Prehistoric Calcium Intakes
Question I received:
[I]t has always bugged me that the fact that humans need to consume other animal’s milk to meet their calcium requirements seems to be evolutionarily illogical or odd. As you said vegans and people who do not eat diary have a lower calcium intake and are in the deficiency range, yet this somehow doesn’t make sense to me from a philosophical point of view….I wonder, have there been studies on vegan children and their calcium requirements? Are they lower than their non-vegan counter-parts?
On average, vegans have lower calcium intakes, with studies showing average intakes well below the RDA of 1,000 mg. But a vegan diet can have a much higher calcium intake if the person eats large amounts of greens every day. It’s just that most vegans do not eat this many greens (at least 3 servings per day of collards, kale, broccoli, mustard greens, turnip greens, or bok choy). And, of course, a vegan eating fortified foods would have higher calcium intakes.
Prehistoric human diets may have contained much larger amounts of calcium than what the average vegan gets without consuming dairy. I spent a few minutes looking around for this information today and the most recent source I could find was a paper by Eaton & Nelson from 1991. They conclude that “Stone Agers” consumed 1500 mg/day of calcium or more without dairy (1). It is a free download so if you are real interested you can take a look at the various foods that provided calcium.
To further complicate this question, sodium can cause significant loss of calcium from bones and there is evidence that our prehistoric ancestors did not consume anywhere close to as much sodium as the average person does today, which could result in a higher RDA than otherwise necessary.
All that said, there are a tremendous number of differences between modern and prehistoric lifestyles, and our ability to study prehistoric diets is rather limited, so I do not put much importance on using diets of our ancestors in order to shed much light on how we need to eat today for optimal health. And just because they might have had calcium intakes of 1500 mg, doesn’t mean that was the ideal amount even for them.
Unfortunately, there have not been any studies on the bone health of vegan children, though, anecdotally, I’m not aware of any vegan children with bone problems.
1. Eaton SB, Nelson DA. Calcium in evolutionary perspective. Am J Clin Nutr. 1991
Jul;54(1 Suppl):281S-287S. | link