Not everyone needs a dietary supplement, but they can help some people. 

“Supplements can’t take the place of a healthy diet,” says Carol Haggans, a registered dietitian with the National Institutes of Health Office of Dietary Supplements. 

Unlike drugs, supplements aren’t for preventing or treating illness or disease. But like drugs, they can have side effects. Though many of these things are naturally in foods, more isn’t always better – even for vitamins and minerals, Haggans says. 

What Are Dietary Supplements? 

In addition to vitamins and minerals, supplements include:

  • Microbials (probiotics)
  • Herbs (echinacea)
  • Botanical compounds (curcumin)
  • Amino acids (lysine)

 Dietary supplements can come in pills, gummies, powders, bars, and liquids. 

Who Needs Nutritional Supplements?

If you have a chronic disease or condition and can’t get the nutrients you need from food alone, or don’t have access to certain foods, a supplement may be an option. You may need more or less of a certain substance based on other health conditions. 

That’s when taking a supplement may help, says Monique Richard, a registered dietitian nutritionist and spokesperson for the Academy of Nutrition and Dietetics.

Top Dietary Supplements

Some popular supplements include:


They contain several vitamins and minerals your body needs, but most adults get enough from a well-rounded diet.

Don’t expect multivitamins to stop you from getting diseases.

They can be ideal for children or athletes, as well as people who are older, pregnant, lactating, or those with eating disorders or malabsorption issues, Richard says. 

What to look for: Check the Daily Value (DV) – a percentage of each nutrient included. Don’t choose one with 100% for each nutrient, as too much can be toxic. 


This protein in your body breaks down as you get older. It comes from plant and animal protein sources like chicken.

Some studies have shown oral collagen plumps up your skin and makes it more elastic (or flexible). But more research is needed to determine if this is true. Generally, there aren’t major side effects. 

What to look for: Collagen peptides are the broken-down form of collagen. Studies suggest that between 2.5 grams and 15 grams per day is safe.


These live microorganisms can maintain a healthy level of helpful bacteria in your gut, which can support immunity and digestion. They are in fermented foods like yogurt.

Probiotics can contain different bacteria types (or strains), or combinations of them. They’re measured in colony forming units (CFUs) – the weight of the microorganisms. A higher CFU figure doesn’t mean it’s a better product, though. They may cause gas, and it’s best to ask your doctor if this supplement is right for you.

What to look for: There’s no recommended amount. Take the supplement while the microorganisms are still alive to get the benefits. See if it should be refrigerated. Look for the CFUs at the end of the product’s shelf life – not when it’s made. 


It’s in seeds, milk, some nuts, and leafy vegetables, but many people aren’t getting enough. That can raise your risk for heart disease, high blood pressure, osteoporosis, and type 2 diabetes. 

Magnesium supports muscles and nerves, and helps make DNA, bones, and protein. It can help keep blood sugar at healthy levels. 

Too much can cause belly cramps, nausea, and diarrhea. It can interact with medications like antibiotics. 

What to look for: Adult men should get between 400 milligrams and 420 milligrams per day, and women from 310 milligrams to 320 milligrams per day. Pregnant and nursing women need more.


This mineral is in dairy products, some veggies, and most grains and is great for your bones. It helps your nerves, blood vessels, and hormones, too. Most adults don’t get enough. Vitamin D helps your body absorb it. 

It can interact with thyroid, mood disorder, antibiotic, and HIV medications. Too much can cause nausea and vomiting. Post-menopausal women absorb less, which can affect their bones. If you have kidney problems, ask your doctor about taking extra.

What to look for: Women from ages 19 to 50 and men ages 19 to 70 should get 1,000 milligrams of calcium a day. Women 51 and older and men 71 and older should get 1,200 milligrams a day.

Vitamin D

Vitamin D is a must for healthy bones. Your body makes its own vitamin D when you’re exposed to the sun, but about half of people worldwide don’t get enough. 

It’s in fatty fish, fortified milk, and cereals, but not many other foods. Vitamin D is important for bone and immune health and helps with nerve signaling.

It’s generally safe, but too much can cause vomiting, weakness, or constipation. It can interact with medications like statins or steroids. Breastfed babies should take extra because human breastmilk doesn’t contain much.

What to look for: Adults up to age 70 should get 600 IU (international units) daily. People over 70 should get 800 IU a day.


Women who can reproduce can prevent serious birth defects like spina bifida if they have enough folate (a B vitamin) when they become pregnant. 

Folic acid is the manmade version of folate. 

The vitamin supports cell function and DNA. It’s in cereal, pasta, beans, peas, nuts, bananas, oranges, and dark green veggies. 

In high doses, it can cause allergic reactions, nausea, confusion, loss of appetite, sleep problems, and crankiness. Ask your doctor about possible interactions with anticonvulsants, barbiturates, and other medicines.

What to look for: Most adults need 400 micrograms a day. If you’re pregnant, you will need 600 micrograms a day.


This carb can help you stay regular and may help you maintain your weight, control blood sugar, and lower your risk for heart disease, diabetes, and some cancers. 

You can get fiber from fruits, veggies, beans, nuts, and whole grains. More than 90% of women and 97% of men don’t get as much as they should. Both types of fiber – soluble and insoluble – have health benefits. 

Who it’s for: Ask your doctor about extra fiber if you have impacted stools. If you have diverticulitis, you may have been told to avoid fiber-rich foods like nuts, seeds, and popcorn, but evidence suggests they don’t worsen the condition – fiber can actually help. 

Fiber can delay or reduce how you absorb medications. Some experts say to take medicines at least 1 hour before taking fiber, or 2 hours to 4 hours after.

What to look for: Men should try for about 38 grams a day. Women should get 25 grams. 

Fish Oil

The evidence goes back and forth on fish oil’s power to support heart health or ease arthritis pain. 

Supplements typically include two omega-3s called docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) – they’re naturally in some fish. Another omega-3, alpha-linolenic acid (ALA), is in some seeds, nuts, and vegetable oils – most Americans get enough from food. 

“Your body can use omega 3s … to keep the heart, lungs, and hormones systems functioning and play an important role for your immune system,” Richard says.

Fish oil can interact with some anticoagulant and antiplatelet drugs and supplements, as well as medicines for blood pressure and birth control. It can lower your vitamin E levels. If you’re on orlistat (Xenical, Alli), take it about 2 hours apart from the medicine. 

Too much may raise your risk for bleeding or impact your immune system. It’s unclear if they’re safe if you’re allergic to seafood. 

What to look for: There aren’t recommended amounts of EPA and DHA.

Vitamin B12

If you eat foods like chicken, salmon, or milk, you’re likely getting vitamin B12 in your diet. But if you’re a vegan, you may not be getting enough. And if you’re breastfeeding, your baby may not either.

Vitamin B12 helps with nerve function, red blood cells, and generates DNA. 

“It’s a good idea for all people over 50 to supplement,” says Sharon Palmer, a registered dietitian nutritionist.

If you’re on a proton pump inhibitor or other medications, you may be prone to vitamin B12 deficiency. High doses can cause nausea, headache, or fatigue. 

What to look for: Most adults should get 2.4 micrograms daily. Women need 2.6 micrograms during pregnancy and 2.8 micrograms daily if breastfeeding. 

How Are Dietary Supplements Regulated?

The FDA regulates dietary supplements under a different set of rules than they do for medicines and food products. They do not check supplements for safety or effectiveness before they go on the market.

Supplement makers can’t claim their product can help with symptoms, or prevent or treat disease the way drugmakers do. The FDA inspects facilities, and it reviews promotions and can take action if they’re not accurate.

How to Find Quality Supplements

“The quality of dietary supplements can vary widely,” Haggans says. 

To make sure you’re getting a quality supplement:

  • Seek certifications. United States Pharmacopeia (USP), NSF International, and ConsumerLab verify ingredients and put seals on approved products. 
  • Do your research. The National Institutes of Health Office of Dietary Supplements offers supplement fact sheets. All products have a Supplement Facts panel on them, similar to food labels. Check the Dietary Supplement Label Database to view labels online.
  • Understand labels. The Dietary Allowance (RDA), or how much of a nutrient you need daily, is different from the DV, a percentage that shows how much of a nutrient is in a serving. 

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