Effect of a micronutrient–fortified beverage on cognition and nutritional status of primary school children

Abstract

Childhood micronutrient deficiencies have negative effects on cognition. Little is known about the effects of combined consumption of micronutrients and sugar on growth and cognitive function. The aim of this thesis was to 1) investigate the effects of micronutrients and sugar, alone and in combination, in a beverage, on growth and cognition in South African children and 2) review recent evidence on iron status and anaemia prevalence in South African children since the National Food Consumption Survey-Fortification Baseline-2005 (NFCS-FB-2005). Children (n = 408, 6−11 years) were randomly allocated to a beverage containing 1) micronutrients with sugar, 2) micronutrients with non-nutritive sweetener, 3) no micronutrients with sugar, or 4) no micronutrients with non-nutritive sweetener for 8.5 months. Cognition was assessed using sub-tests from the Kaufman Assessment Battery for Children-II. Growth was assessed as weight-for-age (WAZ), height-for-age and body-mass-index-for-age z-scores. Relevant internet search engines identified studies reporting iron status of South African children after 2005. Secondary analysis was conducted on NFCS-FB-2005 provincial data for children 7−9 years old. Positive intervention effects were observed for micronutrients (0.76; 95% CI: 0.10, 1.42) and sugar (0.71; 95% CI: 0.05, 1.37) on Atlantis (measure learning ability), and sugar on Rover (measure simultaneous processing) (0.72; 96% CI: 0.08, 1.35) test scores. Attenuating micronutrient x sugar interactions were observed on Atlantis, Number Recall (measure sequential processing) and Rover test performance. Micronutrients or sugar alone lowered WAZ. In combination, this effect was attenuated (significant micronutrient x sugar interaction). Four studies from four different provinces were identified. All reported lower anaemia prevalence than the NFCS-FB-2005 (KwaZulu-Natal (11.5% vs 14.4%), North West (6.9% vs 27%) Western Cape (17.2% vs 18.8%) and Northern Cape (5.4% vs 22.2%). A beverage fortified with micronutrients or added sugar had beneficial effects on cognition, but a lowering effect on WAZ in the children. Unexpectedly, the combination of micronutrients and sugar attenuated these effects. In the identified studies, anaemia prevalence in school-aged children was lower than reported in the NFCS-FB-2005.