>Is there anything similar in the science of anti-aging? Where (A) The body of research is large, well established, and mostly uncontroversial; (B) The benefits and safety profile are good; (C) The majority of people who are serious about this stuff use it/take it/do it.
The sodium/potassium ratio, and particularly keeping it smaller. The top answer right now is "nutrition", but that's a hairball, and the Na/K is a bright spot that gets left out of the discussion precisely because it is much less controversial than the endless debate over macronutrients and staples. The sodium/potassium ratio has effects on:
In general, potassium is found in fruits and vegetables. It has to be spread throughout the day, because high quantities of potassium at once have a laxative effect. The highest concentrations are found in some vegetable concentrates — the densest source in your cabinet is probably tomato sauce. It is present in milk and yogurt but not in cheese.
Potatoes and other starchy vegetables like squash and plantains have significantly more potassium than grains, but it's not necessary to completely give up grains. I usually put a 50/50 potassium/sodium ("Lite") salt on the oatmeal or grits I make for lunch (work requires speed), but I don't bother with it otherwise.