Milk for Diabetes Prevention
brief summary
Individuals with lactase non-persistence (LNP; determined by a functional variant in the LCT gene \[rs4988235, GG genotype\]) are susceptible to lactose intolerance in adulthood due to deficiency of lactase, the enzyme which digests milk lactose sugars. However, many LNP individuals still drink ≥1 cup of milk daily. Recent analysis in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL) found that consumption of 1 serving (cup) of milk/day was associated with \~30% lower risk of type 2 diabetes among LNP individuals, but not among individuals with lactase persistence (LP). This beneficial effect might be partially explained by favorable alterations in gut microbiota and related metabolites associated with higher milk consumption among LNP individuals. Based on these observational study findings, the investigator team proposes to conduct a randomized, controlled trial of lactose-containing vs. lactose-free milk in LNP individuals with pre-diabetes, to comprehensively investigate the effects of milk intake on the gut microbiome and glycemic outcomes.
detailed description
The trial will feature a 2-week milk washout period, followed by 1:1 randomization to lactose-containing (1% or 2%) or lactose-free (1% or 2%) milk for 12 weeks (4 weeks each of ½ cup, 1 cup, and 2 cups milk). Before and after the 12 weeks, visits will entail lactose challenge hydrogen breath tests (HBT; i.e., lactose tolerance tests) and blood tests for fasting glucose, hemoglobin A1c, and metabolomics; while stool samples and continuous glucose monitoring (CGM) data will be collected at home using provided kits/devices.
Specific aims of the study are to: (1) establish feasibility and tolerability of a randomized trial of lactose-containing vs. lactose-free milk; (2) to examine the effect of lactose-containing milk on gut microbiome species, functions, and metabolites in LNP individuals with pre-diabetes; and (3) to examine the effect of lactose-containing milk on glycemic outcomes in LNP individuals with pre-diabetes.