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The Dietary Guidelines for Americans states that your nutritional needs should be met primarily through your diet. But the guidelines go on to say that for some people, supplements may be a useful way to get nutrients they might otherwise lack.
Before you shop for supplements, get the facts on what they will and won't do for you.
Supplements vs. whole foods
Supplements aren't intended to substitute for food. They can't replicate all of the nutrients and benefits of whole foods, such as fruits and vegetables. Whole foods offer three main benefits over dietary supplements:
Greater nutrition. Whole foods are complex, containing a variety of the micronutrients your body needs.
Essential fiber. Whole foods, such as whole grains, fruits, vegetables and legumes, provide dietary fiber. As part of a healthy diet, fiber can help prevent certain diseases, such as type 2 diabetes and heart disease, and it can also help manage constipation.
Protective substances. Many whole foods are also good sources of antioxidants — substances that slow down a natural process leading to cell and tissue damage. It isn't clear that antioxidant supplements offer the same benefits as antioxidants in food. Some high-dose antioxidant supplements have been associated with health risks.
Who needs supplements?
If you're generally healthy and eat a wide variety of foods, including fruits, vegetables, whole grains, legumes, low-fat dairy products, lean meats and fish, you likely don't need supplements.
But supplements — or fortified foods — might be appropriate in some situations:
Women who may become pregnant should get 400 micrograms a day of folic acid from fortified foods or supplements, in addition to eating foods that naturally contain folate.
Women who are pregnant should take a prenatal vitamin that includes iron or a separate iron supplement.
Adults age 50 or older should eat foods fortified with vitamin B-12, such as fortified cereals, or take a multivitamin that contains B-12 or a separate B-12 supplement.
Adults age 65 and older should take 800 international units of vitamin D daily to reduce the risk of falls.
Dietary supplements also may be appropriate if you:
Don't eat well or consume fewer calories than needed
Are a vegan or a vegetarian who eats a limited variety of foods
Follow any other type of diet that restricts an entire category of foods
Don't obtain two to three servings a week of seafood, which supplies omega-3 fatty acids for heart health
Have limited milk intake due to lactose intolerance or milk allergy, or simply don't consume enough dairy foods. Have heavy bleeding during your menstrual period. Have a medical condition that affects how your body absorbs or uses nutrients, such as chronic diarrhea, food allergies, food intolerance, or a disease of the liver, gallbladder, intestines or pancreas. Have had surgery on your digestive tract and are not able to digest and absorb nutrients properly

Talk to your doctor or a dietitian about which supplements and what doses might be appropriate for you.

Be sure to ask about possible side effects and interactions with any medications you take.

Choosing and using supplements

If you decide to take a vitamin or mineral supplement, it's important to:

Talk to your doctor. Supplements can cause harmful effects if taken in certain combinations, with certain prescription medications or before surgery or other medical procedures.

Check the label. Product labels can tell you what the active ingredient or ingredients are, which nutrients are included, the serving size and the amount of nutrients in each serving.

Watch what you eat. Vitamins and minerals are being added to a growing number of foods, including breakfast cereals and beverages. If you're also taking supplements, you may be getting more than you realize of certain nutrients. Taking more than you need is expensive and can raise your risk of side effects.

Avoid mega doses. Taking more than the recommended daily values (DVs) can increase your risk of side effects. Children are especially vulnerable to overdoses of vitamins and minerals.
Keep up with supplement safety alerts
Being sold in the marketplace doesn't make a supplement safe or effective.
The Food and Drug Administration (FDA) keeps a list of dietary supplements that are under regulatory review or that have been reported to cause adverse effects. If you're taking a supplement, it's a good idea to check the FDA website periodically for updates.
Keep in mind, though, that the FDA doesn't regulate or oversee vitamin and supplement content or claims to the same degree as it does prescription medications.
If you think that a dietary supplement may have caused you to have a serious reaction or illness, stop using the product and fill out a safety report through the Safety Reporting Portal website.

Do you want to adopt a healthy diet but aren't sure where to start? As you consider the parade of healthy diets in magazines and cookbooks, make sure to look for one that:
• Includes a variety of foods from the major food groups: fruits; vegetables; whole grains; low-fat dairy products and lean protein, including beans and other legumes, nuts and seeds; and healthy fats
• Provides guidelines for how much food to choose from each group
• Includes foods you can find in your local grocery store — rather than specialty or gourmet store items
• Fits your tastes, lifestyle and budget
Also consider your health risks. For example, do you have high cholesterol or high blood pressure?
If so, be sure to follow a diet that's low in salt, saturated fat and cholesterol, and high in fruits, vegetables, whole grains and healthy fats. For personalized advice, talk with your doctor or a dietitian.