I’ve worried about the relatively low calcium amounts provided by most paleo diets. Maybe I shouldn’t. Fanatic Cook Bix has a new post about various calcium absorption mechanisms in our bodies. If intake is low, certain mechanisms kick in, allowing us to absorb more than is usual. I quote:
So, someone who is eating less than 400 mg – which is half the recommended amount (the DRIs are 800-1000 mg/day, some groups recommend up to 1300 mg) – may, all else being equal, end up with a similar calcium status as someone eating 1000 mg or more because an active transport mechanism kicks in at lower intakes. As well, more calcium may be absorbed from the colon.
Calcium is not unusual in this regard. Absorption of nutrients is often higher when intake is low, and vice versa. Zooming in on one nutrient, in this case calcium, and fretting over whether we’re “getting enough” has a downside if it leads to taking supplements. Many nutrients compete for intestinal absorption, e.g. zinc supplements have been shown to substantially reduce calcium absorption. And, it should be said, what the body doesn’t absorb goes out with the feces.
It may be better to focus on eating a variety of minimally processed foods than to focus on discrete nutrients, and let the body take care of itself.
At any given time, I usually have at least one little old lady on my hospital service who has fallen and fractured her hip, wrist, pelvis, or humerus (arm bone that’s part of the shoulder). Nearly always she has the bone-thinning disease called osteoporosis, which may be related to calcium consumption. If we can prevent osteoporosis with diet and exercise, that’s much preferable to dealing with the fractures.