Benefits
Use as Part of
Your Diet to Help Maintain a Healthy Blood Sugar Level*
In Vitro and Animal Studies
Research has revealed that
a number of herbs and spices have insulin-like activity.2 In a
study published in 2000 by the U.S. Department of Agriculture (USDA),
cinnamon demonstrated the greatest ability to stimulate cellular glucose
metabolism among 49 botanicals tested.3
In a 2001 study,
researchers at the USDA’s Human Nutrition Research Center showed that
bioactive compounds in cinnamon trigger an insulin-like response in fat
cells.4 These compounds stimulated glucose uptake into cells and
increased glycogen (stored glucose) production via activation of the enzyme,
glycogen synthase.
The bioactive compounds in cinnamon appear to
potentiate insulin activity at the level of the cell receptor for insulin.
It has been shown that insulin resistance involves downregulation of
“insulin signaling” characterized by dephosphorylation of the receptor.5
Enzymes called “protein tyrosine kinases” (PTPases) are believed to decrease
receptor phosphorylation, and increased PTPase activity has been observed in
insulin resistant rats.6 Cinnamon compounds have demonstrated the
in vitro ability to inhibit PTP-1 and increase autophosphorylation of
the insulin receptor.7
In a recent animal study, cinnamon (cassia)
extract was administered to rats for three weeks. Following this, the rats
were infused with insulin and glucose to assess their insulin response.
Increased phosphorylation of the insulin receptor was observed in skeletal
muscle of these rats, suggesting that cinnamon has the ability to potentiate
insulin function by normalizing insulin signaling, leading to improved
uptake of glucose into skeletal muscle.8
Until recently, the precise
molecular structure of the bioactive compounds in cinnamon had not been
clearly defined. The USDA has now determined that the bioactive compounds in
cinnamon are water-soluble procyanidin Type-A polymers of catechin and
epicatechin. In a 2004 study, type-A polymers were isolated from cinnamon
and characterized by nuclear magnetic resonance and mass spectroscopy.
Type-A polymers were found to increase in vitro insulin activity by a
factor of 20. Type-A polymers also exhibited antioxidant activity, as
measured by inhibition of free radical production in platelets. These
results suggest that, in addition to regulating glucose metabolism, cinnamon
may help protect cell membranes by controlling the lipid peroxidation
associated with disruptions in insulin function.9
Human Clinical Trial
The effect of cinnamon on
glucose and blood lipids levels on people with type 2 diabetes was tested in
a recent randomized, placebo-controlled trial. A total of 60 subjects were
divided into six groups administered 1, 3, or 6 grams of cinnamon daily, in
500 mg capsules, or equal numbers of placebo capsules. The cinnamon or
placebo capsules were consumed for two periods of 20 days each. Serum
glucose, triglyceride, cholesterol, LDL cholesterol and HDL cholesterol were
measured after 20 days, 40 days and again at the end of a 20-day wash-out
period, during which neither cinnamon nor placebo was consumed.
In all three cinnamon
groups, statistically significant reductions in blood glucose levels
occurred, with decreases ranging from 18 to 29 percent. Interestingly,
glucose levels remained significantly lower after the 20-day wash-out period
(60 days from the study start) only in the group that took the lowest
cinnamon dose (1 gram daily). The placebo groups showed no significant
changes.
Decreases in triglyceride
levels ranging from 23 to 30% were observed in all three cinnamon groups
after 40 days. When the study ended at 60 days, triglyceride levels remained
lower than at the study start in the 1 and 3 gram cinnamon groups, but not
in the group taking 6 grams daily. Cholesterol reductions also occurred with
the three cinnamon doses, with decreases ranging from 13 to 25% that were
maintained at the study end. For LDL, the 3 and 6 gram cinnamon groups
showed significant reductions from 10 to 24%, while in the 1 gram cinnamon
group, non-significant reductions occurred after 40 days; LDL levels
continued to decrease, reaching statistical significance at 60 days. With
respect to HDL, significant increases were seen only in the 3 gram cinnamon
group after 20 days; non-significant changes occurred in the 1 and 6 gram
groups after 40 days.
The overall results of this
trial demonstrate that cinnamon exerts a beneficial effect on blood glucose
and lipid levels in people with type 2 diabetes, at daily intakes of 1 gram,
and that this low dose is equally efficacious as are the higher doses of 3
and 6 grams.10
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