https://www.foxnews.com/health/daily-coffee-drinking-linked-major-health-benefit-women-age-study-finds
I've been thinking about this lately because when I tell people that tea blocks iron absorption (and I think other minerals), they immediately assume that it's because of the caffeine. Actually caffeine has no impact on iron absorption.
And it's not a trivial effect - if you drink a strong cup of tea and then take an iron supplement, I've read you absorb 70% less than if you did it more than two hours apart from drinking tea.
It appears that it is the polyphenols in tea and it appears that tea has a more pronounced effect than coffee, even though both are high in polyphenols.
All that to say that I think a lot of people read about health effects of coffee and assume those effects (good or bad) are from the caffeine because it's the one thing we know.
As it turns out, the science of nutrition is immensely complex and in some ways we're still in an early phase compared to, say, physics.
>some ways we're still in an early phase
Very, very early. When I went on dialysis, we soon learned that clinical nutritionists were just taking up space. Luckily, I could do deep search.
>tea
Black tea is restricted for dialysis patients. Black tea is rich in oxalate which can lead to kidney stones or deposits in the kidneys.
For transplant patients, green tea is known to alter tacrolimus (major immunosuppressant drug) levels.