Alternative medicine (also known as complementary medicine) has become a multibillion dollar industry. A subset of complementary medicine is dietary supplements–many of which may hold promise as adjuncts to more traditional therapies and treatments. The evidence basis for many of these ”therapies,” however, often remains immature and at best anecdotal in nature. 

 

At the same time interest amongst the public and traditional healthcare providers has increased in recent years, as have formal studies with increasing scientific rigor led by the NIH and other prominent academic medical centers. 

 

 

It is with this backdrop that we examine a popular natural additive/supplement used by many for the treatment of diabetes: cinnamon.   When examining cinnamon (and any therapy) we must weigh the known benefits against the real and theoretic harms as well as the cost (both real and opportunity) when deciding on use.

 

Cinnamon comes as a powder, capsule, stick, raw bark, and other forms and can be purchased in a variety of locations–ranging from health food stores to the supermarket. So, what are the purported benefits of cinnamon and what does the scientific evidence tell us?  From a high level the easiest statement to make is that the scientific data are mixed. Multiple studies have been conducted (both animal and human) in the last two decades. The benefits of cinnamon seem to focus on several mechanisms including: insulin mimetic action driving glycogen synthesis from glucose^[1] , increased glucose uptake in muscles^[2]  and increased glucose transporter mechanisms (GLUT-4) that assist in removing glucose from the blood^[3].  Additionally, cinnamon may delay gastric emptying ^[4] and thus lead to less post-prandial sugar elevations. I found no studies supporting direct activity of cinnamon on the beta cells of the pancreas, however.

 

 

From this basic science we move to actual clinical trials and find a mixed bag.   Unfortunately, most of the trials were small studies involving only several dozen patients each. Each trial evaluated quantities of cinnamon that ranged from 1 to 6 grams per day. While a recent trial ^[5]  involving 109 type 2 diabetic patients demonstrated an improvement in A1C of 0.46% greater than placebo in the group randomized to take cinnamon, other studies do not demonstrate benefit.   However, a recent meta-analysis ^[6] of eight studies demonstrated a net benefit of cinnamon ingestion on fasting blood sugars. The study found that cinnamon intake, either as a whole cinnamon or as an extract, results in a “statistically significant lowering in fasting blood glucose (FBG) (-0.49±0.2 mmol/L; n=8, P=.025). Intake of cinnamon extract only also lowered FBG (-0.48 mmol/L±0.17; n=5, P=.008)."

 

In addition to the possible affect on glucose metabolism, many other health benefits are attributed (mostly by the manufacturer) to insulin, including the relief of congestion,  pain and stiffness of joints and symptoms of arthritis, and menstrual discomfort, as well as the stimulation of circulation. Many of these are other claims are based on anecdotal reports and / or less than optimally designed trials.

 

 

So what to make of all of these alleged benefits?

 

First a basic primer on supplements: they are poorly regulated.  The FDA defines dietary supplements as a product taken by mouth that contains a "dietary ingredient" intended to supplement the diet. The "dietary ingredients" in these products may include: vitamins, minerals, herbs or other botanicals, amino acids, and substances such as enzymes, organ tissues, glandulars, and metabolites. Dietary supplements can also be extracts or concentrates, and may be found in many forms such as tablets, capsules, softgels, gelcaps, liquids, or powders. The FDA has little oversight over the manufacturing or safety of supplements.  

 

Additionally existing law and regulations allow for marketing and labeling by which manufacturers can make health claims that link a food substance and disease or a health-related condition and the intended benefits of using the product. This language can be confusing and potentially misleading to the public. Details of the FDA oversight can be found at: http://www.fda.gov/food/dietarysupplements/default.htm . Example to the claims found on popular cinnamon supplement labels include: