Large amounts of vitamin D can heal lots of conditions...even cancer. Instead of saying that Daniel has a vitamin D deficiency, I would say he has/had some internal condition that large amounts of vitamin D healed. Since he also ate lots of salmon, he could have also had an omega 3 deficiency. Vitamin deficiencies are internal. It is just that vitamin D is unique in that you can also get it from the sun instead of ingesting vitamins internally.