Summary
Which cinnamon supplement is highest in PACs?
Cinnamon may modestly help control blood sugar levels (see What It Does) and the active compounds in cinnamon are believed to be proanthocyanidins (PACs). Among the supplements we tested, PACs were found to range from 7.2 mg to 33 mg per daily serving. Interestingly, just a ¼ to ½ teaspoon of some of the ground cinnamon spices provided more PACs than some supplements. However, supplements were lower in toxins, making them a safer choice for daily use. (See PAC amounts in Supplements and Spices and How Products Were Evaluated).
Our tests included cinnamon supplements from Swanson, Trunature (Costco), GNC, and NutriFlair and ground cinnamon spices from 365 (Whole Foods), Anthony's, FGO, Frontier Co-Op, Kirkland Signature (Costco), McCormick, Penzeys, Simply Organic, and Trader Joe's.
How much lead and coumarin did ConsumerLab find in cinnamon?
A concern with cinnamon is that it may contain significant amounts of coumarin — a naturally occurring compound that may cause liver toxicity and is a potential carcinogen. Coumarin can be high in cassia cinnamon (the most common type of cinnamon, often labeled as Vietnamese, Saigon, Chinese or Indonesian cinnamon) but should be low in Ceylon cinnamon — also called "true" cinnamon or Cinnamomum verum — and in cinnamon extracts.
However, ConsumerLab discovered a considerable amount of coumarin in single servings of two cinnamon supplements, one of which should have virtually none, suggesting that it was mislabeled. In addition, one of the spices exceeded the coumarin limit for adults and several others approached this limit if taken at just 1 gram (1/2 teaspoon) per day. (See coumarin amounts found in Supplements and Spices).
One of the cinnamon spices had a particularly high concentration of lead — just above ConsumerLab's limit. Lead in cinnamon is of growing concern based on government reports.
Which cinnamon supplement is best?
In our tests, one supplement stood out among the others for providing a high amount of PACs, a safe amount of coumarin, passing all contamination testing, and being relatively inexpensive. It was chosen as our Top Pick among cinnamon supplements.
Which ground cinnamon spice is best?
We chose one overall Top Pick ground cinnamon and one Top Pick Ceylon cinnamon based on lower levels of lead and coumarin, higher levels of PACs, and good value.
Cautions with cinnamon
Small amounts of cinnamon are generally safe, but daily use of large amounts of cinnamon can affect blood sugar levels, interact with blood thinners, and may increase the risk of liver damage due to coumarin and interactions with medications (see Concerns and Cautions).
