Year-end Sale % OFF 
Abstract
Little is known about how milk proteins affect gastrointestinal (GI) transit, particularly for the elderly, in whom digestion has been observed to be slowed. We tested the hypothesis that GI transit is faster for whey than for casein and that this effect is accentuated with hydrolysates, similar to soy. Adult male rats (18 months old) were fed native whey or casein, hydrolyzed whey (WPH) or casein (CPH), hydrolyzed blend (HB; 60% whey:40% casein), or hydrolyzed soy for 14 days then treated with loperamide, prucalopride, or vehicle-control for 7 days. X-ray imaging tracked bead-transit for: gastric emptying (GE; 4 h), small intestine (SI) transit (9 h), and large intestine (LI) transit (12 h). GE for whey was 33 ± 12% faster than that for either casein or CPH. SI transit was decreased by 37 ± 9% for casein and 24 ± 6% for whey compared with hydrolyzed soy, and persisted for casein at 12 h. Although CPH and WPH did not alter transit compared with their respective intact counterparts, fecal output was increased by WPH. Slowed transit by casein was reversed by prucalopride (9-h), but not loperamide. However, rapid GE and slower SI transit for the HB compared with intact forms were inhibited by loperamide. The expected slower GI transit for casein relative to soy provided a comparative benchmark, and opioid receptor involvement was corroborated. Our findings provide new evidence that whey slowed SI transit compared with soy, independent of GE. Increased GI transit from stomach to colon for the HB compared with casein suggests that including hydrolyzed milk proteins in foods may benefit those with slowed intestinal transit.
Highlights
Milk is a widely consumed natural beverage renowned as a nutritious protein source [1].Research has revealed additional health properties that may be conferred via the pharmacological actions of digested milk peptides on cardiovascular function, regulation of food intake, and metabolism [2,3,4]
The slowed GI transit for whey, was not due to delayed gastric emptying (GE) but rather is likely to be localised to slower bead movement through the small intestinal (SI)
Our findings provide new evidence that whey protein slows SI transit compared with hydrolyzed soy and indicate that this is independent of GE
Summary
Milk is a widely consumed natural beverage renowned as a nutritious protein source [1].Research has revealed additional health properties that may be conferred via the pharmacological actions of digested milk peptides on cardiovascular function, regulation of food intake, and metabolism [2,3,4]. Milk is a widely consumed natural beverage renowned as a nutritious protein source [1]. Nutrients 2017, 9, 1351 supplement for those needing an digestible nutritious protein source including, the elderly, infants, and athletes. During gastrointestinal (GI) digestion, the behaviour of milk proteins differs, with casein considered as a slowly digestible protein and whey a rapidly digestible protein [6]. Whey is rapidly expelled from the stomach, whereas caseins precipitate in the low pH of the stomach and coagulate, slowing gastric emptying (GE). Structure, and solubility of casein micelles in the stomach affect digestibility and alter GI transit. Casein has long been known to slow both GE (due to curd formation) and small intestinal (SI) transit, these effects may be altered by specific hydrolysis methods
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
