- Sep 29, 2012
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Would like to state that this is not my post! Taking this from another board, just sharing the wealth of information and B, the guy who I am taking the post from has helped me out alot.
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Introduction
Common cinnamon (Cinnamomum verum, C. zeylanicum) and cassia (C. aromaticum) have a long history of uses as spices, flavoring agents, preservatives, and pharmaco-logical agents. A review of the safety and efficacy of cinnamon on antioxidant activity, Heliobacter pylori infection, activation of olfactory cortex and brain, oral candidiasis in human immunodeficiency virus, and chronic salmonellosis has been published.1 In addition, several studies have examined the effects of cinnamon on glucose, insulin, and lipid metabolism associated with metabolic syndrome, which are the focus of this review. This review is an update of previous reviews.2,3
In 1990, we reported that compounds found in cinnamon have insulin-potentiating properties and may be involved in the alleviation of the signs and symptoms of diabetes and cardiovascular diseases related to insulin resistance and metabolic syndrome.4 Furthermore, when compared to herbs, spices, and medicinal extracts for insulin-like or insulin-potentiating activity in an in vitro model,5 aqueous cinnamon extracts (CE) potentiated insulin activity more than 20-fold, higher than any other compound tested at comparable dilutions. The effects of adding more of the aqueous extract of cinnamon appear similar to adding more insulin. This is important from a human health standpoint because it results in increased insulin sensitivity and less insulin is required to have larger insulin effects. People with metabolic syndrome have adequate amounts of insulin but the insulin is not efficient. Components of cinnamon make insulin more efficient.
Anderson and colleagues6 demonstrated that the in vitro insulin-potentiating activity found in cinnamon is present in the aqueous fraction. The aqueous extract of “spent cinnamon” (product that is left when cinnamon oil is removed) in which many of the organic components found in cinnamon, including cinnamaldehyde, are largely removed has basically the same in vitro insulin-potentiating activity as extracts from the cinnamon before the cinnamon oil is removed. In addition, cinnamon oil and its major components, including cinnamaldehyde, cinnamic acid, eugenol, and coumarin, have no in vitro insulin-enhancing activity in epididymal fat cells.6 The structure of a class of water-soluble cinnamon polyphenol compounds that display insulin-potentiating, antioxidant, and related activities is shown in Figure 1. These are type A polyphenols. Several of these have been isolated from cinnamon, and the most abundant ones are trimers with a molecular weight (MW) of 864 and a tetramer with a molecular weight of 1152 daltons.6 The two major trimers can be converted to two other trimers with the same molecular weight (unpublished observation). The activities of a purified trimer7–10 and tetramer10 have been documented.
Figure 1.
Structure of a class of water-soluble cinnamon polyphenol compounds that display insulin-potentiating and antioxidant activities. One tetramer and four type A trimers have been isolated from cinnamon and all were shown to have in vitro insulin-potentiating (more ...)
Cinnamon Increases Insulin Sensitivity and Glucose Transport
Insulin resistance is a core defect in obesity, type 2 diabetes mellitus (T2DM), and metabolic syndrome. Cinnamon extract-treated rats have significantly higher glucose infusion rates compared with controls.11 The insulin- stimulated insulin receptor (IR) β and IR substrate-1 (IRS1) tyrosine phosphorylation levels and IRS1/phospho-inositide 3-kinase (PI3K) in skeletal muscle of chow diet-fed rats are enhanced by CE. It was also demonstrated12 that CE improves glucose utilization in normal male rats fed a high fructose diet (HFD). The decreased glucose infusion rate in HFD-fed rats (60% of normal controls) was improved by CE to the level of controls, and the improving effects of CE on the glucose infusion rates of HFD-fed rats were blocked by N-monomethyl-L-arginine (an inhibitor of nitric oxide, NO). The decreased muscular insulin-stimulated IRβ and IRS1 tyrosine phosphorylation levels and IRS1 associated with PI3K in HFD-fed rats are also improved significantly by CE. These data suggest that CE prevents the development of insulin resistance, at least in part by enhancing insulin signaling and possibly via the NO pathway in skeletal muscle. An aqueous extract of cinnamon has also been shown to improve insulin sensitivity in humans.13
The glucose transporter, GLUT4, facilitates the transport of glucose across plasma membranes into skeletal muscle and adipocytes. Previous studies reported that CE increases glucose uptake and GLUT4 expression in 3T3-L1 adipose cells. It has been observed14 that a water extract of cinnamon (Cinnulin PF®) reduced blood glucose, plasma insulin, and soluble cluster of differentiation 36 (CD36), which is reported as a novel marker of insulin resistance.15 Cinnamon extracts also inhibited retinol-binding protein 4 (RBP4), a novel adipokine that contributes to insulin resistance in plasma and adipose tissues.16 Retinol-binding protein 4 is increased in the serum of insulin-resistant humans and rodents and mediates insulin resistance in muscle and increases glucose production in liver.17,18 Plasma RBP4 levels are inversely correlated with the expression of GLUT4 in adipose tissue.17,18 Cinnamon extract consumption also appears to regulate glucose uptake-related genes, such as Glut1, Glut4, glycogen synthesis 1, and glycogen synthase kinase 3β mRNA expression in adipose tissue.14
---------------------------------------------------------------------
Introduction
Common cinnamon (Cinnamomum verum, C. zeylanicum) and cassia (C. aromaticum) have a long history of uses as spices, flavoring agents, preservatives, and pharmaco-logical agents. A review of the safety and efficacy of cinnamon on antioxidant activity, Heliobacter pylori infection, activation of olfactory cortex and brain, oral candidiasis in human immunodeficiency virus, and chronic salmonellosis has been published.1 In addition, several studies have examined the effects of cinnamon on glucose, insulin, and lipid metabolism associated with metabolic syndrome, which are the focus of this review. This review is an update of previous reviews.2,3
In 1990, we reported that compounds found in cinnamon have insulin-potentiating properties and may be involved in the alleviation of the signs and symptoms of diabetes and cardiovascular diseases related to insulin resistance and metabolic syndrome.4 Furthermore, when compared to herbs, spices, and medicinal extracts for insulin-like or insulin-potentiating activity in an in vitro model,5 aqueous cinnamon extracts (CE) potentiated insulin activity more than 20-fold, higher than any other compound tested at comparable dilutions. The effects of adding more of the aqueous extract of cinnamon appear similar to adding more insulin. This is important from a human health standpoint because it results in increased insulin sensitivity and less insulin is required to have larger insulin effects. People with metabolic syndrome have adequate amounts of insulin but the insulin is not efficient. Components of cinnamon make insulin more efficient.
Anderson and colleagues6 demonstrated that the in vitro insulin-potentiating activity found in cinnamon is present in the aqueous fraction. The aqueous extract of “spent cinnamon” (product that is left when cinnamon oil is removed) in which many of the organic components found in cinnamon, including cinnamaldehyde, are largely removed has basically the same in vitro insulin-potentiating activity as extracts from the cinnamon before the cinnamon oil is removed. In addition, cinnamon oil and its major components, including cinnamaldehyde, cinnamic acid, eugenol, and coumarin, have no in vitro insulin-enhancing activity in epididymal fat cells.6 The structure of a class of water-soluble cinnamon polyphenol compounds that display insulin-potentiating, antioxidant, and related activities is shown in Figure 1. These are type A polyphenols. Several of these have been isolated from cinnamon, and the most abundant ones are trimers with a molecular weight (MW) of 864 and a tetramer with a molecular weight of 1152 daltons.6 The two major trimers can be converted to two other trimers with the same molecular weight (unpublished observation). The activities of a purified trimer7–10 and tetramer10 have been documented.
Figure 1.
Structure of a class of water-soluble cinnamon polyphenol compounds that display insulin-potentiating and antioxidant activities. One tetramer and four type A trimers have been isolated from cinnamon and all were shown to have in vitro insulin-potentiating (more ...)
Cinnamon Increases Insulin Sensitivity and Glucose Transport
Insulin resistance is a core defect in obesity, type 2 diabetes mellitus (T2DM), and metabolic syndrome. Cinnamon extract-treated rats have significantly higher glucose infusion rates compared with controls.11 The insulin- stimulated insulin receptor (IR) β and IR substrate-1 (IRS1) tyrosine phosphorylation levels and IRS1/phospho-inositide 3-kinase (PI3K) in skeletal muscle of chow diet-fed rats are enhanced by CE. It was also demonstrated12 that CE improves glucose utilization in normal male rats fed a high fructose diet (HFD). The decreased glucose infusion rate in HFD-fed rats (60% of normal controls) was improved by CE to the level of controls, and the improving effects of CE on the glucose infusion rates of HFD-fed rats were blocked by N-monomethyl-L-arginine (an inhibitor of nitric oxide, NO). The decreased muscular insulin-stimulated IRβ and IRS1 tyrosine phosphorylation levels and IRS1 associated with PI3K in HFD-fed rats are also improved significantly by CE. These data suggest that CE prevents the development of insulin resistance, at least in part by enhancing insulin signaling and possibly via the NO pathway in skeletal muscle. An aqueous extract of cinnamon has also been shown to improve insulin sensitivity in humans.13
The glucose transporter, GLUT4, facilitates the transport of glucose across plasma membranes into skeletal muscle and adipocytes. Previous studies reported that CE increases glucose uptake and GLUT4 expression in 3T3-L1 adipose cells. It has been observed14 that a water extract of cinnamon (Cinnulin PF®) reduced blood glucose, plasma insulin, and soluble cluster of differentiation 36 (CD36), which is reported as a novel marker of insulin resistance.15 Cinnamon extracts also inhibited retinol-binding protein 4 (RBP4), a novel adipokine that contributes to insulin resistance in plasma and adipose tissues.16 Retinol-binding protein 4 is increased in the serum of insulin-resistant humans and rodents and mediates insulin resistance in muscle and increases glucose production in liver.17,18 Plasma RBP4 levels are inversely correlated with the expression of GLUT4 in adipose tissue.17,18 Cinnamon extract consumption also appears to regulate glucose uptake-related genes, such as Glut1, Glut4, glycogen synthesis 1, and glycogen synthase kinase 3β mRNA expression in adipose tissue.14