I have vitamin d3 gummies that are 1000 iu each it says take two a day. is it safe to take four per day?

It is safe, but I am wondering why you want to take 4 instead of 2. If in fact you have vitamin D deficiency, you should have your family doctor monitor your levels and make sure that you are taking the proper dose and maintaining the proper levels. Just guessing at a dose or taking more because you can, is ill advised.

Vitamin D is indeed important for bone health and numerous immunological functions, and traditionally, sunlight exposure would be supportive, but many folks use sunblock. Supplementing vitamin D may help reach the optimal level of 50-70 ng/ml, but best this be done with your doctor checking your serum levels. Since this is fat soluble, it may take months for a level to stabilize.