- Burn the fat & vitamin D in the body which had been added with summer feasting
- Winters were times of famine/fasting - and burning of fat and retrieving vitamin D stored in the fat
- Campfires? - some small amount of vitamin D
- Dried fish?
- Lard and many game meats had lots of vitamin D - which could be consumed in the winter
Since flame detectors sometimes monitor UV there must be some UV in a fire - perhaps enough to generate some vitamin D
- UV Flame Detector - Honeywell
- How to Select a Flame Detector
- WikiPedia Flame Detector
- WikiPedia Flame Detection
- Do birds migrate South in the winter to get food AND vitamin D?
- Do mammals which do not migrate (deer, rabbits,...) store vitamin D in fat and body tissue long enough to get to Spring?
- Do mammals which burn fat during hibernation (bears, ground squirrels, ...) get vitamin D from their fat as well?
- Interesting: Vitamin D2 in bears is higher in winter than in summer
- Some animals eat dried grass in the winter
- Sun-cured hay has 2,000 IU per kg - "Vitamin D is the only nutrient more abundant in dried forage than in fre
- Many animals (which do not migrate) add fat in the summer - when vitamin D happens to be available
This gives one possible reason that evolution (in humans and many animals) caused the storing of vitamin D in fat