This primer answers the questions clients commonly ask about taking vitamin and mineral supplements.
Did you know that roughly 40% of Americans took some type of vitamin or mineral supplement in the past month, according to the most recent government surveys on usage (Balluz et al. 2000)? The most commonly popped pill? The multivitamin. In fact, Americans spent a whopping $3.8 billion on multivitamin supplements in 2004, says Katja Rauhala, research manager for the Nutrition Business Journal.
But do people who maintain a healthy diet really need to take a daily multivitamin? And which kind is best? Will multivitamins give athletes the extra energy needed to fuel a heavy workout? Should you buy “generic” multivitamins or stick with a name brand? What about those new vitamins that are specially formulated for women, men, or people wishing to lose weight? Are natural multivitamins superior to synthetic versions? How do you choose the best products and doses?
When it comes to multivitamins, the concerns are, indeed, multiple. Here are some answers to have at the ready when your clients pose questions about supplementation.
In a perfect world, you’d get everything you need from a balanced diet full of whole foods, such as lean protein, whole grains and a wide variety of fruits and vegetables. After all, such foods are more than the sum of their individual vitamins and minerals: Rather, they are each made up of a number of complex components. In fact, many nutrition experts believe that it’s the interactions among these various components that confer long-term health benefits, like disease prevention.
“It’s a false assumption that foods are good because of singular nutrients,” says Roberta Anding, RD, spokeswoman for the American Dietetic Association (ADA) and dietitian for the National Football League’s Houston Texans. “It’s really the package deal that Mother Nature puts together.”
Unfortunately, in the real world, our clients skip meals, rely on fast foods and eat a diet that is rarely (if ever) perfect. So while a multivitamin supplement is certainly not a substitute for whole foods and healthy eating—as the name implies, it’s designed to “supplement” a wholesome diet—it can provide a safety net of important nutrients that may be missed on a regular basis.
Some experts think multivitamins may offer even more than a safety net. In a study published in The Journal of the American Medical Association, researchers concluded that augmenting your nutrient intake with a daily multivitamin may actually protect against chronic disease (Fletcher & Fairchild 2002). These findings led the study authors to recommend that all adults consider taking a multi, in light of strong evidence that suboptimal intakes of vitamins (i.e., not low enough to cause clinical deficiency but lower than the recommended daily levels) may be a risk factor for cardiovascular disease and cancer, among other illnesses.
Nutrition experts seem to agree that taking a basic daily multivitamin is the better choice for most people. For one thing, it is far easier and cheaper to take just one tablet every day rather than popping separate pills. Plus, it makes sense to cover your bases with a wide variety of vitamins and minerals instead of focusing on just a few.
Still, some people may need separate pills in addition to a multi. For example, the recommended daily intake of calcium to help prevent the bone-thinning disease osteoporosis ranges from 1,000 to 1,300 milligrams (mg) for women, depending on their age (Institute of Medicine 1997). Unfortunately, few women actually meet this recommendation through diet alone, and most multivitamins contain only about 10%–20% of that amount (calcium is a big nutrient that doesn’t fit easily in a multi). That’s why many nutrition experts recommend that women take a daily calcium supplement in the form of one or two 500 mg doses, with added vitamin D to help absorption, in addition to taking a multivitamin. Women diagnosed with iron deficiency may also be prescribed iron supplements, but these should be taken only under a physician’s care.
As for the benefits of taking separate doses of other vitamins and minerals, there’s no clear answer. Antioxidant vitamins, like C and E, have been touted as having a positive impact on health, including the potential for lowering the risk of heart disease and Alzheimer’s disease. A recent study concluded that even high doses of vitamin E (up to 1,600 International Units) and vitamin C (up to 2,000 mg per deciliter) are safe (Hathcock et al. 2005). However, the American Heart Association does not recommend additional supplementation of these vitamins, citing lack of evidence that extra antioxidant vitamins provide health benefit.
Research to date suggests that many people can benefit from taking a multivitamin and—perhaps more important—there is no evidence that taking one causes any harm. However, certain groups of people are especially ideal candidates for vitamin supplementation.
For example, women who could become pregnant need 400 micrograms (mcg) of synthetic folic acid every day, in addition to folate gleaned from foods, to help prevent neural-tube birth defects (ADA 2001). (Because 50% of pregnancies are unplanned, this guideline holds true for all women of childbearing age, whether or not they’re trying to conceive [ADA 2001].)
Men and women over the age of 50 can also benefit from taking a multivitamin (ADA 2001). One reason is that up to 30% of older adults have difficulty processing vitamin B12 from food sources, owing to atrophic gastritis, a condition that interferes with absorption of that vitamin; the synthetic form of vitamin B12 contained in a multivitamin is more easily absorbed (ADA 2001). The elderly also tend to be low in stores of vitamin D, owing to low intake of dairy products and less exposure to sunlight, which helps the body produce the vitamin. Vegetarians and vegans are also strongly encouraged to take a multivitamin, since obtaining essential nutrients can be difficult through plant foods alone.
Finally, women on low-calorie diets could use the extra coverage provided by a multivitamin. “Their diets are healthy, but you can pick out the nutrient holes, like calcium, iron and zinc,” says Anding.
Not exactly. You can derive energy only from the calories found in food. Since vitamins and minerals contain no calories, they don’t directly supply the body with energy. However, many fat- and water-soluble vitamins, such as the various B vitamins, do aid in energy-producing reactions in the body. So they help the body release and use the energy taken in through food.
“Vitamins and minerals are the spark plugs in the car; they’re not the gas,” says Nancy Clark, RD, author of Nancy Clark’s Sports Nutrition Guidebook (Human Kinetics 2003).
Although taking a multivitamin won’t give you an instant energy boost, adding one may help pick up some of the slack in your diet. Consistently consuming subpar amounts of certain vitamins and minerals can lead to sluggishness, which hampers workouts. For example, women who maintain a low-calorie diet or eat very little meat tend to get too little iron, which can cause fatigue. Drinking alcohol also depletes the body of B vitamins and magnesium, which are required to free energy from food.
Keep in mind, however, that if you’re dragging through your workouts, eating less than you need is often the culprit, says Clark. “A lot of athletes are low on energy because they’re not eating enough calories at breakfast and lunch,” she says. “They’re calorie deficient, not vitamin deficient.”
Don’t exceed the Daily Values (DVs), which were developed by the U.S. Food and Drug Administration (FDA) and are listed on the right side of the nutrition facts label. DVs aren’t tailored to gender or age and are usually set at the highest amount recommended for any one group. For example, the DV for iron is 18 mg, based on the amount recommended for premenopausal women, despite the fact that men need only 8 mg of iron daily (www.fda.gov; Institute of Medicine 2001). So even though DVs aren’t a perfect match for every population, choosing a multi with vitamins and minerals at or near 100% of DVs is an easy way to ensure you’re meeting your approximate needs.
“Unless you’re under the direction of a doctor, there’s really no circumstance that would dictate needing high levels of vitamins and minerals,” says Mary Frances Picciano, PhD, senior nutrition research scientist with the National Institutes of Health’s Office of Dietary Supplements. “There’s no evidence that values over the recommended amounts provide greater benefit.”
Taking more than the DVs can present a real danger since it is possible to take in toxic levels of vitamins and minerals—especially through supplements. That’s why the government has also established Upper Limits (ULs), the highest amounts unlikely to pose health risks for certain nutrients. Going beyond these ULs is especially easy for people who eat a lot of foods and beverages fortified with vitamins and minerals; for example, energy bars, fortified breakfast cereal, vitamin water and protein shakes. In fact, consuming a daily multivitamin along with a diet high in fortified foods can easily put someone at 300% of the recommended amounts for many nutrients (ADA 2001). “I see many more athletes with nutrient toxicities than deficiencies, especially B6, magnesium and iron,” says Anding.
A recent study of supplement users found that nearly 50% exceeded the UL for niacin, which can cause flushing and heart palpitations (Troppman, Gray-Donald & Johns 2002). This study also found incidences of vitamin B6 megadoses in amounts linked to neurological damage. In addition, there were cases of excess vitamin A intake, which when taken in toxic amounts can cause gastrointestinal problems, headaches and chronic liver damage. Large quantities of vitamin A are especially dangerous during pregnancy, as they can cause congenital malformations, such as cleft lip and heart defects in the fetus.
Fat-soluble vitamins are especially risky when taken in excess. Fat-soluble vitamins, such as A, D, E and K, can accumulate in body tissues and cause toxicity. Water-soluble vitamins, like vitamin C, don’t pose the same level of risk because they are not stored in tissues and instead pass through in the urine. However, they can still be problematic when ingested in large amounts. For example, megadoses of vitamin C can cause diarrhea and increase the risk for kidney stones.
In addition, some vitamins and minerals consumed in big quantities can interfere with medications. Some common interactions include calcium and heart medicines, such as digoxin; magnesium and loop diuretics, like Lasix; and vitamin K and blood thinners, such as Coumadin®. Vitamin and mineral overload can even cause complications during surgery. That is why, when you give your physician your medical history, it is essential to mention any multivitamin or other supplements you are taking.
There’s no hard-and-fast rule when it comes to the quality of generics versus brand names, according to Tod Cooperman, MD, president of ConsumerLab.com, a company that tests health and wellness products. In theory, as long as you carefully read labels (see “How to Choose a Multivitamin” on page 55), generic vitamins should be equivalent in every aspect to the costlier name brands. In fact, a recent evaluation of dozens of multivitamins by the Center for Science in the Public Interest found that several store-brand vitamins were actually superior to the brand-name versions.
When comparing brands of multivitamins, be sure to check the supplement facts labels on generics to make sure the nutrient levels are comparable to those provided by the name brands. If all things are equal, you may be able to save $10–$20 a year by going the generic route. One word of caution, however: “There seems to be a higher chance of problems with the very, very small brands than with the larger brands,” says Cooperman, whose company has tested nearly 50 multivitamins. It makes little difference where you buy your multi, but if you’re shopping at a health food store, watch out for formulations that pack potentially toxic megadoses of vitamins and minerals.
The best time to take a multivitamin is whenever you can remember to do it! That might be first thing in the morning or right before bed. While this is simple to remember, there are a few things to consider: It’s ideal to take a multi- vitamin either with or following a meal. That’s because any fat-soluble vitamins contained in the multi require some dietary fat for transport and absorption. What’s more, many people find that the iron contained in multivitamins can cause nausea when taken on an empty stomach.
But what’s in that meal can also affect how well your body uses the multivitamin. For instance, high-fiber foods, such as fiber-rich cold cereal or oatmeal, may interfere with absorption when the phytic-acid compounds in the fiber bind to minerals and prevent them from being used. You’ll also want to avoid drinking coffee or tea with your multivitamin, since the tannins (found in both regular and decaffeinated varieties) can limit iron absorption by as much as 40%, says Anding.
Targeting special-interest groups may seem like just another clever marketing ploy by the vitamin manufacturers. But the special formulations for men, women and seniors can be advantageous, since these multivitamins are designed to meet the unique needs and issues of special populations.
For example, women’s multivitamins contain higher amounts of calcium (because of a higher need for bone health) and lower amounts of vitamin A (since large doses can be unsafe during pregnancy) than the average multivitamin offers. Men’s formulations, on the other hand, tend to pack less (or no) iron, because men are at higher risk for iron overload. (Men are more likely to take in larger amounts through food, and Caucasian males are more likely to carry the gene for hemochromatosis, a disorder that causes excessive absorption of iron and subsequent health problems.) Preparations for older adults may contain little or no iron—postmenopausal women are no longer losing iron through menstruation—but instead may provide the extra vitamin B12 recommended for those over 50 years of age.
One caveat: Depending on the brand, some special multivitamin formulations do tend to be costlier than the regular products. For example, a check at the local grocery store showed that Centrum® Silver (designed for older adults) was a couple of dollars more than the regular Centrum multivitamin.
Formulations advertised for active people or for those wishing to lose weight usually include substances designed to enhance performance (such as ginseng) or to speed metabolism (such as green-tea extract). They may also pack more B vitamins and magnesium, which help release energy from food. The trouble is that these substances are usually in quantities too small to make much of a difference. For example, clinical studies involving ginseng have typically employed doses of several hundred milligrams, yet one major multivitamin brand that promises to boost performance, One-A-Day, includes a scant 55 mg of ginseng (www.oneaday.com/products/active.shtml).
It’s also important to note that simply loading up on more vitamins—above and beyond your daily needs—doesn’t mean your body will release any more energy from the food you eat. Still not convinced? “Exercise doesn’t increase vitamin needs or deplete your stores in any significant way,” says Clark. In fact, research has shown that the blood levels of vitamins in athletes are similar to those in nonathletes (Fogelhom 1995).
To be fair, there may be some advantage to taking one of these specially formulated multivitamins. Some of them do contain higher levels of antioxidant vitamins, like C and E, believed to neutralize the free radicals produced as a result of the extra oxidative stress caused by exercise. That said, researchers have determined that supplementation of antioxidant vitamins does not appear to improve measures such as aerobic performance, VO2max, time to exhaustion or muscle soreness (Clarkson 1995).
In the case of low-carb formulations, these do contain extra amounts of the vitamins and minerals typically lacking in low-carb diets, such as vitamin C (found in fruit) and B vitamins (found in fortified whole grains). It’s true that people following low-carb plans should be concerned about missing important vitamins, but doses over 100% of the DVs are just overkill. Low-carb dieters will actually derive more benefit by simply adding more vitamin-rich foods to their daily diet.
It depends. Certain vitamins, such as vitamin E, are more bioavailable, meaning they are easily used by the body, when present in their natural form. For other vitamins, the synthetic form is actually preferable. For instance, natural folate is only about 50% bioavailable, whereas the synthetic form, folic acid, is 100% bioavailable (Wardlaw & Kessel 2002). In the case of vitamin B12, the synthetic form is better for people over age 60, who lack the ability to absorb natural B12.
Natural vitamins also tend to be pricier than the synthetic versions. And because the term natural on a food label doesn’t yet have a legal definition, it’s still a case of buyer beware: In tests conducted by ConsumerLab.com, some products labeled as “natural” vitamin E were found to be synthetic.
As for liquid formulations, “they’re more unstable than pills,” says Picciano. For example, the B vitamins are often destroyed in chemical reactions that take place in water. Still, liquid vitamins may be a good choice for those who can’t swallow large tablets or for clients over the age of 60, who may not produce sufficient stomach acid to dissolve tablets. However, keep in mind that there is an increased risk of overdosing with the liquid form.
As with adults, the best way for children to get vitamins and minerals is through a healthy diet. Plus, many children today regularly eat a lot of fortified foods, such as breakfast cereal. Even picky eaters tend to get the vitamins and minerals they need through food sources.
“Children have a better sense of regulating food intake than adults do,” says Kathleen J. Motil, MD, PhD, associate professor of pediatrics at Baylor College of Medicine in Houston and a research scientist with the U.S. Department of Agriculture/Agricultural Research Service Children’s Nutrition Research Center. “If a child is gaining weight and growing well, it’s unlikely [he or she would] have a nutrient deficiency.” Research also indicates that intakes that do tend to be lower among kids—such as iron, zinc and calcium—are still considered adequate, says Motil.
However, a basic multivitamin won’t do any harm to children—even if they don’t really need it. And if your child eats a very limited diet or is a vegetarian or a vegan, you may want to ask your pediatrician about using one as augmentation.
When selecting a multivitamin for your kids, always choose a children’s formulation (in liquid form for toddlers or younger). Because the current DVs are based on an adult’s diet, some of the values in children’s multivitamins may fall below 100% but still be adequate for children. Avoid any megadoses, since children are especially vulnerable to toxicity—“Excesses are just as unhealthy as deficiencies,” says Motil—and always keep the bottle out of the reach of little hands.
Multivitamins are no replacement for a healthy, balanced diet and should instead be viewed as a supplement to whole foods. For certain groups of people, like women of childbearing age, vegetarians and older adults, a daily multivitamin can help fill in the missing nutrient gaps in their diet.
The best choice for most people is to take a daily multivitamin with levels of essential nutrients at or below the amounts set by the Daily Values. Taking megadoses of any vitamin or mineral is not only overkill—it can actually be hazardous to your health.
With so many multivitamins on store shelves today, how can you be sure you’re selecting wisely? Here’s what you and your clients should look for when reading and comparing product labels:
Reasonable Doses. Levels of vitamins and minerals should be at or near 100% of the Daily Values established by the U.S. Food and Drug Administration.
A Balance of Vitamins and Minerals. Some preparations contain only a select few. For example, one new name-brand chewable product contains vitamins but no minerals.
Proof of External Certification. Certification programs are voluntary, but they do indicate that an independent organization has tested the product for quality. Two examples of seals to look for are USP (United States Pharmacopeia) and CL (ConsumerLab.com).
A Distant Expiration Date. Most multis have a shelf life of about 2 years, but they do tend to degrade over time. So the longer there is from the purchase date to the expiration date, the more potent the pill will be.
The Manufacturer’s Contact Information: You’ll need this if you have problems with the supplement or if you have questions or comments; contact information also tends to ensure that the company has quality control standards in place.
The following resources can provide additional information on multivitamins.
ConsumerLab.com (www.consumerlab.com). Independently tests more than 1,200 health and wellness products, including dietary supplements, protein powders and nutrition bars. Consumers can access summaries of product reviews at no cost, or they can subscribe to the company’s website ($24 for 1 year) for the complete listings.
MedlinePlus: Vitamins and Minerals (www.nlm.nih.gov/medlineplus/vitaminsand minerals.html). Offers a roundup of news, fact sheets and research on vitamins and minerals.
National Institutes of Health, Office of Dietary Supplements (http://ods.od.nih.gov/). Is dedicated to strengthening knowledge about dietary supplements by evaluating scientific information, supporting research and educating the public. The website offers fact sheets on various supplements, tips for reading labels and evaluating claims, and downloadable charts on dietary reference intakes.
U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition (http://vm.cfsan.fda.gov/; click on “Dietary Supplements”). Gives information on the safety of dietary supplements, general tips on supplements, and how to report an adverse reaction.
Vitamins, Minerals and Dietary Supplements by Marsha Hudnall (a pocket guide available through the American Dietetic Association, www.eatright .org). Offers insights into the functions and food sources of vitamins and minerals and describes how to determine whether supplements are right for you.