More Vitamins Are Always Better
THE CLAIM
"Taking high doses of vitamins is always beneficial and can only help your health."
[EVIDENCE SUMMARY]
Fat-soluble vitamins (A, D, E, K) can accumulate to toxic levels. Even water-soluble vitamins can cause adverse effects at high doses. Mega-dosing provides no additional benefit for most people and may increase health risks. Nutrients from food are generally safer and more effective than high-dose supplements.
The Danger of Fat-Soluble Vitamins
Vitamins A, D, E, and K dissolve in fat and are stored in body tissues. Unlike water-soluble vitamins that are excreted in urine, these can accumulate to dangerous levels. Vitamin A toxicity can cause liver damage, vitamin D excess can lead to dangerous calcium levels.
Even Water-Soluble Vitamins Have Limits
- Vitamin B6 excess can cause nerve damage
- Vitamin C mega-doses may cause kidney stones
- High-dose niacin causes flushing and liver issues
- Folic acid excess may mask B12 deficiency
The Research Verdict
Large clinical trials have found that vitamin supplements do not reduce mortality in well-nourished populations and may increase risks for certain conditions.
[KEY TAKEAWAYS]
- More is not better—vitamins have upper tolerable limits
- Fat-soluble vitamins can accumulate to toxic levels
- Most people get adequate vitamins from a varied diet
- Supplements should address specific deficiencies, not exceed needs
[SOURCES] (2)
Vitamin and Mineral Supplements: What Clinicians Need to Know
Rautiainen S, et al.
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