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increased further and remained elevated compared to glucose ingested alone.
The relative area under the insulin response curve was greatest for cottage
cheese ingested with glucose (360%) and least with egg white ingested with
glucose (190%), compared to glucose alone. Overall, each of the seven dif-
ferent protein sources ingested with glucose resulted in a reduced glucose
response with the exception of the egg white meal. The glucagon concen-
tration increased following protein
þ
glucose meals, in contrast to glucose
alone which had decreased glucagon concentrations. The 5-h insulin
response to the ingested protein was similar from these different sources
of proteins except the magnitude of the response varied greatly between cot-
tage cheese
þ
glucose and egg white
þ
glucose, which was speculated to be
due to the difference in amino acid composition of the proteins. The simul-
taneous ingestion of glucose with cottage cheese or egg white protein
decreased the glucose area response by 11% and 20%, respectively in another
study by
Gannon et al. (1992)
. Similar to
Gannon et al. (1988)
, the insulin
area response was also greater after ingesting cottage cheese compared to egg
white suggesting that the glucose lowering effect was insulin mediated. The
insulin area response was twofold from ingesting cottage cheese in normal
subjects
(
Nuttall & Gannon, 1990
) but in this study it was up to fourfold
higher for type 2 diabetics. Thus in subjects with diabetes, cottage cheese
was a more potent insulin secretagogue relative to egg white protein than
in normal individuals. The glucagon area response to both protein sources
were similar (
Gannon et al., 1992
)
; but in normal subjects, cottage cheese
protein showed a twofold greater glucagon response than egg white protein
(
Nuttall & Gannon, 1990
). The metabolic response by type 2 diabetics to
different proteins coingested with glucose is therefore markedly different
to that of normal individuals.
In vitro
, whey had an insulinogenic effect by preferential elevation of
plasma concentrations of plasma amino acids, GIP and GLP-1 responses
(
Salehi et al., 2012
)
. Whey protein showed insulinotropic and glucose
lowering effects in several
in vivo
studies. The addition of a whey protein
supplement to a 50-g glucose drink reduced postprandial glycemia in a
dose-dependent manner (
Petersen et al., 2009
)
. Another study showed that
when whey protein (10-40 g) was consumed before a high carbohydrate
meal, blood glucose and insulin levels reduced in a dose-dependent manner
(
Akhavan, Luhovyy, Brown, Cho, & Anderson, 2010
)
. Whey protein con-
sumed in relatively small amounts just before a meal reduced postmeal blood
glucose while reducing insulin response. However, in another study, when
whey protein was consumed before a carbohydrate meal,
insulin and
