Sugar pills: fighting diabetes with supplements.
New York City is suffering the advance wave of a national diabetes epidemic, according to a chilling series in The New York Times earlier this year. More than one in every eight New Yorkers now has the disease, and the numbers are rising.
Across the nation, an estimated 21 million people--one in ten adults--have diabetes. A third of them don't know it. For people 60 and older, it's one in five. And 41 million more have blood sugar high enough to give them "pre-diabetes."
But diabetes isn't inevitable. Losing 10 to 15 pounds and doing moderate-intensity exercise like brisk walking for 2 1/2 hours a week can cut the risk by 60 percent, according to a three-year government study of more than 3,200 overweight middle-aged men and women.
Is there an easier way? Can people with pre-diabetes, a family history, or other risk factors ward off diabetes by popping over-the-counter pills? Can those with the disease use supplements to keep their blood sugar under control?
Here's the evidence.
The idea: Insulin needs chromium to get sugar out of the blood.
The evidence: Chromium supplements came up empty in all but one of the six good studies that looked at people at risk of diabetes (they were overweight, had a family history, or had abnormal responses to a glucose tolerance test). Four of the studies used chromium picolinate and two used chromium chloride. The supplements didn't improve glucose tolerance or lower fasting blood sugar or glycated hemoglobin. (1) (Glycated hemoglobin, or HbA1c, is a measure of blood sugar over the previous several months.) But in the one study that looked at insulin resistance, chromium helped.
In 1999, William Cefalu, then at the University of Vermont, and his colleagues gave 1,000 micrograms a day of chromium (from chromium picolinate) or a placebo to 29 men and women at high risk of diabetes. (2) After eight months, those who took the chromium were less insulin resistant than those who took the placebo.
What about people with diabetes? Of the four good studies, only one found a benefit--lower levels of fasting blood glucose, insulin, and glycated hemoglobin--in people who were given 1,000 micrograms a day of chromium (from chromium picolinate) for four months. But the study, done more than ten years ago in China, "might simply show the benefits of supplementation in a chromium-deficient population," according to the Office of Dietary Supplements at the National Institutes of Health. If so, the results wouldn't apply to most Americans.
In 2003, Nutrition 21, the company that holds a patent on the use of chromium picolinate to lower blood sugar, petitioned the Food and Drug Administration to approve eight health claims. Among them: chromium picolinate "may reduce abnormally elevated blood sugar levels," "may reduce the risk of insulin resistance," and "may reduce the risk of type 2 diabetes."
The FDA denied the request last August. But, based on the University of Vermont results, it did allow this claim: "One small study suggests that chromium picolinate may reduce the risk of insulin resistance, and therefore possibly may reduce the risk of type 2 diabetes. FDA concludes, however, that the existence of such a relationship between chromium picolinate and either insulin resistance or type 2 diabetes is highly uncertain."
Cost of a month's supply: $5-$10.
The idea: In test tubes, a constituent of cinnamon called methylhydroxyl chalcone polymer (MHCP) mimics insulin by activating insulin receptors on cell walls.
U.S. Department of Agriculture investigators discovered cinnamon's insulin-like properties by accident. "We were looking at the effects of common foods on blood sugar," recalls USDA researcher Richard Anderson. One was apple pie spiced with cinnamon. "We expected the pie to be bad," he says. "But it helped."
The evidence: No studies have looked at whether cinnamon can prevent diabetes. And in people with the disease, the evidence isn't clear. Anderson and colleagues gave one, three, or six grams a day of finely ground cinnamon to 50 Pakistanis with diabetes. After 40 days, no matter which amount of cinnamon they got, their fasting blood sugar levels were 25 percent lower than the blood sugar of 30 similar people who were given a placebo. (3)
But when Dutch researchers gave 13 women with diabetes 1 1/2 grams of ground cinnamon (3/4 teaspoon) every day for six weeks, they did no better on an oral glucose tolerance test than similar women who were given a placebo. (4)
Clearly, more research is needed.
Cost of a month's supply: $2-$7.
The idea: Coenzyme Q10 can help cells burn sugar for energy.
The evidence: No studies have looked at whether coenzyme Q10 can help prevent diabetes. And only one study has tested it on people with the disease.
When Australian researchers gave 20 people with diabetes 200 mg a day of coenzyme Q10 for 12 weeks, they ended up with lower levels of glycated hemoglobin than 20 similar people who were given a placebo. (5)
But one small study isn't enough. "The evidence is not sufficient to evaluate CoQ10's effectiveness," concluded the National Center for Complementary and Alternative Medicine at the National Institutes of Health.
Cost of a month's supply: $30-$70.
The idea: In cells in test tubes, some of the compounds in ginseng reduce insulin resistance.
The evidence: Six years ago, Vladimir Vuksan and his colleagues at the University of Toronto gave 19 people with diabetes and 32 non-diabetics single doses of one to nine grams of American ginseng before feeding them a sugar-laced beverage. After their blood glucose spiked, it returned to its pre-beverage level faster than when the same people were given a placebo before drinking a sugar-laced beverage on other occasions. (6)
But Vuksan used an extract of cultivated American ginseng that isn't available commercially. When he tried single doses of a different extract, they had no impact on blood sugar. Neither did extracts from three other kinds of ginseng--Japanese, Asian red, and Sanchi. (7)
Worse still, single doses of Asian ginseng--the kind most commonly found in supplements--raised blood glucose levels in people without diabetes. So did wild American ginseng. (Vuksan hasn't tested either kind on people with diabetes.)
"Until we know more about why the effects of ginseng are so variable," says Vuksan, "we can't assume that it's safe and effective for lowering blood glucose levels."
Cost of a month's supply: $5-$15.
The idea: This woody climbing plant is used in India and Southeast Asia to treat "sweet urine" (high blood sugar or diabetes).
The evidence: No good studies have looked at whether gymnema can prevent or treat diabetes.
Cost of a month's supply: $5-$15.
The idea: Oxidative stress--whether from aging, pollutants, or other sources--creates free radicals that may interfere with insulin's ability to move sugar from the blood into cells. Lipoic acid can prevent the damage from free radicals.
The evidence: No studies have looked at whether lipoic acid can prevent diabetes. And only one good study has compared lipoic acid pills to a placebo in people with the disease. In 1999, German researchers found less insulin resistance in 55 people with diabetes who were given lipoic acid (600 mg, 1,200 mg, or 1,800 mg a day) for four weeks than in 19 similar people who were given a placebo. (8)
"The encouraging findings of this pilot trial need to be substantiated by further investigations," the researchers concluded. Seven years later, they haven't been.
Cost of a month's supply: $10-$30.
The idea: People with diabetes tend to have low levels of magnesium.
The evidence: In the Nurses' Health Study of 85,000 women, those who consumed the most magnesium from food and supplements (they averaged 375 mg a day) had about a 25 percent lower risk of being diagnosed with diabetes than those who consumed the least magnesium (an average of 220 mg a day) over an 18-year period. (9) But no studies have looked at whether giving people magnesium helps prevent the disease.
As for people who have diabetes, extra magnesium lowered insulin resistance or blood glucose levels in only four of the 11 good studies.
Bottom line: it's not clear whether magnesium can keep a lid on blood sugar.
Cost of a month's supply: $1-$2.
The idea: In large doses, the mineral can reduce blood sugar levels in laboratory animals.
The evidence: In four small studies, large doses of vanadium lowered insulin resistance in a total of 37 people with diabetes. (10-13)
But the amounts they were given--enough vanadyl sulfate to supply 20 to 30 mg a day of vanadium--was more than 10 times higher than the tolerable upper intake level (UL) of 1.8 mg. That's the highest daily dose that the National Academy of Sciences' Institute of Medicine considers safe for long-term use. In animal studies, high doses of vanadium cause kidney damage.
Some products exceed the UL. Vanadyl sulfate supplements from The Vitamin Shoppe and Ultimate Nutrition, for example, recommend the equivalent of 2 mg of vanadium a day. So does Blood Sugar Defense. And Optimum Nutrition VS-10 recommends 6 mg. None of them mention that vanadium might be toxic.
Our advice: don't take vanadium to lower your blood sugar. Come to think of it, there's no reason to take vanadium, period.
Cost of a month supply: $15-$70.
The pancreas makes insulin, which helps transfer sugar (glucose) from the blood into the body's cells, where it's either burned for energy or stored.
If your body produces no insulin, you have type 1 diabetes. If you produce, insulin but it's not very efficient at getting glucose out of the blood, you have insulin resistance (or poor insulin sensitivity). If that elevates your blood sugar slightly, you have pre-diabetes. If it pushes your blood sugar even higher, you have type 2 diabetes,
The blood sugar cutoffs depend on whether your blood is tested after a 12-hour fast (fasting blood sugar) or two hours after you're given a glucose-laden liquid to drink (oral glucose tolerance test).
Fasting Blood Sugar
126 mg/dL or higher below 126 mg/dL
100 mg/dL or higher below 100 mg/dL
Oral Glucose Tolerance Test
200 mg/dL or higher below 200 mg/dL
140 mg/dL or higher below 140 mg/dL
Source: American Diabetes Association (www.diabetes.org/pre-diabetes/pre-diabetes-symptoms.jsp).
(1) Am. J. Clin. Nutr. 76: 148, 2002.
(2) J. Trace Elem. Exp. Med. 12: 71, 1999.
(3) Diabetes Care 26: 3215, 2003.
(4) Journal of Nutrition 136: 977, 2006.
(5) Eur. J. Clin. Nutr. 56: 1137, 2002.
(6) J. Am. Coll. Nutr. 19: 738, 2000.
(7) J. Am. Coll. Nutr. 23: 248, 2004.
(8) Free Radical Bio. Med. 27: 309, 1999.
(9) Diabetes Care 27: 134, 2004.
(10) Metabolism 49: 400, 2000.
(11) Metabolism 45: 1130, 1996.
(12) Diabetes 45: 659, 1996.
(13) J. Clin. Invest. 95: 2501, 1995
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|Publication:||Nutrition Action Healthletter|
|Date:||Jun 1, 2006|
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