Many people believe the old saying, "If some is good for you, then more is better." However, this does not always apply to vitamins because overconsuming certain vitamins can have negative health effects on your body. Fat-soluble vitamins (A, D, E, K) can easily accumulate in your fat tissues to toxic levels because they are not as easily excreted as B vitamins and vitamin C, which are water-soluble. Therefore, you do not necessarily need to take fat-soluble vitamins as supplements unless prescribed by a registered dietitian or physician.
Vitamin A
Vitamin A is essential to proper vision, cell differentiation, and immunity. Hypervitaminosis A is where the storage of vitamin A (in the form of retinoids) in the liver has exceeded the capacity. The excess vitamin A is circulated in the bloodstream and cause hair loss, skin lesions, malaise and swelling of the eyes. Chronic conditions will lead to coma and death.
Vitamin D
Vitamin D maintains adequate calcium and phosphorus concentration in normal range that supports neuromuscular function and bone calcification. Hypervitaminosis D causes dehydration, vomiting, irritability, kidney stones, constipation, and chronic fatigue. Other effects include production too much calcium in the bloodstream which causes overcalcification of bones, soft tissues and heart.
Vitamin C and B5
Overconsuming vitamin C can cause too much iron absorption because vitamin C aids in the iron absorption in the body. Along with pantothenic acid (B5), both of these vitamins cause heartburn (lowers in pH level in the stomach), indigestion and diarrhea.
B-vitamins
Although B-vitamins are water-soluble and are easily excreted in the body, they, too, can build up to toxic levels if megadoses are consumed. However, there are some B-vitamins do not have any known toxicity in large amounts, such as riboflavin (B2), B12 and folate (B9).
Overconsuming of thiamine (B1), though rare, causes too much muscle relaxation and drowsiness. Niacin (B3) in large quantities causes liver damage, elevate blood sugar, itchy, dry skin and cardiac arrhythmia. Too much vitamin B6 causes nerve damage and reduced proprioception (body awareness) to deadening of the nerves. Many negative effects of water-soluble vitamins can be reversed when the megadoses are discontinued.
References
- "Perspectives in Nutrition;" Gordon Wardlaw and Margaret Kessel; 2002
- "Ultimate Sports Nutrition"; Ellen Coleman; 2004
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