Evidence Level
Vitamin A plays a critical role in human health, as evidenced by extensive research. Imdad et al. (2010) conducted a landmark meta-analysis of 43 trials involving over 215,000 children, demonstrating that vitamin A supplementation reduced all-cause mortality by 24% and diarrhea-related mortality by 28% in deficient populations. This underscores the importance of addressing vitamin A deficiency, particularly in vulnerable groups such as children and pregnant women.
Recent studies have explored additional benefits and risks associated with vitamin A. Farashi et al. (2023) conducted a systematic review and meta-analysis of 21 studies involving over 5,789 stroke patients, finding an inverse association between vitamin A compounds (retinol, beta-carotene) and stroke risk/mortality. Conversely, Knapik and Hoedebecke (2021) found that high dietary intake of total vitamin A or retinol increases the risk of hip fractures (RR = 1.29 and 1.23), while certain carotenoids may reduce this risk (RR = 0.62 to 0.81). These findings highlight the need for balanced intake and targeted supplementation.
In the context of COVID-19, Sinopoli et al. (2024) reviewed 37 randomized trials, concluding that while some vitamins showed benefits, vitamin C (RR=0.84) and regular vitamin D use (RR=0.67) demonstrated consistent protective effects. This suggests potential synergistic roles of micronutrients in immune function.
Overall, Vitamin A supplementation remains a vital public health strategy, particularly for populations at risk of deficiency, but must be approached with consideration of dosage and individual circumstances to maximize benefits while minimizing risks.