Every time we crack a hen's egg and throw away the shell, we discard something like ten grammes of calcium carbonate (minus the membrane - i've just weighed one). That would be about four grammes of calcium we lose each time, which is four times the RDI of calcium.
So, i propose this: take an egg, wash it, crack it and do what you will with it. Then, put it in a cup, add nineteen grammes of citric acid, possibly in the form of lime juice, dissolve the calcium, filter it and either recrystallise or drink the result.-- nineteenthly, Jan 30 2011 Video version on YouTube http://www.youtube....ndex=1&feature=plcpDemonstration [nineteenthly, Oct 12 2012] I've done exactly this, using lemon juice. I didn't bother to filter it, just fished out the membrane.
I was also working on a theory that crushed eggshells, mixed with a binder, could be used as a dental filling material. It would create a slightly alkaline, mineral rich environment which may assist with remineralisation.
(A few minutes later) I just chewed and swallowed a raw, rinsed eggshell on the grounds that my stomach can produce perfectly good acid all on its own.
Your calculation for the amount of calcium in an eggshell may be a little off, as eggshell is not pure calcium carbonate; I think it contains some protein and magnesium salts. If anything, however, that probably makes eggshells an even better supplement.-- spidermother, Jan 30 2011 Yes it can but the thing is, as it stands calcium carbonate is alkaline and so is not too marvellous for the stomach's oxyntic cells. It'd be like taking calcium carbonate as a dietary supplement, which some people do of course, but calcium citrate is more neutral. Anyway, good.-- nineteenthly, Jan 30 2011 OK, i have now done another video version of this. I'm probably going to do a lot of video versions. Has anyone got suggestions about whether it's just going to be annoying for me to churn my ideas this way by posting links and how to avoid this? Should i just set up a playlist and put it on the profile page or what? Or is it not as annoying as i think it might be?-- nineteenthly, Oct 12 2012 kinda baked since 1700s I recycle mine, the chickens eat their egg shells. I use either a microwave or plain old oven to heat them to make them easier to crush and probably less chance of feeding them bacteria etc.(which they probably already have)-- PainOCommonSense, Oct 12 2012 ... so RDI eggshell is about a quarter of one ?-- FlyingToaster, Oct 12 2012 Do eggshells contain magnesium also? Calcium supplements in the absence of corresponding magnesium supplementation are extremely bad news.-- MaxwellBuchanan, Oct 12 2012 they have quite a lot of water in them. once made into a fine powder and dried they weigh very little indeed. Depending on your diet you may already be getting plenty of calcium, otherwise I recommend eating the joints and marrow of bones.-- WcW, Oct 12 2012 The usual practice with eggs seems to be to throw away the shells, possibly into compost and therefore potentially back into food you eat in the end, and chucking it in with some kind of nutrient-rich acidic juice would seem to be a worthwhile use of the things. I have to say i'm inclined towards eating wood ash from safe sources right now though.-- nineteenthly, Oct 12 2012 having a few times consumed powdered eggshell I do not consider it to be a desirable food. It is possible that it is more palatable in liquified form. Given my consumption of dairy and meat (chicken and chicken bones) is quite adequate I do not worry much about it. Recently it came to my attention that you can overdo on calcium and so, meh.-- WcW, Oct 12 2012 You can overdo it, but this idea was mainly aimed at women concerned about bone density who already had osteopenia when i thought of it, so that's not a problem here. There is also a difference between the absorption of calcium phosphate in bone and teeth, and calcium citrate prepared this way. There would be a risk with overdose as usual, but daily requirements are higher with calcium than for any other inorganic nutrient unless you count water.-- nineteenthly, Oct 13 2012 Even for osteoporosis (is that the same as osteopenia? I thought osteopenia was the penis bone?), the ratio of magnesium to calcium intake is probably more important than calcium intake per se.-- MaxwellBuchanan, Oct 13 2012 I think there is magnesium in eggshells. Magnesium is available from other sources anyway. It might be worthwhile looking for a good source of magnesium in an acidic food. Spinach fits the bill but calcium oxalate isn't suitable, unfortunately.-- nineteenthly, Oct 13 2012 Studies with calcium supplements from tablets have shown adverse effects, whereas studies where dietary calcium was raised by eating more dark leafy vegetables showed benefits; one possible reason is that the vegetables also provide magnesium, maintaining a good ratio of instake.
I know this stuff because of a long correspondence with a doctor who's interested in human responses to microgravity. There are lots of little-discussed adverse effects, and magnesium/calcium problems play a huge part. Microgravity also accelerates ageing, which I didn't know before.-- MaxwellBuchanan, Oct 13 2012 That makes this particular ex-vegan happy, [MB].-- nineteenthly, Oct 14 2012 Why? Did you spend a long time in microgravity en route from Vega?-- MaxwellBuchanan, Oct 14 2012 random, halfbakery