Nanoemulsion Vitamin D may be a substantially better form updated March 2019
There are a variety of Vitamin D emulsions on Amazon (US) as of 2019
Bio Emulsion Forte is what I started buying in 2012.
I have given out 3 bottles (as of 2019) of it to friends with gut problems who were getting no benefit from standard vitamin D.
It worked well for them in each case
Since ~2017 I also have been purchasing Micro D3 Nanoemulsion for inhaled Vitamin D experiments
see further down this page details on nutrasal.com product
In March 2019 I also purchased PreventiX, Hi-Pro Emulsi-D3, Bio-Emulsion-D3, and Liquid Vitamin D3
They were added because
1) They had good Amazon reviews
2) Were likely to have a micro/nano size,
3) Seemed to have a > 1,000 IU per drop.
4) Were fairly low cost (per 5,000 IU)
I also have been getting some Vitamin D Nanoemulsion from Bio-Tech Pharmacal since ~2016.
They are making it for some Vitamin D clinical trials, and I have used it for inhaled tests.
Bio-Tech Pharmacal emulsion is not (as of 2019) being sold commercially.
Note: March 2019 Dried beans and peas in meal appear to decrease uptake of oil-based Vitamin D
If you often eat pulses when supplementing with Vitamin D, you might need to have a non-oil-based vitamin D, such as in the above picture