The regular consumption of dairy food in individuals with difficulties to digest lactose could lead to an adaptation of their gut microbiota (the microorganism population that lives in the digestive tract) and to an improvement of symptoms, which allow them to consume more dairy foods.
The consumption of live bacteria can increase the presence of certain bacteria strain without, however, changing the overall gut microbiota constitution. Yogurt contains live bacteria, Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus, which break down some of the lactose it contains, making it easier for individuals who have difficulty digesting lactose.
Moreover, if it is not digested in the small intestine, lactose may be used by the intestinal microbiota as a nutrient (prebiotic). Lactose and other milk sugars also promote the growth of bifidobacteria in the gut and may play a life-long role in countering the aging-associated decline of some immune functions.
Sources:
Amaretti et al. Appl Microbiol Biotechnol 2006;73:654-62.
Efsa Panel on Dietetic Products N, Allergies. Scientific Opinion on the substantiation of health claims related to live yoghurt cultures and improved lactose digestion (ID 1143, 2976) pursuant to Article 13(1) of Regulation (EC) No 1924/2006. EFSA Journal 2010;8:n/a-n/a.
He et al. Eur J Clin Invest 2008;38:541-7.
Vandenplas et al. Asia Pac J Clin Nutr 2015;24 Suppl 1:S9-13.
Vulevic et al. Br J Nutr 2015;114:586-95.
