Turmeric
Demonstrably works on pain, and on its own barely reaches your blood. That is why black pepper stands next to it.
How to use it
Through hot food, in a curry, through soup, through rice. Always with black pepper and some fat.
The best version
Fresh root, or ground powder from a single origin. Turmeric is one of the spices that gets cut and dyed, so buy from a seller who says where it came from.
How to prepare it
Cook it in fat, with a pinch of black pepper. It stains everything it touches, your worktop and your fingers included.
What it does
Against knee osteoarthritis it has been tested and it works. Eleven randomised trials with 1258 people between them found less pain on both the visual scale and the WOMAC questionnaire, and against anti-inflammatory drugs turmeric came out ahead on pain. A higher dose did no better than a lower one.
Watch out
Curcumin on its own is barely absorbed. After 2 grams of powder, blood levels in healthy volunteers were undetectable or very low; with 20 milligrams of piperine, the compound in black pepper, absorption rose by 2000 percent. Turmeric without pepper is mostly colour.
The trials use curcuminoids in capsules, at doses a teaspoon of powder does not reach. Through your food it is a good habit rather than a treatment.