Cinnamon

Cinnamon may be the most pharmacologically active ingredient in your spice rack. Multiple meta-analyses of randomised controlled trials confirm it lowers fasting blood glucose, HbA1c, and cholesterol -- but there is a critical detail most people miss: there are two very different kinds, and one of them can damage your liver.

Why It Matters for Longevity

The book identifies cinnamon's potential to lower blood glucose and reverse fructose-induced insulin resistance, and the external evidence strongly supports this. Allen et al. (2013, PMID 24019277) pooled 10 RCTs and found cinnamon supplementation (120 mg to 6g/day) reduced fasting blood glucose by an average of 24.6 mg/dL, with significant reductions in total cholesterol, LDL, and triglycerides. Costello et al. (2016, PMID 27756683) confirmed the finding specifically in type 2 diabetes patients, reporting a clinically meaningful HbA1c reduction of roughly 0.8% -- comparable to some first-line diabetes medications.

The mechanism involves multiple pathways. Ranasinghe et al. (2013, PMID 24019249) identified that cinnamon's proanthocyanidins mimic insulin signalling, enhance glucose uptake into cells, improve glycogen synthesis, and inhibit gluconeogenesis in the liver. These are Type A proanthocyanidins, which are more bioavailable than the Type B form found in most other foods.

Now the critical distinction: most cinnamon sold worldwide is cassia (Cinnamomum cassia), which contains 0.3-1.2 g of coumarin per 100g. Coumarin is hepatotoxic at high doses, and the EU tolerable daily intake is just 0.1 mg/kg body weight. If you weigh 70 kg, that is 7 mg of coumarin -- roughly one teaspoon of cassia cinnamon. Ceylon cinnamon (Cinnamomum verum) contains 250 times less coumarin and is strongly preferred for regular daily consumption. If you are using cinnamon therapeutically, check which species you are buying.

How to Use It

Use Ceylon cinnamon several times per week in cooking and teas. The book recommends adding it to poached fruit, lentil soups, and herbal teas. Buy sticks rather than pre-ground -- sticks retain flavour for up to three years, while ground cinnamon goes flat within months. Grind sticks fresh as needed. For blood glucose management, consume with or shortly before carbohydrate-containing meals. Therapeutic doses in studies ranged from 1-6g per day.

What to Pair It With

Flavor Profile

Cinnamon is warm, sweet, and woody with a gentle spiciness that is never aggressive. Ceylon cinnamon has a more delicate, slightly citrusy complexity; cassia is sharper and more one-dimensional. The aroma is distinctly sweet and comforting -- one of the most universally appealing smells in food. Sticks impart a subtler flavour over long cooking; ground cinnamon delivers immediate intensity.

The Science

• Allen et al. (2013): Cinnamon reduces fasting glucose by 24.6 mg/dL, plus LDL and triglycerides (PMID 24019277)
• Costello et al. (2016): HbA1c reduction of ~0.8% in type 2 diabetes patients (PMID 27756683)
• Ranasinghe et al. (2013): Multiple anti-diabetic mechanisms including insulin mimicry (PMID 24019249)
• Examine.com: Moderate evidence for glucose and HbA1c reduction; distinguish Ceylon from cassia

Key Nutrients