More sun. The best for a pale-skinned person is the kind before 10am or after 3pm. See below for more to chew on regarding this...
Green Pasture's "Blue Ice Gold Therapeutics" is a juiced-up CLO, very concentrated and with a touch of X-Factor Butter Oil to enhance the absorption. I have the liquid (cinnamon flavor) and the capsules available at the same prices as through Green Pastures directly, if you are interested.
Personally, the synthetic Ds are junk, IMO.
Okay. Vitamin D precursors are made from cholesterol. Your bro-in-law (BIL) avoids the sun and likely avoids most vitamin D containing foods. His body wants more vitamin D, so, it cranks up the production of cholesterol in the liver so that if/when his skin ever sees sunlight, it can jump on the opportunity to make as much as possible.
So, it is very likely that your BIL getting some CLO and lots more sunlight will fix two problems at once--the vitamin D deficiency AND his high cholesterol!
Links to read more about this, found by Google searching under "Vitamin D statin effect":
Statins and Vitamin D Deficiency
Are statin drugs an expensive version of vitamin D?
Scott, I haven't been back to your blog in a while, but if you'd like to refer the woman who was inquiring about medicine to this page to see how physiology is applied by an ND, this might not be a bad reference for her.