The Scoop - February 2011

The Scoop: A Newsletter for Consumers from the Office of Dietary Supplements, National Institutes of Health

February 2011

Welcome to the first issue of The Scoop!

The Scoop is for health-conscious people like you who may use dietary supplements or are curious about them but have some questions. It will bring you information and news that you can use to make more informed decisions about taking dietary supplements.

Some issues of The Scoop will address questions we’ve received about supplements. Others will focus on one topic, such as multivitamins or dietary supplements and aging. But the goal of each issue remains the same—to help you navigate the always interesting but sometimes confusing world of dietary supplements.

The Scoop is brought to you by the Office of the Dietary Supplements (ODS) at the National Institutes of Health (NIH)—the world’s largest medical research agency. ODS promotes high-quality scientific research on the many different ingredients in dietary supplements. We also provide reliable information on these products to consumers and scientists. We hope you find The Scoop valuable.

We designed our new Web site with you in mind.

The NIH Office of Dietary Supplements Web site is newly designed with consumers like you in mind. Under the Health Information tab, you’ll find accurate, up-to-date information to help you make educated decisions about dietary supplements. We also offer a series of consumer-oriented fact sheets on dietary supplements to complement those written for health care professionals.

Dietary supplements: there’s a free app for that!

The My Dietary Supplements App, free for the Apple iPhone and iPadMy Dietary Supplements
(myDS) is a new, free mobile app for the Apple iPhone and iPad that provides an easy way to keep track of the vitamins, minerals, herbs, and other supplements you take.

Dietary supplements: what you need to know.

The NIH Office of Dietary Supplements has created a brochure—“Dietary Supplements: What You Need To Know”—that serves as a one-stop resource for accurate information about dietary supplements. This brochure talks about effectiveness, safety and risk, quality, regulation, and other important factors to consider before buying and taking dietary supplements. The brochure also provides an extensive list of other relevant Federal Government information resources.

What Consumers Like You Want To Know

Doctor consulting with a patient

Should I take a vitamin D supplement?

It depends. You need vitamin D for strong, healthy bones and to help prevent osteoporosis. Researchers are also studying vitamin D to see if it affects your risk of getting diseases such as diabetes and cancer, but they still don't fully understand all of its effects in the body.

A scientific committee recently issued new recommended intakes for vitamin D. Most children and adults should get 600 International Units (IUs) a day, while those age 70 and older need 800 IUs.

It’s always best to get nutrients from food first, if you can, before taking supplements. Good sources of vitamin D include tuna and fortified milk. Our bodies also make vitamin D when our skin is exposed to the sun. Knowing exactly how much vitamin D you’re getting can be difficult. Your health care provider can help you determine whether you might need a vitamin D supplement based on such factors as the foods you eat, your skin type, and the amount of sun you're exposed to. Your health care provider can also test your vitamin D blood levels.

Vitamin D2 and D3 supplement pills

What is the difference between vitamin D2 and vitamin D3?

Vitamin D comes in two forms: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). When taken at the recommended levels listed above, both increase the amount of vitamin D in your blood equally well. But if you're taking a very large dose on the advice of your health care provider, the D3 form may be more effective than the same amount of D2.

Have more questions? See our fact sheets on vitamin D.

Oranges rich in vitamin C

Can vitamin C prevent colds or make them shorter?

This is a common question and one that many scientists have tried to answer. Overall, the research shows that for most people, taking vitamin C regularly does not reduce the chances of getting the common cold. Vitamin C supplements might slightly shorten the duration of a cold and lessen its severity. However, taking vitamin C after the onset of cold symptoms doesn’t appear to help.

Taking too much vitamin C can cause diarrhea, nausea, and stomach cramps. Most adults need between 75 and 90 milligrams (mg) of vitamin C per day and shouldn't get more than 2,000 mg.

Have more questions? See our fact sheets on vitamin C.

Supplement information label

How do I know if a dietary supplement contains what the label says or if it might be contaminated?

Manufacturers of supplements must follow good manufacturing practices to help ensure their identity, purity, strength, and composition. These practices are designed to prevent problems such as including the wrong ingredient, adding the wrong amount of an ingredient, or contamination. The U.S. Food and Drug Administration has begun to periodically inspect facilities that manufacture dietary supplements, but it does not routinely analyze the content of dietary supplements.

Several independent organizations test the quality of dietary supplements and allow products that pass their tests to display their seals of approval. These seals provide assurance that the product was properly manufactured, contains the ingredients listed on the label, and does not contain harmful amounts of contaminants. Seals of approval don't guarantee that a product is safe or effective. Organizations that offer this testing include the U.S. Pharmacopeia,, NSF International, and the Natural Products Association.

Woman walking briskly

I'm thinking about using an herbal product but there are so many different brands. I don't know which one to buy or how much to take.

Many herbs are available in different forms, so it can be hard to compare one product to another. This is partly because scientists have not identified or clearly defined the components responsible for the effects of most herbs or the best amount to take. If you want to try an herbal product, talk with your health care provider first and ask whether he or she can recommend a particular brand and dosage.

Safety is also an important consideration. Many people believe that products labeled "natural" are safe and good for them. This is not necessarily true. The safety of an herbal supplement depends on many things, such as its chemical makeup, how it works in the body, how it's prepared, and how much you take. Many supplements contain active ingredients that can have strong effects in the body and can interact with certain prescription drugs in ways that might cause problems. So, always be alert to the possibility of unexpected side effects, especially when taking a new product.

Have more questions? See our background fact sheet on botanical dietary supplements.

Calcium supplement pills

What is the difference between calcium carbonate, calcium citrate, and other forms of calcium supplements?

The main difference between various calcium supplements is the form of calcium they contain, and one isn’t necessarily better than another for you. The two most common forms are calcium carbonate and calcium citrate. Calcium carbonate is absorbed best when taken with food. Calcium citrate is more expensive, but it’s absorbed well on an empty or a full stomach. In addition, people with low levels of stomach acid (which is more common in people age 50 and older) absorb calcium citrate more easily than calcium carbonate.

One of the most important things to consider about calcium supplements, aside from the form of calcium, is how much to take at one time. The body absorbs calcium best in doses of 500 mg or less at a time. So, for example, if you take 1,000 mg of calcium from supplements per day, you might split the dose and take 500 mg at two separate times during the day.

Have more questions? See our fact sheets on calcium.

Man examining perscription bottle

Dietary supplements and prescription drugs: what should I be aware of?

Some dietary supplements can cause problems if taken with certain prescription or over-the-counter drugs. For example, vitamin K can interfere with the effect of Coumadin® (warfarin), a commonly prescribed blood thinner. Vitamin E, ginkgo, garlic, St. John’s wort, and other dietary supplements can also interact with Coumadin® in different ways. Calcium supplements can interfere with bisphosphonates (to treat osteoporosis), certain antibiotics, levothyroxine (a thyroid medication), phenytoin (an anticonvulsant), and tiludronate disodium (to treat Paget’s disease).

These are just a few examples of some of the interactions that can occur. If you are taking any medications and also want to take dietary supplements, talk to your health care provider first and be on the lookout for any side effects or problems.

ODS has also developed a free iPhone and iPad app called My Dietary Supplements, or MyDS. Keep a convenient mobile record of the dietary supplements you take and share this information with your health care providers to help decrease the potential for interactions between dietary supplements and prescription medications.

B12 injection and supplements

Is it common to need vitamin B12 injections?

Vitamin B12 is found naturally in a wide variety of animal foods, including fish, meat, poultry, eggs, and milk. It’s also added to some fortified breakfast cereals and nutritional yeasts.

Most people in the United States get enough vitamin B12 from the foods they eat. Vitamin B12 deficiency is still common, though, affecting up to 15 percent of us. This is mainly because some people—particularly older adults and those with certain health conditions such as pernicious anemia—have trouble absorbing vitamin B12 from food. Although many of these people can absorb the synthetic vitamin B12 added to fortified foods and dietary supplements, some can’t. So, it’s possible to have a vitamin B12 deficiency even if you’re getting the recommended amount of vitamin B12 from your diet. Vitamin B12 deficiency is usually treated with injections, so it goes directly into your body and doesn't have to be absorbed like vitamin B12 taken orally.

Have more questions? See our fact sheets on vitamin B12.

Zinc supplements

Can zinc make your hair grow?

Like all vitamins and minerals, it’s important to get enough zinc for good health. In most cases, hair loss is hereditary and is not related to the amount of zinc you consume. But it is true that a zinc deficiency can cause hair loss in otherwise healthy individuals. If you have a zinc deficiency, increasing your zinc intake to correct the deficiency should help. But this doesn’t mean that taking extra zinc will make your hair thicker or longer. Most Americans get enough zinc from their diets, about 8 to 11 mg per day for adults. You can get the recommended amount from a variety of foods, including red meat, poultry, oysters and other seafood, beans, nuts, whole grains, and dairy products. Taking too much zinc—more than 40 mg per day for adults—can cause problems such as nausea, vomiting, and low copper levels. So, the bottom line is, make sure you're getting enough zinc but not too much.

Have more questions? See our fact sheets on zinc.

What should I do if I have a bad reaction to a supplement?

Tell your health care provider immediately. In addition to treating you, he or she may report your experience to the U.S. Food and Drug Administration (FDA). You may also report your reaction to the FDA by calling 1-800-FDA-1088 (1-800-332-1088) or completing the FDA’s online reporting formexternal link disclaimer. In addition, report your reaction to the dietary supplement’s manufacturer using the contact information on the product label. Following these steps could help someone else avoid the same problem, and it allows the FDA and the manufacturer to take corrective action if needed.

The Scoop provides information from the Office of Dietary Supplements (ODS) on vitamins, minerals, herbs, and other dietary supplement ingredients. The Scoop is not copyrighted and is in the public domain. If you copy or distribute its content, please credit the National Institutes of Health Office of Dietary Supplements and include the publication title and date. Do not use our information in any way that suggests we endorse any commercial product or service.

We welcome your comments and suggestions for future issues of The Scoop. To contact ODS, go to the Contact Us page of the ODS Web site. Please note that we cannot answer specific medical questions, make referrals, or provide guidance on the use of dietary supplements. Those questions are best answered by a physician or other qualified health care provider who can tell you if dietary supplements are right for you and what effects they could have on your health.

About ODS

The Office of Dietary Supplements (ODS) is part of the National Institutes of Health (NIH), the principal biomedical and behavioral research agency of the United States Government. NIH is a component of the U.S. Department of Health and Human Services.

Contact Us

Office of Dietary Supplements
National Institutes of Health
6100 Executive Blvd., Room 3B01
Bethesda, MD 20892-7517

Email: [email protected]
Web site: