Nutrition & Diet

How Aging Changes Your Gut's Ability to Digest and Absorb Protein

As we age, maintaining muscle mass becomes harder — and one underexplored reason may be that the aging gut digests and absorbs dietary protein less efficiently. This completed Maastricht University trial enrolled 12 young adults (18–35) and 12 older adults (67+) to directly measure brush border enzyme expression, amino acid transporter activity, and mucosal protein synthesis rates in the duodenum via gastroscopy and biopsy. Using a heavy water labeling protocol, researchers tracked how efficiently amino acids are actually absorbed at the intestinal wall. Fecal samples also captured shifts in the gut microbiome. The findings could reveal why older adults need higher protein intakes to achieve the same anabolic response as younger people, ultimately informing dietary strategies to preserve muscle and support healthy aging.