
- Vitamin A deficiency is highly prevalent across the Eastern Mediterranean Region (EMR) in children under 5 years and women of childbearing age 5.
- Infants and young children, pregnant women, and postpartum women are commonly targeted by supplementation programs 5.
- Approximately 127 million preschool-aged children and 7 million pregnant women are vitamin A deficient, with 4.4 million preschool children having xerophthalmia and 6 million mothers suffering night blindness during pregnancy 3.
Role of Vitamin A in Inflammation
- Vitamin A has a role as an anti-inflammatory agent, with supplementation found to be beneficial in a number of inflammatory conditions, including skin disorders and some forms of precancerous and cancer states 6.
- Vitamin A deficiency induces inflammation and aggravates existing inflammatory states, while supplementation with vitamin A in selected cases could ameliorate inflammation 6.