Diabetes

Nutritional Supplementation for Diabetics

Type 1 diabetics will need to be on insulin therapy for life, although the supplements mentioned in this section may help offset some of the complications caused by diabetes (e.g., reduced antioxidant capacity and glycation) as well enhance glucose metabolism. Type 2 diabetics can counteract the progression of their disease by improving insulin sensitivity, enhancing glucose metabolism, and attempting to mitigate the complications of diabetes. The following supplements have been shown to improve blood sugar control or limit diabetic damage:

Lipoic acid. As a powerful antioxidant, lipoic acid positively affects important aspects of diabetes, including blood sugar control and the development of long-term complications such as disease of the heart, kidneys, and small blood vessels (Jacob S et al 1995, 1999; Kawabata T et al 1994; Melhem MF et al 2002; Nagamatsu M et al 1995; Song KH et al 2005; Suzuki YJ et al 1992).

Lipoic acid plays a role in preventing diabetes by reducing fat accumulation. In animal studies, lipoic acid reduced body weight, protected pancreatic beta cells from destruction, and reduced triglyceride accumulation in skeletal muscle and pancreatic islets (Doggrell SA 2004; Song KH et al 2005).

Lipoic acid has been approved for the prevention and treatment of diabetic neuropathy in Germany for nearly 30 years. Intravenous and oral lipoic acid reduces symptoms of diabetic peripheral neuropathy (Ametov AS et al 2003). Animal studies have suggested that lipoic acid is more effective when taken with gamma-linolenic acid (GLA) (Cameron NE et al 1998; Hounsom L et al 1998).

Diabetes also damages deep nerves that control vital organs, such as the heart and digestive tract. In a large clinical trial, people with diabetes who had symptoms caused by nerve damage affecting the heart showed significant improvement without significant side effects from 800 mg oral lipoic acid daily (Ziegler D et al 1997a,b).

Biotin. Biotin enhances insulin sensitivity and increases the activity of glucokinase, the enzyme responsible for the first step in the utilization of glucose by the liver. Glucokinase concentrations in diabetics are very low. Animal studies have shown that a high biotin diet can improve glucose tolerance and enhance insulin secretion (Zhang H et al 1996; Furukawa Y 1999).

Carnitine. An extensive body of literature supports the use of carnitine in diabetes (Mingrone G 2004). Carnitine lowers blood glucose and HbA1c levels, increases insulin sensitivity and glucose storage, and optimizes fat and carbohydrate metabolism. Carnitine deficiency is common in type 2 diabetes. In a large human trial, acetyl-L-carnitine helped prevent or slow cardiac autonomic neuropathy in people with diabetes (Turpeinen AK et al 2005).

Carnosine. Carnosine is a glycation inhibitor that has been shown to exhibit protective effects against diabetic nephropathy and reduce the formation of AGEs (Janssen B et al 2005; Yan H et al 2005).

Chromium. Chromium is an essential trace mineral that plays a significant role in sugar metabolism. Chromium supplementation helps control blood sugar levels in type 2 diabetes and improves metabolism of carbohydrates, proteins, and lipids. Several studies have shown encouraging results from chromium supplementation:

• A controlled human study of type 2 diabetics compared two forms of chromium (brewer’s yeast and chromium chloride) (Bahijiri SM et al 2000). Both forms of chromium significantly improved blood sugar control. Positive results were also seen in two smaller human trials (Ghosh D et al 2002; Jovanovic L et al 1999).
• A large human trial compared the effects of 1000 mcg chromium, 200 mcg chromium, and placebo (Anderson RA et al 1997). HbA1c values improved significantly in the group receiving 1000 mcg after two months and in both chromium groups after four months. Fasting glucose was also lower in the group taking the higher dose of chromium.

Coenzyme Q10. Coenzyme Q10 (CoQ10) improves blood sugar control, lowers blood pressure, and prevents oxidative damage caused by disease. In a controlled human trial, type 2 diabetics given 100 mg CoQ10 twice daily experienced improved glycemic control as measured by lower HbA1c levels and blood pressure (Hodgson JM et al 2002). In a separate study, CoQ10 improved blood flow in type 2 diabetics, an outcome attributed to CoQ10’s ability to lower vascular oxidative stress (Watts GF et al 2002). In a third study, improved blood flow correlated with decreased HbA1c (Playford DA et al 2003).

In animal studies, CoQ10 quenched free radicals, improved blood flow, lowered triglyceride levels, and raised HDL levels, suggesting a role for CoQ10 in preventing and managing complications of diabetes (Al-Thakafy HS et al 2004). Animal studies have also shown that CoQ10 levels are depleted by diabetes (Kucharska J et al 2000).

Dehydroepiandrosterone. Recent studies have yielded very encouraging results supporting dehydroepiandrosterone (DHEA) supplementation in diabetics. DHEA has been shown to improve insulin sensitivity and obesity in human and animal models (Yamashita R et al 2005). Although its mechanism of action is poorly understood, it is thought that DHEA improves glucose metabolism in the liver (Yamashita R et al 2005).

Animal studies have also demonstrated that DHEA increases beta cells on the pancreas, which are responsible for producing insulin (Medina MC et al 2006).

In humans, DHEA levels are sensitive to elevated glucose: higher glucose levels tend to be associated with decreased DHEA levels (Boudou P et al 2006). One proposed mechanism of action in humans is linked to DHEA’s metabolism into testosterone. DHEA is an adrenal hormone that can be converted into either testosterone or estrogen. Studies have shown that testosterone improves insulin sensitivity in men, suggesting that DHEA’s conversion into testosterone may be responsible for its beneficial effects in improving insulin sensitivity (Kapoor D et al 2005).

Essential fatty acids. In human experiments, omega-3 fatty acids lowered blood pressure and triglyceride levels, thereby relieving many of the complications associated with diabetes. In animals, omega-3 fatty acids cause less weight gain than other fats do; they have also been shown to have a neutral effect on LDL, while raising HDL and lowering triglycerides (Petersen M et al 2002). There are two types of essential fatty acids:

• Omega-3. Marine oil contains omega-3 fatty acids. The research on omega-3 fatty acids stems from studies of the Inuit (Eskimo) people, who seldom suffer from heart attacks even though their diets contain an enormous amount of fat from fish, seals, and whales, presumably because those sources of fat are very high in omega-3 fatty acids. Omega-3 fatty acids found in marine oil, lower blood triglyceride levels, contribute to “thinning” the blood, and also decrease inflammation (Ebbesson SO et al 2005). These effects partially explain many of fish oil’s benefits.
• Omega-6. Diabetic neuropathy is a gradual degeneration of peripheral nerve tissue. There is some evidence that GLA, an omega-6 fatty acid, can be helpful if given long enough to work. In one double-blind, placebo-controlled study, 111 people with mild diabetic neuropathy received either 480 mg daily of GLA or placebo. After 12 months, the group taking GLA was doing significantly better than the placebo group in 13 out of 16 measures of nerve function, with patients whose diabetes was under control doing best (Keen H et al 1993). There is also evidence that GLA is more effective for diabetic neuropathy when it is combined with lipoic acid (Hounsom L et al 1998).

Fiber. It is difficult to overstate the benefits from fiber in regard to blood glucose control. Eating a diet rich in high-fiber foods prevents and reduces the harm caused by chronically elevated blood glucose.

One study reported the results of diabetic individuals consuming a diet supplying 25 g soluble fiber and 25 g insoluble fiber (about double the amount currently recommended by the American Diabetes Association). The fiber was derived from foodstuffs, with no emphasis placed on special or unusual fiber-fortified foods or fiber supplements. A high-fiber diet reduced blood glucose levels by an average of 10 percent (Chandalia et al 2000).

Fiber is also valuable because it produces a feeling of satiety, reducing the desire to overeat. Because high-fiber foods are digested more slowly than other foods, hunger pangs are forestalled. For the most part, fibrous foods are healthful (nutrient dense and low in fat).

Fiber should be added slowly, gradually replacing low-fiber foods, for the following reasons: (1) insulin and prescription drugs may have to be adjusted to accommodate lower blood glucose levels, and (2) without a gradual introduction of the new material, intestinal distress could occur, including bloating, flatulence, and cramps.

Some individuals prefer to bolster fiber volume by adding supplemental fiber in the form of pectin, gums, and mucilages to each meal. Calculate the amount of fiber gained from foodstuffs and supplement with enough to compensate for shortfalls. Monitor blood glucose levels closely to assess gains and to adjust oral or injectable hypoglycemic agents.

Flavonoids. Flavonoids are antioxidants that help reduce damage associated with diabetes. In animal studies, quercetin, a potent flavonoid, decreases levels of blood glucose and oxidants. Quercetin also normalizes levels of the antioxidants superoxide dismutase, vitamin C, and vitamin E. Quercetin is more effective at lower doses and ameliorates the diabetes-induced changes in oxidative stress (Mahesh T et al 2004).

Magnesium. People with diabetes are often deficient in magnesium, which is depleted both by medications and by the disease process (Eibl NL et al 1995; Elamin A et al 1990; Tosiello L 1996). One double-blind study suggested that magnesium supplementation enhanced blood sugar control (Rodriguez-Moran M et al 2003).

N-acetylcysteine. N-acetylcysteine (NAC) is a powerful antioxidant that is used to treat acetaminophen overdose. Among diabetic rats, it has also demonstrated the ability to protect the heart against endothelial damage and oxidative stress that is associated with heart attacks among diabetics. In one study, NAC was able to increase the availability of nitric oxide in diabetic rats, thus improving their blood pressure as well as reducing the level of oxidative stress in their hearts (Xia Z et al 2006). In a human study examining the effects of broad-based antioxidants, NAC, in addition to vitamin C and vitamin E, was able to reduce oxidative stress after a moderate-fat meal (Neri S et al 2005).

Silymarin. In animal studies, silymarin was shown to improve insulin levels among induced cases of diabetes (Soto C et al 2004). A small, controlled clinical study evaluated type 2 diabetics with alcohol-induced liver failure (Velussi M et al 1997). Those receiving 600 mg silymarin daily experienced a significant reduction in fasting blood and urine glucose levels. Fasting glucose levels rose slightly during the first month of supplementation but declined thereafter from an average of 190 mg/dL to 174 mg/dL. As daily glucose levels dropped (from an average of 202 mg/dL to 172 mg/dL), HbA1c also substantially decreased. Throughout the course of treatment, fasting insulin levels declined by almost one-half, and daily insulin requirements decreased by about 24 percent. Liver function improved. A lack of hypoglycemic episodes suggests silymarin not only lowered blood glucose levels but also stabilized them.

Vitamin B3. Vitamin B3 (niacin) is required for the proper function of more than 50 enzymes. Without it, the body is not able to release energy or make fats from carbohydrates. Vitamin B3 is also used to make sex hormones and other important chemical signal molecules.

In the past, the use of niacin was discouraged in diabetic individuals because it was found to increase insulin resistance and degrade glycemic control, particularly at high doses (Sancetta SM et al 1951). However, emerging clinical evidence shows that niacin is both safe and effective for diabetics (Meyers CD et al 2004).

There is evidence that niacin reduces the risk of developing type 1 diabetes (Pocoit F et al 1993; Pozzilli P et al 1993). Niacinamide helps restore beta cells, or at least slow their destruction. Because niacin can disrupt blood sugar control in diabetics, individuals taking any form of niacin, including inositol hexaniacinate, must closely monitor blood sugar levels and discontinue treatment in the event of worsening of diabetic control. Inositol hexaniacinate has long been used in Europe to lower cholesterol levels and also to improve blood flow in individuals with intermittent claudication.

Vitamin C. Several preclinical studies evaluated vitamin C’s role during mild oxidative stress. The aqueous humor of the eye provides surrounding tissues with a source of vitamin C. Since animal studies have shown that glucose inhibits vitamin C uptake, this protective mechanism may be impaired in diabetes (Corti A et al 2004). Supplementation with antioxidant vitamins C and E plays an important role in improving eye health (Peponis V et al 2004). High vitamin C intake depresses glycation, which has important implications for slowing diabetes progression and aging (Krone CA et al 2004).

Vitamin C, through its relationship to sorbitol, also helps prevent ocular complications in diabetes. Sorbitol, a sugar-like substance that tends to accumulate in the cells of people with diabetes, tends to reduce the antioxidant capacity of the eye, with a number of possible complications. Vitamin C appears to help reduce sorbitol buildup (Will JC et al 1996).

Vitamin C also has a role in reducing the risk of other diabetic complications. In one clinical study, vitamin C significantly increased blood flow and decreased inflammation in patients with both diabetes and coronary artery disease (Antoniades C et al 2004). Three studies suggest that vitamin C, along with a combination of vitamins and minerals (Farvid MS et al 2004), reduces blood pressure in people with diabetes (Mullan BA et al 2002) and increases blood vessel elasticity and blood flow (Mullan BA et al 2004).

Vitamin E. Vitamin E has been shown to significantly reduce the risk of developing type 2 diabetes (Montonen J et al 2004). One double-blind trial found a reduction in the risk of cardiac autonomic neuropathy, or damage to the nerves that supply the heart, which is a complication of diabetes (Manzella D et al 2001). Additional evidence documented benefits for diabetic peripheral neuropathy (Tutuncu NB et al 1998), blood sugar control (Kahler W et al 1993; Paolisso G et al 1993a,b, Paolisso G et al 1994), and cataract prevention (Paolisso G et al 1993a,b; Paolisso G et al 1994; Seddon JM et al 1994). In addition, vitamin E enhances sensitivity to insulin in type 2 diabetics (Paolisso G et al 1993a,b).

Botanical Supplements for Diabetes

Before insulin, botanical medicines were used to treat diabetes. They are remarkably safe and effective. However, because many botanical medicines function similarly to insulin, people taking oral diabetes medications or insulin should use caution to avoid hypoglycemia. Botanical medicines should be integrated into a regimen of adequate exercise, healthy eating, nutritional supplements, and medical support.

Cinnamon. Cinnamon has been used for several thousand years in traditional Ayurvedic and Greco-European medical systems. Native to tropical southern India and Sri Lanka, the bark of this evergreen tree is used to manage conditions such as nausea, bloating, flatulence, and anorexia. It is also one of the world’s most common spices, used to flavor everything from oatmeal and apple cider to cappuccino. Recent research has revealed that regular use of cinnamon can also promote healthy glucose metabolism.

A study at the US Department of Agriculture’s Beltsville Human Nutrition Research Center isolated insulin-enhancing complexes in cinnamon that are involved in preventing or alleviating glucose intolerance and diabetes (Anderson RA et al 2004). Three water-soluble polyphenol polymers were found to have beneficial biological activity, increasing insulin-dependent glucose metabolism by roughly 20-fold in vitro (Anderson RA 2004). The nutrients displayed significant antioxidant activity as well, as did other phytochemicals found in cinnamon, such as epicatechin, phenol, and tannin. Moreover, scientists at Iowa State University determined that these polyphenol polymers are able to upregulate the expression of genes involved in activating the cell membrane’s insulin receptors, thus increasing glucose uptake and lowering blood glucose levels (Imparl-Radosevich J et al 1998).

Coffee berry. Coffee berry contains some well-studied phytochemicals such as chlorogenic acid, caffeic acid, ferulic acid, and quinic acid (Charles-Bernard M et al 2005). Some of coffee berry’s most impressive effects can be seen in blood glucose management. Chlorogenic acid and caffeic acid are the two primary nutrients in coffee that benefit individuals with high blood sugar. Glucose-6-phosphatase is an enzyme crucial to the regulation of blood sugar. Since glucose generation from glycogen stored in the liver is often overactive in people with high blood sugar (Basu R et al 2005), reducing the activity of the glucose-6-phosphatase enzyme leads to reduced blood sugar levels, with consequent clinical improvements.

Chlorogenic acid has been shown to inhibit the glucose-6-phosphatase enzyme in a dose-dependent manner, resulting in reduced glucose production (Hemmerle H et al 1997). In a trial at the Moscow Modern Medical Center, 75 healthy volunteers were given either 90 mg chlorogenic acid daily or a placebo. Blood glucose levels of the chlorogenic acid group were 15 percent to 20 percent lower than those of the placebo group (Abidoff MT 1999). Chlorogenic acid also has an antagonistic effect on glucose transport, decreasing the intestinal absorption rate of glucose (Johnston KL et al 2003), which may help reduce blood insulin levels and minimize fat storage.

Caffeic acid has benefits for elevated blood sugar as well. At National Cheng Kung University in Taiwan, scientists determined that this acid increases glucose uptake into cells, helping remove it from the bloodstream (Cheng JT et al 2000). When researchers at nearby Taipei Medical College injected caffeic acid into diabetic rats, they saw a dose-dependent reduction in plasma glucose (Hsu FL et al 2000). However, a similar effect was not observed in normal rats, suggesting that insulin is not involved in this action. In a related experiment, the researchers observed that caffeic acid reduced elevated plasma glucose in insulin-resistant rats receiving a glucose challenge test (Hsu FL et al 2000).

Garlic. Allium is the active component in garlic and onions. Allium compounds are sulfur-donating compounds that help reconstitute glutathione, a major internal antioxidant. This mechanism is probably responsible for allium’s positive effects. Allium has a number of positive effects that may help reduce the risk of diabetic complications, including the following:

• Reducing the risk of cardiovascular disease, including atherosclerosis (Breithaupt-Grogler K et al 1997; Efendy JL et al 1997; Koscielny J et al 1999; Turner B et al 2004)
• Decreasing oxidative stress (Dhawan V et al 2004)
• Promoting weight loss and insulin sensitivity in animal models of diabetes (Elkayam A et al 2003)
• Lowering blood pressure (Auer W et al 1990; Sharifi AM et al 2003; Silagy CA et al 1994; Wilburn AJ et al 2004)
• Improving cholesterol profile (Durak I et al 2004; Gardner CD et al 2001; Holzgartner H et al 1992; Isaacsohn JL et al 1998; Kannar D et al 2001; Kris-Etherton PM et al 2002; Mader FH 1990; Neil HA et al 1996; Silagy CA et al 1994; Steiner M et al 1996; Superko HR et al 2000; Warshafsky S et al 1993)

Green tea. The compounds in these plants, including epicatechin, catechin, gallocatechin, and epigallocatechin, are powerful antioxidants, particularly against pancreas and liver toxins (Okuda T et al 1983). Animal studies have shown that epigallocatechins, in particular, may have a role in preventing diabetes (Crespy V et al 2004). In studies with rats, epigallocatechins prevented cytokine-induced beta cell destruction by downregulating inducible nitric oxide synthase, which is a pro-oxidant (Kim MJ et al 2004; Song EK et al 2003). This process could help slow the progression of type 1 diabetes. In vitro studies have also shown that green tea suppresses diet-induced obesity (Murase T et al 2002), a key risk factor in developing diabetes and metabolic syndrome (Hung PF et al 2005).

Ginkgo biloba. Animal studies demonstrate that ginkgo improves glucose metabolism in muscle fibers and prevents atrophy (Punkt K et al 1999). Animal studies also show that Ginkgo biloba extracts significantly inhibit postmeal sugar levels and act as antihyperglycemic agents (Tanaka S et al 2004).

Ginkgo biloba extract has been shown to prevent diabetic retinopathy in diabetic rats, suggesting it has a protective effect in human diabetics (Doly M et al 1988). In a preliminary clinical trial (Huang SY et al 2004), type 2 diabetics were given ginkgo extract orally for three months, which significantly reduced free radical levels, decreased fibrinogen levels, and improved blood viscosity. Ginkgo extracts also improved retinal capillary blood flow rate in type 2 diabetic patients with retinopathy.

Ginkgo has also been observed to lower blood glucose levels. It was studied in type 2 diabetics at a dose of 120 mg for three months. Ginkgo supplementation produced an increase in liver metabolism of insulin and oral hypoglycemic medications, which corresponded to a reduction in plasma glucose levels (Kudolo GB 2001). Type 2 diabetics with pancreatic exhaustion received the most benefit. Ginkgo does not appear to increase beta cell production; rather it enhances liver uptake of existing insulin, thereby reducing high insulin levels.