A variety of vitamins, minerals, amino acids, and other supplements may help with symptoms and deficiencies associated with diabetes.
Multiple Vitamin�Mineral SupplementIn a double-blind study, supplementation of middle-aged and elderly diabetics with a multiple vitamin and mineral preparation for one year reduced the risk of infection by more than 80%, compared with a placebo.78
ChromiumMedical reports dating back to 1853, as well as modern research, indicate that chromium-rich brewer�s yeast (9 grams per day) can be useful in treating type 2 diabetes.79 80 In recent years, chromium has been shown to improve glucose levels and related variables in people with glucose intolerance and type 2, gestational, and steroid-induced diabetes.81 Improved glucose tolerance with lower or similar levels of insulin have been reported in more than ten trials of chromium supplementation in people with varying degrees of glucose intolerance.82 Chromium supplements improve glucose tolerance in people with type 2 diabetes,83 apparently by increasing sensitivity to insulin.84 Chromium improves the processing of glucose in people with prediabetic glucose intolerance and in women with diabetes associated with pregnancy.85 86 Chromium even helps healthy people,87 although one such report found chromium useful only when accompanied by 100 mg of niacin per day.88 Chromium may also lower levels of total cholesterol, LDL cholesterol, and triglycerides (risk factors in heart disease).89 90
A few trials have reported no beneficial effects from chromium supplementation.91 92 93 All of these trials used 200 mcg or less of supplemental chromium, which is often not adequate for people with diabetes, especially if it is in a form that is poorly absorbed. The typical amount of chromium used in research trials is 200 mcg per day, although as much as 1,000 mcg per day has been used.94 Many doctors recommend up to 1,000 mcg per day for people with diabetes.95
Supplementation with chromium or brewer�s yeast could potentially enhance the effects of drugs used for diabetes (e.g., insulin or other blood sugar-lowering agents) and possibly lead to hypoglycemia. Therefore, people with diabetes taking these medications should supplement with chromium or brewer�s yeast only under the supervision of a doctor.
MagnesiumPeople with type 2 diabetes tend to have low magnesium levels.96 Double-blind research indicates that supplementing with magnesium overcomes this problem.97 Magnesium supplementation has improved insulin production in elderly people with type 2 diabetes.98 However, one double-blind trial found no effect from 500 mg magnesium per day in people with type 2 diabetes, although twice that amount led to some improvement.99 Elders without diabetes can also produce more insulin as a result of magnesium supplements, according to some,100 but not all, trials.101 However, in people with type 2 diabetes who nonetheless require insulin, Dutch researchers have reported no improvement in blood sugar levels from magnesium supplementation.102 The American Diabetes Association acknowledges strong associations between magnesium deficiency and insulin resistance but has not said magnesium deficiency is a risk factor103 Many doctors, however, recommend that people with diabetes and normal kidney function supplement with 200 to 600 mg of magnesium per day.
Diabetes-induced damage to the eyes is more likely to occur in magnesium-deficient people with type 1 diabetes.104 In magnesium-deficient pregnant women with type 1 diabetes, the lack of magnesium may even account for the high rate of spontaneous abortion and birth defects associated with type 1 diabetes.105 The American Diabetes Association admits �strong associations...between magnesium deficiency and insulin resistance� but will not say magnesium deficiency is a risk factor.106 Many doctors, however, recommend that people with diabetes and normal kidney function supplement with 200�600 mg of magnesium per day.
Alpha lipoic acidAlpha lipoic acid is a powerful natural antioxidant. Preliminary and double-blind trials have found that supplementing 600 to 1,200 mg of lipoic acid per day improves insulin sensitivity and the symptoms of diabetic neuropathy.107 108 109 110 111 112 113 In a preliminary study, supplementing with 600 mg of alpha lipoic acid per day for 18 months slowed the progression of kidney damage in patients with type 2 diabetes.114
Evening primrose oilSupplementing with 4 grams of evening primrose oil per day for six months has been found in double-blind research to improve nerve function and to relieve pain symptoms of diabetic neuropathy.115
GlucomannanGlucomannan is a water-soluble dietary fiber derived from konjac root (Amorphophallus konjac)that delays stomach emptying, leading to a more gradual absorption of dietary sugar. This effect can reduce the elevation of blood sugar levels that is typical after a meal. 116 After-meal blood sugar levels are lower in people with diabetes given glucomannan in their food, 117 and overall diabetic control is improved with glucomannan-enriched diets, according to preliminary and controlled clinical trials. 118 119 120 One preliminary report suggested that glucomannan may also be helpful in pregnancy-related diabetes. 121 For controlling blood sugar, 500 to 700 mg of glucomannan per 100 calories in the diet has been used successfully in controlled research.
Vitamin EPeople with low blood levels of vitamin E are more likely to develop type 1 and type 2 diabetes.122 123 Vitamin E supplementation has improved glucose tolerance in people with type 2 diabetes in most,124 125 126 but not all,127 double-blind trials. Vitamin E has also improved glucose tolerance in elderly people without diabetes.128 129 Three months or more of at least 900 IU of vitamin E per day may be required for benefits to become apparent.
In one of the few trials to find vitamin E supplementation ineffective for glucose intolerance in people with type 2 diabetes, damage to nerves caused by the diabetes was nonetheless partially reversed by supplementing with vitamin E for six months.130 Animal and preliminary human data indicate that vitamin E supplementation may protect against diabetic retinopathy and nephropathy,131 132 serious complications of diabetes involving the eyes and kidneys, respectively, though no long-term trials in humans have confirmed this preliminary evidence.
Glycosylation is an important measurement of diabetes; it refers to how much sugar attaches abnormally to proteins. Excessive glycosylation appears to be one of the causes of the organ damage that occurs in diabetes. Vitamin E supplementation has reduced the amount of glycosylation in many,133 134 135 136 137 although not all,138 139 140 studies.
In one report, vitamin E was found to impair glucose tolerance in obese patients with diabetes.141 The reason for the discrepancy between reports is not known.
Vitamin E appears to lower the risk of cerebral infarction, a type of stroke, in people with diabetes who smoke. A review of a large Finnish study of smokers concluded that smokers with diabetes (or hypertension) can benefit from small amounts of vitamin E (50 IU per day).142
Vitamin CAs with vitamin E, vitamin C may reduce glycosylation.143 Vitamin C also lowers sorbitol levels in people with diabetes.144 Sorbitol is a sugar that can accumulate inside the cells and damage the eyes, nerves, and kidneys of people with diabetes. Vitamin C may improve glucose tolerance in type 2 diabetes,145 146 although not every study confirms this benefit.147 Vitamin C supplementation (500 mg twice a day for one year) has significantly reduced urinary protein loss in people with diabetes. Urinary protein loss (also called proteinuria) is associated with poor prognosis in diabetes.148 Many doctors suggest that people with diabetes supplement with 1 to 3 grams per day of vitamin C. Higher amounts could be problematic, however. In one person, 4.5 grams per day was reported to increase blood sugar levels.149
One study examined antioxidant supplement intake, including both vitamins E and C, and the incidence of diabetic retinopathy (damage to the eyes caused by diabetes).150 Surprisingly, people with extensive retinopathy had a greater likelihood of having taken vitamin C and vitamin E supplements. The outcome of this trial, however, does not fit with most other published data and might simply reflect the fact that sicker people are more likely to take supplements in hopes of getting better. For the present, most doctors remain relatively unconcerned about the outcome of this isolated report.
B VitaminsMany people with diabetes have low blood levels of vitamin B6.151 152 Levels are even lower in people with diabetes who also have nerve damage (neuropathy).153 Vitamin B6 supplementation has improved glucose tolerance in women with diabetes caused by pregnancy.154 155 Vitamin B6 supplementation is also effective for glucose intolerance induced by birth control pills.156 In a trial that included people with type 2 diabetes, 1,800 mg per day of a special form of vitamin B6�pyridoxine alpha-ketoglutarate�improved glucose tolerance dramatically.157 Standard vitamin B6 has helped in some,158 but not all, trials.159
A controlled trial in Africa found that supplementing with both vitamin B1 (25 mg per day) and vitamin B6 (50 mg per day) led to significant improvement of symptoms of diabetic neuropathy after four weeks.160 However, since this was a trial conducted among people in a vitamin B1�deficient developing country, these improvements might not occur in other people with diabetes. Another trial found that combining vitamin B1 (in a special fat-soluble form) and vitamin B6 plus vitamin B12 in high but variable amounts led to improvement in some aspects of diabetic neuropathy in 12 weeks.161 As a result, some doctors recommend that people with diabetic neuropathy supplement with vitamin B1, though the optimal level of intake remains unknown.
Biotin is a B vitamin needed to process glucose. When people with type 2 diabetes were given 9 mg of biotin per day for two months, their fasting glucose levels dropped dramatically.162 Biotin may also reduce pain from diabetic nerve damage.163 Some doctors try 9 to 16 mg of biotin per day for a few weeks to see if blood sugar levels will fall.
Vitamin B12 is needed for normal functioning of nerve cells. Vitamin B12 taken orally has reduced symptoms of nerve damage caused by diabetes in 39% of people studied; when given both intravenously and orally, two-thirds of people improved.164 In a preliminary trial, people with nerve damage due to kidney disease or to diabetes plus kidney disease received intravenous injections of 500 mcg of methylcobalamin (the main form of vitamin B12 found in the blood) three times a day for six months in addition to kidney dialysis. Nerve pain was significantly reduced and nerve function significantly improved in those who received the injections.165 Oral vitamin B12 up to 500 mcg three times per day is recommended by some practitioners.
The intake of large amounts of niacin (a form of vitamin B3), such as 2 to 3 grams per day, may impair glucose tolerance and should be used by people with diabetes only with medical supervision.166 167 Smaller amounts (500 to 750 mg per day for one month followed by 250 mg per day) may help some people with type 2 diabetes,168 though this research remains preliminary.
Coenzyme Q10Coenzyme Q10 (CoQ10) is needed for normal blood sugar metabolism. Animals with diabetes have been reported to be CoQ10 deficient. People with type 2 diabetes have been found to have significantly lower blood levels of CoQ10 compared with healthy people.169 In one trial, blood sugar levels fell substantially in 31% of people with diabetes after they supplemented with 120 mg per day of CoQ7, a substance similar to CoQ10.170 The importance of CoQ10 supplementation for people with diabetes remains an unresolved issue, though some doctors recommend approximately 50 mg per day as a way to protect against possible effects associated with diabetes-induced depletion.
L-carnitineL-carnitine is an amino acid needed to properly utilize fat for energy. When people with diabetes were given DL-carnitine (0.5 mg per 2.2 pounds of body weight), high blood levels of fats�both cholesterol and triglycerides�dropped 25 to 39% in just ten days in one trial.171
Acetyl-L-carnitineIn a double-blind study of people with diabetic neuropathy, supplementing with acetyl-L-carnitine was significantly more effective than a placebo in improving subjective symptoms of neuropathy and objective measures of nerve function.172 People who received 1,000 mg of acetyl-L-carnitine three times per day tended to fare better than those who received 500 mg three times per day.
ZincPeople with type 2 diabetes tend to be zinc deficient,173 but some evidence indicates that zinc supplementation does not improve their ability to process sugar.174 Nonetheless, many doctors recommend that people with type 2 diabetes supplement with moderate amounts of zinc (15 to 25 mg per day) as a way to correct the deficit.
AntioxidantsBecause oxidation damage is believed to play a role in the development of diabetic retinopathy, antioxidant nutrients might be protective. One doctor has administered a daily regimen of 500 mcg selenium, 800 IU vitamin E, 10,000 IU vitamin A, and 1,000 mg vitamin C for several years to 20 people with diabetic retinopathy. During that time, 19 of the 20 people showed either improvement or no progression of their retinopathy.175 People who wish to supplement with more than 250 mcg of selenium per day should consult a healthcare practitioner.
Vitamin DVitamin D is needed to maintain adequate blood levels of insulin.176 Vitamin D receptors have been found in the pancreas where insulin is made, and preliminary evidence suggests that supplementation can improve some measures of blood sugar control in people with type 2 diabetes.177 178 Not enough is known about optimal amounts of vitamin D for people with diabetes, and high amounts of vitamin D can be toxic; therefore, people with diabetes considering vitamin D supplementation should talk with a doctor and have their vitamin D status assessed.
InositolInositol is needed for normal nerve function. Diabetes can cause a type of nerve damage known as diabetic neuropathy. This condition has been reported in some, but not all, trials to improve with inositol supplementation (500 mg taken twice per day).179
TaurineAnimal studies have shown that supplementing with taurine, an amino acid found in protein-rich food, may affect insulin secretion and action, and may have potential in protecting the eyes and nerves from diabetic complications.180 However, a double-blind trial found no effect on insulin secretion or sensitivity when men with high risk for developing diabetes were given 1.5 grams per day of taurine for eight weeks.181 In another double-blind trial, taurine supplementation (2 grams per day for 12 months) failed to improve kidney complications associated with type 2 diabetes.182
Fish oilGlucose tolerance improves in healthy people taking omega-3 fatty acid supplements,183 and some studies have found that fish oil supplementation also improves glucose tolerance,184 high triglycerides,185 and cholesterol levels in people with type 2 diabetes.186 And in one trial, people with diabetic neuropathy and diabetic nephropathy experienced significant improvement when given 600 mg three times per day of purified eicosapentaenoic acid (EPA)�one of the two major omega-3 fatty acids found in fish oil supplements�for 48 weeks.187 However, other studies have found that type 2 diabetes worsens with fish oil supplementation.188 189 190 191 Until this issue is resolved, people with diabetes should feel free to eat fish, but they should consult a doctor before taking fish oil supplements.
QuercetinDoctors have suggested that quercetin might help people with diabetes because of its ability to reduce levels of sorbitol�a sugar that accumulates in nerve cells, kidney cells, and cells within the eyes of people with diabetes�and has been linked to damage to those organs.192 Clinical trials have yet to explore whether quercetin actually protects people with diabetes from neuropathy, nephropathy, or retinopathy.
VanadiumVanadyl sulfate, a form of vanadium, may improve glucose control in people with type 2 diabetes.193 194 195 Over a six-week period, a small group of people with type 2 diabetes were given 75 to 300 mg of vanadyl sulfate per day.196 Only in the groups receiving 150 mg or 300 mg was glucose metabolism improved, fasting blood sugar decreased, and another marker for chronic high blood sugar reduced. At the 300 mg level, total cholesterol decreased, although not without an accompanying reduction in the protective HDL cholesterol. None of the amounts improved insulin sensitivity. Although there was no evidence of toxicity after six weeks of vanadyl sulfate supplementation, gastrointestinal side effects were experienced by some of the participants taking 150 mg per day and by all of the participants taking 300 mg per day. The long-term safety of the large amounts of vanadium needed to help people with type 2 diabetes (typically 100 mg per day) remains unknown. Many doctors expect that amounts this high may prove to be unsafe in the long term.
Fructo-oligosaccharidesIn a preliminary trial, supplementation with fructo-oligosaccharides (FOS) (8 grams per day for two weeks) significantly lowered fasting blood-sugar levels and serum total-cholesterol levels in people with type 2 diabetes.197 However, in another trial, supplementing with FOS (15 grams per day) for 20 days had no effect on blood-glucose or lipid levels in people with type 2 diabetes.198 In addition, some double-blind trials showed that supplementing with FOS or galacto-oligosaccharides (GOS) for eight weeks had no effect on blood-sugar levels, insulin secretion, or blood lipids in healthy people.199 200 Because of these conflicting results, more research is needed to determine the effect of FOS on diabetes and lipid levels.
ManganesePeople with diabetes may have low blood levels of manganese.201 Animal research suggests that manganese deficiency can contribute to glucose intolerance and may be reversed by supplementation.202 A young adult with insulin-dependent diabetes who received oral manganese chloride (3 to 5 mg per day as manganese chloride) reportedly experienced a significant fall in blood glucose, sometimes to dangerously low levels. In four other cases, manganese supplementation had no effect on blood glucose levels.203 People with diabetes wishing to supplement with manganese should do so only with a doctor�s supervision.
Medium-chain triglyceridesBased on the results of a short-term clinical trial that found that medium-chain triglycerides (MCT) lower blood glucose levels,204 a group of researchers investigated the use of MCT to treat people with type 2 diabetes mellitus. Supplementation with MCT for an average of 17.5% of their total calorie intake for 30 days failed to improve most measures of diabetic control.205
Starch blockersStarch blockers are substances that inhibit amylase, the digestive enzyme required to break down dietary starches for normal absorption. Controlled research has demonstrated that concentrated starch blocker extracts, when given with a starchy meal, can reduce the usual rise in blood sugar levels of both healthy people and diabetics.206 207 208 209 210 While this effect could be helpful in controlling diabetes, no research has investigated the long-term effects of taking starch blockers for this condition.
Are there any side effects or interactions?Refer to the individual supplement for information about any side effects or interactions.
Multiple Vitamin�Mineral SupplementIn a double-blind study, supplementation of middle-aged and elderly diabetics with a multiple vitamin and mineral preparation for one year reduced the risk of infection by more than 80%, compared with a placebo.78
ChromiumMedical reports dating back to 1853, as well as modern research, indicate that chromium-rich brewer�s yeast (9 grams per day) can be useful in treating type 2 diabetes.79 80 In recent years, chromium has been shown to improve glucose levels and related variables in people with glucose intolerance and type 2, gestational, and steroid-induced diabetes.81 Improved glucose tolerance with lower or similar levels of insulin have been reported in more than ten trials of chromium supplementation in people with varying degrees of glucose intolerance.82 Chromium supplements improve glucose tolerance in people with type 2 diabetes,83 apparently by increasing sensitivity to insulin.84 Chromium improves the processing of glucose in people with prediabetic glucose intolerance and in women with diabetes associated with pregnancy.85 86 Chromium even helps healthy people,87 although one such report found chromium useful only when accompanied by 100 mg of niacin per day.88 Chromium may also lower levels of total cholesterol, LDL cholesterol, and triglycerides (risk factors in heart disease).89 90
A few trials have reported no beneficial effects from chromium supplementation.91 92 93 All of these trials used 200 mcg or less of supplemental chromium, which is often not adequate for people with diabetes, especially if it is in a form that is poorly absorbed. The typical amount of chromium used in research trials is 200 mcg per day, although as much as 1,000 mcg per day has been used.94 Many doctors recommend up to 1,000 mcg per day for people with diabetes.95
Supplementation with chromium or brewer�s yeast could potentially enhance the effects of drugs used for diabetes (e.g., insulin or other blood sugar-lowering agents) and possibly lead to hypoglycemia. Therefore, people with diabetes taking these medications should supplement with chromium or brewer�s yeast only under the supervision of a doctor.
MagnesiumPeople with type 2 diabetes tend to have low magnesium levels.96 Double-blind research indicates that supplementing with magnesium overcomes this problem.97 Magnesium supplementation has improved insulin production in elderly people with type 2 diabetes.98 However, one double-blind trial found no effect from 500 mg magnesium per day in people with type 2 diabetes, although twice that amount led to some improvement.99 Elders without diabetes can also produce more insulin as a result of magnesium supplements, according to some,100 but not all, trials.101 However, in people with type 2 diabetes who nonetheless require insulin, Dutch researchers have reported no improvement in blood sugar levels from magnesium supplementation.102 The American Diabetes Association acknowledges strong associations between magnesium deficiency and insulin resistance but has not said magnesium deficiency is a risk factor103 Many doctors, however, recommend that people with diabetes and normal kidney function supplement with 200 to 600 mg of magnesium per day.
Diabetes-induced damage to the eyes is more likely to occur in magnesium-deficient people with type 1 diabetes.104 In magnesium-deficient pregnant women with type 1 diabetes, the lack of magnesium may even account for the high rate of spontaneous abortion and birth defects associated with type 1 diabetes.105 The American Diabetes Association admits �strong associations...between magnesium deficiency and insulin resistance� but will not say magnesium deficiency is a risk factor.106 Many doctors, however, recommend that people with diabetes and normal kidney function supplement with 200�600 mg of magnesium per day.
Alpha lipoic acidAlpha lipoic acid is a powerful natural antioxidant. Preliminary and double-blind trials have found that supplementing 600 to 1,200 mg of lipoic acid per day improves insulin sensitivity and the symptoms of diabetic neuropathy.107 108 109 110 111 112 113 In a preliminary study, supplementing with 600 mg of alpha lipoic acid per day for 18 months slowed the progression of kidney damage in patients with type 2 diabetes.114
Evening primrose oilSupplementing with 4 grams of evening primrose oil per day for six months has been found in double-blind research to improve nerve function and to relieve pain symptoms of diabetic neuropathy.115
GlucomannanGlucomannan is a water-soluble dietary fiber derived from konjac root (Amorphophallus konjac)that delays stomach emptying, leading to a more gradual absorption of dietary sugar. This effect can reduce the elevation of blood sugar levels that is typical after a meal. 116 After-meal blood sugar levels are lower in people with diabetes given glucomannan in their food, 117 and overall diabetic control is improved with glucomannan-enriched diets, according to preliminary and controlled clinical trials. 118 119 120 One preliminary report suggested that glucomannan may also be helpful in pregnancy-related diabetes. 121 For controlling blood sugar, 500 to 700 mg of glucomannan per 100 calories in the diet has been used successfully in controlled research.
Vitamin EPeople with low blood levels of vitamin E are more likely to develop type 1 and type 2 diabetes.122 123 Vitamin E supplementation has improved glucose tolerance in people with type 2 diabetes in most,124 125 126 but not all,127 double-blind trials. Vitamin E has also improved glucose tolerance in elderly people without diabetes.128 129 Three months or more of at least 900 IU of vitamin E per day may be required for benefits to become apparent.
In one of the few trials to find vitamin E supplementation ineffective for glucose intolerance in people with type 2 diabetes, damage to nerves caused by the diabetes was nonetheless partially reversed by supplementing with vitamin E for six months.130 Animal and preliminary human data indicate that vitamin E supplementation may protect against diabetic retinopathy and nephropathy,131 132 serious complications of diabetes involving the eyes and kidneys, respectively, though no long-term trials in humans have confirmed this preliminary evidence.
Glycosylation is an important measurement of diabetes; it refers to how much sugar attaches abnormally to proteins. Excessive glycosylation appears to be one of the causes of the organ damage that occurs in diabetes. Vitamin E supplementation has reduced the amount of glycosylation in many,133 134 135 136 137 although not all,138 139 140 studies.
In one report, vitamin E was found to impair glucose tolerance in obese patients with diabetes.141 The reason for the discrepancy between reports is not known.
Vitamin E appears to lower the risk of cerebral infarction, a type of stroke, in people with diabetes who smoke. A review of a large Finnish study of smokers concluded that smokers with diabetes (or hypertension) can benefit from small amounts of vitamin E (50 IU per day).142
Vitamin CAs with vitamin E, vitamin C may reduce glycosylation.143 Vitamin C also lowers sorbitol levels in people with diabetes.144 Sorbitol is a sugar that can accumulate inside the cells and damage the eyes, nerves, and kidneys of people with diabetes. Vitamin C may improve glucose tolerance in type 2 diabetes,145 146 although not every study confirms this benefit.147 Vitamin C supplementation (500 mg twice a day for one year) has significantly reduced urinary protein loss in people with diabetes. Urinary protein loss (also called proteinuria) is associated with poor prognosis in diabetes.148 Many doctors suggest that people with diabetes supplement with 1 to 3 grams per day of vitamin C. Higher amounts could be problematic, however. In one person, 4.5 grams per day was reported to increase blood sugar levels.149
One study examined antioxidant supplement intake, including both vitamins E and C, and the incidence of diabetic retinopathy (damage to the eyes caused by diabetes).150 Surprisingly, people with extensive retinopathy had a greater likelihood of having taken vitamin C and vitamin E supplements. The outcome of this trial, however, does not fit with most other published data and might simply reflect the fact that sicker people are more likely to take supplements in hopes of getting better. For the present, most doctors remain relatively unconcerned about the outcome of this isolated report.
B VitaminsMany people with diabetes have low blood levels of vitamin B6.151 152 Levels are even lower in people with diabetes who also have nerve damage (neuropathy).153 Vitamin B6 supplementation has improved glucose tolerance in women with diabetes caused by pregnancy.154 155 Vitamin B6 supplementation is also effective for glucose intolerance induced by birth control pills.156 In a trial that included people with type 2 diabetes, 1,800 mg per day of a special form of vitamin B6�pyridoxine alpha-ketoglutarate�improved glucose tolerance dramatically.157 Standard vitamin B6 has helped in some,158 but not all, trials.159
A controlled trial in Africa found that supplementing with both vitamin B1 (25 mg per day) and vitamin B6 (50 mg per day) led to significant improvement of symptoms of diabetic neuropathy after four weeks.160 However, since this was a trial conducted among people in a vitamin B1�deficient developing country, these improvements might not occur in other people with diabetes. Another trial found that combining vitamin B1 (in a special fat-soluble form) and vitamin B6 plus vitamin B12 in high but variable amounts led to improvement in some aspects of diabetic neuropathy in 12 weeks.161 As a result, some doctors recommend that people with diabetic neuropathy supplement with vitamin B1, though the optimal level of intake remains unknown.
Biotin is a B vitamin needed to process glucose. When people with type 2 diabetes were given 9 mg of biotin per day for two months, their fasting glucose levels dropped dramatically.162 Biotin may also reduce pain from diabetic nerve damage.163 Some doctors try 9 to 16 mg of biotin per day for a few weeks to see if blood sugar levels will fall.
Vitamin B12 is needed for normal functioning of nerve cells. Vitamin B12 taken orally has reduced symptoms of nerve damage caused by diabetes in 39% of people studied; when given both intravenously and orally, two-thirds of people improved.164 In a preliminary trial, people with nerve damage due to kidney disease or to diabetes plus kidney disease received intravenous injections of 500 mcg of methylcobalamin (the main form of vitamin B12 found in the blood) three times a day for six months in addition to kidney dialysis. Nerve pain was significantly reduced and nerve function significantly improved in those who received the injections.165 Oral vitamin B12 up to 500 mcg three times per day is recommended by some practitioners.
The intake of large amounts of niacin (a form of vitamin B3), such as 2 to 3 grams per day, may impair glucose tolerance and should be used by people with diabetes only with medical supervision.166 167 Smaller amounts (500 to 750 mg per day for one month followed by 250 mg per day) may help some people with type 2 diabetes,168 though this research remains preliminary.
Coenzyme Q10Coenzyme Q10 (CoQ10) is needed for normal blood sugar metabolism. Animals with diabetes have been reported to be CoQ10 deficient. People with type 2 diabetes have been found to have significantly lower blood levels of CoQ10 compared with healthy people.169 In one trial, blood sugar levels fell substantially in 31% of people with diabetes after they supplemented with 120 mg per day of CoQ7, a substance similar to CoQ10.170 The importance of CoQ10 supplementation for people with diabetes remains an unresolved issue, though some doctors recommend approximately 50 mg per day as a way to protect against possible effects associated with diabetes-induced depletion.
L-carnitineL-carnitine is an amino acid needed to properly utilize fat for energy. When people with diabetes were given DL-carnitine (0.5 mg per 2.2 pounds of body weight), high blood levels of fats�both cholesterol and triglycerides�dropped 25 to 39% in just ten days in one trial.171
Acetyl-L-carnitineIn a double-blind study of people with diabetic neuropathy, supplementing with acetyl-L-carnitine was significantly more effective than a placebo in improving subjective symptoms of neuropathy and objective measures of nerve function.172 People who received 1,000 mg of acetyl-L-carnitine three times per day tended to fare better than those who received 500 mg three times per day.
ZincPeople with type 2 diabetes tend to be zinc deficient,173 but some evidence indicates that zinc supplementation does not improve their ability to process sugar.174 Nonetheless, many doctors recommend that people with type 2 diabetes supplement with moderate amounts of zinc (15 to 25 mg per day) as a way to correct the deficit.
AntioxidantsBecause oxidation damage is believed to play a role in the development of diabetic retinopathy, antioxidant nutrients might be protective. One doctor has administered a daily regimen of 500 mcg selenium, 800 IU vitamin E, 10,000 IU vitamin A, and 1,000 mg vitamin C for several years to 20 people with diabetic retinopathy. During that time, 19 of the 20 people showed either improvement or no progression of their retinopathy.175 People who wish to supplement with more than 250 mcg of selenium per day should consult a healthcare practitioner.
Vitamin DVitamin D is needed to maintain adequate blood levels of insulin.176 Vitamin D receptors have been found in the pancreas where insulin is made, and preliminary evidence suggests that supplementation can improve some measures of blood sugar control in people with type 2 diabetes.177 178 Not enough is known about optimal amounts of vitamin D for people with diabetes, and high amounts of vitamin D can be toxic; therefore, people with diabetes considering vitamin D supplementation should talk with a doctor and have their vitamin D status assessed.
InositolInositol is needed for normal nerve function. Diabetes can cause a type of nerve damage known as diabetic neuropathy. This condition has been reported in some, but not all, trials to improve with inositol supplementation (500 mg taken twice per day).179
TaurineAnimal studies have shown that supplementing with taurine, an amino acid found in protein-rich food, may affect insulin secretion and action, and may have potential in protecting the eyes and nerves from diabetic complications.180 However, a double-blind trial found no effect on insulin secretion or sensitivity when men with high risk for developing diabetes were given 1.5 grams per day of taurine for eight weeks.181 In another double-blind trial, taurine supplementation (2 grams per day for 12 months) failed to improve kidney complications associated with type 2 diabetes.182
Fish oilGlucose tolerance improves in healthy people taking omega-3 fatty acid supplements,183 and some studies have found that fish oil supplementation also improves glucose tolerance,184 high triglycerides,185 and cholesterol levels in people with type 2 diabetes.186 And in one trial, people with diabetic neuropathy and diabetic nephropathy experienced significant improvement when given 600 mg three times per day of purified eicosapentaenoic acid (EPA)�one of the two major omega-3 fatty acids found in fish oil supplements�for 48 weeks.187 However, other studies have found that type 2 diabetes worsens with fish oil supplementation.188 189 190 191 Until this issue is resolved, people with diabetes should feel free to eat fish, but they should consult a doctor before taking fish oil supplements.
QuercetinDoctors have suggested that quercetin might help people with diabetes because of its ability to reduce levels of sorbitol�a sugar that accumulates in nerve cells, kidney cells, and cells within the eyes of people with diabetes�and has been linked to damage to those organs.192 Clinical trials have yet to explore whether quercetin actually protects people with diabetes from neuropathy, nephropathy, or retinopathy.
VanadiumVanadyl sulfate, a form of vanadium, may improve glucose control in people with type 2 diabetes.193 194 195 Over a six-week period, a small group of people with type 2 diabetes were given 75 to 300 mg of vanadyl sulfate per day.196 Only in the groups receiving 150 mg or 300 mg was glucose metabolism improved, fasting blood sugar decreased, and another marker for chronic high blood sugar reduced. At the 300 mg level, total cholesterol decreased, although not without an accompanying reduction in the protective HDL cholesterol. None of the amounts improved insulin sensitivity. Although there was no evidence of toxicity after six weeks of vanadyl sulfate supplementation, gastrointestinal side effects were experienced by some of the participants taking 150 mg per day and by all of the participants taking 300 mg per day. The long-term safety of the large amounts of vanadium needed to help people with type 2 diabetes (typically 100 mg per day) remains unknown. Many doctors expect that amounts this high may prove to be unsafe in the long term.
Fructo-oligosaccharidesIn a preliminary trial, supplementation with fructo-oligosaccharides (FOS) (8 grams per day for two weeks) significantly lowered fasting blood-sugar levels and serum total-cholesterol levels in people with type 2 diabetes.197 However, in another trial, supplementing with FOS (15 grams per day) for 20 days had no effect on blood-glucose or lipid levels in people with type 2 diabetes.198 In addition, some double-blind trials showed that supplementing with FOS or galacto-oligosaccharides (GOS) for eight weeks had no effect on blood-sugar levels, insulin secretion, or blood lipids in healthy people.199 200 Because of these conflicting results, more research is needed to determine the effect of FOS on diabetes and lipid levels.
ManganesePeople with diabetes may have low blood levels of manganese.201 Animal research suggests that manganese deficiency can contribute to glucose intolerance and may be reversed by supplementation.202 A young adult with insulin-dependent diabetes who received oral manganese chloride (3 to 5 mg per day as manganese chloride) reportedly experienced a significant fall in blood glucose, sometimes to dangerously low levels. In four other cases, manganese supplementation had no effect on blood glucose levels.203 People with diabetes wishing to supplement with manganese should do so only with a doctor�s supervision.
Medium-chain triglyceridesBased on the results of a short-term clinical trial that found that medium-chain triglycerides (MCT) lower blood glucose levels,204 a group of researchers investigated the use of MCT to treat people with type 2 diabetes mellitus. Supplementation with MCT for an average of 17.5% of their total calorie intake for 30 days failed to improve most measures of diabetic control.205
Starch blockersStarch blockers are substances that inhibit amylase, the digestive enzyme required to break down dietary starches for normal absorption. Controlled research has demonstrated that concentrated starch blocker extracts, when given with a starchy meal, can reduce the usual rise in blood sugar levels of both healthy people and diabetics.206 207 208 209 210 While this effect could be helpful in controlling diabetes, no research has investigated the long-term effects of taking starch blockers for this condition.
Are there any side effects or interactions?Refer to the individual supplement for information about any side effects or interactions.
No comments:
Post a Comment