Cinnamon: What It Does and How to Choose It

Cinnamon is more than a warming spice — trials link it to modest blood-sugar effects. Here’s the cassia vs Ceylon difference, the evidence, and the coumarin caveat.

By PGP Iyer · May 28, 2026 · 1 min read

Cinnamon is the inner bark of Cinnamomum trees and one of the oldest trade spices. Beyond its warming flavor, it has been studied most for blood-sugar effects.

Blood sugar

A systematic review and meta-analysis found cinnamon was associated with modest reductions in fasting glucose in people with type 2 diabetes, though results varied across studies and effects on long-term control (HbA1c) were less consistent. Treat it as a possible supportive nudge, not a replacement for diabetes care.

Cassia vs Ceylon

Most supermarket cinnamon is cassia; Ceylon (“true” cinnamon) is milder and far lower in coumarin. The difference matters if you consume large amounts daily — see our guide on why the EU regulates coumarin and how the US differs.

In a daily cup

Tea-amounts of cinnamon are flavorful and generally well within safe coumarin limits for adults. If you drink heavily spiced cassia products every day, Ceylon is the lower-coumarin choice.

Types, sources, and active compounds

Ceylon (“true”) cinnamon comes from Cinnamomum verum, while cassia comes from Cinnamomum cassia (also called Cinnamomum aromaticum). Both owe their warming flavor largely to cinnamaldehyde, with related compounds such as cinnamic acid. Both are used across sweet and savory cooking; cassia is bolder and the more common supermarket type, while Ceylon is milder.