Vitamin A deficiency is still common in developing countries and has been proven difficult to combat. A promising approach is to replace common crops with varieties that are naturally richer in vitamin A, which is referred to as biofortification. For cassava, yellow β-carotene rich varieties have recently been introduced in Nigeria, and these varieties are now ready to be tested for their efficacy to improve vitamin A status in humans.
We have recently shown that consumption of boiled yellow cassava improved vitamin A status (serum retinol) of school children in Kenya. Cassava is a common staple food in most areas of Africa. In Kenya, cassava is usually boiled whereas in West Africa, cassava is commonly processed into fermented flour and consumed as gari, lafun, eba and fufu. Pre-schoolers are more affected by vitamin A deficiency compared to older children. While serum retinol is a relatively insensitive response marker, isotope dilution retinol as a proxy for hepatic stores is a sensitive and more convincing marker.
The primary objective is to assess the efficacy of daily consumption of pro-vitamin A rich cassava during 18 weeks on body retinol pools of 3-4 year old children in South-Western Nigeria. This will be studied in a randomized controlled trial with three parallel groups. For this, children (n=1500) will be screened for eligibility. Out of these, n=350 will undergo a 4-week run-in phase with further selection, after which approximately 321 children will be randomly allocated to three different treatments: 1) Yellow cassava providing ~50% of the RDA for vitamin A; and a placebo oil dose; 2) White cassava; and a placebo oil dose; 3) White cassava and an oil dose containing 200 µg RAE of retinyl acetate. The primary outcome is the difference in body retinol pools as assessed by an isotope dilution method between groups 1 and 2 at the end of intervention, whereas the difference in retinol body pools between groups 1 and 3 will be used to calculate the bioequivalence of provitamin A from yellow cassava.
Preceding study in Kenya (CASSAVITA I), 2008-2013