Few, if any...: Historically vitamins were largely discovered by deficiencies (3rd world countries); in 1st world countries this is rare. Vitamins are extremely prevalent in most foods (i.e. Cheap to isolate & sell), needed in only trace amounts (tiny quantities adequate), thus have become a big industry in 1st world countries, despite no/limited evidence of efficacy for many issues search via google & add "nih".
Answered 1/2/2019
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A doctor has provided 1 answer
A doctor has provided 1 answer
A doctor has provided 1 answer
A doctor has provided 1 answer
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