Dietary supplements (also called nutritional supplements, or supplements for short) were definied in a law passed by Congress in 1994.
- Are taken by mouth
- Contain a dietary ingredient intended to supplement the diet. Examples of dietary ingredients include vitamins, minerals, herbs (as single herbs or mixtures), other botanicals, amino acids, and dietary substances such as enzymes and glandulars.
- Come in different forms, such as tablets, capsules, softgels, gelcaps, liquids, and powders.
- Are not represented for use as a conventional food or as a sole item of a meal or the diet.
- Are labeled as being a dietary supplement.
Dietary supplements are sold in grocery, health food, drug, and discount stores, as well as through mail-order catalogs, TV programs, the Internet, and direct sales.
Why do people take supplements?
People take supplements for many reasons. A scientific study on this topic was published in 2002. In it, over 2,500 Americans reported on supplements they used (given the categories of vitamins/minerals and herbal products/natural supplements) and for what reasons. Their responses are summarized in the table below.
"The other thing that has gotten a lot of media attention is the increased risk of infectious diseases," said Parker. "This is of greater concern to other parts of the world than the United States." That's because the U.S. has good public health systems that can track down infectious diseases, such as malaria, and intervene so they don't spread, she said.
Is using supplements considered conventional medicine or complementary and alternative medicine?
Some uses of dietary supplements have become part of conventional medicine. For example, scientists have found that the vitamin folic acid prevents certain birth defects, and a regimen of vitamins and zinc can slow the progression of the eye disease age-related macular degeneration.
On the other hand, some supplements are considered to be complementary and alternative medicine either the supplement itself or one or more of its uses. An example of a complementary supplement would be an herbal formula that claims to relieve arthritis pain, but has not been proven to do so through scientific studies. An example of a complementary use of a supplement would be taking 1,000 milligrams of vitamin C per day to prevent or treat a cold, as the use of large amounts of vitamin C for these purposes has not been proven.
How can I get science-based information on a supplement?
There are several ways to get information on supplements that is based on the results of rigorous scientific testing, rather than on testimonials and other unscientific information.
- Ask your health care provider. Even if your provider does not happen to know about a particular supplement, he can access the latest medical guidance about its uses and risks.
- Dietitians and pharmacists also have helpful information.
- You can find out yourself whether there are any scientific research findings on the supplement you are interested in. Federal agencies have free publications, clearinghouses, and databases with this information.
If I am interested in using a supplement, how can I do so most safely?
Here are some points to keep in mind:
It is important to talk to your health care provider (or providers, if you have more than one) about the supplement. This is for your safety and a complete treatment plan. It is especially important to talk to your provider if you:
- Are thinking about replacing your regular medical care with one or more supplements.
- Are taking any medications (whether prescription or over-the-counter). Some supplements have been found to interact with medications.
- Have a chronic medical condition.
- Are planning to have surgery. Certain supplements may increase the risk of bleeding or affect anesthetics and painkillers.
- Are pregnant or nursing a baby.
- Are thinking about giving a child a supplement. Many products being marketed for children have not been tested for their safety and effectiveness in children.
- Do not take a higher dose of a supplement than what is listed on the label, unless your health care provider advises you to do so.
- If you experience any side effects that concern you, stop taking the supplement, and contact your provider. You can also report your experience to the U.S. Food and Drug Administration's (FDA) MedWatch program, which tracks consumer safety reports on supplements.
- If you are considering or using herbal supplements, there are some special safety issues to take into account.
I see the word natural on a lot of supplement labels. Does natural always mean safe?
There are many supplements and prescription drugs that come from natural sources and are both useful and safe. However, natural does not always mean safe or without harmful effects. For example, consider mushrooms that grow in the wild; some are safe to eat, while others are poisonous.
The FDA issues warnings about supplements that pose risks to consumers, including those used for complementary therapies. A sample list is in the box below. The FDA found these products of concern because they:
- Could damage health in some cases severely.
- Were soiled by other unlabeled herbs, pesticides, heavy metals, or prescription drugs.
- Interacted dangerously with prescription drugs
Examples of supplements that have carried FDA cautions about safety:
- Some dieter's teas
- GHB (gamma hydroxybutyric acid), GBL (gamma butyrolactone), and BD (1,4-butanediol)
- PC SPES and SPES
- Aristolochic acid
- St. John's wort
- Certain products, marketed for sexual enhancement and claimed to be natural versions of the drug Viagra, which were found to contain an unlabeled drug (sildenafil or tadalafil)
Does the Federal Government regulate supplements?
Yes, the Federal Government regulates supplements through the FDA. Currently, the FDA regulates supplements as foods rather than drugs. In general, the laws about putting and keeping foods (including supplements) on the market are less strict than the laws for drugs. Specifically:
- Research studies in people to prove a supplement's safety are not required before the supplement is marketed, unlike for drugs.
- The manufacturer does not have to prove that the supplement is effective, unlike drugs. The manufacturer can say that the product addresses a nutrient deficiency, supports health, or reduces the risk of developing a health problem, if that is true. If the manufacturer does make such a claim, it must be followed by the statement 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.
- The manufacturer does not have to prove supplement quality.
- The FDA does not analyze the content of dietary supplements.
- At this time, supplement manufacturers must meet the requirements of the FDA's Good Manufacturing Practices (GMPs) for foods. GMPs describe conditions under which products must be prepared, packed, and stored. Food GMPs do not always cover all issues of supplement quality. Some manufacturers voluntarily follow the FDA's GMPs for drugs, which are stricter.
- Some manufacturers use the term standardized to describe efforts to make their products consistent. However, U.S. law does not define standardization. Thus, the use of this term (or similar terms such as verified or certified) does not guarantee product quality or consistency.
- If the FDA finds a supplement to be unsafe once it is on the market, only then can it take action against the manufacturer and/or distributor, such as by issuing a warning or requiring the product to be removed from the marketplace.
In March 2003, the FDA published new proposed guidelines for supplements that would require manufacturers to avoid contaminating their products with other herbs, pesticides, heavy metals, or prescription drugs. The guidelines would also require supplement labels to be accurate. These new guidelines could take effect as early as 2004.
The Federal Government also regulates supplement advertising through the Federal Trade Commission, which dictates that any and all information about supplements be truthful and not misleading to consumers.
What's in the bottle does not always match
A supplement might:
- Not contain the correct ingredient (plant species). For example, one study that analyzed 59 preparations of echinacea found that about half did not contain the species listed on the label.
- Contain higher or lower amounts of the active ingredient. For example, an NCCAM-funded study of ginseng products found that most contained less than half the amount of ginseng listed on their labels.
- Be contaminated.
More information on supplements and heart health can be found in
Bragg's Healthy Heart Book