Cinnamon: A Therapeutic Alternative?Posted February 22, 2012 by Doron Schneider, MD, FACP
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 , increased glucose uptake in muscles and increased glucose transporter mechanisms (GLUT-4) that assist in removing glucose from the blood. Additionally, cinnamon may delay gastric emptying  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.
Clinical Trials: A Mixed Bag
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  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  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.
Does it Add Up?
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:
· Research suggests that cinnamon may be a powerful nutrient for maintaining blood sugar levels already within the normal range
· Clinical studies using Cinnamon show positive effects promoting healthy glucose metabolism.
· Dietary Supplement Cardiovascular Support May Support Healthy Serum Lipids Potent Antioxidant* True Cinnamon Bark has been historically used as a digestive aid and to promote other health benefits. Recent studies indicate that Cinnamon may also help support healthy serum lipid levels. In addition, Cinnamon contains potent antioxidants that help to support cardiovascular function. * Free of: sugar, salt, starch, yeast, wheat, gluten, corn, soy, milk, egg or preservatives. *This statement has not been evaluated by the FDA. This product is not intended to diagnose, treat, cure or prevent any disease.
· Cinnamon's natural polyphenols have a beneficial effect on sugar metabolism, helping to maintain healthy blood sugar levels already within a normal range.
Can It Hurt To Try?
So what is the potential harm of cinnamon? There are two types of cinnamon that are readily found – Ceylon and Cassia cinnamon. Cassia cinnamon contains coumarin– from which warfarin is derived. While coumarin may yield improvements in glucose metabolism, it may also lead to liver damage (in individual who are susceptible or sensitive). In its powder form it may also lead to severe burning in the mouth and throat if ingested in large quantities, given its propensity of drying out the mucus membranes (this being the root of this increasingly popular ”Cinnamon Challenge”). Finally, as with any ingested compound or chemical, there is always a risk of allergic reaction.
The most concerning harm, in my opinion is the opportunity cost. When an individual takes cinnamon in an attempt to lower A1C and delays taking agents that have been proven to lower glucose (e.g., diabetes medications regulated by the FDA) then likelihood of end organ damage due to hyperglycemia is increased.
So what should a practicing physician do to counsel an individual who presents with diabetes and is interested in cinnamon? First, remember the maxim “do no harm.” For individuals who have liver disease it simply may not be worth the risk (no matter how small) of any exposure to significant quantities of cinnamon. Second, if the individual is not at goal A1C, I would recommend an agent that is on the ADA or AACE guidelines that is appropriate for the A1C level. Cinnamon, in my opinion, may be used adjunctively, but not as a substitute to evidence-based therapies.
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