Glycemia and insulinemia in healthy subjects after lactose-equivalent meals of milk and other food proteins: the role of plasma amino acids and incretins1,2,3
Mikael Nilsson, Marianne Stenberg, Anders H Frid, Jens J Holst and Inger ME Björck
1 From the Department of Applied Nutrition and Food Chemistry, Lund University, Sweden (MN, MS, and IMEB); the Clinic of Endocrinology, University Hospital MAS, Malmö, Sweden (AHF); and the Department of Medical Physiology, The Panum Institute, University of Copenhagen, Denmark (JJH)
Background: Milk products deviate from other carbohydrate-containing foods in that they produce high insulin responses, despite their low GI. The insulinotropic mechanism of milk has not been elucidated.
Objective: The objective was to evaluate the effect of common dietary sources of animal or vegetable proteins on concentrations of postprandial blood glucose, insulin, amino acids, and incretin hormones [glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1] in healthy subjects.
Design: Twelve healthy volunteers were served test meals consisting of reconstituted milk, cheese, whey, cod, and wheat gluten with equivalent amounts of lactose. An equicarbohydrate load of white-wheat bread was used as a reference meal.
Results: A correlation was found between postprandial insulin responses and early increments in plasma amino acids; the strongest correlations were seen for leucine, valine, lysine, and isoleucine. A correlation was also obtained between responses of insulin and GIP concentrations. Reconstituted milk powder and whey had substantially lower postprandial glucose areas under the curve (AUCs) than did the bread reference (–62% and –57%, respectively). Whey meal was accompanied by higher AUCs for insulin (90%) and GIP (54%).
Conclusions: It can be concluded that food proteins differ in their capacity to stimulate insulin release, possibly by differently affecting the early release of incretin hormones and insulinotropic amino acids. Milk proteins have insulinotropic properties; the whey fraction contains the predominating insulin secretagogue.
High intakes of milk, but not meat, increase s-insulin and insulin resistance in 8-year-old boys
Guarantor: C Hoppe.
Contributors: CH conducted the statistical analyses and prepared the first draft of the manuscript in collaboration with CM, AV and KFM. VB was responsible for all measurements of amino acids. All contributors participated in interpreting the results and were involved in preparing the final draft of the manuscript. No author had a financial or personal conflict of interest related to this research or its source of funding.
C Hoppe1, C Mølgaard1, A Vaag2, V Barkholt3 and K F Michaelsen1
1Department of Human Nutrition and Centre for Advanced Food Studies, The Royal Veterinary and Agricultural University, Frederiksberg, Denmark
2Steno Diabetes Centre, Gentofte, Denmark
3BioCentrum-DTU, Biochemistry and Nutrition and Centre for Advanced Food Studies, Technical University of Denmark, Lyngby, Denmark
Correspondence: C Hoppe, Department of Human Nutrition and Centre for Advanced Food Studies, The Royal Veterinary and Agricultural University, Rolighedsvej 30, DK-1958 Frederiksberg, Denmark. E-mail: firstname.lastname@example.org
Received 30 March 2004; Revised 10 August 2004; Accepted 6 September 2004; Published online 17 November 2004.
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Objective: Our objective was to examine if a high animal protein intake from milk or meat increased s-insulin and insulin resistance in healthy, prepubertal children. A high animal protein intake results in higher serum branched chain amino acids (BCAA; leucine, isoleucine and valine) concentrations, which are suggested to stimulate insulin secretion. Furthermore, milk possesses some postprandial insulinotrophic effect that is not related to its carbohydrate content.
Design: A total of 24 8-y-old boys were asked to take 53 g protein as milk or meat daily. At baseline and after 7 days, diet was registered, and insulin, glucose, and amino acids were determined. Insulin resistance and beta cell function were calculated with the homeostasis model assessment.
Results: Protein intake increased by 61 and 54% in the milk- and meat-group, respectively. In the milk-group, fasting s-insulin concentrations doubled, which caused the insulin resistance to increase similarly. In the meat-group, there was no increase in insulin and insulin resistance. As the BCAAs increased similarly in both groups, stimulation of insulin secretion through BCAAs is not supported.
Conclusions: Our results indicate that a short-term high milk, but not meat, intake increased insulin secretion and resistance. The long-term consequences of this are unknown. The effect of high protein intakes from different sources on glucose–insulin metabolism needs further studying.
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With white bread as reference, the
GIs were very low for the milk products and ranged from 12
to 30. This low range in GI is in accordance with data from
the literature. However, the IIs of the milk products were
high and similar to that of white bread. This inconsistency
has not been acknowledged, and milk products appear to be
an exception in that the IIs cannot be predicted from the GIs.
The fact that lactose induced a substantially lower II than
the milk products indicates that some other milk component
adds to the insulin response. An insulinotrophic effect of
milk and fruit juices has been reported previously from
studies in type II diabetic subjects (Gannon et al. 1986;
Bucalossi et al. 1990), but with food products having a very
different gross composition, making interpretation regarding
The insulinogenic features of milk observed in healthy
subjects in the present study is likely to increase insulinaemia
from mixed meals. Accordingly, we have observed that
inclusion of milk (150 ml) with a barley-based breakfast
increased the II of the meal by approximately 20 units
(Liljeberg et al. 1996). The potential metabolic consequences of this insulinotrophic capacity of milk need to be
La dissociazione tra GI e II del latte non è dovuta ai grassi del latte ma... Aggiungo io agli ormoni in esso contenuti.
Dissociation of the glycaemic and insulinaemic responses to whole and skimmed milk
Garrett Hoyta1, Matthew S. Hickeya1 and Loren Cordaina1 c1
a1 Department of Health and Exercise Science, Fort Collins, CO 80523, USA
In most carbohydrate-containing foods, the blood insulin response is predictable and is closely linked to the food's glycaemic index (GI). A single study, examining whole milk and fermented milk products made from whole milk, recently reported a large dissociation between the GI and insulinaemic index (II) in healthy normal adults. Because the fat component of a food may influence the GI and II, it is unclear if a similar dissociation may exist for skimmed milk in normal adults. We determined the GI and II of both skimmed and whole milk in nine healthy, male (n 6) and female (n 3) subjects (23·6 (sd 1·4) years). No significant (P>0·05) differences existed between GI and II for skimmed and whole milks. Significant (P<0·05) differences were observed between the actual and predicted areas under the insulin curves for both skimmed milk (predicted 1405 (sd 289) pmol×min/l; actual 6152 (sd 1177) pmol×min/l) and whole milk (predicted 1564 (sd 339) pmol×min/l; actual 5939 (sd 1095) pmol×min/l). Consequently, a large and similar dissociation of the GI and II existed for both whole milk (42 (sd 5) and 148 (sd 14)) and skimmed milk (37 (sd 9) and 140 (sd 13)). It is concluded that the dissociation of the GI and II in milk is not related to its fat content.
(Received May 10 2004)
(Revised August 10 2004)
(Accepted September 14 2004)
Credo sia sufficiente.