Associations between lactase persistence and the metabolic syndrome in a cross-sectional study in the Canary Islands

The single nucleotide polymorphism (SNP) LCT -13910 C > T, associated with genetically determined phenotypes of lactase persistence (LP) or non-persistence (LNP), was studied in relation to the metabolic syndrome (MS). The aim was to determine if milk intake and MS are associated. We applied Mendelian randomization (MR). The SNP, LCT -13910 C > T, with the genotypes LP (TT/CT) and LNP (CC), was taken as a proxy for milk consumption. A representative sample of adults belonging to the Canary Islands Nutrition Survey (ENCA) in Spain aged 18-75 years (n = 551) was genotyped for the LCT -13910 C > T polymorphism. We used the International Diabetes Federation (IDF) criteria to define MS. 60% of the population was LP and 40% LNP. One hundred seven LP subjects (35.0%) and 53 LNP subjects (25.6%) showed MS (chi (2) = 5.04, p = 0.025). LP subjects showed a significantly higher odds ratio (OR) for MS than LNP subjects computed for the whole population: both the crude OR (1.56; 95% CI 1.06-2.31) and adjusted OR for sex, age, daily energy intake, physical activity and educational level (1.57; 95% CI 1.02-2.43). Adjusted OR for women with LP was 1.93; 95% CI 1.06-3.52. The T allele of the SNP might constitute a nutrigenetic factor increasing the susceptibility of LP subjects, especially women, to develop MS in the Canary Islands.