Should I Take a Multivitamin and Mineral Supplement?

Knowing Whether You Need One or Not

Man shopping for supplements
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It is no mystery that the typical American diet is less than perfect. Often high in fat and carbohydrates and low in fiber and essential nutrients, the dietary habits in the United States has to lead to sharp increases in the rate of obesity, diabetes, and heart disease across all population groups.

Even people with the best intentions can fall short of their nutritional needs. It is for this reason that many Americans will reach for a multivitamin/mineral (MVM) supplement as a means to fill the dietary gap. Not only can MVMs improve nutrition, but they can also reduce certain health risks if used appropriately.

Most MVM brands in the United States include the following essential vitamins and minerals:

Nutritional Statistics

The National Health and Nutrition Examination Survey (NHANES), conducted by the National Center for Health Statistics, reports that Americans fall well below the average requirements for many nutrients, including vitamin A (45 percent deficiency), vitamin C (37 percent), vitamin D (93 percent), calcium (49 percent), and magnesium (55 percent).

Along the same lines, the 2015-2020 Dietary Guidelines for Americans suggest that as many 40 percent of Americans fail to meet the estimated average requirement (EAR)—the intake needed to meet the dietary needs of half of the population—for many key micronutrients.

Calcium, vitamin D, and potassium are of special concern because most Americans, including children, do not meet the EAR for these nutrients, Similarly, vitamin B12 is typically lacking in people over 50, as is iron in younger children and pregnant women.

Among the elderly, malnutrition is common in the United States, while smoking, alcohol, and low-calorie diets can compromise the way in which nutrients are consumed or absorbed. In short, almost all of us are falling short of our nutritional needs.

According to the National Institutes of Health, around one-third of Americans take an MVM. The use tends to increase with age, with 40 percent of adults over 70 taking a daily MVM. Smokers and adolescents are less likely to use them.

Uses

Multivitamin/mineral (MVM) supplements contain a combination of vitamins and minerals. They may also include other ingredients like glucosamine and echinacea considered beneficial to one's health. MVMs are often referred to simply as vitamins or multivitamins.

MVMs are commonly taken on a daily basis as an "insurance policy" that your nutritional needs are being met. The nutrients in an MVM are each consigned a recommended dietary allowance (RDA), a calculation derived from the EAR to aid in product labeling.

A daily value (DV) is described for each nutrient as a percentage (%) of the RDA. For example, a 20% DV for calcium means that the pill is providing you 20 percent of the calcium you need for that day.

High-potency MVMs are primarily designed to treat people with a known or suspected deficiency or those with specific nutritional needs. While some people will take a high-potency supplement because they believe "more is better," most of the vitamins and minerals are not warehoused but are quickly excreted from the body in urine or feces.

Health Benefits

Beyond ensuring that you get enough of the vitamins and minerals you need for your age and sex, MVMs may be prescribed with people with certain health risks. Increased doses may be recommended in the following circumstances:

  • Vitamin A, vitamin D, and calcium to prevent bone loss and breakage in postmenopausal women
  • Vitamin B-6 to increase serotonin and reduce depression during menopause
  • Vitamin C, vitamin E, beta-carotene, lutein, zeaxanthin, and zinc to help prevent aging-related macular degeneration
  • Vitamin B12 for people over 50 due to the increased risk of B12 deficiency
  • Vitamin C, vitamin E, beta-carotene, and L-arginine to reduce the risk of preeclampsia during pregnancy
  • Iron during pregnancy to prevent iron-deficiency anemia
  • Folic acid (400 mcg daily) to prevent neural tube birth defects
  • Vitamin D (400 IU daily) for breastfeeding babies (since human breast milk is a poor source of vitamin D)

MVM supplements may also be prescribed for individuals who need extra vitamins and minerals either because they are lactose intolerant, are strict vegetarians, smoke, have food allergies, are alcoholic, are deprived of sunlight, or have conditions that affect digestion or nutrient absorption (such Crohn's disease, ulcerative colitis, celiac disease, cystic fibrosis, or a parasitic infection).

Despite what some may tell you, MVMs are not able to reduce the risk of cancer, heart disease, stroke, high blood pressure, or diabetes. Neither are the supplements able to slow the progression of Alzheimer's disease, diabetes, HIV, arthritis, Parkinson's disease, or chronic obstructive pulmonary disease (COPD).

Possible Side Effects

If taken as prescribed, MVMs are generally safe. Common side effects include diarrhea, constipation, and upset stomach. Most side effects are mild and will resolve on their own without treatment.

Higher potency MVMs may pose a greater risk of side effects, but even then the risk is considered low. The only exception may be when additional supplements are taken with an MVM.

HIgh doses of vitamin C, for example, can cause watery diarrhea if the daily intake exceeds 2,000 milligrams per day. Too much selenium can lead to stomach upset, fatigue, and even hair loss. High zinc levels can also diarrhea and stomach upset.

Precautions

Serious problems can develop if certain vitamins or minerals are taken during certain medical conditions or in people with certain risk factors. Examples include:

  • Excessive vitamin A during pregnancy can increase the risk of birth defects. The same applies to beta-carotene as it is converted to vitamin A.
  • High doses of vitamin A and beta-carotene should also be avoided in smokers as it may increase the risk of lung cancer.
  • Iron in excess of 18 milligrams per day should be avoided in postmenopausal women or adult men as the iron can accumulate in organs and cause damage.
  • Iron supplements are avoided in kids as they are the leading cause of poisoning in children under six.

If your MVM supplement contains iron, you should not take it at the same time as your thyroid medications, levodopa, and tetracycline antibiotics. Iron decreases the absorption of these drugs and makes them less effective.

Overdose

While vitamin toxicity is rare, it can sometimes occur with fat-soluble vitamins like vitamin A, vitamin D, vitamin E, and vitamin K. Water-soluble vitamins, like vitamin C and the B complex vitamins, are less likely to cause toxicity as they are quickly excreted from the body in urine.

The same is not true for minerals. These can rapidly accumulate if overconsumed and lead to potentially serious conditions such as hypercalcemia (high calcium), hyperkalemia (high potassium), hypermagnesemia (high magnesium), and iron overload.

To this end, it is important to speak with your doctor about any nutritional supplement you may be taking in order to understand the risks, benefits, and correct usage.

What to Look For

While MVMs can support a healthy, balanced diet, they should never be used as a substitute for the nutrients you derive from real food. Food remains the best source of nutrition and provides you with the protein, carbohydrates, fats, fiber, antioxidants, and phytochemicals needed to support good health.

Generally speaking, if you eat a balanced diet, exercise regularly, don't smoke, maintain a healthy weight, and drink in moderation, you probably won't need an MVM supplement.

However, if you feel your diet is lacking, you can speak with your doctor about the best supplement based on your age, sex, and health conditions (such as diabetes). Basic MVMs are usually the best as they will rarely go over the recommended DV for each nutrient.

Some MVM brands are specific to different ages and sex, For example:

  • MVMs for men often contain little or no iron.
  • MVMs for seniors often provide less iron and more calcium, vitamins D, and vitamin B12.
  • Prenatal MVMs usually provide more vitamin A, beta-carotene, and folic acid.

Effervescent and gummy MVMs, while popular, usually provide fewer vitamins and minerals than tablet formulations. Check the product label for the complete list of nutrients and daily values.

To ensure the highest quality and safety, only choose supplements approved by a recognized certifying body like the U.S. Pharmacopeia (USP), NSF International, or ConsumerLab.

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