Multivitamin Overdose: Too Much Of A Good Thing

By Tiffany Tseng. May 7th 2016

Today, many people are concerned with maintaining their health and taking preventative measures to protect their bodies for the long haul. Along with a healthy, nutrient-dense diet and regular exercise, the practice of popping one multivitamin a day has also become extremely popular. However, certain vitamins follow the old adage that there can always be “too much of a good thing.” This has many people wondering whether or not you can overdose on multivitamins and harm your health, rather than help it. Read on to get more information on how to properly use multivitamins.


A multivitamin is most commonly known a supplement taken in addition to a healthy diet to further fortify the body against harm. In the past, many medical conditions happened as a result of vitamin deficiency; for example, scurvy is due to a lack of vitamin c, while anemia is due to a lack of iron. Since many foods today are already fortified with vitamins, it is possible to overdose on certain vitamins that are included in a multivitamin, causing harm to the body instead.

Vitamins To Be Cautious Of

Generally, fat-soluble vitamins, which tend to accumulate in the fatty tissues of the body, are the items of concern in the issue of overdose. They generally take longer than water-soluble vitamins to become expelled from the body, so they should be taken carefully. These vitamins include:

  • Vitamin A. Also known as vitamin A acetate, it can become dangerous when consumed above 200 percent of the daily recommended value, or 10,000 IU. Vitamin A overdose can result in increased risk of hip fractures, damage to the nervous system, and damage to the liver. If a person is a smoker, he or she will have an even higher risk for overdose. Hence, if you love eating carrots or foods fortified with beta or alpha carotene, you may want to choose a multivitamin that does not meet 100 percent of the daily recommended value.
  • Vitamin D. Vitamin D overdose is almost unheard of if the source is from sunlight exposure and fortified foods. However, supplement overdose has been documented, resulting in liver toxicity and calcium buildup in the blood.
  • Vitamin E. Although there has not been too much documentation of vitamin E overdose from food sources, it is still possible to have too much of this nutrient in the system. Supplemental overdose, however, has records of excess bleeding and severe fatigue. Hence, it is a good idea to intake up to 100 IU of this nutrient to reap its benefits and avoid the excess harms.
  • Vitamin K. Food derived sources of vitamin K will not result in overdose, but synthetic forms found in some multivitamins can. Toxicity includes damage to the liver and abnormal breakdown of red blood cells.
  • Iron. This mineral has shown to cause constipation and raise the risk for heart disease. While it is essential for women and beneficial when taken in the correct amounts, aim for about 8 to 18 milligrams (mg), daily.
  • Zinc. Once it is taken past the daily recommended values of 15mg, zinc can impede the body’s ability to absorb copper, another important mineral, resulting in the weakening of the immune system.

Other water-soluble vitamins and minerals have a lower risk of overdose. However, studies have shown that an excess intake of water-soluble vitamins (all B vitamins and vitamin C, to name a few), while extremely rare, may damage the digestive system in the process of expelling the nutrients. Thus, be sure to consult your doctor on the proper dosage amount and daily recommended values for your age group and specific concern.

Signs And Symptoms

Some possible signs and symptoms of multivitamin overdose may include:

  • Vomiting
  • Abnormal urination
  • Weight loss
  • Poor appetite
  • Constipation
  • Weakness
  • Abnormalities in heart rhythms
  • Kidney stones, characterized by sharp, stabbing pains in the location of the liver

Be sure to seek emergency care if you think you are experiencing vitamin toxicity.

Other Helpful Tips

  • Since there are such a wide variety of multivitamins on the market today, it is best to seek your doctor’s opinion on what is best for you. For example, people living in a place with little sunlight may need a boost in vitamin D, while post-menopausal women may need extra calcium.
  • Be sure to check out the manufacturer of the multivitamin for purity and authenticity. Purchase from brands approved by the government for quality assurance, since you are putting it into your body.
  • Individuals who have pre-existing medical conditions, as well as pregnant women, may need to be extra careful of vitamin intake to prevent possible interference with existing therapy and diet. Be sure to consult a physician.
  • Multivitamins are not meant to replace healthy diets. So if you are planning to eat junk food all day long and pop a multivitamin, you should seriously rethink your diet and implement some nutrient-dense foods.

Taking a multivitamin a day is a good practice and habit to adopt for a healthier lifestyle. However, be sure to seek the opinion of a medical professional for best safety measures and proper dosage.


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