An international study suggests that giving vitamin A supplements to children in low and middle income countries could significantly cut rates of mortality, illnesses and blindness amongst those below the age of five.
Researchers from the University of Oxford and Pakistan's Aga Khan University have shown that vitamin A supplements reduce mortality amongst children from low and middle income countries by nearly a quarter (24 per cent). According to the study, published in the online version of the British Medical Journal, the supplements were found to bring particular benefits in reducing rates of diarrhea and measles.
The researchers from the University of Oxford's Centre for Evidence-Based Intervention and Pakistan's Aga Khan University Hospital are now calling for vitamin A supplements to be given to all children who are at risk of not getting enough of the vitamin in their diet. They believe the benefits are so clear cut that trials comparing vitamin A to placebo are no longer ethical.
The findings are based on 43 trials in which some children received vitamin A while others received no intervention or a placebo. The sample included 215,633 apparently healthy children aged 6 months to 5 years in 19 countries, mostly in Asia. On average, the children were 2.5 years old when they were recruited for the trials and followed for about one year.
Lead author Dr Evan Mayo-Wilson, from the Department of Social Policy and Intervention at the University of Oxford, said: 'Our study shows that, until other sources are available, supplements should be given to all children who are at risk of vitamin A deficiency. After just one year children who had taken supplements were less likely to have died than children who received a placebo.
'We estimate that by providing supplements to all children in countries where they are at risk we could save up to 600,000 lives a year and prevent millions of serious infections. Vitamin A supplements are highly effective and cheap to produce and administer.
'Our study also shows that systematic literature reviews are cost-effective and ethically imperative. Recent editorials criticising vitamin A programmes have received international attention, but the evidence taken as a whole leaves little doubt that vitamin A prevents early childhood mortality.'
The largest clinical trial ever conducted ran from 1999 to 2004 and assigned about 1,000,000 children to receive vitamin A or placebo. Since that trial began, only one relatively small trial has examined vitamin A for childhood mortality.
'Professor Zulfiqar Bhutta, the Chair of the Division of Women and Child Health, Aga Khan University, Pakistan, and the senior corresponding author of the study, said: 'This study underlines the need to shift the focus of attention towards an effective scale up of vitamin A supplementation programmes. We must ensure that the benefits are sustained with effective oversight by national programmes.'
Vitamin A is required for normal functioning of the visual and immune systems. It is an essential nutrient that cannot be synthesized by the human body, so it must be obtained through diet. Deficiency increases vulnerability to a range of infections including diarrhea, measles, malaria and respiratory infections, which are the leading causes of childhood mortality.
According to recent estimates by the World Health Organisation, 190 million under-fives don't get enough vitamin A to stay healthy. Vitamin A is found in plants, such as the orange-fleshed sweet potato, eggs and dairy products. A high intake of synthetic vitamin A over a long period may lead to short-term side effects including vomiting, but side effects are rare, and taking supplements of vitamin A over relatively short periods (e.g. once every six months) should not cause serious adverse effects, says the study.
- E. Mayo-Wilson, A. Imdad, K. Herzer, M. Y. Yakoob, Z. A. Bhutta. Vitamin A supplements for preventing mortality, illness, and blindness in children aged under 5: systematic review and meta-analysis. BMJ, 2011; 343 (aug25 1): d5094 DOI: 10.1136/bmj.d5094
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