Biology Reference
In-Depth Information
large amounts of glycine.
Gannon, Nuttall, and Nuttall (2002a)
fed nine
healthy subjects 1 mM/kg lean body mass glycine and measured insulin
for the subsequent 2 h. They found that glycine only modestly increased
insulin secretions. However, it significantly increased plasma glucagon con-
Von Drateln (2001)
gave six healthy nonobese first-degree relatives of type
2 diabetics a morning dose of 5 g of glycine and then measured insulin secre-
tion and action using a hyperglycemic-hyperinsulinaemic clamp. The study
showed that glycine increased insulin secretion although it had no effect on
insulin action. These studies suggest that glycine stimulates insulin secretion
to a modest level.
Lysine is one of three basic amino acids and is essential to human beings.
It is found in larger quantities in red meat. A limited number of studies have
investigated the effect of lysine on insulin secretion and these show a notable
effect.
Floyd et al. (1966b)
gave 30 g of lysine intravenously to nine healthy
male subjects and observed a moderate insulin secretion (maximal increase
52
m
U/ml). In an attempt to determine the effect of lysine on insulin release,
1 mM/kg lean body mass of lysine to 13 healthy subjects and measured insu-
lin excursions over the subsequent 2.5 h. The study showed an insignificant
increase in insulin following lysine ingestion (compared to a water control).
However, there was a significant rise in glucagon. Similarly,
Isidori, Lo
Monaco, and Cappa (1981)
fed 1200 mg of lysine to 15 males and found
no effect on insulin but a rise in glucagon. These results suggest that lysine
has little effect on insulin secretion when given in doses representative of
dietary levels but stimulates glucagon.
In vitro
work also showed no effect
of lysine on insulin release.
Milner (1970)
incubated pieces of rabbit
pancreas in 5 mM solutions of lysine and found that it did not significantly
stimulate insulin release.
Isoleucine, an isomer of leucine is a branched chain amino acid (BCAA)
found in most proteins.
Floyd et al. (1966b)
infused three healthy subjects
with either 7.5 or 15 g of isoleucine and found a weak effect on insulin secre-
tion.
Nuttall, Schweim, and Gannon (2008)
fed nine healthy subjects
1 mM/kg lean body mass of isoleucine and measured insulin for the subse-
quent 2.5 h. They too observed no effect of isoleucine on insulin expression.
They also saw no effect on glucagon although plasma glucose decreased.
This may suggest a possible role of isoleucine in increasing glucose uptake.
Another study using dogs similarly saw no effect of isoleucine on glucagon
