Objective: The T allele of a functional polymorphism (rs4988235: LCT-13910 C>T), close to the lactase gene, correlates with lactase persistence (LP) in adults. The LP genotype (TT+TC) has been associated with a higher BMI in European populations in cross-sectional studies. In the French D.E.S.I.R. cohort, a high consumption of dairy products was associated with a lower body weight gain over 9-years, and with a lower incidence of high plasma glucose levels and/or the metabolic syndrome. Our aim was to test in this study, the association of rs4988235 with BMI and related metabolic diseases, in interaction with dairy product consumption.
Methods: Among 5212 subjects from D.E.S.I.R., 3575 Caucasians born in mainland France were genotyped and followed over 9years.
Results: Those with the LP genotype (frequency: 78.5%) had a higher dairy product consumption, at inclusion and at year-9 (P<0.001). They also had a higher BMI at both time points (difference=0.3kg/m(2), P=0.05), but this effect was restricted to medium/high dairy product consumers (difference=0.5kg/m(2), P=0.006). This genotype was also associated with the metabolic syndrome (IDF definition), but this association disappeared after adjustment for BMI. In the whole population, the C allele was associated with a higher prevalence of impaired fasting glycemia and/or type 2 diabetes.
Conclusions: The lactase persistence genotype was shown to be associated with a higher BMI in a longitudinal study, mainly in those consuming high amounts of dairy products. The association of the C allele, responsible for lactase non-persistence, with the risk of hyperglycemia needs to be replicated.
Keywords: D.E.S.I.R; Data from the Epidemiological Study on the Insulin-Resistance syndrome; IDF; IFG; International Diabetes Federation; LP; Lactase genetic polymorphism; Longitudinal study; MetS; T2D; Type 2 diabetes; impaired fasting glycemia; lactase persistence; metabolic syndrome; type 2 diabetes.
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