Cinnamon and sugar — blood sugar, that is

Each January brings advice on how to start the New Year off right, revitalize ourselves and get healthy. Superfoods are credited with special powers to protect us from cancer, heart disease and other diseases of aging. Cinnamon is one such food. It has been widely heralded for its ability to stabilize blood sugars and ward off diabetes.

Cinnamon’s reputation for controlling glucose and cholesterol levels in diabetics isn’t surprising. Its purported abilities have been widely reported for years in popular magazines like Science Daily, newspapers, television news, and even WebMD for medical professionals. What may be surprising, however, is to learn that the media has been silent on a new study of five randomized controlled clinical trials which found no support for these claims surrounding cinnamon.

Beliefs surrounding healthy foods are hard to shake when the science is never reported. How many still believe that fruits and vegetables can prevent cancers and heart disease, even though none of the claims have held up in clinical trials?

So, here is another study the news forgot.

Pharmacists and doctors at the University of Connecticut and Hartford Hospital, led by William L. Baker, PharmD, BCPS, conducted a systematic literature search for all randomized, placebo-controlled, clinical trials of cinnamon and its effects on A1C, fasting blood sugars or lipid parameters for diabetics that had been conducted through July 2007. Their results were published in this month’s issue of the journal Diabetes Care.

Given how intensely cinnamon’s properties have been acclaimed worldwide, the few number of studies and their small sizes were surprising. Only five clinical trials were identified on 282 diabetics. They all used the common cinnamomum cassia and one trial examined three different doses and found no dose-response relationship. The trials lasted a median of 3 months, which was long enough to observe clinically significant changes in fasting blood sugars and lipid levels, they reported. While the full effects on A1C wouldn’t be evident, if a clinical benefit truly existed, the Connecticut researchers said, there would have been notable changes in A1C during this study duration.

“Instead, A1C levels increased to a greater extent with cinnamon than with placebo in our meta-analysis, thus reducing our confidence in cinnamon’s impact on long-term glycemic control,” they reported.

They also identified possible weaknesses which could explain the only disparate findings reported in 2003 by one study from Pakistan, such as small sample size (only 5 people at each dose), those receiving cinnamon and the placebo were not blinded, and findings were so small they could be due to chance. Reading that study, in fact, found that diet and exercise and other diabetes interventions were not controlled for, the only sustained change in fasting blood sugars was a small change seen among those receiving the least amount of cinnamon (no dose reponse); and changes in triglyceride and HDL-cholesterol levels were not signficant after 40 days among those who had received even the highest amounts of cinnamon. [The media had neglected to report this critical information in 2003, too.] Perhaps a larger meta-analysis might have been able to bring some of the endpoint effects into statistical significance, Baker and colleagues said, but “their clinical significance could still be debated.”

Their analysis found no significant effect on A1C, fasting blood sugars or lipid parameters of eating measured daily amounts of cinnamon. Separate analyses excluding nonblinded trials or evaluating the type of diabetes separately did not change their results. Baker and colleagues concluded:

In this meta-analysis of five randomized placebo controlled trials, patients with type 1 or type 2 diabetes receiving cinnamon did not demonstrate statistically or clinically significant changes in A1C, FBG, or lipid parameters in comparison with subjects receiving placebo... Cinnamon does not appear to improve A1C, FBG, or lipid parameters in patients with type 1 or type 2 diabetes.

Cinnamon makes our favorite baked apple and fruit desserts, cookies and scones, cinnamon rolls, cinnamon-raisin bread, and countless other sweet and savory recipes taste wonderful. But there is no evidence it is a substitute for insulin or can prevent diabetes.