A comparative, randomised MRI study of the physiological and appetitive responses to gelling (alginate) and non-gelling nasogastric tube feeds in healthy men

Inclusion in a NGTF of an acid-sensitive, seaweed-derived alginate, expected to form a reversible gel in the stomach, may create a more normal intragastric state and modified gastrointestinal responses. This may ameliorate NGTF-associated increased risk of diarrhoea, upper gastrointestinal symptoms, and appetite suppression. In a randomised, crossover, comparison study, undertaken in 12 healthy males, an alginate containing feed (F+ALG), or one that was alginate free (F-ALG) (300ml) was given over 1-hour with a 7-14 day washout period between treatments. Baseline and for four hours, post feed initiation, MRI measurements were made to establish small bowel water content (SBWC), gastric contents volume and appearance, and superior mesenteric artery blood flux. Blood glucose and gut peptides were measured. Scores for subjective appetite and upper gastrointestinal symptoms were obtained. Ad libitum pasta consumption three-hours post-feeding was measured. F+ALG exhibited a gastric appearance consistent with gelling surrounded by a freely mobile water halo. Significant main effects of feed were seen for SBWC (P=0.03) and PYY (P=0.004) which were attributed to generally higher values for SBWC with F+ALG (max difference between adjusted means 72mL at 210min) and generally lower values for PYY with F+ALG. Gastric contents volume showed a faster reduction with F+ALG, less between-participant variation and a feed by time interaction (P=0.04). Feed by time interactions were also seen with GLP-1 (P=0.02) and GIP (P=0.002), both showing a blunted response with F+ALG. Apparent intra-gastric gelling with F+ALG and subsequent differences in gastrointestinal and endocrine responses have been demonstrated between an alginate-containing and alginate-free feed.