Hydrogen (H₂) measurement in exhaled breath is a reliable and non-invasive method to diagnose carbohydrate malabsorption. Currently, breath H₂ measurement is typically limited to clinic-based equipment. A portable breath analyser (AIRE, FoodMarble Digestive Health Limited, Dublin, Ireland) is a personalised device marketed for the detection and self-management of food intolerances, including lactose malabsorption (LM). Currently, the validity of this device for breath H₂ analysis is unknown. Individuals self-reporting dairy intolerance (six males and six females) undertook a lactose challenge and a further seven individuals (all females) underwent a milk challenge. Breath samples were collected prior to and at frequent intervals post-challenge for up to 5 h with analysis using both the AIRE and a calibrated breath hydrogen analyser (BreathTracker, QuinTron Instrument Company Inc., Milwaukee, WI, USA). A significant positive correlation (p < 0.001, r > 0.8) was demonstrated between AIRE and BreathTracker H₂ values, after both lactose and milk challenges, although 26% of the AIRE readings demonstrated the maximum score of 10.0 AU. Based on our data, the cut-off value for LM diagnosis (25 ppm H₂) using AIRE is 3.0 AU and it is effective for the identification of a response to lactose-containing foods in individuals experiencing LM, although its upper limit is only 81 ppm.

Background/objectives: Self-reported digestive intolerance to dairy foods is common. As dairy can be an important source of dietary protein, this study aimed to identify whether milk protein digestion is compromised in individuals with digestive intolerance. Subjects/methods: Adult women (n = 40) were enroled in this double-blinded, randomised cross-over trial, with digestive symptoms characterised using a lactose challenge and self-reported digestive symptom questionnaire. Participants were classified as either lactose intolerant (LI, n = 10), non-lactose dairy intolerant (NLDI, n = 20) or dairy tolerant (DT, n = 10). In a randomised sequence, participants consumed three different kinds of milk (750 ml); conventional milk (CON), a2 Milk™ (A2M), and lactose-free conventional milk (LF-CON). Circulatory plasma amino acid (AA) concentrations were measured at baseline and every 30 min until 3 h post-ingestion. Results: In all participants across all milk types, plasma AA concentrations (AUC_0-180) increased after milk ingestion with no significant differences in responses observed between milk types or participants (P > 0.05), with the exception of the suppressed lysine response in the DT group following A2M ingestion, relative to the other two groups and milk types (P < 0.05). Conclusion: Milk protein digestion, as determined by circulatory AAs, is largely unaffected by dairy- and lactose- intolerances.

Background: Lactose intolerance is due to the malabsorption of lactose, the predominant sugar present in milk

Milk structural assemblies (e.g., casein micelles) occur naturally and can be altered during processing, and this may influence the milk’s nutritional properties. Heat treatment of dairy ensures microbiological safety and extends shelf-life. Both pasteurisation and ultra-high temperature (UHT) processing are known to alter natural structural assemblies, but despite widespread use, only four human studies have addressed how heat treatment affects nutrient delivery. In vitro, animal, and human models have all shown more rapid nutrient release or appearance from UHT vs. pasteurised milk, with altered gastric emptying rate proposed as a mechanism. We hypothesised that differences in bovine milk structural assemblies arising from different processing methods would speed up gastric emptying and nutrient delivery following consumption of UHT relative to pasteurised milk. A randomised double-blind crossover trial assessed gastric emptying rate (using magnetic resonance imaging measuring gastric content volume) over 3 h and plasma amino acid appearance (using ultra-performance liquid chromatography) over 5 h following 500 mL of each milk in healthy women (n = 20). Gastric electrical activity was measured using body surface gastric mapping, and abdominal distension using stretch sensors. The time to empty 25% of the stomach contents was greater following UHT vs. pasteurised milk (45 ± 4 vs. 33 ± 4 min p < 0.05). While gastric content remained greater for longer following UHT milk, the incremental area under the curve of plasma essential amino acids was greater than pasteurised milk (55324 ± 3809 vs. 36598 ± 5673 μmol·min·L⁻¹ p < 0.05). The greater amino acid appearance following UHT milk aligns with more rapid release of proteins from the gastric curd observed in vitro, yet the greater gastric content volume implies gastric content composition (e.g., solid vs. liquid) is an important determinant of nutrient release. Dairy processing using different heat treatments, which induced structural modifications, impacted gastric emptying and plasma amino acid appearance, with implications for appetite regulation and nutrient utilisation for metabolism.

Background: Milk is as an excellent source of B-vitamins, particularly riboflavin.

Background: Lactase non-persistence, a condition affecting 75% of the world’s population, is characterized by inactivity of the lactase enzyme, resulting in lactose intolerance.