Abstract
BackgroundWhey proteins have insulinogenic properties and the effect appears to originate from a specific postprandial plasma amino acid pattern. The insulinogenic effect can be mimicked by a specific mixture of the five amino acids iso, leu, lys, thr and val.ObjectiveThe objective was to evaluate the efficacy of pre-meal boluses of whey or soy protein with or without added amino acids on glycaemia, insulinemia as well as on plasma responses of incretins and amino acids at a subsequent composite meal. Additionally, plasma ghrelin and subjective appetite responses were studied.DesignIn randomized order, fourteen healthy volunteers were served a standardized composite ham sandwich meal with either water provided (250 ml) during the time course of the meal, or different pre-meal protein drinks (PMPD) (100 ml provided as a bolus) with additional water (150 ml) served to the meal. The PMPDs contained 9 g protein and were based on either whey or soy protein isolates, with or without addition of the five amino acids (iso, leu, lys, thr and val) or the five amino acids + arg.ResultsAll PMPD meals significantly reduced incremental area for plasma glucose response (iAUC) during the first 60 min. All whey based PMPD meals displayed lower glycemic indices compared to the reference meal. There were no significant differences for the insulinemic indices. The early insulin response (iAUC 0–15 min) correlated positively to plasma amino acids, GIP and GLP-1 as well as to the glycemic profile. Additionally, inverse correlations were found between insulin iAUC 0–15 min and the glucose peak.ConclusionThe data suggests that a pre-meal drink containing specific proteins/amino acids significantly reduces postprandial glycemia following a composite meal, in absence of elevated insulinemic excursions. An early phase insulinemic response induced by plasma amino acids and incretins appears to mediate the effect.Trial RegistrationClinicalTrials.gov NCT01586780<NCT01586780>
Highlights
In type 2 diabetes (T2D), hyperglycemia is associated with an increased risk of cardiovascular diseases, and reduction of postprandial glycemia has recently been suggested to be as important as lowering fasting blood glucose levels to reach optimal metabolic control and reduce risk of complications [1]
In previous studies we have demonstrated that whey protein, co-ingested with carbohydrates, stimulates insulin secretion and reduces postprandial glycemia in both healthy subjects as well as in T2D patients [9,10]
The insulinogenic effect appears to be mediated through a specific postprandial amino acid (AA) pattern appearing in plasma following whey ingestion, with the highest responses found for lysine, threonine and the branched chained amino acids (BCAA) leucine, isoleucine and valine [10]
Summary
In type 2 diabetes (T2D), hyperglycemia is associated with an increased risk of cardiovascular diseases, and reduction of postprandial glycemia has recently been suggested to be as important as lowering fasting blood glucose levels to reach optimal metabolic control and reduce risk of complications [1]. In previous studies we have demonstrated that whey protein, co-ingested with carbohydrates, stimulates insulin secretion and reduces postprandial glycemia in both healthy subjects as well as in T2D patients [9,10]. The insulinogenic effect appears to be mediated through a specific postprandial amino acid (AA) pattern appearing in plasma following whey ingestion, with the highest responses found for lysine (lys), threonine (thr) and the branched chained amino acids (BCAA) leucine (leu), isoleucine (iso) and valine (val) [10]. We have previously demonstrated that the insulinogenic effect can be mimicked by ingestion of a mixture of the mentioned 5 AA alone, in the absence of a GIP response [11]. The insulinogenic effect can be mimicked by a specific mixture of the five amino acids iso, leu, lys, thr and val
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