In an ideal world, we’d all eat perfectly balanced, healthy meals and snacks all of the time and get all of the nutrients we need.

Reality check: Many people don’t eat as many fruits, veggies, and other recommended foods as they should. That means they may have some missing pieces in their nutrition puzzle. In fact, according to the Centers for Disease Control and Prevention, fewer than one in 10 Americans (including children) eats the recommended daily amount (RDA) of vegetables. Only four in 10 children and one in seven adults eat enough fruit.

Vitamin and mineral deficiencies can cause health and developmental problems for grown-ups and kids alike, from vision impairment and improper bone growth in children to cognitive decline and depression in adults.

But before you pop a vitamin, there are some things to take into consideration.

Which Vitamins Do I Need?

The body requires dozens of nutrients to function, grow, and develop properly, but most of them are only needed in tiny amounts. The essential nutrients our bodies can’t make can usually be found in the foods we eat. Essential macronutrients include protein, carbohydrates, fiber, and fat. Essential micronutrients are vitamins and minerals include iron, iodine, vitamin A, vitamin C, and folate/folic acid (vitamin B9).

While the body doesn’t need a lot of these micronutrients, they’re critical for proper growth and development. Vitamin deficiency can cause a host of problems. Without enough vitamin C, for example, sailors from centuries ago developed scurvy. Insufficient amounts of vitamin D — which we get from food and also from the sun — can cause rickets or brittle bones.

Iron is a mineral, but iron deficiency anemia is the most common, widespread nutritional disorder in the world, according to the World Health Organization (WHO). Anemia affects children and adults in both developing and industrialized nations. Iron is essential for producing red blood cells, sustaining energy, building muscle, and promoting healthy pregnancies.

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How Do I Know if I Need a Vitamin or Mineral Supplement?

Most people can get the nutrients they need from a healthy, well-balanced diet of fruits, vegetables, whole grains, and lean proteins. These common foods are all good sources of important essential vitamins and minerals:

  • 1 cup of canned white beans = 8 milligrams (mg) of iron (44% RDA)
  • ½ cup of raw red bell pepper = 95 mg of vitamin C (106% RDA)
  • 1 baked sweet potato (with the skin) = 1,403 micrograms (mcg) of vitamin A (156% RDA)
  • 3 ounces of cooked trout = 645 mcg of vitamin D (81% RDA)
  • ½ cup boiled spinach = 131 mcg of folate (33% RDA)
  • 1 cup of plain low-fat yogurt = 75 mcg of iodine (50% RDA)

Supplements may be necessary for people who have certain health conditions, such as food allergies, that make it difficult to get all the nutrients their bodies need. Sometimes a supplement is needed only periodically, as when a woman is pregnant, breastfeeding, or experiences anemia during heavy menstruation. Vegetarians and vegans should choose plant-based alternatives for nutrients such as iron, which are more abundant in animal foods.

But it’s also possible to get too much of a good thing. According to the National Institutes of Health, taking too much of a vitamin A supplement, for example, can cause side effects ranging from dizziness and nausea to coma and death. Vitamin D toxicity can lead to vomiting, disorientation, and even kidney damage.

Some supplements may interact with prescribed medications or even prevent other nutrients from being absorbed properly. That’s why you should tell your doctor about any supplements you’re taking. For example, vitamin C in supplement form can interfere with chemotherapy and radiation treatments for cancer. Calcium can inhibit the bioavailability of iron. If you take both of these supplements, be sure to take them at different times of the day. Vegetarians and vegans may want to take calcium supplements at least two hours before — and two hours after — a meal that’s rich in iron. This will prevent the calcium supplements from reducing absorption of any plant-based iron.

Should I Take Prenatal Vitamins if I’m Pregnant?

Pregnant women typically need more of certain nutrients. The WHO recommends daily iron and folic acid supplements for pregnant women (30–60 mg iron and 0.4 mg folic acid) to prevent maternal anemia, low birth weight, preterm birth, and other complications. Folic acid can also help prevent neural tube defects, such as spina bifida and anencephaly.

The WHO also recommends that pregnant women who don’t consume much calcium should supplement their diets by taking 1.5 to 2 grams of calcium per day to reduce the risk of pre-eclampsia.

Doctors will often recommend giving breastfed babies a vitamin D supplement, as the mother’s milk typically doesn’t provide enough.

How Do I Choose the Best Supplement?

If you’re considering adding vitamin supplements to your health regimen, you’re not alone. A 2019 survey by the Council for Responsible Nutrition found 77% of adults in the United States take dietary supplements. Multivitamins, vitamin D, and vitamin C are the three most popular.

Most people who eat a regular diet don’t need vitamin supplements. Make sure to see your doctor for regular lab work and screening tests to find out if you need iron, vitamin D, or vitamin B12 supplements,” says Shane Eikenberry, MD, an internal medicine specialist at Greater Pittsburgh Medical Associates-UPMC.

The Food and Drug Administration doesn’t regulate vitamins and other dietary supplements to ensure they’re safe or effective before they hit store shelves. Instead, it’s up to manufacturers to label their products accurately and follow safety guidelines.

However, U.S. Pharmacopeia, ConsumerLab, and the National Sanitation Foundation do provide third-party verification for quality and accurate labeling for dietary supplements.

Taking a standard multivitamin every day offers the benefit of filling in nutritional gaps. But first you should talk to a registered dietitian nutritionist or your doctor. This will help ensure there are no interactions with other medications or other unwanted side effects.

Academy of Nutrition and Dietetics. Dietary Supplements and Women's Health. Link

Centers for Disease Control and Prevention. Breastfeeding. Vitamin D. Link

Centers for Disease Control and Prevention. Folic Acid Helps Prevent Some Birth Defects. Link

Centers for Disease Control and Prevention. Division of Nutrition, Physical Activity, and Obesity. Making Healthy Eating Easier Fact Sheet. Link

Clinical Epigenetics. Dietary Intakes and Biomarker Patterns of Folate, Vitamin B6, and Vitamin B12 Can Be Associated With Cognitive Impairment by Hypermethylation of Redox-Related Genes NUDT15 and TXNRD1. Link

ConsumerLab. Reviews of Supplements and Health Products. Link

Council for Responsible Nutrition. Dietary Supplements Use Reaches All Time High. Link

Distillations. Science History Institute. The Age of Scurvy. Link

National Institutes of Health. Office of Dietary Supplements. Folate Health Professional Fact Sheet. Link

National Institutes of Health. Office of Dietary Supplements. Iodine Health Professional Fact Sheet. Link

National Institutes of Health. Office of Dietary Supplements. Iron Health Professional Fact Sheet. Link

National Institutes of Health. Office of Dietary Supplements. Vitamin A Health Professional Fact Sheet. Link

National Institutes of Health. Office of Dietary Supplements. Vitamin C Health Professional Fact Sheet. Link

National Institutes of Health. Office of Dietary Supplements. Vitamin D Health Professional Fact Sheet. Link

National Sanitation Foundation. Dietary Supplement Safety. Link

U.S. Department of Agriculture. National Agricultural Library. Macronutrients. Link

U.S. Department of Agriculture. National Agricultural Library. Vitamins and Minerals. Link

U.S. Food & Drug Administration. Dietary Supplements. Link

U.S. Food & Drug Administration. Tips for Dietary Supplement Users. Link

U.S. Food & Drug Administration. What You Need to Know About Dietary Supplements. Link

U.S. Pharmacopeia. Dietary Supplements and Herbal Medicines. Link

World Health Organization. E-Library of Evidence for Nutrition Actions. Calcium Supplementation During Pregnancy to Reduce the Risk of Pre-Eclampsia.

World Health Organization. E-Library of Evidence for Nutrition Actions. Daily Iron and Folic Acid Supplementation During Pregnancy.

World Health Organization. Micronutrient Deficiencies. Iron Deficiency Anaemia. Link

World Health Organization. Micronutrient Deficiencies. Vitamin A Deficiency. Link

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