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| 2. |
- Gunnerud, Ulrika, et al.
(författare)
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Effects of whey proteins on glycaemia and insulinaemia to an oral glucose load in healthy adults; a dose-response study.
- 2013
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Ingår i: European Journal of Clinical Nutrition. - : Springer Science and Business Media LLC. - 1476-5640 .- 0954-3007. ; 67:7, s. 749-753
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Tidskriftsartikel (refereegranskat)abstract
- Background/Objectives:Whey proteins have insulinogenic properties and the effect appears to be mediated from a postprandial plasma amino-acid (AA) response. The aim was to study the possible dose-response relationship between whey intake and glycaemic-, insulinaemic- and plasma AA responses.Subjects/Methods:Twelve healthy volunteers participated in the study. They were provided three whey protein drinks, containing 4.5, 9 or 18 g protein as breakfast meals in random order. All meals contained 25 g available carbohydrates (glucose). The same amount of glucose in water was used as reference.Results:Linear dose-response relations were found between whey protein intake and postprandial glycaemia, insulinaemia and plasma AAs. The two highest doses, 18 g and 9 g, significantly reduced postprandial glycaemia (incremental area under the curve (iAUC) 0-120 min; P< 0.05). The 18 g dose significantly increased the insulin response (iAUC 0-120 min; P<0.05). All measured plasma AAs (15 in total), except glutamic acid, responded in a dose-dependent way, and the 9 and 18 g doses resulted in significantly higher plasma levels of AAs compared with the reference.Conclusions:Whey protein affects glycaemia, insulinaemia and plasma AAs to a glucose load in a dose-dependent manner. Comparatively low doses of whey protein (9 g) reduced postprandial glycaemia significantly when added to a carbohydrate-rich meal.European Journal of Clinical Nutrition advance online publication, 1 May 2013; doi:10.1038/ejcn.2013.88.
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| 3. |
- Gunnerud, Ulrika
(författare)
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Metabolic impact of certain dietary proteins and/or amino acids - Glycaemic and hormonal responses to carbohydrate meals in healthy subject
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Re-occurring hyperglycaemic episodes promote subclinical low-grade inflammation and CVD in type 2 diabetes, emphasising the therapeutic role of tight blood glucose regulation. A tight blood glucose regulation is probably beneficial also in healthy subjects and mild elevations in postprandial glycaemia and triglycerides are associated with impaired flow-mediated dilation and increased markers of oxidative stress in young healthy subjects. Certain dietary proteins and amino acids (AA) have insulinogenic properties and might facilitate glycaemic regulation following a carbohydrate challenge. However, there is a lack of knowledge regarding the impact of different food proteins, and to what extent their effects can be influenced by supplementation with AA. Also, limited information exists with respect to influence of proteins/AA on metabolic response to carbohydrates in a composite meal. The objective of the present thesis was to investigate the impact of whey and soy protein on postprandial blood glucose, plasma AA (p-AA) and hormonal responses when administered to healthy subjects in a glucose drink, as part of milk meals, or in combination with a composite carbohydrate meal. The effect of exchanging half of the protein for specific AA mixtures (5AA: isoleucine, leucine, lysine, threonine and valine) or (6AA: 5AA+arginine) was also examined. Additionally appetite rating in the postprandial phase was performed using VAS scales. Whey protein (4.5-18g) reduced postprandial glycaemia, and increased insulinaemia and p-AA in a dose dependent way to a glucose challenge, and the p-5AA (iAUC 0-60 min) correlated to the insulin response (iPeak; P < 0.009). Lactose-equivalent amounts of bovine and human milk resulted in similar postprandial glycaemia and insulinaemia. A rapid response in GIP, GLP-1 and p-AA correlated to an early insulinogenic effect that was associated to reduction of glycaemia (iAUC 0-90 min; P < 0.001). Hydrolysed and intact whey had similar effects on glycaemic responses when co-ingested with glucose, although hydrolysed way tended to be more insulinogenic, possible due to its higher early insulin and faster p-AA response compared with intact whey. Exchanging half of the intact or hydrolysed whey protein for 5AA magnified the insulinogenic effect and reduced postprandial glycaemia (iAUC 0-120min; P < 0.05). Intake of whey or soy protein with or without addition of 5AA or 6AA, as a pre-meal protein drink (PMPD) prior a composite meal, considerably attenuated postprandial blood glucose incremental peak value (iPeak; P < 0.05). Also, all whey PMPDs with or without added AA reduced glycaemia (iAUC 0-120min; P < 0.05) and increased the Glycaemic Profile (GP; P < 0.05). Arginine had no additional effect on glycaemic responses when added to the 5AA mixture. Early GLP-1 and p-AA responses (iAUC 0-15 min) were associated with early insulin response (iAUC 0-15min). Early increment in insulin possibly explain the attenuation of over-all course of post-prandial glycaemia to the composite carbohydrate meal post the PMPDs. Interestingly, the lowering of glycaemic excursions was observed in the absence of elevated insulinaemic peak. Intake of a PMPD prior a composite meal had no effects on appetite rating (VAS) or plasma ghrelin.
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| 4. |
- Gunnerud, Ulrika, et al.
(författare)
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The glycemic, insulinemic and plasma amino acid responses to equi-carbohydrate milk meals, a pilot- study of bovine and human milk
- 2012
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Ingår i: Nutrition Journal. - : Springer Science and Business Media LLC. - 1475-2891. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Background: Dairy proteins, in particular the whey fraction, exert insulinogenic properties and facilitate glycemic regulation through a mechanism involving elevation of certain plasma amino acids, and stimulation of incretins. Human milk is rich in whey protein and has not been investigated in this respect. Method: Nine healthy volunteers were served test meals consisting of human milk, bovine milk, reconstituted bovine whey-or casein protein in random order. All test meals contributed with 25g intrinsic or added lactose, and a white wheat bread (WWB) meal was used as reference, providing 25g starch. Post-prandial levels in plasma of glucose, insulin, incretins and amino acids were investigated at time intervals for up to 2 h. Results: All test meals elicited lower postprandial blood glucose responses, expressed as iAUC 0-120 min compared with the WWB (P < 0.05). The insulin response was increased following all test meals, although only significantly higher after whey. Plasma amino acids were correlated to insulin and incretin secretion (iAUC 0-60 min) (P <= 0.05). The lowered glycemia with the test meals (iAUC 0-90 min) was inversely correlated to GLP-1 (iAUC 0-30 min) (P <= 0.05). Conclusion: This study shows that the glycemic response was significantly lower following all milk/milk protein based test meals, in comparison with WWB. The effect appears to originate from the protein fraction and early phase plasma amino acids and incretins were involved in the insulin secretion. Despite its lower protein content, the human milk was a potent GLP-1 secretagogue and showed insulinogenic properties similar to that seen with reconstituted bovine whey-protein, possibly due to the comparatively high proportion of whey in human milk.
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| 5. |
- Salehi, S Albert, et al.
(författare)
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The insulinogenic effect of whey protein is partially mediated by a direct effect of amino acids and GIP on beta-cells
- 2012
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Ingår i: Nutrition & Metabolism. - : Springer Science and Business Media LLC. - 1743-7075. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Background: Whey protein increases postprandial serum insulin levels. This has been associated with increased serum levels of leucine, isoleucine, valine, lysine, threonine and the incretin hormone glucose-dependent insulinotropic polypeptide (GIP). We have examined the effects of these putative mediators of whey's action on insulin secretion from isolated mouse Langerhans islets. Methods: Mouse pancreatic islets were incubated with serum drawn from healthy individuals after ingestion of carbohydrate equivalent meals of whey protein (whey serum), or white wheat bread (control serum). In addition the effect of individual amino acid combinations on insulin secretion was also tested. Furthermore, the stimulatory effects of whey serum on insulin secretion was tested in vitro in the absence and presence of a GIP receptor antagonist ((Pro(3)) GIP[mPEG]). Results: Postprandial amino acids, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) responses were higher after whey compared to white wheat bread. A stimulatory effect on insulin release from isolated islets was observed with serum after whey obtained at 15 min (+87%, P < 0.05) and 30 min (+139%, P < 0.05) postprandially, compared with control serum. The combination of isoleucine, leucine, valine, lysine and threonine exerted strong stimulatory effect on insulin secretion (+270%, P < 0.05), which was further augmented by GIP (+558% compared to that produced by glucose, P < 0.05). The stimulatory action of whey on insulin secretion was reduced by the GIP-receptor antagonist (Pro(3)) GIP[mPEG]) at both 15 and 30 min (-56% and -59%, P < 0.05). Conclusions: Compared with white wheat bread meal, whey causes an increase of postprandial insulin, plasma amino acids, GIP and GLP-1 responses. The in vitro data suggest that whey protein exerts its insulinogenic effect by preferential elevation of the plasma concentrations of certain amino acids, GIP and GLP-1.
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