Bear in mind that Vitamin D3 is fat soluble, therefore it's likely the largest meal of the day contains the most fat.
Probably accounts for the fact that oil based gel caps are more reliable than solid tablets (tablets may not have dissolved while the fat is about).
I prefer the carrier oil to be MCT (medium chain triglyceride oil) this is very easily absorbed and quickly metabolised, so it's less likely to be stored (taking the D3 into storage and out of circulation) MCT's are also extremely stable so less likely to go rancid in storage.
Country Life, Vitamin D3, 5,000 IU, 200 Softgels
These are what I use. I get mine from IHERB those new to IHERB may want to save $5 with code WAB666. Iherb are cheapest including postage to the UK but you may find them cheaper including P&P elswhere. (haven't time to do a price comparison.)
Those who are not good at remembering to take supplements at the right time may prefer to use BIOTEC 50,000IU VITAMIN D3 FREE SHIPPING
1000iu/daily for each 25lbs you weigh is usually sufficient.
So 175lbs weight = 7000iu/daily =49,000iu week
So ONE ONLY X 50,000iu capsule EACH WEEK is all you require.
These are a dry powder filled capsules. So if you take it just before you eat it should be absorbed well with your food. It's possible to pull the capsule shell apart and sprinkle the fine white powder into your food.
Vitamin D3 is very robust, you could include it before you do your cooking, so it could go in a cookie recipe with the fat or you could mix it with the fat in your own home-made ice-cream and freeze it.
This may be an easy way to provide a daily D3 supplement for elderly people or children. Make a cookie mix, add the contents of one 50,000iu capsule. Mix well, Divide into 14 portions, each will contain roughly 3500iu or divided into 28 cookies for 1750iu/each.
What Vitamin D3 cannot stand is LIGHT EXPOSURE so leaving the capsules exposed to UVA will degrade the Vitamin D content.