The main ingredient is silica, not calcium.
Once a day one heaping tablespoon about 2 hours after breakfast in water.
Made from fossilized algae that is high in silica. Not good to breathe but have not read much on the stuff.
6 or 7 years of it should tell if there is a problem eating it, apparently there is not. What led you to adding it to your diet?
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As stated, not good to breathe.
From what I have read, DE is not made from calcium.
Have you eaten it? I have never felt any irritation from food grade DE.