Feeling Good Begins on the Inside
Dietary Supplements: What You Need to Know
Many adults in the world take one or more dietary supplements, either every day or occasionally. Dietary supplements include vitamins, minerals, herbals and botanicals, 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
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 fillers, binders, and flavourings). The manufacturer suggests the serving size, but you or your health care provider might decide that a different amount is more appropriate for you.
If you don’t eat a nutritious variety of foods, some supplements might help you get adequate amounts of essential nutrients. However, 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.
Scientific evidence shows that some dietary supplements are beneficial for overall health and for managing some health conditions. For example, 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
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.
Supplements are most likely to cause side effects or harm when people take them instead of prescribed medicines or when people take many supplements in combination. 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.
Keep in mind that 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. For example, 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.
Be cautious about taking dietary supplements if you are pregnant or nursing. Also, 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.
If you suspect that you have had a serious reaction from a dietary supplement, let your health care provider know. Report your reaction to the dietary supplement company by using the contact information on the product label.
Dietary supplements are complex products. The FDA has established good manufacturing practices (GMPs) for dietary supplements to help ensure their identity, purity, strength, and composition. These GMPs are designed to prevent the inclusion of the wrong ingredient, the addition of too much or too little 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.
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 safe or effective. Organizations that offer this quality testing include:
- U.S. Pharmacopeia
- NSF International
Keep in Mind
Don’t decide to take dietary supplements to treat a health condition that you have diagnosed yourself, without consulting a health care provider.
- Don’t take supplements in place of, or in combination with, prescribed medications without your health care provider’s approval.
- Check with your health care provider about the supplements you take if you are scheduled to have any type of surgical procedure.
- 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 example, comfrey and kava) 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?
If you don’t know the answers to these questions, use the information sources listed in this brochure and talk to your health care providers. The FDA provides a useful form, ”My Medicine Record”, to record the medicines and dietary supplements that you take which you can share with your health care providers.
Talk with Your Health Care Provider
Let your health care providers (including doctors, pharmacists, and dietitians) 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.
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. You can also bring the products you use with you when you see your health care provider.
From the National Institute of Health.