In light of the new advice to 'let our skins be exposed to sunshine' (for the Vitamin D it gives us), but also taking into account the increased risks we then have of skin cancer and the carcinogenic chemicals in sunscreens (when we do use them), is there a definitive protocol for exposing ourselves to the sun, supplementing with cod liver/fish oil and/or using homemade sunscreens?
KGH has written extensively about this subject:
IMHO, a lot of the advice on getting D from sun overcomplicates the question of exposure time.
Basically, everybody has a minimum and a maximum level of repeated sun exposure. Below the minimum you're not getting enough; you can find out with a blood test. Above the maximum you're in sunburn territory: you're peeling and wrinkling in a fairly obvious way.
Between the two extremes, if you regularly get roughly the same amount of sun exposure, then your skin will automatically adjust. Like the rest of your organs, your skin understands homeostasis. You've got a thermostat to regulate body temperature; you've got a tan-o-stat to regulate D production. You don't need to micromanage it: your body knows how make the right amount of D across a range of inputs. Near the high end, you'll tan. Near the low end, your skin will stay fair. Either way the right amount of D gets made. That's homeostasis at work.
Once you're above the minimum, the range of acceptable exposure is wider than you think. So there's no need to be neurotic about it. Just ramp up to whatever level works for your lifestyle and don't worry about going ten minutes over or under. You only need sunscreen if you regularly go over the max, even after your skin has reached its darkest tan.
If in doubt, supplement orally.
If you want to get vitamin D form the sun, expose as much skin as possible to the sun but stop before it turns pink.
If you want to get vitamin D from supplements, I would skip the cod liver oil and go with a D3 supplement alone. Why take your D3 with a large dose of retinol that you likely don't need and that may interfere with the D?