I'm taking 2, 000 mg of vitamin d daily. Should I take it all at once or take 1, 000 mg in morn/1, 000 mg at night? And best to take with food?

At once with food. I hope you're taking 2000 iu ; not 2000 mg which is 80 million iu, a massive overdose. There's no need to take d more than once a day, in fact some people choose to take a large dose once a week. It's better absorbed after food. While 2000 iu/day is adequate, optimal blood levels are 50-80 ; most adults need to take 5-8000 iu/day to achieve that. I advise vit k2 with d see http://bit.Ly/1dc7vna.