Responding to the reader:
Chromium, stevia, and cinnamon
Nutrition researchers respond to a reader's question about impact on blood-sugar levels.
About this feature
AHFMR frequently receives letters requesting information about Heritage research or about various medical conditions. "Responding to the reader" is an AHFMR Research News feature intended to provide up-to-date information related to readers' questions, with the help of experts in the Alberta research community. AHFMR cannot provide medical advice, however; please consult your family physician about your specific health concerns.
Glucose is an essential fuel for life. Yet almost two million Canadians suffer from type 2 diabetes, a chronic disease in which the cells of the body cannot use glucose for energy. The hormone insulin helps transport glucose from the blood into cells. But some people with type 2 diabetes don't make enough insulin; others make it, but their cells don't respond to it, essentially locking glucose out. Consequently, that glucose circulates and builds up in the blood, causing heightened sugar levels and leading to complications such as heart disease, kidney damage, and even blindness.
A reader has asked if research exists on the impact of chromium, stevia, and cinnamon on blood-sugar levels. To find out more, we talked to Dr. Rhonda Bell, an associate professor of human nutrition, and Dr. Catherine Field, a professor of nutrition and metabolism, both based at the University of Alberta.
"Chromium is important for insulin secretion," explains Dr. Bell. "Studies looking at chromium-deficient mice show they have reduced carbohydrate metabolism, which leads to higher blood-glucose levels." And is chromium deficiency a problem in humans? "As a general rule our population has adequate chromium intake," says Dr. Bell. "There may be a genetic subpopulation of type 2 diabetics that can't utilize chromium, and in that case chromium supplementation could be beneficial. We're still too early in the research picture to understand if this subpopulation really exists. I would steer the average person away from supplementing with additional chromium until we know more. It could interfere with the absorption of other important nutrients such as calcium or iron, and cause problems rather than help."
While the picture on chromium is still forming, research on the sweetener stevia is scant at best. There has not yet been a project examining the effect of stevia on blood sugar in humans, but research in rodents shows that it has a negligible effect on blood glucose, even when given in high doses. "Stevia doesn't lower blood sugar levels and it doesn't raise them either," Dr. Field explains. Given that stevia is 300 times sweeter than sugar, it shows promise as a possible substitute for sugar or aspartame. But Dr. Field is quick to caution: "Although stevia is available, it has not been approved for use as a sweetener in Canada. It's probably safe, but it's best to take the ‘wait and see' approach."
Of the three compounds mentioned in the reader's question, only Cinnamomum cassia (the cinnamon found at the grocery store) has been demonstrated to have insulin-like activity. But while some studies show that cinnamon can lower blood sugar, others show that it has no effect. As with chromium, it could be that cinnamon is effective only in certain populations that have yet to be identified. Dr. Field stresses that the amount of cinnamon administered in these studies is high. "People are taking up to twelve 500-milligram capsules per day. We're not looking at a small amount of cinnamon sprinkled on your oatmeal in the morning; these are therapeutic doses."
Both Dr. Bell and Dr. Field agree that no supplement can replace a healthy diet and physical activity, especially when managing type 2 diabetes. "Eat a diet that emphasizes a wide variety of foods," stresses Dr. Bell. A supplement may contain only one compound; food contains a variety of compounds and nutrients that interact. "These interactions can be beneficial in ways we don't yet understand. Moderation and good food choices-that's the key to being healthy and keeping blood sugar in check."