RSD, when I found how low I was I was taking 4K D3 daily and it took about 6 months to get up to 35 or so....then along the way the info came out that we need to add K2 for best absorption of the D3 which I added....but it took a while to get levels up. Once I got to 80 I was feeling so good, then hip replacement surgery knocked off 40 pts of D3....so I started to work my way up again. I don't know where I am now but I sure don't feel as good as I did at 80 but hip surgery really did a job on my body.