GENOTYPE FREQUENCY IN THE β-CAROTENE CONVERSION TO VITAMIN A: IMPLICATIONS ON REDUCING VITAMIN A DEFICIENCY IN THE PHILIPPINES

Abstract

Vitamin A is required for normal organogenesis, immune function and visual cycle regeneration. Worldwide, vitamin A deficiency(VAD) is estimated to be 190 million individuals in pre-school-age children. VAD prevalence among children in the Philippines is 11.1%, which is considered a public health problem of moderate severity. The requirements for vitamin A can be satisfied either from animal foods or from plant foods containing provitamin A, such as carotenoids. The key enzyme responsible for carotenoid conversion into the active form of vitamin A is β-carotene 15,15`-monooxygenase(BCMO1). However, conversion efficiency of carotenoid into vitamin A is highly variable in different individuals or population groups due to genetic variants in BCMO1 gene. The study determined the BCMO1 single nucleotide polymorphism (SNP) frequency among 6-18-year-old children of the 2013 Philippine National Nutrition Survey (NNS), particularly rs7501331 and rs12934922. A total of 555 individual survey participants with BCMO1 SNPs rs7501331 and 723 respondents with rs12934922 were analyzed. Results showed that 56.0%, 37.7% and 6.3% of CC, CT and TT for rs7501331 genotype were found among Filipino children, while 80.4%, 19.5% and 0.14% genotype frequencies of AA, AT and TT were obtained for rs12934922. Genotype frequencies of both SNP targets follow the Hardy-Weinberg equilibrium indicating good data quality. The results suggest that a portion of the Filipino children (43.96% for rs7501331 and 19.6% for rs12934922) carries the risk allele that may decrease β-carotene to vitamin A conversion efficiency. Pre-determination of the proportion of the population who are at risk for VAD by genetic profiling is an important step in prioritizing those that need intervention either by increasing intake of β-carotene or preformed vitamin A supplements. We can envisage adapting recommended dietary intake of carotenoids, or carotenoids incorporated in functional foods/supplements, to population groups with genetic variants that affect carotenoid status.