The Power of Vitamin A: Beyond Vision and into Respiratory Health

Vitamin A, also known as retinol, is a vital fat-soluble vitamin found in various sources. It can be obtained directly from animal-based foods like liver, milk, and eggs, or indirectly from plant-based sources containing carotenoids, such as carrots and sweet potatoes. However, the conversion of carotenoids to vitamin A in the body, especially from plant sources, is not very efficient [1].

Vitamin A plays a critical role in maintaining healthy vision, skin, the immune system, reproductive organs, and embryonic development. While many individuals associate vitamin A primarily with its role in preventing night blindness and supporting vision, its significance extends well beyond ocular health. In fact, vitamin A is among the most relevant nutrients when it comes to dealing with respiratory infections and related symptoms, such as coughing and nasal congestion [2]. This post focuses on vitamin A’s significance beyond vision and its impact on respiratory health.

Vitamin A and Respiratory Tract Infection

A study in 2020 discovered that up to 10% of children and adolescents under the age of 14 had subclinical vitamin A deficiency[3]. Among those with frequent respiratory infections, 21.3% lacked vitamin A. Prevalence rates were 16.5% for children aged 6-11 and 21.1% for those aged 12-17. Toddlers exhibited the most severe deficiency, with 35% of 2-6-year-olds lacking vitamin A, peaking at 42.7% among 5-year-olds [4].

Prospective studies show infants with upper respiratory infections recover faster with vitamin A. However, after three months of supplementation, 61% of previously infected children remained deficient [5]. Deficiency increases recurrent infections [6]. Vitamin A is beneficial for prevention and recovery. Case-control studies confirm a higher risk of respiratory infections with vitamin A deficiency. It’s also linked to mycoplasma pneumonia [7]. In COVID-19, low vitamin A levels are associated with severe illness and higher mortality, making vitamin A a potential adjunctive treatment [8-9].

Vitamin A effectively treats childhood pneumonia. A 2018 meta-analysis of 15 clinical studies, involving over 3,000 participants, showed it alleviates symptoms, shortens hospital stays, and prevents recurrence [10].

Studies also confirm vitamin A supplementation reduces the risk and eases symptoms of respiratory infections [11-12]. In Australia, a study with 140 preschoolers, given daily vitamin A (450 µg) for nearly a year, saw 19% fewer respiratory symptoms. Interestingly, their blood vitamin A levels didn’t rise, suggesting an increased loss of vitamin A during inflammation [13]. In Indonesia, 800 children (2-5 years) receiving daily zinc (10 mg) and vitamin A (200,000 IU every 2 months) had 20% shorter respiratory infection durations [14]. Case-control studies also support faster recovery from upper respiratory infections with vitamin A supplementation [15].

Should vitamin A be Supplemented During Pregnancy and Lactation?

While excessive vitamin A intake theoretically increases the risk of birth defects, it’s crucial to note that a deficiency can also cause birth defects. Thus, vitamin A supplementation during pregnancy, especially in the early stages, remains controversial [16]. The World Health Organization recommends 3,000 µg (10,000 IU) daily for pregnant women in developing countries with vitamin A deficiency, but in developed countries, intake should not exceed 1,500 µg (5,000 IU). 

Studies show vitamin A depletes faster in lactating women [17]. Maintaining balance is vital, as insufficient vitamin A during pregnancy carries risks. A 2022 meta-analysis, including six case-control studies, showed that vitamin A supplementation around conception reduced the risk of various cleft lip subtypes in infants by 13-33%. [18] In Saudi Arabia, a cohort study found that higher vitamin A and E levels in pregnant women correlated with a lower risk of gestational diabetes [19].

Summary

Beyond its vision benefits, vitamin A plays a pivotal role in combating respiratory infections and symptoms, such as coughing and congestion.

Research shows widespread subclinical vitamin A deficiency, especially among children, with severe deficiency in toddlers.

Vitamin A supplementation expedites recovery from upper respiratory infections,  and reduces the risk of recurrence.

Pregnant women should carefully balance vitamin A intake, as both deficiency and excess can pose risks. Studies also reveal rapid vitamin A depletion during lactation.