You should probably read this before buying multivitamins

multivitaminsMultivitamins have become popular as a supplement that many people believe can help them get the micronutrients necessary for good health.

More people than ever invest money in multivitamins billed as a sort of “all-in-one” fix for poor dietary habits, hoping that popping a pill every day to deliver essential nutrients may cut the risk of developing chronic disease. (1)

Every multivitamin is different; depending on the brand, multivitamins may contain a range of vitamins, minerals, and other ingredients, such as herbs, fatty acids or amino acids.

You can find multivitamins (also called multis, multi-minerals, multiples and other names) in many forms, including liquids, powders, tablets, capsules, and chewables.

They’re designed to be taken once or twice daily; dosage instructions on the label detail the amount of vitamins and minerals provided by the recommended dose.

If you’re considering adding a multivitamin to your nutritional plan, or if you already take one, read on to learn how to make an informed choice when it comes to this type of supplement.

Micronutrients are Essential to Good Health

Vitamins and minerals play an important role in many biological processes; some act as a catalyst for enzymatic reactions while others may be needed to send signals on structural or biological levels.

Some even function as hormones in the body.

Thirteen different vitamins and at least sixteen minerals are essential to health and proper physical function, including growth, reproduction and routine maintenance.

Dietary supplements like multivitamins aren’t regulated, and manufacturing processes vary by company; this means products may not always contain what labels say they do. (2) Many companies have been found to make fraudulent claims about what’s in their products. There may be more, less, or none of the nutrients listed.

Also keep in mind that nutrients can either be derived from natural food sources, or created synthetically in laboratories.

Multivitamins and Chronic Disease

Marketing campaigns are likely the biggest reason people may believe taking a multivitamin can reduce their risk of developing heart disease and cancer.

More people die of heart disease worldwide than from any other cause. (3)

Observational studies returned mixed results on the effectiveness of multivitamins in reducing the rate of heart disease; some showed lower ratios, while others showed no effect at all. (4, 5, 6, 7)

Reports from a decade-long study following the health of 14,000 male doctors during middle age indicated those who took multivitamins suffered the same rates of stroke, heart attack and fatalities as those who didn’t. (8)

A study conducted with women who used multivitamin supplement for at least three years showed significantly different results. Women taking multivitamins were 35% less likely to die of heart disease. (9) Similar mixed results have been noted from data gathered about the effect of multivitamins on cancer rates. (10, 11)

An analysis of five separate randomized trials with a total of nearly 50,000 participants found that men who took multivitamins were 31% less likely to be diagnosed with cancer, but no difference was found in rates of cancer for women. (12)

Long-term rates of developing colon cancer may be the exception.

The Nurses’ Health Study indicated women who take multivitamins develop this type of cancer at lower rates. (13) In another study with both male and female participants, similar results were reported. (14)

In the Physician’s Health Study mentioned above, male doctors with no history of cancer reduced their risk of developing any type of cancer, but there was no difference in cancer mortality rates during the course of the study. (15)

Other Health Benefits

Taking multivitamins appears to have positive effects on two health issues related to aging.

Macular degeneration is the most common cause of preventable blindness in the world. (16)

Including a supplement containing minerals and antioxidant vitamins has been shown to slow down the progression of macular degeneration. (17) However, there’s no indication that taking a supplement can act as a preventive measure to decrease the incidence of this disease.

Multivitamins may help reduce the chances of developing cataracts, which is another common disease of the eyes. (18)

Cognitive function is often negatively impacted by age, and it appears taking multivitamins may help improve the memory capacity of older adults. (19, 20)

Poor moods have been linked to nutritional deficiencies in several studies. (21, 22) Supplements may help decrease symptoms of depression and improve mood. (23, 24)

Be Cautious With Supplements

Taking high doses of certain vitamins and minerals can be beneficial in some cases and harmful in others.

There are two kinds of vitamins:

  • Fat-soluble vitamins like A, D, E and K can build up over time, and since they’re stored in the body, levels can become toxic.
  • Water-soluble vitamins like B and C are flushed from the body when they’re present in excess.

Of the fat-soluble vitamins, E and K are not toxic in high levels, but vitamins A and D may have detrimental effects when you take too much.

If you’re pregnant, be very careful supplementing vitamin A; birth defects have been noted when toxic levels of vitamin A are present in the body during the fetal development. (25)

Taking enough Vitamin D to create toxicity is unlikely, but has been reported. (26) This is where it’s important to trust the manufacturer, since mislabeling of ingredients has been an issue in the case of high levels of vitamin D in multivitamins. (27)

Smokers should not take a supplement rich in vitamin A, since it can increase the risk of developing lung cancer. (28)

If you’re getting enough iron in your diet, taking a multivitamin containing generous amounts of this mineral can create toxicity. (29)

Adding a vitamin supplement on top of a diet rich in nutrient-dense foods could also be risky.


If you’re eating a healthy diet, taking multivitamins probably isn’t necessary and may even cause problems.

These three groups of people may realize substantial benefits from including a quality multivitamin in their regime:

  • Women who are pregnant or lactating should discuss nutritional needs with their doctor to make certain they get what they need and don’t add micronutrients that could cause harm, like vitamin A.
  • Elderly people may need to supplement with vitamin D, calcium and B12 due to the body’s decreasing efficiency in absorption. (30, 31)
  • Vegetarians and vegans should supplement vitamin B12, since this vital nutrient is found only in animal foods. Other areas of concern may include omega-3 fatty acids, iron, zinc, and calcium. (32, 33)

People with poor appetites, those who have had surgery to aid in weight loss, and anyone eating an extremely low-calorie diet may also need multivitamins.

If you have known deficiencies, it’s best to supplement with the vitamin or mineral in question, rather than a multivitamin.

Summary: It is not possible to compensate for poor dietary habits through taking a multivitamin; cultivate overall good health through eating whole foods loaded with natural micronutrients.


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