Drugs

Is It Possible To Overdose On Vitamins?

The body needs essential vitamins in order to stay healthy. When taken in recommended doses, these do not pose any added risk to a healthy person. However, it is a common practice for some doctors to advise taking more than what is recommended in order to correct certain health deficiencies; the problem is that some vitamins are prone to creating a variety of adverse side effects when taken above the needed upper intake levels (UL), which are set to indicate the maximum dose of a nutrient that is not likely to harm nearly all people.

Water-Soluble Vitamins vs. Fat-Soluble Vitamins

Water-Soluble Vitamins

More in number compared to fat-soluble ones, water-soluble vitamins are readily excreted from the body and are not easily stored in tissues. Even when taken in high doses, they are less likely to cause issues in the body. However, some water-soluble vitamins can cause potentially dangerous side effects when taken in megadoses. Water-soluble vitamins include all eight B vitamins plus vitamin C. 

Fat-Soluble Vitamins

Unlike water-soluble vitamins, fat-soluble ones do not dissolve in water and are easily stored in the body's tissues. They are also most likely to lead to toxicity because they can accumulate in the body. Though rare, excessive intake of fat-soluble vitamins can lead to potentially harmful side effects. There are four fat-soluble vitamins in total: Vitamins A, D, E and K.

Overdose-Prone Vitamins

Although many vitamins are generally harmless, it is because they are consumed naturally through food even in large amounts. 
In supplement form, however, they are prone to overdose, leading to negative health outcomes ranging from diarrhea to even death. 
Some water-soluble vitamins and most fat-soluble ones are most prone to overdose, all of which have set ULs for safe intake:

     Water-soluble vitamins

  • Vitamin B3 (niacin) - In its nicotinic acid form, B3 causes blood pressure, abdominal pain, impaired vision and liver damage at doses of 1-3 grams daily. One case report found that excessively high doses of more than 5 grams can result in death due to metabolic acidosis (acid buildup in body fluids) and acute liver failure.
  • Vitamin B6 (pyridoxine) - Long-term B6 overconsumption can result in severe neurological symptoms, in addition to skin lesions, 
    light sensitivity, nausea and heartburn, with some of which occurring at a daily intake of 1-6 grams.
  • Vitamin B9 (folate) - In supplement form, excessive amounts of folate can affect mental function, damage the immune system and mask a potentially severe Vitamin B12 deficiency.
  • Vitamin C - Its low toxicity does not stop it from causing gastrointestinal problems such as diarrhea, cramps, nausea and vomiting when taken in high doses. At 6 grams per day, it can result in migraine.

     Fat-soluble vitamins

  • Vitamin A - A result of excess Vitamin A intake in the body, hypervitaminosis A is mostly associated with dietary supplements, but can result in nausea, coma and even death.
  • Vitamin D - High doses of Vitamin D supplements can lead to a variety of dangerous symptoms, including weight and appetite loss, and irregular heartbeat. It also leads to organ damage through increased blood calcium levels.
  • Vitamin E - At high doses, it can interfere with blood clotting and cause hemorrhages, even leading to hemorrhagic stroke. 

How To Avoid Vitamin Overdose

Although a well-balanced diet is the best way for the body to get essential nutrients, many people need vitamin supplements for a variety of reasons. Age, genetic disorders, medical conditions and diet all increase the need for certain nutrients. Fortunately, vitamin supplements are safe to take by following the recommended daily intake and UL for each. For questions about proper dosing, it is prudent to consult with a trusted health professional.

Vitamin overdose Vitamin overdose can trigger several health issues such as nausea, kidney and heart problems. Photo courtesy of Pixabay, public domain

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