Curcumin is the compound turmeric is named for, and nearly all the research you have heard about is done on concentrated curcumin extracts rather than on the spice in your food.
Absorption is why that distinction matters. Human volunteers given 2 grams of curcumin, far more than any recipe delivers, had blood levels that were undetectable or very low. The same study found that piperine, the compound that makes black pepper hot, slowed curcumin’s breakdown and raised what reached the blood (Shoba et al., Planta Medica, 1998). That is where the turmeric and pepper pairing comes from, and it is a real mechanism rather than folklore.
This page used to say research suggests turmeric supports joint comfort and mobility, and that studies indicate benefits for brain function and memory. Those are claims about health conditions and neither was carrying a source. Both are gone, and the change is logged on the corrections page.
A tablespoon of ground turmeric is 9 calories with almost nothing in the way of macronutrients. Use it for color, for flavor, and with black pepper. Do not expect a curry to deliver a study dose.