A dash of cinnamon can enhance the flavor of an apple pie, but there may be more to this familiar spice than meets the tastebuds. Though evidence is mixed, some studies suggest cinnamon may help to reduce the levels of glucose (sugar) in blood.

Read on to learn if adding a dash of cinnamon to your diet here and there, or even taking a supplement, can help if you have or ).

Cinnamon is sourced from the inner bark of the tree. When removed from the trunk of the tree and allowed to dry, the bark naturally rolls up into quills commonly known as cinnamon sticks. The quills are sold as is or ground into a fine powder.

Both forms are easy to find on grocery store shelves and anywhere spices and cooking ingredients are sold.

Two types of cinnamon are available in the United States: Ceylon, or "true cinnamon" is the more expensive. The other variety of cinnamon, cassia, is used to flavor most food products.

The distinctive flavor and aroma of cinnamon come from an essential oil called cinnamaldehyde. It's believed that this essential oil has both antimicrobial and anti-inflammatory properties. Cinnamon also has significant amounts of antioxidants, higher than 25 other spices. 

Research looking at the potential effects of cinnamon on blood sugar levels have proposed two ways that the spice may be beneficial.

The first is by having an in the body—in other words, triggering cells to remove glucose from the blood. The second is by increasing the activity of the transporter proteins that move glucose out of the bloodstream and into cells.

Conclusive studies investigating the use of cinnamon in are lacking. Those that do exist are contradictory, with some showing significant positive effects and others showing little to no effect.

However, there have been some positive findings. The conclusions tend to be limited given the small size of the studies. Others are simply poorly designed.

Among the positive findings, a 2013 meta-analysis of 10 randomized controlled trials concluded that ingesting cinnamon can lower fasting blood sugars.

The analysis also found that cinnamon had a positive effect on total cholesterol, triglycerides, and "bad" low-density lipoprotein (LDL) cholesterol.

In addition to adding cinnamon to your food, there are also cinnamon supplements that you can buy online and at nutritional supplements stores. There are no guidelines for the appropriate use of these supplements, although some manufacturers recommend 2,000 milligrams (mg) per day.

An April 2019 review in  reported that the most common side effects from cinnamon consumption include gastrointestinal symptoms and . Side effects tended to be transient and improve on their own treatment was stopped.

That said, adding reasonable amounts of cinnamon to food isn't likely to be harmful. In studies that found cinnamon had a positive effect on blood sugar levels, subjects ingested the equivalent of one teaspoon per day —amounts small enough to easily work into a regular diet simply by sprinkling it on morning oatmeal, adding it to a chili recipe, or sipping it in tea.

As with all dietary supplements, it should be noted that supplements are not regulated by the U.S. Food and Drug Administration.