March 21, 2023

Many people take vitamins and supplements daily. However, excessive supplements can cause unwanted health effects.

For many Americans, multivitamins and supplements represent a part of daily routines. In fact, as of 2018, 57.6% of U.S. adults over the age of 20 claimed to have used dietary supplements within the past 30 days, according to the Centers for Disease Control and Prevention. These habits have built a thriving supplement industry in America that produces billions of dollars of revenue annually.

Many people take supplements to ensure they get essential vitamins and minerals. However, Dr. Akua Amankwaah, associate professor of nutrition, said people should strive to gain the recommended servings for vitamins through eating whole foods rather than supplements unless otherwise directed by a doctor.

In fact, when people take high doses of vitamins, health conditions such as hypervitaminosis can develop. 

Amankwaah said the risk of reaching toxic levels of vitamins increases when people take supplements in addition to food.

“The problem is you get excess intake of a particular nutrient,” Amankwaah said. “With whole foods, it is harder for you to get excess levels because you have to eat so much. When you are adding supplements to your foods, you can get beyond.”

The potential for toxicity depends on the type of vitamin. Water-soluble vitamins, including the B vitamins and Vitamin C, do not remain in the body for a long time, so toxicity is less likely. However, the body can store fat-soluble vitamins (Vitamins A, D, E and K) for longer periods of time, presenting the potential for reaching toxic levels over time if excessive intake continues.

Hypervitaminosis remains rare, with about 60,000 cases occurring in 2017. However, when it does occur, the effects of hypervitaminosis can become extremely dangerous.

While hypervitaminosis requires an extremely high intake of vitamins, other concerns about supplements exist. For example, the use of most supplements does not accomplish the health goals that most people desire. 

Dr. Alexandra Shin, associate professor of biology, said that it is important to recognize that multivitamins and supplements have not been tested by the Food and Drug Administration (FDA) and she encourages consumers to be aware of the potential for false claims.

“Currently, there is a huge boom of vitamin and other supplements with several thousands of products out there, and this is creating confusion for consumers as many of them make several health claims such as ‘immune boosting,’ ‘anti-aging’ or ‘anti-cancer,’” Shin said. “It is important to note that vitamins and supplements are legally regarded as ‘food items’ and are not regulated by the FDA. This means the dose of different ingredients as well as their claims are not vetted or tested.”

A study conducted by Johns Hopkins University researchers examined these claims for supplements.

“Johns Hopkins researchers reviewed evidence about supplements, including three very recent studies: an analysis of research involving 450,000 people, which found that multivitamins did not reduce risk for heart disease or cancer; a study that tracked the mental functioning and multivitamin use of 5,947 men for 12 years found that multivitamins did not reduce risk for mental declines such as memory loss or slowed-down thinking; (and) a study of 1,708 heart attack survivors who took a high-dose multivitamin or placebo for up to 55 months,” said a Johns Hopkins Medicine article. “Rates of later heart attacks, heart surgeries and deaths were similar in the two groups.”

When people add supplements to a diet that already provides the body with the correct dose of essential vitamins, the addition of supplements will, at best, have no effect.

“A nutrient functions at a certain threshold,” Amankwaah said. “There is a certain threshold that must be taken for you to see effects, and there is a maximum threshold. Beyond that maximum threshold, it does not help you.”

In fact,  Amankwaah said that extra doses of vitamins provide the liver with unnecessary work as the organ eliminates them from the body.

Amankwaah recommends that people take steps to ensure they get the recommended dose of vitamins. These steps include getting advice from a doctor and becoming aware of the proper daily intake for vitamins. 

Daily Value, a measure provided by the FDA, provides people with the amount of each nutrient to take daily and is available as a guide to consumers.

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