Food Nutrition & Health Team, Food & Bio-Based Products Group, AgResearch, Grasslands Research Centre, Palmerston North 4442, New Zealand.
Riddet Institute, Massey University, Palmerston North 4442, New Zealand.
Nutrients. 2017 Dec 13;9(12):1351. doi: 10.3390/nu9121351.
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.
对于老年人而言，人们对牛奶蛋白如何影响胃肠道（GI）转运知之甚少，因为人们观察到老年人的消化能力下降。我们验证了一个假设，即乳清蛋白比酪蛋白的 GI 转运速度更快，并且这种效应类似于大豆蛋白，会因水解而增强。成年雄性大鼠（18 个月大）喂食天然乳清或酪蛋白、水解乳清（WPH）或酪蛋白（CPH）、水解混合物（HB；60%乳清：40%酪蛋白）或水解大豆 14 天后，用洛哌丁胺、普芦卡必利或载体对照处理 7 天。X 射线成像跟踪珠粒转运：胃排空（GE；4 h）、小肠（SI）转运（9 h）和大肠（LI）转运（12 h）。与 CPH 相比，乳清的 GE 速度快 33 ± 12%。与水解大豆相比，酪蛋白的 SI 转运减少 37 ± 9%，乳清减少 24 ± 6%，并且酪蛋白在 12 h 时仍保持这种状态。尽管 CPH 和 WPH 与相应的完整形式相比没有改变转运，但 WPH 增加了粪便排出量。普芦卡必利（9 h）逆转了酪蛋白引起的转运减慢，但洛哌丁胺没有。然而，与完整形式相比，HB 快速的 GE 和较慢的 SI 转运被洛哌丁胺抑制。与大豆相比，酪蛋白预期较慢的 GI 转运为提供了一个比较基准，并证实了阿片受体的参与。我们的研究结果提供了新的证据，表明与大豆相比，乳清蛋白会减缓 SI 转运，而与 GE 无关。与酪蛋白相比，HB 从胃到结肠的 GI 转运增加，这表明在食物中添加水解牛奶蛋白可能有益于那些肠道转运缓慢的人。
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