I don't know. I'm a retired chip-maker and all I know about this stuff is what I read.
I have read that Vitamin D from flax is not an effective vitamin D source though and that D3 is the desired type.
My Dr says I can safely take up to 10,000 per day of D3. I have been taking 5000-7000 per day for about a year and experienced a great improvement in my over all health. Not a cold, flu or other bacterial/viral illness. I also experienced a susceptibility to bronchitis for decades that seems to be history now. Yea!