Data_Sheet_1_Comparing Response of Sheep and Cow Milk on Acute Digestive Comfort and Lactose Malabsorption: A Randomized Controlled Trial in Female Dairy Avoiders.pdf

Background: Sheep milk (SM) is a possible alternate dairy source for those who experience digestive symptoms with cow milk (CM). While both the milks contain lactose, one of the causes for self-reported intolerance to CM, the composition of SM and CM also differs across proteins and fats, which have been shown to impact digestive processes.
Objective: To compare the acute digestive comfort and lactose malabsorption of SM to CM in female dairy avoiders.
Method: In a double-blinded, randomized cross over trial, 30 dairy-avoiding females (aged 20–30 years) drank 650 mL of SM or CM (each reconstituted from spray dried powder) following an overnight fast, on two separate occasions at least 1 week apart. Blood samples were collected for glucose and insulin assessment, and single nucleotide polymorphisms of the lactase (LCT) gene (C/T13910 and G/A22018). Breath H2 and visual analog scale (VAS) digestive symptom scores were recorded at fasting and regular intervals over 4 h after ingestion.
Results: Eighty percentage of study participants were lactase non-persistent (LNP; CC13910 and GG22018 genotype). Digestive symptoms, including abdominal cramps, distension, rumbling, bloating, belching, diarrhea, flatulence, vomiting, and nausea, were similar in response to SM and CM ingestion (milk × time, P > 0.05). Breath H2 was greater after CM than SM (72 ± 10 vs. 43 ± 6 ppm at 240 min, P < 0.001), which may be due to greater lactose content in CM (33 vs. 25 g). Accordingly, when corrected for the lactose content breath H2 did not differ between the two milks. The response remained similar when analyzed in the LNP subset alone (n = 20).
Conclusions: Despite a higher energy and nutrient content, SM did not increase adverse digestive symptoms after ingestion, relative to CM, although there was a reduced breath H2 response, which could be attributed to the lower lactose content in SM. The tolerability of SM should be explored in populations without lactose intolerance for whom underlying trigger for intolerance is unknown.

背景：绵羊乳（Sheep Milk, SM）是对牛乳（Cow Milk, CM）存在消化不适人群的潜在替代乳品来源。尽管两种乳类均含有乳糖——这是自我报告牛乳不耐受的诱因之一——但绵羊乳与牛乳在蛋白质与脂肪组成上存在差异，而这些组分已被证实会对消化过程产生影响。
研究目的：旨在对比绵羊乳与牛乳在回避乳制品女性群体中引发的急性消化舒适度及乳糖吸收不良状况。
研究方法：本研究采用双盲随机交叉试验设计，招募30名年龄介于20~30岁的回避乳制品女性受试者。受试者于隔夜空腹状态下，在两次间隔至少1周的独立试验中，分别饮用650mL由喷雾干燥粉复原的绵羊乳或牛乳。研究采集血液样本以检测葡萄糖、胰岛素水平，以及乳糖酶（lactase, LCT）基因的单核苷酸多态性（C/T13910与G/A22018位点）；并于空腹状态及摄入后4小时内的固定时间点采集呼气样本检测氢气浓度，同时采用视觉模拟评分法（Visual Analogue Scale, VAS）记录消化症状评分。
研究结果：本研究中80%的受试者为乳糖酶非持久型（Lactase Non-Persistent, LNP；基因型为CC13910与GG22018）。受试者摄入绵羊乳与牛乳后出现的消化症状（包括腹部绞痛、腹胀、肠鸣、胀气、嗳气、腹泻、排气增多、呕吐及恶心）反应程度相似（乳类×时间交互作用，P>0.05）。摄入牛乳后的呼气氢气浓度高于绵羊乳（240分钟时分别为72±10与43±6 ppm，P<0.001），这可能与牛乳乳糖含量更高（33g vs 25g）有关。因此，在对乳糖含量进行校正后，两种乳类的呼气氢气浓度并无显著差异。仅对乳糖酶非持久型亚组（n=20）进行分析时，上述结果仍保持一致。
结论：尽管绵羊乳的能量与营养成分含量更高，但与牛乳相比，受试者摄入绵羊乳后并未出现更严重的不良消化症状，仅呼气氢气反应有所降低，这可归因于绵羊乳更低的乳糖含量。对于乳糖耐受且不耐受诱因不明的人群，仍需进一步探究绵羊乳的耐受情况。