Cinnamon Journal Diabetic Asociation

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    Cinnamon Improves Glucose and Lipidsof People With Type 2 DiabetesALAM KHAN, MS, PHD

    1,2,3

    MAHPARA SAFDAR, MS1,2

    MOHAMMAD MUZAFFAR ALI KHAN, MS, PHD1,2

    KHAN NAWAZ KHATTAK, MS1,2

    RICHARD A. ANDERSON, PHD3

    OBJECTIVE The objective of this study was to determine whether cinnamon improvesblood glucose, triglyceride, total cholesterol, HDL cholesterol, and LDL cholesterol levels inpeople with type 2 diabetes.

    RESEARCH DESIGN AND METHODS A total of 60 people with type 2 diabetes, 30men and 30 women aged 52.2 6.32 years, were divided randomly into six groups. Groups 1,2, and 3 consumed 1,3, or6 g of cinnamon daily, respectively, and groups 4,5, and 6 were givenplacebo 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 serumglucose (1829%), triglyceride (2330%), LDL cholesterol (727%), and total cholesterol (1226%) levels; no significant changes were noted in the placebo groups. Changes in HDL choles-terol were not significant.

    CONCLUSIONS The results of this study demonstrate that intake of 1, 3, or 6 g ofcinnamon per day reduces serum glucose, triglyceride, LDL cholesterol, and total cholesterol inpeople with type 2 diabetes and suggest that the inclusion of cinnamon in the diet of people withtype 2 diabetes will reduce risk factors associated with diabetes and cardiovascular diseases.

    Diabetes Care 26:32153218, 2003

    The incidence of cardiovascular dis-eases is increased two- to fourfold inpeople with type 2 diabetes (1). Al-

    though the causes of type 2 diabetes andcardiovascular diseases are multifactorial,diet definitely plays a role in the incidenceand severity of these diseases. The dietarycomponents beneficial in the preventionand treatment of these diseases have notbeen clearly defined, but it is postulatedthat spices may play a role. Spices such ascinnamon, cloves, bay leaves, and tur-meric display insulin-enhancing activity

    in vitro (2,3). Botanical products can im-prove glucose metabolism and the overallcondition of individuals with diabetes not

    only by hypoglycemic effects but also byimproving lipid metabolism, antioxidantstatus, and capillary function (4). A num-ber of medicinal/culinary herbs have beenreported to yield hypoglycemic effects inpatients with diabetes. Examples of theseinclude bitter melon, Gymnema, Koreanginseng, onions, garlic, flaxseed meal, andspecific nutrients including -lipoic acid,biotin, carnitine, vanadium, chromium,magnesium, zinc, and vitamins B

    3, E, and

    K (5).Rashwan (6) reported that supple-

    mentation of the diet of rabbits withfenugreek decreased total serum lipidlevel. In rats, curry leaf and mustard seeds

    decreased total serum cholesterol, LDL

    cholesterol, and VLDL cholesterol and in-creased HDL cholesterol levels (7) and re-duced cholesterol, triglycerides, andphospholipids in aorta, liver, and heart(8). The LDL and VLDL fractions werealso decreased and the HDL fraction wasincreased. Coriander seeds fed to rats con-suming a high-fat diet led to decreasedLDL, VLDL, and total cholesterol and in-creased HDL cholesterol (9). Zhang et al.(10) reported that turmeric may also havea role in reducing the risk of atherosclerosis.

    Aqueous ext racts from cinnamon

    have been shown to increase in vitro glu-cose uptakeand glycogen synthesis and toincrease phosphorylation of the insulinreceptor; in addition, these cinnamon ex-tracts are likely to aid in triggering theinsulin cascade system (11,12). Becauseinsulin also plays a key role in lipid me-tabolism, we postulated that consump-tion of cinnamon would lead to improvedglucose and blood lipids in vivo. There-fore, this study was designed to determinewhether there is a dose response of cinna-mon on clinical variables associated withdiabetes and cardiovascular diseases in

    people with type 2 diabetes.

    RESEARCH DESIGN AND

    METHODS This study was con-ducted in the Department of Human Nu-trition, NWFP Agricultural University,Peshawar, Pakistan and was approved bytheEthics Committeeand Human StudiesReview Board of the University of Pesha-war. Selection criteria for the study in-cluded the following for people with type2 diabetes: age 40 years, not on insulintherapy, not taking medicine for other

    health conditions, and fasting blood glu-cose levels between 7.8 and 22.2 mmol/l(140400 mg/dl). A total of 60 individu-als with type 2 diabetes, 30 men and 30women, were selected for the study. Themean age of the subjects was 52.0 6.87years in the placebo groups and 52.0 5.85 years in the groups consuming cin-namon. The duration of diabetes was alsosimilar: 6.73 2.32 years for the placebogroup and 7.10 3.29 years for the cin-namon groups. There was also an equalnumber of men and women in the pla-

    From the 1Department of Human Nutrition, NWFP Agricultural University, Peshawar, Pakistan; the 2PostGraduate Medical Institute, Hayatabad Medical Complex, Peshawar, Pakistan; and the 3Nutrients Require-ments and Functions Laboratory, Beltsville Human Nutrition Research Center, Beltsville, Maryland.

    Address correspondence and reprint requests to Dr. Richard A. Anderson, Nutrient Requirements andFunctions Laboratory, Beltsville Human Nutrition Research Center, Bldg. 307, Rm. 224, Beltsville, MD20705. E-mail: [email protected].

    Received for publication 30 June 2003 and accepted in revised form 22 August 2003.A table elsewhere in this issue shows conventional and Systeme International (SI) units and conversion

    factors for many substances. 2003 by the American Diabetes Association.

    C l i n i c a l C a r e / E d u c a t i o n / N u t r i t i o n

    O R I G I N A L A R T I C L E

    DIABETES CARE, VOLUME 26, NUMBER 12, DECEMBER 2003 3215

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    cebo and cinnamon groups. All subjectswere taking sulfonylurea drugs, i.e., glib-

    enclamide; medications did not changeduring the study.Cinnamon (Cinnamomum cassia) cer-

    tified by the Office of the Director, Re-search and Development/Non-TimberForest Products, NWFP Forest Depart-ment, Peshawar, Pakistan, was used inthis study. Cinnamon and wheat flourwere ground finely and put into capsules(Mehran Traders Pharmaceutical Suppli-ers, Peshawar, Pakistan). Each capsulecontained either 500 mg of cinnamon orwheat flour. Both the cinnamon and pla-cebo capsules were packaged in plasticbags containing 40 capsules (1 g or twocapsules per day for 20 days), 120 cap-sules (3 g or six capsules per day for 20days), or 240 capsules (6 g or 12 capsulesper day for 20 days) and prepared for dis-tribution to the subjects. When subjectsfinished testing after the first 20days, theywere given the second package of cap-sules. Compliance was monitored by cap-sule count and contact with the subjects.Compliance was considered excellent andall capsules were consumed.

    The study was conducted for 60 days

    with 60 individuals with type 2 diabetesdivided randomly into six equal groups.Group 1 consumed two 500-mg capsulesof cinnamon per day, group 2 consumedsix capsules of cinnamon per day, andgroup 3 consumed 12 capsules of cinna-mon per day. Groups 4, 5, and 6 wereassigned to respective placebo groups,which consumed a corresponding num-ber of capsules containing wheat flour.Subjects consumed their normal diets andcontinued their medications throughoutthe study. From days 41 to 60, no cinna-

    mon or placebo was given. The 1-g doseof cinnamon and placebo was spread over

    the day as 0.5 g (one capsule) after lunchand 0.5 g after dinner. The 3-g and 6-gdoses of cinnamon and placebo werespread over the day as 1 g (two capsules)and 2 g (four capsules) after breakfast,lunch, and dinner, respectively. The sub-

    jects were instructed to take the capsulesimmediately after meals.

    On days 0, 20, 40, and 60,5 ml offasting blood was collected from eachsubject. Blood samples were transferredto sterilized centrifuge tubes and allowedto clot at room temperature. The bloodsamples were centrifuged for 10 min in atabletop clinical centrifuge at 4,000 rpmfor serum separation. Serum sampleswere stored in a freezer at 0C for lateranalyses.

    Glucose level was determined usingan autoanalyzer (Express Plus; CibaCorning Diagnostics, Palo Alto, CA). Tri-glyceride levels were determined by the

    enzymatic colorimetric method ofWerner et al. (13) using an autoanalyzer(Express Plus; Ciba Corning) and anElitech kit (Meditek Instrument, Pesha-war, Pakistan). Cholesterol levels weredetermined by enzymatic colorimetricmethod of Allain et al. (14) using the sameautoanalyzer. Chylomicrons, VLDL, andLDL were precipitated by adding phos-photungstic acid and magnesium ions tothe sample. Centrifugation left only theHDL in the supernatant (15). LDL choles-terol was calculated by dividing the trig-lycerides by 5 and subtracting the HDLcholesterol (16).

    Two-way ANOVA and randomizedcomplete block design were used for sta-tistical analysis (17). Values are means SD.

    RESULTS The addition of 1, 3, or6 g of cinnamon to the diet led to signifi-cant decreases in serum glucose levels af-ter 40 days. Values after 20 days weresignificantly lower only in the group re-ceiving 6 g of cinnamon (Table 1). At thelevels tested, there was no evidence of adose response because the response to allthree levels of cinnamon was similar. De-creases ranged from 18 to 29%. After thesubjects no longer consumed the cinna-mon for 20 days, glucose levels were sig-ni fic a nt ly lowe r only in t he groupconsuming the lowest level of cinnamon.Glucose values in the three placebogroups were not significantly different atany of the time points.

    The consumption of cinnamon alsoled to a time-dependent decrease in se-rum triglyceride levels at all amounts ofcinnamon tested after 40 days (Table 2).

    Values after 20 days were significantly

    Table 1Effects of cinnamon on glucose levels in people with type 2 diabetes

    Group*

    Doses of

    cinnamon

    (g/day)

    Fasting serum glucose level (mmol/l)

    Beforecinnamon

    intake During cinnamon intake

    Aftercinnamon

    intake

    Day 0 Day 20 Day 40 Day 60

    1 1 11.6 1.7a 10.5 1.8ab 8.7 1.6c 9.7 1.4bc

    2 3 11.4 1.2a 9.9 1.1ab 9.4 1.1b 9.9 1.6ab

    3 6 13.0 1.4a 10.2 1.3bc 9.2 1.5c 11.4 1.8ab

    4 Placebo 1 12.2 1.0a 12.7 0.8a 12.4 1.1a 12.6 1.0a

    5 Placebo 2 12.4 1.0a 11.8 0.9a 12.7 1.0a 12.6 1.3a

    6 Placebo 3 16.7 1.4a 16.7 1.6a 16.8 1.7a 17.0 1.3a

    Data are means SD.*Ten individuals in each group; means followed by differentsuperscriptletters in thesame row are significantly different at P 0.05.

    Table 2Effects of cinnamon on triglyceride levels in people with type 2 diabetes

    Group*

    Doses of

    cinnamon(g/day)

    Fasting serum triglyceride level (mmol/l)

    Beforecinnamon

    intake During cinnamon intake

    Aftercinnamon

    intake

    Day 0 Day 20 Day 40 Day 60

    1 1 2.25 0.35a 1.92 0.18ab 1.57 0.21b 1.67 0.21b

    2 3 2.75 0.30a 2.74 0.49a 2.01 0.36b 2.16 0.52b

    3 6 2.48 0.39a 1.81 0.28b 1.91 0.30b 2.07 0.32ab

    4 Placebo 1 2.31 0.32a 2.38 0.34a 2.50 0.30a 2.45 0.32a

    5 Placebo 2 2.38 0.29a 2.42 0.31a 2.39 0.28a 2.21 0.29a

    6 Placebo 3 2.55 0.34a 2.66 0.38a 2.52 0.40a 2.65 0.35a

    Data aremeans SD.*Ten individuals in each group; means followed by differentsuperscriptletters in thesame row are significantly different at P 0.05.

    Cinnamon decreases glucose and lipids

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    lower only in the group consuming 6 g ofcinnamon per day. Decreases after 40

    days of cinnamon consumption rangedfrom 23 to 30%. These data indicate thatconsumption of cinnamon for 20 dayswas more beneficial than shorter use forreduction of triglyceride levels in peoplewith type 2 diabetes. The mean fastingserum triglyceride levels of the subjectswho consumed1 g or 3 g of cinnamon perday for 40days followedby 20days of notconsuming cinnamon were still signifi-cantly lower than the mean fasting serumtriglyceride levels of the same groups atthe beginning of the study. Decreases inthe 6-g group were no longer significant.There were no changes in triglyceride lev-els in any of the three placebo groups(Table 2).

    There were also significant decreasesin serum cholesterol levels in all threegroups consuming cinnamon, and nochanges were noted in the respective pla-cebo groups (Table 3). Decreases weresignificant after 20 days, and values weresimilar after 40 days, except in the groupconsuming 3 g per day, which continuedto decrease. These decreases in serumcholesterol level ranging from 13 to 26%

    were maintained even after not consum-ing additional cinnamon for 20 days (Ta-ble 3, last column).

    Decreases in LDL were significant inthe 3- and 6-g groups after 40 days withdecreases of 10 and 24% (Table 4). De-creases in the 1-g group were not signifi-cant after 40 days but continued todecline during the washout period andwere significant after 60 days (Table 4,last column).

    There were nonsignificant changes inHDL in the subjects consuming 1 or 6 g of

    cinnamon for 40 days. Decreases in the3-g group were significant after 20 days.

    These values remained relatively un-changed after the 20-day washout period.

    CONCLUSIONS This study dem-onstrates effects of low levels (1 6 g perday) of cinnamon on the reduction of glu-cose, triglyceride, LDL cholesterol, andtotal cholesterol levels in subjects withtype 2 diabetes. The study design servesto replicate the results because there weresimilar effects at the three doses tested. Itis not clear whether even less than 1 g ofcinnamon per day would also be benefi-cial. The data are also reinforced by theobservation that there were no significantchanges in any of the placebo groups.There were also no problems with com-pliance or problems associated with theconsumption of6 g of cinnamon perday.

    The mechanism of the effects of cin-namon on glucose and blood lipids must

    be determined. Symptoms of insulin re-sistance include decreased stimulation ofmuscle glycogen synthesis as well as de-fects in glycogen synthase activity andglucose uptake (18). In addition, alteredenzymatic activities, such as an increasedphosphatase activity and/or seryl phos-phorylation of the insulin receptor sub-strate by glycogen synthase kinase-3(GSK-3), have also been shown to be in-volved in some cases of type 2 diabetes(19,20). Dephosphorylation of the recep-tor -subunit is associated with the deac-tivation of its kinase activity and,therefore, is associated with insulin signaldownregulation (21). Maximal phos-phorylation of the insulin receptor is as-s o c i a t e d w i t h i n c r e a s e d i n s u l i nsensitivity, which is associated with im-proved glucose and lipid levels. Extracts

    of cinnamon activated glycogen synthase,increased glucose uptake, and inhibitedglycogen synthase kinase-3 (11,12). Ex-tracts of cinnamon also activated insulinreceptor kinase and inhibited dephos-phorylation of the insulin receptor, lead-ing to maximal phosphorylation of theinsulin receptor (12). All of these effectswould lead to increased insulin sensitiv-ity. We have shown that extracts of cin-n am o n a ls o f u nc ti o n a s p o te ntantioxidants, which would lead to addi-tional health benefits of this substance(unpublished data). Dhuley (22) showedthat cinnamon displays antioxidant activ-ity in rats fed a high-fat diet.

    The maintenance of lower serum glu-cose and lipid levels, even when the indi-viduals were not consuming cinnamonfor 20 days, denotes sustained effects ofcinnamon, indicating that cinnamonwould not need to be consumed every

    Table 3Effects of cinnamon on cholesterol levels in people with type 2 diabetes

    Group*

    Doses of

    cinnamon

    (g/day)

    Fasting serum cholesterol level (mmol/l)

    Beforecinnamon

    intake During cinnamon intake

    Aftercinnamon

    intake

    Day 0 Day 20 Day 40 Day 60

    1 1 4.91 0.23a 4.32 0.21b 4.32 0.27b 4.09 0.30b

    2 3 5.51 0.29a 4.76 0.32b 4.09 0.26c 4.03 0.34c

    3 6 5.30 0.22a 4.63 0.21b 4.65 0.24b 4.86 0.19b

    4 Placebo 1 4.58 0.28b 4.67 0.35b 4.58 0.31b 4.78 0.31a

    5 Placebo 2 4.81 0.30a 4.71 0.30a 5.04 0.31a 4.94 0.35a

    6 Placebo 3 5.51 0.41c 5.69 0.44ab 5.66 0.43bc 5.84 0.42a

    Data are means SD.*Ten individuals in each group; means followed by differentsuperscriptletters in thesame row are significantly different at P 0.05.

    Table 4Effects of cinnamon on LDL levels in people with type 2 diabetes

    Group*

    Doses of

    cinnamon(g/day)

    Fasting serum LDL level (mmol/l)

    Beforecinnamon

    intake During cinnamon intake

    Aftercinnamon

    intake

    Day 0 Day 20 Day 40 Day 60

    1 1 2.66 0.12a 2.28 0.15b 2.48 0.10ab 2.35 0.13b

    2 3 2.77 0.18a 2.43 0.28ab 2.04 0.19bc 1.97 0.18c

    3 6 2.87 0.18a 2.56 0.13b 2.59 0.16b 2.72 0.11ab

    4 Placebo 1 2.30 0.22a 2.30 0.31a 2.20 0.22a 2.40 0.22a

    5 Placebo 2 2.56 0.25a 2.40 0.22a 2.66 0.27a 2.79 0.27a

    6 Placebo 3 3.03 0.31b 3.15 0.33ab 3.28 0.34a 3.36 0.37a

    Data aremeans SD.*Ten individuals in each group; means followed by differentsuperscriptletters in thesame row are significantly different at P 0.05.

    Khan and Associates

    DIABETES CARE, VOLUME 26, NUMBER 12, DECEMBER 2003 3217

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    day. The levels of cinnamon tested in thisstudy, 1 6 g per day, suggest that there isa wide range of cinnamon intake that maybe beneficial and that intake of1 g dailyis likely to be beneficial in controllingblood glucose and lipid levels.

    In conclusion, cinnamon reduced se-rum glucose, triglyceride, total choles-terol, and LDL cholesterol levels in peoplewith type 2 diabetes. Because cinnamonwould not contribute to caloric intake,those who have type 2 diabetes or thosewho have elevated glucose, triglyceride,LDL cholesterol, or total cholesterol levelsmay benefit from the regular inclusion ofcinnamon in their daily diet. In addition,cinnamon may be beneficial for the re-mainder of the population to prevent andcontrol elevated glucose and blood lipidlevels.

    Acknowledgments T h is p r oj e c t w a sfunded, in part, by the University GrantsCommission/NWFP Agricultural University,Peshawar, Pakistan.

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    Cinnamon decreases glucose and lipids

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