Confused About Multivitamins? Here's How to Choose the Best One for You

Ideally, you eat a well-balanced diet that feeds your body the perfect array of essential vitamins and minerals. But in reality, life isn't perfect, and very likely, neither is your meal planning. That's where multivitamins come in, to help you fill in nutritional gaps.

According to the National Institutes of Health, more than one-third of Americans take multivitamin supplements. But finding the right one for your specific needs can be challenging.

Here, we'll break down these complicated supplements to help you determine which type may benefit you the most.

"Multivitamin" is actually a bit of a misnomer, because these supplements contain vitamins ​and​ minerals, both of which are micronutrients. You need both vitamins and minerals in relatively small amounts to support a wide array of physical and mental functions.

The vitamins are: A, C, D, E, K and the eight B-complex vitamins, which include thiamine, riboflavin, pantothenic acid, biotin, niacin, B6, B12 and folate. Your body needs the right amount of these vitamins to help it function properly, and food is typically the best source.

Minerals are also essential to a healthy body. Like vitamins, they're best gotten through food. This category includes nutrients such as calcium, potassium, iron, copper, magnesium and iodine.

A multivitamin isn't designed to fully replace nutrients in your diet.

"A supplement is just that — something that supplements a quality, nutrient-dense diet. It fills in the gaps of the nutrients that you personally need due to stress, general food quality and lifestyle factors," explains Nicole Crane, a Chicago-based functional nutritionist with Evolt Training, a personal training and wellness company.

Nicola Schuler, a certified nutritionist and functional medicine practitioner in the Denver, Colorado, area, agrees. "We know that we should all eat more vegetables, but for supplements, there are no general rules. It is better to eat a well-rounded, healthy and balanced diet than to take a multivitamin."

However, some people may benefit from taking a supplement to improve their overall nutrient intake. Indeed, a study in the February 2018 issue of ​Nutrients​ found that the use of multivitamins reduced the prevalence of inadequate micronutrient intake among adults in the U.S.

The Academy of Nutrition and Dietetics recommends you talk to your doctor about a multivitamin supplement if you:

• Eat fewer than 1,600 calories per day
• Have limited food choices due to allergies or a medical condition
• Are vegan or vegetarian, or make other restricted dietary choices

Other people may have special needs for vitamins and minerals based on their age, sex or other lifestyle factors. Older adults, for example, are at risk for being low in vitamin D, while menstruating women may require more iron.

The Academy of Nutrition and Dietetics warns in its position paper on micronutrients published in November 2018 that deciphering supplement labels can be very difficult.

Crane agrees, and warns that quality can vary widely in this area.

Case in point: No standard definition for a multivitamin exists. Like other supplements, they're not closely regulated by the U.S. Food & Drug Administration (FDA), so they don't have to carry any specific nutrients or levels of nutrients.

"About 75 percent or more of the vitamins available on the general market are totally synthetic, of very poor quality and subject to questionable manufacturing standards," Crane says. She offers the following guidelines for finding a good quality multivitamin:

• Look for "CGMP" on the label, which means the product abides by the FDA's Current Good Manufacturing Practices — guidelines that ensure quality production, accurate labeling and the absence of contaminants.
• Seek out companies known for quality. High-quality supplement companies usually choose to have their products verified through a third party such as NSF International or ConsumerLab.com.
• Choose vitamins that contain active forms of nutrients, like methylated B vitamins instead of synthentic; methylfolate rather than folic acid; active D3 (cholecalciferol) instead of inactive D2 (ergocaliferol); active E (d-alpha) rather than undesirable dl-alpha; and K2 (menaquinone) versus K1 (phylloquinone).
• Check that minerals are in their chelated forms, as these are best absorbed by the body.
• Steer clear of artificial flavors and sweeteners, as well as binders, fillers and other unnecessary ingredients.

Like with diet, no one type of multivitamin is right for every person, says Crane.

As directed in a comprehensive review in ​Nutrition Journal​ in July 2014, you should choose a preparation that's relevant for your age, sex, stage of life and health history or health risk factors.

For optimum health, you need about 30 vitamins and minerals in various amounts each day, according to Harvard Health Publishing. Ideally, you should have a nutritional assessment by your doctor or a dietitian to check for insufficiencies that could lead to a deficiency in the future.

"This would include comprehensive blood work as well as an in-depth review of the person's symptoms and health situation," Schuler says. "Only then would it be feasible to make supplement recommendations. And then I would not expect a multivitamin to top the list, but rather, targeted whole-food nutrients to address specific health issues that the person is facing."

However, such an assessment isn't always possible, so taking a comprehensive multivitamin supplement is sometimes your best bet.

Women and men have different physiologies, metabolisms and hormones, which means their daily nutrient requirements are slightly different.

According to the Office on Women's Health of the U.S. Department of Health & Human Services, most women don't need a vitamin or mineral supplement; healthy foods should supply all you need. But if you're pregnant or could become pregnant, post-menopausal or a vegetarian, you may be short on some key nutrients.

When choosing a multivitamin, women may look for one that offers adequate amounts of:

• Folic acid or folate
• Vitamin B12
• Vitamin D
• Calcium
• Iron

The Academy of Nutrition and Dietetics suggests a man who doesn't eat a balanced diet, is sedentary or doesn't sleep enough could benefit from a multivitamin supplement.

Men have specific nutrient needs, too. An ideal men's multivitamin contains vitamin E to support prostate health. It may offer extra magnesium to boost energy levels and the antioxidant vitamins A, C and E, as well as selenium and zinc to support heart health.

Men should also prioritize nutrients that support healthy bones, namely calcium and vitamin D. The carotenoids, often found in vitamin A, such as lutein and zeaxanthin, support men's eye health.

When you're pregnant or thinking about getting pregnant, optimal nutrition is key to helping your baby thrive while in the womb. A multivitamin, or prenatal vitamin, also helps Mom feel her best.

The Centers for Disease Control and Prevention recommend that all women capable of becoming pregnant take 400 micrograms of folic acid daily to help prevent certain neural tube birth defects.

Also, a 2014 ​Nutrition Journal​ article notes that pregnant women should avoid taking a multivitamin with excessive vitamin A, as it can increase the risk of birth defects. Talk to your doctor about the right dosage.

Older adults have different supplemental nutritional needs as their metabolism slows down. Their appetites are often reduced, so it's harder to get nutrients from whole foods, and their ability to absorb certain nutrients is compromised, too.

The Academy of Nutrition and Dietetics explains that, as you age, you benefit from more calcium and vitamin D to help you maintain strong bones. Plus, vitamin B12 levels, which are essential to energy and many metabolic functions, can begin to lag in older adults. You may benefit from a multivitamin offering a healthy amount of this nutrient.

Older adults should also make sure their multivitamin contains adequate potassium, as it can reduce the risk of high blood pressure, especially when coupled with a low-sodium diet.

Iron needs increase at certain times of life, especially in women who are pregnant or who have especially heavy menstrual bleeding or abnormal bleeding due to fibroids, according to the U.S. Department of Health & Human Services' Office on Women's Health. People with cancer or gastrointestinal disorders as well as those who have recently had surgery may also need extra iron.

Follow your doctor's recommendations when it comes to extra iron in your supplements. If you're already on an iron supplement, you probably don't need a multivitamin with the mineral. The same is true if you eat a healthy diet with lots of iron-rich foods such as beef, spinach and fortified cereals. Too much iron can cause side effects, such as constipation and nausea, and it can even be toxic in some people.

Losing weight requires that you burn more calories than you take in. Although no magic supplement exists for weight loss, there's some very limited evidence to suggest that taking a multivitamin may help you burn more calories.

One small randomized controlled trial divided 96 Chinese women with obesity into three groups: one group took a daily multivitamin and mineral supplement, another took just a daily calcium supplement and the third took a placebo tablet for 26 weeks. At the end of the trial period, those who had taken the daily multivitamin had significantly lower body weight, body mass index (BMI) and fat mass, and they also had lower total cholesterol and "bad" cholesterol levels.

The researchers, who published their findings in June 2010 in the ​International Journal of Obesity​, thought the multivitamin may have supported a faster metabolism and better fat-burning abilities.

This is just one small study, though, so more research is needed before we can say for sure that multivitamins help you lose weight.

Getting adequate amounts of vitamins and minerals is vital for proper metabolism. And some vitamins, such as the B vitamins, play an important role in metabolizing dietary carbohydrates, fats and proteins. But again, it's best to get these nutrients through a healthy diet whenever possible.

If you are on a very-low-calorie diet for weight loss for health reasons, your doctor or dietitian may suggest adding a multivitamin to fill in any nutritional gaps.

Smoking cigarettes can make it hard for your body to absorb and use certain nutrients, including calcium and vitamins C and D, according to Winchester Hospital. Indeed, some older studies have noted that smokers tend to have lower levels of these nutrients as well as vitamin B12 and the antioxidants lutein and zeaxanthin. This could lead to nutritional deficiencies, especially if you're not eating a healthy diet. But that doesn't mean a multivitamin will help.

Taking multivitamins either daily or occasionally has been linked to a lower risk of death from lung cancer among current smokers, according to an April 2019 review in ​Nutrients​. But the review also found contradictory results across studies and noted that it's difficult to draw any firm conclusions around the effects of supplements on smokers. Plus, the review noted that certain supplements, such as beta-carotene and vitamin E, have been linked to a higher risk of lung cancer.

If you're a smoker, talk to your doctor about whether a multivitamin is right for you. And consider quitting cigarettes for good.