The digestive system -- which can be up to 30 feet in length in adults -- is usually divided into eight parts: the mouth, the esophagus, the stomach, the small.
Of course, problems with digestion can occur at any age. Yet nearly 40% of older adults have one or more age-related digestive symptom each.
Hum Biol. Oct;69(5) Phylogenetic analysis of the evolution of lactose digestion in adults. Holden C(1), Mace R. Author information: (1) Department.