The Facts About Dietary Supplements

dietary supplements

All products labeled as a dietary supplement carry a Supplement Facts panel that lists the contents, amount of active ingredients per serving, and other added ingredients (like binders, fillers, and flavorings). The manufacturer suggests the serving size, but you or your health care provider might decide that a different amount is more appropriate for you.


The majority of adults in the United States take one or more dietary supplements either every day or occasionally. Today’s dietary supplements include vitamins, minerals, botanicals and herbals, amino acids, enzymes, and many other products. Dietary supplements come in a variety of forms: traditional tablets, capsules, and powders, as well as drinks and energy bars. Popular supplements include vitamins D and E; minerals like calcium and iron; herbs such as echinacea and garlic; and specialty products like glucosamine, probiotics, and fish oils.

The Dietary Supplement Label

Scientific evidence shows that some dietary supplements are beneficial for overall health and for managing some health conditions. Calcium and vitamin D are important for keeping bones strong and reducing bone loss; folic acid decreases the risk of certain birth defects; and omega-3 fatty acids from fish oils might help some people with heart disease. Other supplements need more study to determine their value. The U.S. Food and Drug Administration (FDA) does not determine whether dietary supplements are effective before they are marketed.

Safety and Risk

Some supplements might help you get adequate amounts of essential nutrients if you don’t eat a nutritious variety of foods. Supplements can’t take the place of the variety of foods that are important to a healthy diet. Good sources of information on eating well include the Dietary Guidelines for Americans and MyPlate.

Many supplements contain active ingredients that can have strong effects in the body. Always be alert to the possibility of unexpected side effects, especially when taking a new product.

When people take them instead of prescribed medicines or when people take many supplements in combination, supplements are most likely to cause side effects or harm. Some supplements can increase the risk of bleeding or, if a person takes them before or after surgery, they can affect the person’s response to anesthesia. Dietary supplements can also interact with certain prescription drugs in ways that might cause problems. Here are just a few examples:

  • Vitamin K can reduce the ability of the blood thinner Coumadin ® to prevent blood from clotting.
  • St. John’s wort can speed the breakdown of many drugs (including antidepressants and birth control pills) and thereby reduce these drugs’ effectiveness.
  • Antioxidant supplements, like vitamins C and E, might reduce the effectiveness of some types of cancer chemotherapy.

If you are pregnant or nursing, be cautious about taking dietary supplements. Be careful about giving them (beyond a basic multivitamin/mineral product) to a child. Most dietary supplements have not been well tested for safety in pregnant women, nursing mothers, or children.

Dietary supplements are complex products. The FDA has established good manufacturing practices (GMPs) for dietary supplements to help ensure their identity, purity, composition, and strength. These GMPs are designed to prevent the inclusion of the wrong ingredient, the addition of too little or too much of an ingredient, the possibility of contamination, and the improper packaging and labeling of a product. The FDA periodically inspects facilities that manufacture dietary supplements.

Some ingredients found in dietary supplements are added to a growing number of foods, including breakfast cereals and beverages. As a result, you may be getting more of these ingredients than you think, and more might not be better. Taking more than you need is always more expensive and can also raise your risk of experiencing side effects. Getting too much vitamin A can cause headaches and liver damage, reduce bone strength, and cause birth defects. Excess iron causes nausea and vomiting and may damage the liver and other organs.

Let your health care provider know if you suspect that you have had a serious reaction from a dietary supplement. He or she may report your experience to the FDA. You may also submit a report to the FDA by calling 800-FDA-1088 or completing a form onlineexternal link disclaimer. In addition, report your reaction to the dietary supplement company by using the contact information on the product label.


In addition, several independent organizations offer quality testing and allow products that pass these tests to display their seals of approval. These seals of approval provide assurance that the product was properly manufactured, contains the ingredients listed on the label, and does not contain harmful levels of contaminants. These seals of approval do not guarantee that a product is effective or safe. Organizations that offer this quality testing include:

  • U.S. Pharmacopeia
  • NSF International

Keep in Mind

Manufacturers must follow certain good manufacturing practices to ensure the identity, purity, strength, and composition of their products. If the FDA finds a product to be otherwise unfit or unsafe for human consumption, it may take enforcement action to remove the product from the marketplace or work with the manufacturer to voluntarily recall the product.

Once a dietary supplement is on the market, the FDA monitors information on the product’s label and package insert to make sure that information about the supplement’s content is accurate and that any claims made for the product are not misleading and truthful. The Federal Trade Commission, which polices product advertising, also requires all information about a dietary supplement product to be not misleading and truthful.

Dietary supplements are products intended to supplement the diet. They are not drugs and, therefore, are not intended to treat, diagnose, mitigate, prevent, or cure diseases. The FDA is the federal agency that oversees both dietary supplements and medicines.

  • Don’t take supplements in place of, or in combination with, prescribed medications without your health care provider’s approval.
  • If you are scheduled to have any type of surgical procedure, check with your health care provider about the supplements you take.
  • The term “natural” doesn’t always mean safe. A supplement’s safety depends on many things, such as its chemical makeup, how it works in the body, how it is prepared, and the dose used. Certain herbs (for kava, comfrey and example) can harm the liver.
  • Before taking a dietary supplement, ask yourself these questions:

What are the potential health benefits of this dietary supplement product?
What are its potential benefits for me?
Does this product have any safety risks?
What is the proper dose to take?
How, when, and for how long should I take it?

The federal government can take legal action against companies and Web sites that sell dietary supplements when the companies make deceptive or false statements about their products, if they promote them as treatments or cures for diseases, or if their products are unsafe.

Don’t decide to take dietary supplements to treat a health condition that you have diagnosed yourself, without consulting a health care provider.

Dietary supplement labels may carry certain types of health-related claims. Manufacturers are permitted to say, for example, that a dietary supplement addresses a nutrient deficiency, supports health, or is linked to a particular body function (like immunity or heart health). Such a claim must be followed by the words, “This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.”

Use the information sources listed in this brochure and talk to your health care providers if you don’t know the answers to these questions.

Talk with Your Health Care Provider

Let your health care providers (including doctors, dietitians, and pharmacists) know which dietary supplements you’re taking so that you can discuss what’s best for your overall health. Your health care provider can help you determine which supplements, if any, might be valuable for you.

In general, the FDA regulations for dietary supplements are different from those for prescription or over-the-counter drugs. Unlike drugs, which must be approved by the FDA before they can be marketed, dietary supplements do not require premarket review or approval by the FDA. While the supplement company is responsible for having evidence that their products are safe and the label claims are not misleading and truthful, they do not have to provide that evidence to the FDA before the product is marketed.

Keep a record of the supplements you take in one place, just as you should be doing for all of your medicines. Note the specific product name, the dose you take, how often you take it, and the reason why you use each one. When you see your health care provider, you can also bring the products you use with you.
Federal Regulation of Dietary Supplements


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