Originally Posted by
Carbonfiberboy
Appropriate vitamin levels have always been controversial, particularly vitamin D. It was fairly easy to determine the lowest healthy level, that's the RDA, but much harder to determine the optimal level for an individual. Probably impossible. Anyway, my D was at 61.5, 10/11/21. Doc was pleased.
Vitamin D is tricky and dependent on other health factors. To offset my thyroid dysfunction I take 5,000 IU vitamin D daily, which sounds like a lot, but recent research says is nowhere near an overdose or toxic level. Some research suggests up to 100,000 IU to offset the effects of sunburn -- but that's just one study I've found.
Even with 5,000 IU in supplements, plus whatever I get from diet, my blood level is still just barely within the low normal limit. When early news about the pandemic hit the US (late 2019-early 2020) my doc insisted I increase my dosage to improve my immunity.
Ditto my iron. Even eating red meat a few times a week and dietary supplements, I'm still just barely within the low normal limit. When I tried a vegan diet for most of 2018 I was anemic. For most humans heme iron is the best, and we can only get that from animal sources, mostly red meat. And I don't suffer the digestive upsets from iron supplements.