Cinnamon
Study on Type 2 Diabetes, Blood Glucose and Cholesterol
ABSTRACT
Objective – The
objective of this study was to determine whether cinnamon improves
blood glucose, triglyceride, total cholesterol, HDL cholesterol,
and LDL cholesterol levels in people with type 2 diabetes.
Research Design & Methods –
A total of 60 people with type 2 diabetes, 30 men and 30 women aged
52.2 ± 6.32 years, were divided randomly into six groups.
Groups 1, 2, and 3 consumed 1, 3, or 6 g of cinnamon daily, respectively,
and groups 4, 5, and 6 were given placebo capsules corresponding
to the number of capsules consumed for the three levels of cinnamon.
The cinnamon was consumed for 40 days followed by a 20-day washout
period.
Results – After 40 days,
all three levels of cinnamon reduced the mean fasting serum glucose
(18–29%), triglyceride (23–30%), LDL cholesterol (7–27%),
and total cholesterol (12–26%) levels; no significant changes
were noted in the placebo groups. Changes in HDL cholesterol were
not significant.
Conclusions – The results of
this study demonstrate that intake of 1, 3, or 6 g of cinnamon per
day reduces serum glucose, triglyceride, LDL cholesterol, and total
cholesterol in people with type 2 diabetes and suggest that the
inclusion of cinnamon in the diet of people with type 2 diabetes
will reduce risk factors associated with diabetes and cardiovascular
diseases.
INTRODUCTION
The incidence of cardiovascular diseases is increased two- to fourfold
in people with type 2 diabetes (http://care.diabetesjournals.org/cgi/content/full/26/12/3215#R1#R1
1). Although the causes of type 2 diabetes and cardiovascular diseases
are multifactorial, diet definitely plays a role in the incidence
and severity of these diseases. The dietary components beneficial
in the prevention and treatment of these diseases have not been
clearly defined, but it is postulated that spices may play a role.
Spices such as cinnamon, cloves, bay leaves, and turmeric display
insulin-enhancing activity in vitro (http://care.diabetesjournals.org/cgi/content/full/26/12/3215#R2#R2
2, http://care.diabetesjournals.org/cgi/content/full/26/12/3215#R3#R3
3). Botanical products can improve glucose metabolism and the overall
condition of individuals with diabetes not only by hypoglycemic
effects but also by improving lipid metabolism, antioxidant status,
and capillary function ( http://care.diabetesjournals.org/cgi/content/full/26/12/3215#R4#R4
4). A number of medicinal/culinary herbs have been reported to yield
hypoglycemic effects in patients with diabetes.
Examples of these
include bitter melon, Gymnema, Korean ginseng, onions, garlic, flaxseed
meal, and specific nutrients including -lipoic acid, biotin, carnitine,
vanadium, chromium, magnesium, zinc, and vitamins B3, E, and K (http://care.diabetesjournals.org/cgi/content/full/26/12/3215#R5#R5
5). Rashwan (http://care.diabetesjournals.org/cgi/content/full/26/12/3215#R6#R6
6) reported that supplementation of the diet of rabbits with fenugreek
decreased total serum lipid level. In rats, curry leaf and mustard
seeds decreased total serum cholesterol, LDL cholesterol, and VLDL
cholesterol and increased HDL cholesterol levels (http://care.diabetesjournals.org/cgi/content/full/26/12/3215#R7#R7
7) and reduced cholesterol, triglycerides, and phospholipids in
aorta, liver, and heart (http://care.diabetesjournals.org/cgi/content/full/26/12/3215#R8#R8
8). The LDL and VLDL fractions were also decreased and the HDL fraction
was increased. Coriander seeds fed to rats consuming a high-fat
diet led to decreased LDL, VLDL, and total cholesterol and increased
HDL cholesterol (http://care.diabetesjournals.org/cgi/content/full/26/12/3215#R9#R9
9). Zhang et al. (http://care.diabetesjournals.org/cgi/content/full/26/12/3215#R10#R10
10) reported that turmeric may also have a role in reducing the
risk of atherosclerosis.
Aqueous extracts from cinnamon have been shown to increase in vitro
glucose uptake and glycogen synthesis and to increase phosphorylation
of the insulin receptor; in addition, these cinnamon extracts are
likely to aid in triggering the insulin cascade system (http://care.diabetesjournals.org/cgi/content/full/26/12/3215#R11#R11
11, http://care.diabetesjournals.org/cgi/content/full/26/12/3215#R12#R12
12). Because insulin also plays a key role in lipid metabolism,
we postulated that consumption of cinnamon would lead to improved
glucose and blood lipids in vivo. Therefore, this study was designed
to determine whether there is a dose response of cinnamon on clinical
variables associated with diabetes and cardiovascular diseases in
people with type 2 diabetes.
RESEARCH DESIGN AND METHODS
This study was conducted in the Department of Human Nutrition, NWFP
Agricultural University, Peshawar, Pakistan and was approved by
the Ethics Committee and Human Studies Review Board of the University
of Peshawar. Selection criteria for the study included the following
for people with type 2 diabetes: age >40 years, not on insulin
therapy, not taking medicine for other health conditions, and fasting
blood glucose levels between 7.8 and 22.2 mmol/l (140–400
mg/dl). A total of 60 individuals with type 2 diabetes, 30 men and
30 women, were selected for the study. The mean age of the subjects
was 52.0 ± 6.87 years in the placebo groups and 52.0 ±
5.85 years in the groups consuming cinnamon. The duration of diabetes
was also similar: 6.73 ± 2.32 years for the placebo group
and 7.10 ± 3.29 years for the cinnamon groups. There was
also an equal number of men and women in the placebo and cinnamon
groups. All subjects were taking sulfonylurea drugs, i.e., glibenclamide;
medications did not change during the study.
Cinnamon (Cinnamomum cassia) certified by the Office of the Director,
Research and Development/Non-Timber Forest Products, NWFP Forest
Department, Peshawar, Pakistan, was used in this study. Cinnamon
and wheat flour were ground finely and put into capsules (Mehran
Traders Pharmaceutical Suppliers, Peshawar, Pakistan). Each capsule
contained either 500 mg of cinnamon or wheat flour. Both the cinnamon
and placebo capsules were packaged in plastic bags containing 40
capsules (1 g or two capsules per day for 20 days), 120 capsules
(3 g or six capsules per day for 20 days), or 240 capsules (6 g
or 12 capsules per day for 20 days) and prepared for distribution
to the subjects. When subjects finished testing after the first
20 days, they were given the second package of capsules. Compliance
was monitored by capsule count and contact with the subjects. Compliance
was considered excellent and all capsules were consumed.
The study was conducted for 60 days with 60 individuals with type
2 diabetes divided randomly into six equal groups. Group 1 consumed
two 500-mg capsules of cinnamon per day, group 2 consumed six capsules
of cinnamon per day, and group 3 consumed 12 capsules of cinnamon
per day. Groups 4, 5, and 6 were assigned to respective placebo
groups, which consumed a corresponding number of capsules containing
wheat flour. Subjects consumed their normal diets and continued
their medications throughout the study. From days 41 to 60, no cinnamon
or placebo was given. The 1-g dose of cinnamon and placebo was spread
over the day as 0.5 g (one capsule) after lunch and 0.5 g after
dinner. The 3-g and 6-g doses of cinnamon and placebo were spread
over the day as 1 g (two capsules) and 2 g (four capsules) after
breakfast, lunch, and dinner, respectively. The subjects were instructed
to take the capsules immediately after meals.
On days 0, 20, 40, and 60, 5 ml of fasting blood was collected from
each subject. Blood samples were transferred to sterilized centrifuge
tubes and allowed to clot at room temperature. The blood samples
were centrifuged for 10 min in a tabletop clinical centrifuge at
4,000 rpm for serum separation. Serum samples were stored in a freezer
at 0°C for later analyses. Glucose level was determined using
an autoanalyzer (Express Plus; Ciba Corning Diagnostics, Palo Alto,
CA). Triglyceride levels were determined by the enzymatic colorimetric
method of Werner et al. (http://care.diabetesjournals.org/cgi/content/full/26/12/3215#R13#R13
13) using an autoanalyzer (Express Plus; Ciba Corning) and an Elitech
kit (Meditek Instrument, Peshawar, Pakistan). Cholesterol levels
were determined by enzymatic colorimetric method of Allain et al.
(http://care.diabetesjournals.org/cgi/content/full/26/12/3215#R14#R14
14) using the same autoanalyzer. Chylomicrons, VLDL, and LDL were
precipitated by adding phosphotungstic acid and magnesium ions to
the sample. Centrifugation left only the HDL in the supernatant
(http://care.diabetesjournals.org/cgi/content/full/26/12/3215#R15#R15
15). LDL cholesterol was calculated by dividing the triglycerides
by 5 and subtracting the HDL cholesterol (http://care.diabetesjournals.org/cgi/content/full/26/12/3215#R16#R16
16).
Two-way ANOVA and randomized complete block design were used for
statistical analysis (http://care.diabetesjournals.org/cgi/content/full/26/12/3215#R17#R17
17). Values are means ± SD.
RESULTS
The addition of 1, 3, or 6 g of cinnamon to the diet led to significant
decreases in serum glucose levels after 40 days. Values after 20
days were significantly lower only in the group receiving 6 g of
cinnamon (http://care.diabetesjournals.org/cgi/content/full/26/12/3215#T1#T1
Table 1). At the levels tested, there was no evidence of a dose
response because the response to all three levels of cinnamon was
similar. Decreases ranged from 18 to 29%. After the subjects no
longer consumed the cinnamon for 20 days, glucose levels were significantly
lower only in the group consuming the lowest level of cinnamon.
Glucose values in the three placebo groups were not significantly
different at any of the time points.
Alam Khan, MS, PHD1,2,3, Mahpara Safdar, MS1,2,
Mohammad Muzaffar Ali Khan, MS, PHD1,2, Khan Nawaz Khattak, MS1,2
and Richard A. Anderson, PHD3
1 Department of Human Nutrition, NWFP Agricultural University, Peshawar,
Pakistan
2 Post Graduate Medical Institute, Hayatabad Medical Complex, Peshawar,
Pakistan
3 Nutrients Requirements and Functions Laboratory, Beltsville Human
Nutrition Research Center, Beltsville, Maryland
The Food and Drug
Administration has not evaluated these statements. This product is
not intended to diagnose, treat, cure or prevent any disease.
Copyright 2006 eFoodSafety.com