Fortified Foods Can Be Too Much of a Good Thing

From the WebMD Archives

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.

Some new products are fortified with herbs, which can also interfere with medications, Ruth Kava, PhD, RD, director of nutrition at the American Council on Science and Health, tells WebMD.

"If you take medications on a daily basis, talk to your doctor before eating any heavily supplemented foods," she says. "You have to look at your diet and see if you are weak in something before eating fortified foods. If you are low on calcium, for example, maybe you can start drinking calcium-fortified orange juice or taking supplements, depending on how much you need."

Kava says the take-home message is: "If you take medicine, check with your doctor" before eating lots of fortified foods or taking high-dose supplements.

All of this is not to say that fortified foods and supplements don't have a place in our diets. While some people may get too much of certain nutrients, others don't get enough.

For example, all women who could become pregnant should be taking a folic acid supplement to reduce the risk of delivering a child with neural tube defects such as spina bifida, a crippling condition in which the spinal cord does not fuse properly before birth.

Since January 1998, the FDA has required that certain grain products be fortified with folic acid. Some doctors are concerned, however, because too much folic acid may mask a vitamin B-12 deficiency. Deficiencies in this vitamin can cause irreversible damage to the nerves and brain.

But an even bigger problem is that women are still failing to take folic acid. Only 32% of women of childbearing age take a daily vitamin containing the nutrient, despite the fact that 75% of women say they are aware of the benefits of it while trying to conceive, according to a poll by the March of Dimes.

Other people who may benefit from supplements and/or fortified foods include breast-feeding mothers, smokers, heavy drinkers, dieters, senior citizens, and strict vegetarians. Again, the experts say, the safest way to find out if you need a nutritional boost is to check with your doctor.

Vital Information:

  • While the popularity of dietary supplements and fortified foods is on the rise, some experts caution that you can have too much of a good thing.
  • The National Academy of Sciences has issued recommended upper intake levels of certain vitamins and minerals.
  • Some nutrients can affect prescription medications, so it is important to discuss all dietary supplements with your doctor.