The effect of dietary lactose in lactase non-persistent individuals on gut microbiota

Globally, about 70 percent of the adult population is lactase non-persistent (LNP), lacking the enzyme required for the digestion of lactose. It has been shown that most of the LNPers can still consume 12 grams (or more) of lactose in a single dose without suffering from any gastrointestinal (GI) discomfort. Dietary lactose might improve intolerance symptoms via the process of colonic adaptation. This study could provide insight into the threshold levels of repetitive dietary lactose needed to observe colonic adaptation and into what positive health effects the intake of lactose may have when colonic adaptation occurs.
The primary objective of this study is to assess whether repetitive consumption of an increasing dose of dietary lactose in LNPers induces colonic microbial adaptation by a shift in microbiota composition and functional potential of microbiota as measured with shotgun metagenomic sequencing. The secondary objective is to assess whether repetitive consumption of an increasing dose of dietary lactose in LNPers results in decreased symptoms of lactose intolerance, by measurements such as hydrogen breath test, fecal lactase activity, and GI comfort.
This study will consist of a dose-response single-blinded intervention study, with three consecutive 4 week intervention periods.
We aim to recruit 25 healthy Asian volunteers with a LNP genotype avoiding lactose in their habitual diet, 18-50yrs of age, BMI 18.5-30 kg/m2
During the three consecutive intervention periods the study participants will consume twice a day 12 grams of sugar. This dose will consist of different ratios between beta-lactose and dextrose: twice a day respectively 3 grams, 6 grams, and 12 grams of lactose. This will result in a total daily lactose dose of 6, 12, and 24 grams, respectively.
The main study parameter is the change in fecal microbiota based on shotgun metagenomic sequencing upon repetitive consumption of (an increasing dose of) lactose. The secondary study parameters are exhaled hydrogen measured with the hydrogen breath test, stool characteristics, and GI comfort.

Repetitive consumption of an increasing dose of dietary lactose in LNPers induces colonic microbial adaptation and improves intolerance symptoms

Baseline, T=4, 8, and 12 weeks

During the three consecutive intervention periods the study participants will consume twice a day 12 grams of sugar. This dose will consist of different ratios between beta-lactose and dextrose: twice a day respectively 3 grams, 6 grams, and 12 grams of lactose. This will result in a total daily lactose dose of 6, 12, and 24 grams, respectively.