Dietary Supplements: What You Need to Know

Many adults and children in the United States take one or more vitamins or other dietary supplements. In addition to vitamins, dietary supplements can contain minerals, herbs or other botanicals, amino acids, enzymes, and many other ingredients. Dietary supplements come in a variety of forms, including tablets, capsules, gummies, and powders, as well as drinks and energy bars. Popular supplements include vitamins D and B12; minerals like calcium and iron; herbs such as echinacea and garlic; and products like glucosamine, probiotics, and fish oils.

The Dietary Supplement Label

Products sold as dietary supplements come with a Supplement Facts label that lists the active ingredients, the amount per serving (dose), as well as other ingredients, such as fillers, binders, and flavorings. The manufacturer suggests the serving size, but your healthcare provider might decide a different amount is more appropriate for you.

Effectiveness

Some dietary supplements can help you get adequate amounts of essential nutrients if you don’t eat a nutritious variety of foods. However, supplements can’t take the place of the variety of foods that are important to a healthy diet. To learn more about what makes a healthy diet, the Dietary Guidelines for Americans is a good source of information.

Some dietary supplements can improve overall health and help manage some health conditions. For example: 

• Calcium and vitamin D help keep bones strong and reduce bone loss. 
• Folic acid decreases the risk of certain birth defects.
• Omega-3 fatty acids from fish oils might help some people with heart disease. 

A combination of vitamins C and E, zinc, copper, lutein, and zeaxanthin (known as AREDS) may slow down further vision loss in people with age-related macular degeneration (AMD). 

Many other supplements need more study to determine if they have 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 on the body. Always be alert to the possibility of a bad reaction, especially when taking a new product.

You are most likely to have side effects from dietary supplements if you take them at high doses or instead of prescribed medicines, or if you take many different supplements. Some supplements can increase the risk of bleeding or, if taken before surgery, can change your response to anesthesia. Supplements can also interact with some medicines in ways that might cause problems. Here are a few examples:

• Vitamin K can reduce the ability of the blood thinner warfarin to prevent blood from clotting.
• St. John’s wort can speed the breakdown of many medicines and reduce their effectiveness (including some antidepressants, birth control pills, heart medications, anti-HIV medications, and transplant drugs).
• Antioxidant supplements, such as vitamins C and E, might reduce the effectiveness of some types of cancer chemotherapy.

Manufacturers may add vitamins, minerals, and other supplement ingredients to foods you eat, especially breakfast cereals and beverages. As a result, you may get more of these ingredients than you think, and more might not be better. Taking more than you need costs more and might also raise your risk of side effects. For example, 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 supplements to a child, unless recommended by their healthcare provider. Many supplements have not been well tested for safety in pregnant women, nursing mothers, or children.

If you think that you have had a bad reaction to a dietary supplement, let your healthcare provider know. He or she may report your experience to the FDA. You may also submit a report directly to the FDA by calling 800-FDA-1088 or completing an online form. You should also report your reaction to the manufacturer by using the contact information on the product label.

Quality

The FDA has established good manufacturing practices (GMPs) that companies must follow to help ensure the identity, purity, strength, and composition of their dietary supplements. These GMPs can prevent adding the wrong ingredient (or too much or too little of the correct ingredient) and reduce the chance of contamination or improper packaging and labeling of a product. The FDA periodically inspects facilities that manufacture supplements.

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

• ConsumerLab.com
• NSF International
• U.S. Pharmacopeia

Talk with Your Healthcare Providers

Tell your healthcare providers (including doctors, dentists, pharmacists, and dietitians) about any dietary supplements you’re taking. They can help you determine which supplements, if any, might be valuable for you.

Keep a complete record of any dietary supplements and medicines you take. The Office of Dietary Supplements website has a useful form, ”My Dietary Supplement and Medicine Record,” that you can print and fill out at home. For each product, note the name, the dose you take, how often you take it, and the reason for use. You can share this record with your healthcare providers to discuss what’s best for your overall health. 

Keep in Mind

Consult your healthcare provider before taking dietary supplements to treat a health condition.

• Get your healthcare provider’s approval before taking dietary supplements in place of, or in combination with, prescribed medicines.
• If you are scheduled to have any type of surgical procedure, talk with your healthcare provider about any supplements you take. 

Keep in mind the term “natural” doesn’t always mean safe. Some all-natural botanical products, for example, like comfrey and kava, can harm the liver. A dietary supplement’s safety depends on many things, such as its chemical makeup, how it works in the body, how it is prepared, and the amount you take. 

• Before taking any dietary supplement, use the information sources listed in this brochure and talk to your healthcare providers to answer these questions:
• What are its potential benefits for me?
• Does it have any safety risks?
• What is the proper dose to take?
• How, when, and for how long should I take it? 

Federal Regulation of Dietary Supplements

Dietary supplements are products intended to supplement the diet. They are not medicines and are not intended to treat, diagnose, mitigate, prevent, or cure diseases. The FDA is the federal agency that oversees both supplements and medicines, but the FDA regulations for dietary supplements are different from those for prescription or over-the-counter medicines.

Medicines must be approved by the FDA before they can be sold or marketed. Supplements do not require this approval. Supplement companies are responsible for having evidence that their products are safe and that the label claims are truthful and not misleading. However, as long as the product does not contain a “new dietary ingredient” (one introduced on October 15, 1994), the company does not have to provide this safety evidence to the FDA before the product is marketed.

Dietary supplement labels may include certain types of health-related claims. Manufacturers are permitted to say, for example, that a supplement promotes health or supports a body function (like immunity or heart health). These claims 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.”

Manufacturers must follow good manufacturing practices (GMPs) to ensure the identity, purity, strength, and composition of their products. If the FDA finds a dietary supplement to be unsafe, it may remove the product from the marketplace or ask the manufacturer to voluntarily recall the product.

The FDA monitors the marketplace for potential illegal products that may be unsafe or make false or misleading claims. The Federal Trade Commission, which monitors product advertising, also requires information about a supplement product to be truthful and not misleading.

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

Federal Government Information Sources on Dietary Supplements

NATIONAL INSTITUTES OF HEALTH

NIH supports research and provides educational materials on dietary supplements.

• Office of Dietary Supplements
• ODS provides accurate and up-to-date scientific information about dietary supplements.
• National Center for Complementary and Alternative Medicine
• NCCIH also has scientific information about dietary supplement ingredients.
• National Library of Medicine
• Medline Plus provides trusted health information.
• PubMed contains more than 30 million citations to the scientific literature.
• NIH Health Information 
• Information about healthy living and wellness from across NIH.

U.S. FOOD AND DRUG ADMINISTRATION

FDA issues rules and regulations and oversees dietary supplement labeling, marketing, and safety. Recall notices are also posted on the FDA webpage or you can subscribe to receive FDA notices of recalls, market withdrawals, and safety alerts.

FEDERAL TRADE COMMISSION

FTC regulates health and safety claims made in advertising for dietary supplements.

U.S. DEPARTMENT OF AGRICULTURE

USDA provides information on a variety of food and nutrition topics.

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

HHS provides wellness information, personal health tools, and health news.

Should You Take Dietary Supplements?

A Look at Vitamins, Minerals, Botanicals.

When you reach for that bottle of vitamin C or fish oil pills, you might wonder how well they’ll work and if they’re safe. The first thing to ask yourself is whether you need them in the first place.

More than half of all Americans take one or more dietary supplements daily or on occasion. Supplements are available without a prescription and usually come in pill, powder, or liquid form. Common supplements include vitamins, minerals, and herbal products, also known as botanicals.

People take these supplements to make sure they get enough essential nutrients and to maintain or improve their health. But not everyone needs to take supplements.

“It’s possible to get all of the nutrients you need by eating a variety of healthy foods, so you don’t have to take one,” says Carol Haggans, a registered dietitian and consultant to NIH. “But supplements can be useful for filling in gaps in your diet.”

Some supplements may have side effects, especially if taken before surgery or with other medicines. Supplements can also cause problems if you have certain health conditions. The effects of many supplements haven’t been tested in children, pregnant women, and other groups. So talk with your health care provider if you’re thinking about taking dietary supplements.

“You should discuss with your doctor what supplements you’re taking so your care can be integrated and managed,” advises Dr. Craig Hopp, an expert in botanicals research at NIH.

Dietary supplements are regulated by the U.S. Food and Drug Administration (FDA) as foods, not as drugs. The label may claim certain health benefits. But unlike medicines, supplements can’t claim to cure, treat, or prevent a disease.

“There’s little evidence that any supplement can reverse the course of any chronic disease,” says Hopp. “Don’t take supplements with that expectation.”

Evidence does suggest that some supplements can enhance health in different ways. The most popular nutrient supplements are multivitamins, calcium, and vitamins B, C and D. Calcium supports bone health, and vitamin D helps the body absorb calcium. Vitamins C and E are antioxidants—molecules that prevent cell damage and help to maintain health.

Women need iron during pregnancy, and breastfed infants need vitamin D. Folic acid—400 micrograms daily, whether from supplements or fortified food—is important for all women of childbearing age.

Vitamin B12 keeps nerve and blood cells healthy. “Vitamin B12 mostly comes from meat, fish, and dairy foods, so vegans may consider taking a supplement to be sure to get enough of it,” Haggans says.

Research suggests that fish oil can promote heart health. Of the supplements not derived from vitamins and minerals, Hopp says, “Fish oil probably has the most scientific evidence to support its use.”

The health effects of some other common supplements need more study. These include glucosamine (for joint pain) and herbal supplements such as echinacea (immune health) and flaxseed oil (digestion).

Many supplements have mild effects with few risks. But use caution. Vitamin K, for example, will reduce the ability of blood thinners to work. Ginkgo can increase blood thinning. The herb St. John’s wort is sometimes used to ease depression, anxiety, or nerve pain, but it can also speed the breakdown of many drugs—such as antidepressants and birth control pills—and make them less effective.

Just because a supplement is promoted as “natural” doesn’t necessarily mean it’s safe. The herbs comfrey and kava, for example, can seriously damage the liver.

“It’s important to know the chemical makeup, how it’s prepared, and how it works in the body—especially for herbs, but also for nutrients,” says Haggans. “Talk to a health care provider for advice on whether you need a supplement in the first place, the dose, and possible interactions with medicine you’re already taking.”

For vitamins and minerals, check the % Daily Value (DV) for each nutrient to make sure you’re not getting too much. “It’s important to consider the DV and upper limit,” says Haggans. Too much of certain supplements can be harmful.

Scientists still have much to learn even about common vitamins. One recent study found unexpected evidence about vitamin E. Earlier research suggested that men who took vitamin E supplements might have a lower risk of developing prostate cancer. “But much to our surprise, a large NIH-funded clinical trial of more than 29,000 men found that taking supplements of vitamin E raised—not reduced—their risk of this disease,” says Dr. Paul M. Coates, director of NIH’s Office of Dietary Supplements. That’s why it’s important to conduct clinical studies of supplements to confirm their effects.

Because supplements are regulated as foods, not as drugs, the FDA doesn’t evaluate the quality of supplements or assess their effects on the body. If a product is found to be unsafe after it reaches the market, the FDA can restrict or ban its use.

Manufacturers are also responsible for the product’s purity, and they must accurately list ingredients and their amounts. But there’s no regulatory agency that makes sure that labels match what’s in the bottles. You risk getting less, or sometimes more, of the listed ingredients. All of the ingredients may not even be listed.

A few independent organizations conduct quality tests of supplements and offer seals of approval. This doesn’t guarantee the product works or is safe; it just assures the product was properly made and contains the listed ingredients.

“Products sold nationally in the stores and online where you usually shop should be fine,” Coates says. “According to the FDA, supplement products most likely to be contaminated with pharmaceutical ingredients are herbal remedies promoted for weight loss and sexual or athletic performance enhancement.”

To make it easy to find reliable information, NIH has fact sheets on dietary supplements at ods.od.nih.gov/factsheets/list-all/. NIH also recently launched an online Dietary Supplement Label Database. This free database lets you look up the ingredients of thousands of dietary supplements. It includes information from the label on dosage, health claims, and cautions.

For more personalized, on-the-go information about dietary supplements, check out NIH’s free updated app for your smartphone or tablet: My Dietary Supplements (MyDS).

The MyDS app provides the latest supplement information and lets you keep track of the vitamins, minerals, herbs, and other products you take. You can even keep track of supplements taken by your parents, spouse, or children.

“Deciding whether to take dietary supplements and which ones to take is a serious matter,” says Coates. “Learn about their potential benefits and any risks they may pose first. Speak to your healthcare providers about products of interest and decide together what might be best for you to take, if anything, for your overall health.”

Training Adaptations

We know that, if we want to change our bodies, we have to overload the muscles. This is called functional overreaching—which leads to super compensation. The body’s response is an adaptation, which refers to your body’s physiological response to training. When you do new exercises or load your body differently, your body reacts by increasing its ability to cope with that new load.

There are different phases of adaptation that your body experiences.

The Phases of Adaptation 

• First Few Weeks – The first few times you do cardio or strength training, your body kind of freaks out as it gets used to this new stimulus. It’s during this period that you experience soreness and, maybe, the feeling that you’re making a big mistake. But you’re not, so don’t give up.
• 4-16 Weeks – That’s a big range, but experts suggest that it’s during this phase that your body adapts and becomes more efficient at the exercises and activities you’re doing.
• After 16 Weeks – This is where there’s a point of diminishing returns. If you haven’t changed up your workouts, the body will stop responding. But keep in mind that the body will continue to respond if presented with new stimuli—new exercises or new challenges.

Signs You Need to Change Your Workouts 

1. You’ve Hit a Plateau – If you stop losing weight or stop making progress with your strength workouts, it’s time to make a change. Any time you feel stuck in a rut, you probably are. Don’t wait for it to happen, but start making changes as you go along.
2. You’re Bored – The first sign you need to change is when your workouts are so boring, you’d almost rather do anything else.
3. You’re Burned Out – Burnout is a little more serious and you may need to take a break from your routine and try something different. If you exercise alone, try a group fitness class or vice versa. Just about anything new will feel refreshing. 
4. You’re Constantly Injured – This may also be a sign that you’re overtraining. Doing the same thing over and over is never good for the body or mind, so this is a great time to take a bit of a longer break and maybe do other activities to heal your body, like yoga or Pilates.
5. You Start to Hate Exercise – If it feels like a chore every time you work, that may be a sign you need to shake things up.

How to Change Your Workouts 

So, how do you change your workouts? Your first step is to start with the F.I.T.T. Principle—the guidelines that help create an effective workout. Start by manipulating one or all of these elements: Your frequency, intensity, time, and type of activity. The important part of the exercise isn’t the type of program you have, but having one you’ll do. Don’t get too hung up on doing the right thing for a certain period. If your body, and mind, have adapted to what you’re doing, any change is a good thing.

Once you get to a certain fitness level, say after training consistently for 3 or more months, you can change things up every week if you like. It might also be worth it to set up a ​periodization program so that you never have to worry about hitting a plateau.

Keep in mind that you need to track your workouts to make the F.I.T.T. principle work to your advantage. It’s hard to manage what you don’t measure. By keeping track of your workouts, you’ll be able to review and analyze what you’ve been doing and make changes accordingly.

Whatever you do, pay attention to how you’re feeling about your workouts and make the change before you hit that plateau. It’s easy to get into a routine without realizing how long you’ve been doing it.