Fish Oil and Spice and Everything Nice

Can dietary supplements help treat diabetes? Yes. And no.

By Dr. Robert W. Lash|Tuesday, January 08, 2008

A few years ago, I was taking care of a woman who developed diabetes during her pregnancy. Changes in her diet were not working, and I was getting ready to have the dreaded "you might need insulin" talk.

Instead, she asked me if she could try taking cinnamon. She had read that cinnamon was an effective treatment for type 2 diabetes and thought it might be good for her, too. She was right. A 2003 study on Pakistani patients with poorly controlled diabetes showed that cinnamon reduced glucose and cholesterol levels. She gave it a try, and it seemed to work—she was able to avoid insulin during her pregnancy.

Dietary supplements for diabetes have been around for a long time. Many are peddled by con men preying on vulnerable patients. Others, like cinnamon, have some real data backing them up. Two new studies, looking at cinnamon and fish oil, point out both the drawbacks and benefits of dietary supplements.

The cinnamon study, published in DiabetesCare, is the first to look at cinnamon in Americans with type 2 diabetes.The patients received 1,000 milligrams of cinnamon a day for three months. None of their other diabetes medicine could be adjusted during this time—just to keep things fair. At the end of the study, there was no difference between the cinnamon and placebo groups in terms of glucose or cholesterol.

So why did cinnamon have a positive effect on Pakistani patients but no effect on American patients? One difference between the two groups was that the Americans started the study with much better glucose levels than the Pakistani group. The Americans had fasting glucose levels of 139, compared with 232 in the Pakistan study. (For comparison, a normal fasting glucose is less than 100, and diabetesis anything over 126.) It may be that you need to have higher glucose levels to see the effects of cinnamon, or it may be that American diets already have enough of that special something that cinnamon provides.

The fish oil study examined a different question: In children at risk for type 1 (juvenile onset) diabetes, does the consumption of fish oil reduce their risk of developing early signs of the disease? For this study, published in The Journalof the American Medical Association, investigators asked parents to fill out an annual food diary. They then calculated the amount of omega-3 fatty acids the children consumed over six years. To confirm the accuracy of the diaries, they also measured the amount of omega-3 fatty acids in the children's red blood cells. They made no effort to alter the children's diets, and the diet diaries covered everything the children ate, not just fish.

What they found was that the children who had more omega-3 fatty acids in their diets were less likely to develop the earliest signs of type 1 diabetes. This went along well with an earlier study from Norway that showed that children who received cod-liver oil as infants also had a reduced risk of developing type 1 diabetes.

For cinnamon, the jury is still out. It's probably not great for people with mild diabetes, and we don't know if taking that much cinnamon will have any side effects (other than possibly smelling like a Christmas cookie). For fish oil, this is yet another piece of evidence that fish is good for you. Now all we have to do is worry about the mercury in that fish. Unfortunately, there are rarely simple answers to questions about feeding the complicated machine that is the human body.

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