I take one 1000-IU Vitamin D3 tablet a day.
I live in the northeast, where there isn’t much sunlight in the winter. I found that it had a very positive effect on morning stiffness I experienced after sleeping in one position for hours.
However, it is not true that it “has no negative effects.”
Vitamin D is actually a hormone, not a vitamin. More accurately, your body metabolizes vitamin D into a hormone, called 1,25-dihydroxyvitamin D (calcitriol). This is a calcium-regulating hormone.
Taking too much can cause kidney stones, especially in those predisposed to that condition.
I have had kidney stones, so I get a urological workup once a year.
It is recommended that one take Vitamin K2 in conjunction with D3. I take 100mcg K2 and 5,000 iu of D3 daily.