Multivitamins won't fix a poor diet, but targeted supplements might be necessary for some.


If you're trying to lead a healthier lifestyle, you might have considered taking a multivitamin. While these supplements may seem like a simple way to do some good for your body, the truth is that very few people actually need them. According to nutritionist Marisa Moore, most people get the majority of the vitamins we need from food. "We forget that the definition of a dietary supplement is to supplement what we're eating, not to take the place of it," she explains. Plus, research around the health benefits of multivitamins is quite limited, so she rarely recommends them to clients. Some studies even suggest that taking vitamins when you don't need to could actually do more harm than good.

Instead, Moore suggests specific supplements to support any nutritional deficiencies that can't be fixed with food or lifestyle changes. These deficiencies can be determined with blood tests or through an evaluation from a health care provider. Our bodies require dozens of vitamins and minerals, but here are a few examples of dietary supplements that might be helpful and, in some cases, essential for good health.

Omega-3 Fatty Acids

Omega-3 fatty acids are necessary for maintaining healthy blood vessels and—in the case of pregnant women or children—for healthy brain development. "It's one of the most common vitamins I encourage people to take a closer look at, because most Americans don't eat enough seafood," says Moore. Omega-3s primarily come from fatty fish such as salmon or sardines, though flaxseed and chia seeds are a great source, especially for vegetarians. If you don't eat any of these foods, you can also try fish or algal oil.


Women with heavy periods, vegetarians, pregnant women, and people with chronic illnesses are at risk of iron deficiencies which can cause anemia. In such cases, a supplement can be helpful, but it's important to remember that too much iron can cause serious issues. "Iron supplements may cause some gastrointestinal distress such as constipation or nausea," says Moore. "But taking high levels of iron can reduce zinc absorption and in severe cases overdoses can lead to organ damage." Most adults don't need a supplement with more than 45 milligrams, but a blood test will determine exactly how much you need to level out any deficiencies.

Vitamin C

Vitamin C, or ascorbic acid, not only supports the proper functioning of our immune system, but it also makes collagen (which helps wounds heal and keeps wrinkles away) and helps the body absorb iron from plant foods. It's also an antioxidant which helps protect cells against free radicals. It makes sense, then, that the supplement is so prevalent in vitamin aisles—but taking one is likely unnecessary. The average adult only needs between 75-90 milligrams per day, which people can get from fruits and vegetables. In most studies, vitamin C absorbed from a supplement is less effective than when it is absorbed from food.

Taking a regular vitamin C supplement may shorten a common cold, but probably won't do you any good if you're already sick. Taking a high dose of vitamin C won't cause any serious issues—the average adult may experience nausea or diarrhea if they take more than 2,000 mg—but it is just as unlikely to help you. "Just because [a supplement] has more doesn't necessarily mean that it's better for you," says Moore. "Once we get what we need in a day, we just excrete out what we can't use."

Vitamin B12

A B12 deficiency can cause tiredness, constipation, anemia, or damage to the nervous system. Since vitamin B12 is primarily found in animal products, Moore says that it can be difficult for vegetarians or vegans to get the proper amounts from food. Nutritional yeast or fortified foods (such as cereal, bread, or pasta) are good substitutes.

Additional Buying Tips

If your doctor has suggested that you may not be getting all of the vitamins that you need, look for supplements that have been tested by a third party as the FDA does not regulate companies that produce them. The U.S. Pharmacopeia (USP) or NSF International won't confirm the validity of marketing claims, nor will they determine whether or not an ingredient is safe; rather, their seal of approval verifies that the supplements are free of contaminants and have accurate ingredient labels.

Though chewable vitamins may be a bit higher in sugar than pills, they aren't any less effective. "Some people have a really hard time swallowing large pills so they might want to take the supplement in a different format," says Moore. "If it is something that you know you need to take, find the format that works best for you."


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