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  • Publication
    Effects of a casein hydrolysate versus intact casein on gastric emptying and amino acid responses
    Purpose Milk proteins and/or their hydrolysates have been reported to have beneficial effects for improving postprandial glycaemia. Gastric emptying is a major determinant of postprandial glycaemia, yet limited studies have examined the effects of intact milk proteins compared to hydrolysates on gastric emptying. We investigated gastric emptying of a casein hydrolysate compared to intact casein. Methods Nine overweight and obese adults (mean ± SD age: 59.5 ± 6.5 years and BMI 28.4 ± 2.6 kg/m2) were studied in a randomised crossover design. Gastric emptying was assessed by paracetamol absorption test, with HPLC-MS being used for determining paracetamol and its primary metabolites in plasma. Glucose, insulin and amino acid responses were also assessed. Results Linear mixed model analysis showed no effect of treatment [F(1, 55) = 2.1, P = 0.16] or treatment × time interactions [F(6, 54) = 1.5, P = 0.21] for paracetamol concentrations. In addition, there were no significant differences between the intact casein and hydrolysate for any of the gastric emptying outcome measures (Cmax, AUC0–30min, AUC0–60min; AUC0–240min). However, insulin was increased in the early postprandial period (iAUC0–15min, iAUC0–30min; P < 0.05) and there was a treatment effect for glucose [F(1, 53) = 5.3, P = 0.03] following the casein hydrolysate compared to intact casein. No significant differences in amino acids were found between the two conditions. Conclusions Gastric emptying of a casein hydrolysate compared to intact casein does not differ. Mechanisms other than gastric emptying, for example the presence of a bioactive peptide sequence, may contribute to the glycaemic management effects of certain milk protein hydrolysates and warrant further investigation.
    Scopus© Citations 10  431
  • Publication
    Variable glycemic responses to intact and hydrolysed milk proteins in overweight and obese adults reveal the need for precision nutrition
    Background: Dietary modifications can contribute to improved pancreatic beta cell function and enhance glycemic control. Objective: The objectives of this study were to 1) investigate the potential of milk protein hydrolysates to modulate postprandial glucose response, 2) assess individual responses, 3) explore the inter and intra-individual reproducibility of the response. Methods: A 14-day randomized crossover study investigated interstitial glucose levels of participants in response to 12% w/v milk protein drinks (intact caseinate and casein hydrolysate A and B (CH-A and CH-B) consumed in random order with a 2-day washout between treatments. Milk protein drinks were consumed immediately prior to study breakfast and evening meals. Twenty participants (11 male/ 9 female) aged 50 ± 8 y with a body mass index of 30.2 ± 3.1 kg/m2 were recruited. Primary outcome was glucose levels assessed at 15 min intervals using glucose monitors. Results: Repeated measures-ANOVA revealed that for breakfast there was a significant difference across the three treatment groups (P = 0.037). The ability to reduce postprandial glucose was specific to CH-B in comparison to intact caseinate (P = 0.039). However, despite this significant difference further examination revealed that only three out of 18 individuals were classified as responders (P < 0.05). High intraclass correlation coefficients (ICCs) were obtained for glucose response to study meals (ICC: 0.892 for breakfast with intact caseinate). The inter-individual coefficient of variations (CVs) were higher than intra-individual CVs. Mean inter- and intra-individual CVs were 19.4% and 5.7%, respectively, for breakfast with intact caseinate. Conclusion: Ingestion of a specific casein hydrolysate successfully reduced the postprandial glucose response, however at an individual level only three participants were classified as responders, highlighting the need for precision nutrition. Exploration of high inter-individual responses to nutrition interventions is needed, in combination with the development of precision nutrition, potentially through an n-of-1 approach.
    Scopus© Citations 9  169