Giving mothers and children in developing countries twice the World Health Organization (WHO) recommended dose of vitamin A does not have a beneficial effect, according to a new study in the Gambia.
The findings contradict recommendations by an international vitamin organisation to give high-dose regimens to combat vitamin A deficiency.
The study comparing the effect of various doses were published in The Lancet last week (22 June).
Providing vitamin A supplementation in countries where there is a deficiency of the vitamin has been proven to decrease disease and death in children — largely from severe infection — according to the WHO.
As a result, most developing countries have adopted a standard WHO dosing schedule for vitamin A supplementation.
However, after a WHO trial in 1998 failed to show WHO doses had an effect illness and death rates, the International Vitamin A Consultative Group (IVACG) recommended in 2001 a new, untested, high-dose regimen for mothers and infants.
The new study involved 220 mother-infant pairs from Keneba and five surrounding villages in the West Kiang District of the Gambia — an area with moderate vitamin A deficiency — between September 2001 and October 2004, comparing the IVACG high dose with the WHO dose.
In the study one group received the WHO recommended dose, while the other received the IVACG recommended dose. At a 12 month follow-up no significant differences were found between the two groups, with the higher dose showing no benefit in terms of infant growth, health and immunity — though both regimens improved vitamin A deficiency.
"Our results do not lend support to the proposal to increase the existing WHO standard dosing schedule for vitamin A in areas of moderate vitamin A deficiency," write the authors.
They also urge caution for future studies, as trials have shown that higher doses can have adverse effects, including possible negative interactions with vaccines such as diphtheria, pertussis and tetanus — important childhood vaccinations.
Vitamin A deficiency is a major nutritional problem worldwide, and threatens the survival and health of millions of children. An estimated 127 million pre-school children and 7.2 million pregnant women are deficient in vitamin A.
Link to full article/paper in The Lancet*
Reference: The Lancet 369, 2088 (2007)
*Free registration is required to view this article.