Is it possible to overdose on vitamins? Many of the vitamins my patients take have 100% to 400% of the recommended daily allowance of B vitamins and vitamin A. My understanding is that as long as kidney function is normal, excess amounts will be flushed out. — Leigh Bears, ARNP, New London, N.H.
The fat-soluble vitamins (i.e., A, D, E, and K) are much more likely to cause problems with overdose. Excess amounts of these vitamins can even cause liver damage. The other vitamins are water-soluble. As long as the individual’s kidney function is normal, the excess is usually eliminated in the urine.
Adverse effects from some water-soluble vitamins are still possible, however. One example of dangerous overdose is when too much manganese affects the central nervous system in a manner similar to that of Parkinson disease. As always, the best advice is to eat a balanced diet and never supplement above the tolerable upper-intake level. — Julee B. Waldrop, DNP (171-1)
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