While much of the evidence for the health benefits of HMOs and specifically for 2’-FL comes from in vitro and in vivo studies, recently, a number of important clinical studies have been conducted, both in infants and adults, showing the first evidence of both good tolerability and potential efficacy of 2’-FL supplementation.21-22,25-26 In the first study of 420 infants, those with mothers who planned to formula feed were randomized to one of three formula groups, each containing galacto-oligosaccharides, with two containing 2’-FL (at either 0.2 or 1.0 g/L), with a group of non-randomized breastfed infants also included.22 Overall, there were no between-group differences in weight, length or head circumference from birth to 4 months. All three formula preparations were well tolerated. Interestingly, while there were no significant differences in relative absorption of 2’-FL between treatment groups, both plasma concentrations and relative absorption decreased from day 49 to day 119, with the authors suggesting that this may reflect development changes, such as reduced gut permeability and a microbiota population that has evolved to utilize 2’-FL to a greater extent. In a further analysis of the same study, the effect of 2’-FL on inflammatory markers was examined. There was no difference in plasma inflammatory cytokines (IL-1ra, TNFα, IL-1α, IL-1β and IL-6) between those who received formula containing 2’-FL and breast-fed infants. compared with infants who received the control formula, those who received 2’-FL-containing formula and breast-fed infants had 29–83% lower inflammatory cytokines.25
Another study – a multicentre, randomized, double-blind trial of two parallel groups of formula-fed infants – enrolled 175 infants at or before 14 days of age who received formula supplemented with 2’-FL and lacto-N-neotetraose (LNnT).21 2’-FL and LNnT were shown to be safe, well-tolerated and to support age-appropriate growth. Moreover, secondary outcome findings of lower morbidity (particularly bronchitis) and medication use (antipyretics and antibiotics) were reported in infants fed supplemented formula.
In addition to these studies in infants, a randomized, double-blind, placebo-controlled study examined the effect of HMO supplementation in 100 healthy adults. When given at daily doses of up to 20 g for 2 weeks, 2’-FL and LNnT were safe and well tolerated. Furthermore, HMO supplementation led to modifications in gut microbiota: an increase in actinobacteria and Bifidobacterium, as well as a reduction in firmicutes and proteobacteria were found.26
Thus, first clinical results on the benefits of 2′-FL look promising. It is expected that additional studies will be performed in the near future to try and confirm the beneficial effects of 2′-FL on microbiota composition, infection and inflammation, cognition and allergy prevention that were observed in preclinical studies.