If you intend to take vitamin d I read in various places you should also take magnesium and probably vitamin k as well. And less calcium. Everything is interconnected.
I recently started taking 3000mg of magnesium per day as magnesium chelate. The bottle recommends three capsules per day for muscle spasms / cramps.
Historically, I have a couple of basic assault charges, an assault with sexual intent charge, I was charged with two counts of trafficking a controlled drug (later dropped).
Shortly after I commenced taking six capsules a day I started feeling a lot less psychotic.
I would also recommend taking Zinc with it. I was taking Magnesium at one point by itself and developed a muscle twitch which was fixed by adding Zinc.
Everything is very interconnected. The underdose and overdose numbers are determined in isolation, just as any good scientific experiment should.
Casual observation reveals that vitamin D overdose results in hypercalcemia, a condition treatable by vitamin K. Vitamin E overdose results in hemmorrhaging, a condition treatable by vitamin K. There are no known symptoms of vitamin K overdose. Vitamin A overdose (from retinol) can be treated by vitamin E and vitamin K.
Magnesium is balanced with calcium. Sodium is balanced with potassium.
So naturally, I wonder what happens when you supply vitamin K in excess, then determine the overdose amounts for the other fat-soluble vitamins. Once that number is found, reduce the K by steps and repeat, until you have the recommended minimum ratio of K to the other vitamin.
https://www.precisionnutrition.com/stop-vitamin-d