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This article is from the WebMD News Archive
Fortified Foods Can Be Too Much of a Good Thing
July 10, 2000 -- What could be easier than getting all your daily vitamins and minerals in a single bowl of cereal or wrapped up in a burrito? The idea is pretty appealing to a generation of harried, multitasking Americans.
These days, such nutrition-on-the-go is quite possible, as foods ranging from breakfast cereals to orange juice and even burritos are fortified with vitamins and minerals, and some are even packed with herbs. But people who eat fortified foods as part of a healthy diet and also take supplements may be getting too much of a good thing, experts tell WebMD.
Dietary supplements are more popular than ever, and more and more foods are fortified, Mark Kantor, PhD, an associate professor of nutrition and food sciences at the University of Maryland in College Park, tells WebMD.
"So many people eat fortified foods and take dietary supplements, so now there is a double problem," he says. "It is very easy to visualize areas where people can get pretty high levels of certain nutrients. We are in uncharted waters, and there are some theoretical risks."
For these reasons, the National Academy of Sciences is establishing "tolerable upper intake levels," also known as ULs, for certain nutrients. The ULs, which indicate the highest level of daily intake considered safe for healthy people, are being issued along with the academy's updated recommended daily allowances, or RDAs. Nutrients for which a UL has been established include niacin, folate, calcium, vitamin D, and vitamin B-6. The ULs for the remaining nutrients for which information is available should be released in 2001.
For example, Kantor says, many foods are supplemented with iron, which is also included in many vitamin/mineral formulas.
"Some people tend to accumulate iron in the liver, and iron-fortified foods can be dangerous for such people, who have hemochromatosis," he says. "A lot of people don't know they have this until they get sick, so they don't realize they should limit the iron in their diet." Hemochromatosis is an inherited disorder that is more common in men. Symptoms can include irritability, fatigue, and joint pain, but these do not occur until body tissues have already been damaged.
Other nutrients that can harmful in excess include vitamin C -- one to two grams, about 17 times the RDA, can cause stomach irritation -- and niacin, which can harm the liver.
"People should stick to as wholesome and natural a diet as possible," Kantor says. "If you choose unprocessed foods, fruits, vegetables, and grains, you can't go wrong, but people are in a rush and want convenience, so they often don't."
Further, some vitamins and minerals may interfere with the effects of prescription drugs.
"There are certain drugs that don't go well with certain nutrients," Kantor tells WebMD. For example, "vitamin E is a blood thinner, and if you take a prescription blood thinner, blood can become too thin," he says.
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