Vitamins & Minerals

How Much is too much?

Most nutrition experts agree that the best way to get the vitamins, minerals and other nutrients you need is to eat a balanced diet with lots of variety in food choices. If a person does not eat a wide variety of foods with plenty of grains, fruits and vegetables, a daily multivitamin and mineral supplement might be necessary. For those who take supplements, it is important not to take too much.

The National Academy of Sciences published guidelines that can be used to help determine safe levels of vitamin and mineral intake. For some vitamins and minerals, a Tolerable Upper Intake, known as UL, has been set. This level is the highest amount of nutrients from any combination of food, fortified food, and supplements that the body can handle each day. Getting more than the UL from food and/or supplements can cause harm to the body. Vomiting, diarrhea, dry skin, nerve and liver damage are just some of the problems that people have experienced who took supplements with more than the upper limit of vitamins and minerals. There is absolutely no benefit to consuming such high levels for healthy people.

The UL is not a recommended level of intake. It is the maximum level of nutrients from food and supplements that the body can tolerate without harmful effects. The level can also be used as a guide to determine if nutrient amounts in supplements are too high. It is important to check supplement labels to make sure that the supplement has less than the UL because the nutrients consumed from supplements add to the amounts eaten in food. The amounts from food plus supplements should be less than the amounts listed in the table.

Tolerable Upper Intake Levels for Adults 19 to 70 years of age

For some vitamins and minerals, a Tolerable Upper Intake Level has not yet been set due to a lack of research. This does not mean that it is safe to consume more of those vitamins and minerals. There are no laws that limit the amount of nutrients that are in supplements. Consumers may be buying supplements that contain anywhere from 1% to over 600% of their needs. Since there are no laws to guarantee the safety of supplements, it is the consumer's job to police how much they consume. The following guidelines and cautions can be used to decrease the risk of toxicity from supplements.

Guidelines for choosing supplements

Read the label. It is best to choose a supplement that has at least 20 vitamins and minerals and no more than 100 percent Daily Value for each nutrient.

Compare the amount of each vitamin and mineral to the UL. If the supplement has amounts even close to the UL, it should not be taken. High levels can cause headaches, vomiting, diarrhea, dry skin, and other problems.

Check the expiration date. Make sure that the supplement has not expired.

Consider the price. Store brands are just as good as name brands. The cost of advertisement makes name brands more expensive.

Cautions on supplements

Those who are pregnant, breastfeeding, have a disease, or take medication should always seek the advice of a doctor or dietitian before taking a supplement.

Always be sure to follow directions carefully and ask questions when doctors or dietitians recommend supplements.

It is a good practice to take supplement labels when visiting with a doctor or dietitian. Mixing some supplements with medications can be harmful.

Supplements should always be kept out of the reach of children. The leading cause of poisoning in children is overdose from iron supplements.

The body needs more than a pill

Most healthy people do not need to take supplements. The benefits of changing eating habits are far better than taking supplements. Supplements just do not have everything food does. There are many important substances found in foods that help keep the body in good health. Increasing the amounts of fruits, vegetables, low fat dairy products, whole grains, and beans is a great way to get the vitamins and minerals that might be lacking in the diet. Many of these foods have substances that may help prevent cancer and heart disease. By following the Food Guide Pyramid and eating a wide variety of foods, healthy people can get all the nutrients the body needs without having to take a supplement.

References

Johns Hopkins Health Information Intelihealth. Vitamin Supplements. Available at: www.intelihealth.com/IH/intIH/WSIHW000/325/7098.html

U.S. Food and Drug Administration. An FDA guide to Dietary Supplements. Available at: http://vm.cfsan.fda.gov/~dms/fdsupp.html.

Whitney, Eleanor N. Understanding Nutrition. 8th ed. Belmont: Wadsworth, 1999. 13-16, 329-335.