“ Vitamin D3 1000-3000 u/day. Note RDA (Recommended Daily Allowance) is 800-1000 u/day. The safe upper-dose daily limit is likely < 4000 u/day.”
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I’ve taken at least 5,000 units of D3 per day for a decade or more.
My doctor tested my d levels and told me I was the only person he ever tested who had adequate levels.
In winter, I take 10,000 units daily.
If I get the flu I follow the vitamin D hammer, taking 35,000 for each of 3 days. Knocks out symptoms and ends it.
My cousin and her husband both caught it recently. In his 80s, her husband was taking 50,000 IU once a week in a single dosage for some other ailment he had. He didn’t get that sick. The wife, about five years younger, died about three weeks after catching it.
I take 5,000 D3 twice a day (so, 10,000 daily). I have for years.