This is an excerpt from Sara at The Healthy Home Economist here. She has a video on it too.
"Soaking corn or cornmeal overnight in limewater releases the Vitamin B3 and improves the amino acid profile of the corn making for easier digestion.
"If corn is a staple in your diet, then soaking in limewater is a must as the disease pellagra is caused by Vitamin B3 deficiency. Symptoms of pellagra include sore skin, mental problems, and fatigue.
"Even if you don’t eat corn that frequently, limewater is so easy to make and lasts for such a long time in the pantry ..."
"I use 1 cup of limewater for every 2 cups of corn or cornmeal when I am making cornbread, corn casserole and other corn based dishes. Pour the limewater out of the mason jar carefully – you don’t want to use the lime that has settled at the bottom, only the limewater. Soaking for 12-24 hours is sufficient to release the nutrients but cornbread in particular will rise better if soaked for 24 hours."
To make limewater get dolomite powder (brand KAL is recommended for purity). Put 1/2 inch in the bottom of a quart jar or 1 inch at the bottom of a 1/2 gallon jar, then fill the rest with purified water. Put the lid on, shake a couple of times and let it sit. Can keep it in the pantry or in the fridge (if it is warm).