Effects of intraduodenal protein on appetite, energy intake, and antropyloroduodenal motility in healthy older compared with young men in a randomized trial

Abstract

Intraduodenal protein suppresses appetite and energy intake less in healthy older than in young adults. In older subjects, intraduodenal protein at low doses increased overall energy intake, which supports the use of protein supplements in undernourished older people. This trial was registered at www.anzctr.org.au as 12612000906853.

Gastric Emptying in the Elderly

“…9,[32][33][34][35][36] There is little information about the effects of aging on the motor activity of the stomach, but fasting antral and duodenal motility does not differ substantially between young and older individuals. 30,37 Although both antegrade and retrograde transpyloric flow pulses are evident after ingestion of a glucose drink in both healthy older and young people, the antegrade flow pulses are less in the older individuals. 9 Healthy aging is accompanied by loss of enteric neurons and interstitial cells of Cajal throughout the gut; motor function is generally well preserved whereas deficits in sensory function are more apparent.…”

“…The latter, which may be defined as a reduction of appetite and energy intake in older compared with young adults, predisposes older people to weight loss, particularly loss of skeletal muscle. 62,63 Aging is characterized by attenuated regulation of appetite and energy intake, 30,64,65 so that in the fasting state, appetite and energy intake are less in older than in young adults [43][44][45]47,62,64 and the suppression of energy intake by nutrients is also less in older than young adults. 30,64 Appetite and energy intake are modulated by central and peripheral influences, the latter including interrelated gastric and small intestinal sensory and motor functions-including variations in gastric emptying 45 and gastric distension 19 -triggered by the interaction with ingested nutrients.…”

“…[24][25][26] High-resolution manometry is used predominantly for research purposes to record the frequency, amplitude, and organization of lumen-occlusive contractions in the antrum, pylorus, and duodenum using a multilumen catheter with an array of side holes and/or a pyloric sleeve sensor. 30 Proximal gastric relaxation in response to a meal can be evaluated in a laboratory using an electronic barostat; the volume of air required to maintain a fixed pressure in an intragastric bag is used as an index of proximal gastric tone. 31 …”

The ageing gastrointestinal tract

“…Even 'healthy' ageing is characterized by altered regulation of appetite and energy intake, which are both less in young adults, and which appear to be less sensitive to further suppression by ingestion of nutrients including protein ( Fig. 1) [12,13].…”

“…The growing awareness of the prevalence of undernutrition in older people and recognition of the adverse effects of major muscle loss during ageing has led to an increase in the use of oral highprotein supplements to increase the intake of protein and energy in the elderly population and, thereby, attenuate the loss of body weight and muscle mass [11]. The rationale for the use of these supplements is strengthened by the observation that, in healthy older people, protein administered both orally [12] and directly into the small intestine [13] suppresses subsequent energy intake less than in young adults. The following sections focus on recent insights into the pathophysiology of the ageing gut.…”