Cinnamon

Possibly a little, in some groups. A 2024 meta-analysis of 12 trials in women with PCOS found lower fasting blood sugar and improved insulin resistance, plus a small weight drop of about 0.47 kg. That is one population, and pooled trials vary in form and length. Cinnamon is not a treatment for diabetes and shouldn't replace medication.

For safety, Ceylon. A 2012 analysis of retail samples found cassia averaging 2,650 to 7,017 mg of coumarin per kilogram of bark, while a Ceylon sample had none detected. At Europe's 0.1 mg/kg limit, a 70 kg adult reaches the ceiling at roughly 1 to 2.6 g of cassia a day. Most dosing research used cassia, though.

It depends on the form. Bark powder trials used 1 to 6 g a day, while an extract trial used 500 mg a day of a water-soluble form. The two aren't comparable milligram for milligram, so follow your product's label. With cassia, keep coumarin in mind, since a few grams of bark can pass Europe's tolerable intake.

Cassia's coumarin has been linked to liver injury at high, sustained intake. A 2015 case report described hepatitis in a woman taking a cinnamon supplement with a statin; it resolved when both were stopped. Yet a study of 129 patients on cinnamon-bark herbal medicines found most exceeded the coumarin limit with no significant difference in abnormal liver tests. Mixed, not settled.

Not shown in people. A 2023 systematic review found 38 of 40 included studies were in animals or cell cultures. The only two human trials conflicted: one found a memory benefit from chewing gum in adolescents, the other found no effect. That isn't enough to support taking cinnamon for brain function.