Don't come out of your shell.

July 31, 2016 10:25 AM

Is it OK to eat the shells with soft or hard boiled eggs?

The shells have been boiled along with the egg so pathogens aren't the concern.

Googling this shows a lot of discussion on how to grind eggshells to make a calcium-rich powder to sprinkle in small amounts on food. However, I'm talking about just eating the shell along with the egg. (I need to take calcium anyway for a bone issue, and I actually like the crunch of eggshells in egg salad and soft-boiled eggs.)

So: is this amount of calcium carbonate in this form potentially harmful? Some google-comment by a doctor answering a question aboutthis warned that too much calcium carbonate can cause kidney issues. But he was speculating, and I don't know if eating, say, two eggshells a few times a week would be risky over time.
Any reliable source on consuming whole (not pulverized) eggshells that you can point to would be appreciated.

posted by flourpot to Food & Drink (12 answers total)

The shell is porous, meaning it absorbs whatever toxins in the environment were present when the chick was forming. And on a factory farm, where so many chickens are grown, that's can't be good. Do you want to be eco-friendly by not wasting the shells after you consume eggs? Otherwise, it sounds like your question is more about unhealthy levels of calcium. The body tries to expel excesses of vitamins and nutrients that are beyond levels it needs but too much of anything is not good for it. If you like the sensation, and your body is going to do what it will do anyway, why not? This NYT article might help you. Good luck.
posted by CollectiveMind at 10:43 AM on July 31, 2016 [2 favorites]

This is speculation, but if chewing on ice is bad for your teeth, eggshells might wear your teeth down, too.
posted by aniola at 11:23 AM on July 31, 2016 [2 favorites]

This is an interesting question. There are four main components that, off the top of my head, seem to be of issue:

- Is the base material safe to consume at any quantity? (the egg shell and any tag a longs). If not, can it be made safe? (boiling, cleaning...)
- Is the base material safe to consume at the quantity of one egg shell? What is its chemical effect on the body?
- Is the physical form of the egg shell safe for your mouth and teeth? Will it cause undue wear and tear?
- Is the physical form of the egg shell safe for your digestive tract? Will the sharp edges of the egg shell cause harmful lacerations? If there is possible harm, how small does the particle size need to be?

I did a quick search of PubMed, but couldn't find anything. May be worth doing a little digging in some medical journals.
posted by troytroy at 12:15 PM on July 31, 2016

This is completely non scientific but the cracked edges of egg shells are sharp enough to cut up your mouth if contacted at the right angle, and ditto (or moreso) to getting wedged in between your tooth and gum. I had the latter happen to me once with the shell of a popcorn kernel and not only did it not work itself out, it required a trip to the dentist to be extracted. True fact. I wouldn't do it.
posted by telegraph at 12:36 PM on July 31, 2016 [4 favorites]

Just more speculation here—plenty of mammals eat eggs, shell and all. And I've never heard anything about eggs shells being dangerous for pets. So, I imagine you're OK.

I wouldn't serve your egg salad to anyone without fair warning re contents. I find the texture of an eggshell to be quite unpleasant. (I just fished a nearly microscopic bit out of pre-scrambled eggs.)
posted by she's not there at 12:40 PM on July 31, 2016 [5 favorites]

Are you talking about eating eggshell shards? This is not a good idea for your GI tract.

For what it's worth I once had an Anatomy and Physiology professor who would boil eggs in lemon juice and then drink the juice, because calcium citrate is more easily utilized by the body than calcium carbonate.
posted by pintapicasso at 1:37 PM on July 31, 2016 [4 favorites]

If you're a coffee drinker, maybe consider cowboy/scandinavian coffee?
posted by a box and a stick and a string and a bear at 4:16 PM on July 31, 2016

I'd be more worried about your teeth getting ground down and your GI tract getting cut up than about excesses of calcium. This article says an eggshell is about 2 g of calcium, about 2x the daily RDA, which doesn't sound like a big deal to me.
posted by fingersandtoes at 6:20 PM on July 31, 2016 [1 favorite]

For what it's worth I once had an Anatomy and Physiology professor who would boil eggs in lemon juice and then drink the juice, because calcium citrate is more easily utilized by the body than calcium carbonate.
posted by pintapicasso at 1:37 PM on July 31

If you're a coffee drinker, maybe consider cowboy/scandinavian coffee?
posted by a box and a stick and a string and a bear at 4:16 PM on July 31.

Along these lines, I throw my egg shells (cracked, but mostly whole, not ground up) into my stock to give it a calcium boost.
posted by carrioncomfort at 11:53 AM on August 1, 2016

I would think the shell would dissolve pretty rapidly in acid, so I wouldn't be too worried about digestive tract damage from stomach onwards and I assume you'd already know if it was a problem in your esophagus because that has nerves. But I'd check first by putting a crunched-up shell in a glass of vinegar (which is less acidic, but it's at least something). If the shell fragments can still cut you after an hour, then the theory may be busted :)
posted by anonymisc at 2:11 PM on August 1, 2016

Lenny seems to think it's ok.
posted by turbid dahlia at 3:08 PM on August 1, 2016

Eggshells are not going to hurt healthy teeth- they're at most a 3 on the mohs scale, while teeth are 5. There is some concern from side effects (such as indigestion) of talking more than 2000mg of calcium carbonate at a time, and apparently doses below 500mg are more readily absorbed. However it's hard to know exactly how much calcium you are going to absorb from pieces of eggshell. If you like to eat them I say "why not", but if you're trying to replace a dosage-dependent supplement I think that's an iffy proposition.
posted by oneirodynia at 3:34 PM on August 1, 2016