We’re all told that a daily multivitamin supplement packs the same vitamin punch as a varied cornucopia of food. No preparation. Tons of nutrients. Zero calories. No wonder these little short cuts are so popular. Supplements are hard to resist when you’re told they might be the answer to all of your problems.

But are these concoctions too good to be true?

You’ll have to decide for yourself. Here’s what you need to know about vitamin supplements and their long-term effects to get started on your decision.

What are vitamins anyway?

Vitamins aren’t capsules; they’re organic compounds that we need to survive and function. We can’t make them in our bodies; we have to get them from outside sources like food or supplements. Despite what the vitamin aisle of your grocery store might lead you to believe, only 13 recognized vitamins exist.

This infographic from Compound Interest names the 13 vitamins, reveals their alternate names, and summarizes why our bodies need them.

What do they do in our bodies?

We don’t digest vitamins like food, we have to absorb them.

Vitamins A, D, E, and K dissolve in fat, so they need fat to be absorbed. The same stomach acid released to break down fat also breaks down the vitamins so you can absorb them. If a person doesn’t have enough fat in his diet or has digestive problems, he can’t absorb fat-soluble vitamins. On the other end of the spectrum, fat cells store these vitamins long term, and excesses can build up. For example, chronic high intakes of vitamin A can lead to hypervitaminosis A, and symptoms of dizziness, nausea, headaches, and skin irritation.

All of the B vitamins as well as vitamin C dissolve in water. These vitamins are easily absorbed in the bloodstream through water-based blood plasma–no stomach acids required. Unlike fat-soluble vitamins, you can’t store water-soluble ones. Excesses of these vitamins exit the body easily with urine. Since you have no storage system for these vitamins, you have to replenish them often.

How much do we need?

The Food and Drug Administration (FDA) uses Daily Value (DV) as the ultimate guide to how much of each vitamin we need. You’ll see DV on every nutrition label. Don’t worry, they don’t just make them up. They determine DVs using experimental human studies and observational data.

Long-Term Effects of Vitamin Supplements

Studies on the long term effects of multivitamins yield conflicting results, even when the studies focus on the same vitamin. How is that possible? The answer lies in the study’s construction. Conflicting results happen because:

1. The vitamin doses tested were different. A study found vitamin D protects against fractures using a 700-800 IU (international unit) daily dose. If they used a 400 IU dose of vitamin D instead, they might not have seen the same benefits.
2. The study timeframe was different. A study spanning ten years might find benefits that a study over two years missed. Diseases, for example, take a long time to develop. Therefore any benefits a vitamin provides in its prevention would also take a long time to determine.
3. The subjects had different lifestyles. Lifestyle habits, like exercise or smoking, affect disease outcomes and vitamin interactions. If the study fails to control for differing lifestyles, results conflict.
4. The disease or condition was tested at different stages. Vitamins produce results at different times of a disease or condition. Studies show folate supplements might protect against birth defects, but only if taken in the first few weeks of a pregnancy.
5. The results were measured differently. Researchers determine what outcome they’re studying before they begin. They will only pay attention to that outcome and might miss other benefits.

Keep these factors in mind as you read the conflicting good and bad news for vitamin supplements below. Also keep in mind that more studies need to be done on the long-term effects of vitamin supplements, especially as supplement use grows. Currently about half the people in the United States take vitamin supplements; that number may continue to rise.

The Good News For Vitamin Supplements

Most of the good news for vitamin supplements involves specific populations. Here are some groups found to benefit the most from vitamin supplements.

Coronary Heart Disease Patients

Studies have shown that supplements of vitamin E decrease incidence of cardiovascular events in patients with a history of coronary heart disease.

Smokers

Male smokers given a supplement of alpha-tocopherol (a type of Vitamin E) had a 32 percent lower incidence of prostate cancer than those who took a placebo.

Older Adults

One study found supplements of vitamin D reduced bone fractures in older adults. People who took vitamin D had a 22 percent lower fracture rate in general, and a 33 percent lower fracture rate for vulnerable areas like hips, wrists, and vertebrae.

Diabetes Patients

Multivitamin use in people with diabetes might reduce the risk of minor infections. Based on the subjects’ logged reports, all people taking a multivitamin had a lower infection rate than those in the control group. The benefit increased in diabetes patients within the group. Only 17 percent of diabetes patients in the supplement group reported an infection, compared with 93 percent of diabetes patients taking placebos.

Breast Cancer Patients

Women diagnosed with breast cancer who took supplements of vitamins E and C, as well as multivitamins shortly after diagnosis had an 18 percent reduced mortality risk and 22 percent reduced recurrence risk. This study adjusted for multiple lifestyle factors to maintain consistency.

The Bad News For Vitamin Supplements

Suspicions about the long-term benefits of multivitamins have led to numerous studies over the years. Here are some highlights of the not-so-good studies on multivitamins.

Bad News for Breast Cancer

Although a study above indicates that it might be good for people who have breast cancer to take vitamins, this study suggests that multivitamin use might actually increase the risk for breast cancer in the first place. In a study of Swedish women, researchers found that multivitamin use increased the risk of breast cancer. Folic acid surfaced as a possible risk factor. Results from epidemiological studies have not confirmed this association.

Vitamin Supplements Offer No Benefits to People With Balanced Diets 

A found sparse evidence that vitamin supplements benefit people with balanced diets. A systematic evidence review for the U.S. Preventive Services Task Force also found that vitamin supplements failed to reduce cancer and cardiovascular disease risk in adults without nutritional deficiencies.

Vitamin Supplements Do Little For Memory

A long-term, randomized trial of cognitive function in men aged 65 years or older found zero differences in cognitive function between men taking a multivitamin and men taking a placebo. They used established tests to measure cognitive function and memory. Another study sought to test a connection with folic acid, B6, B12 and memory. Previous studies connected deficiencies in these vitamins with memory problems and confusion. They tested supplements on people with normal blood levels of the vitamins, and found no additional benefits after a three-year trial.

Vitamin Supplements Don’t Reduce Risk of Heart Attack

Researchers evaluated the benefits of a high dose multivitamin supplement in men and women with a history of heart attack. After nearly five years, the supplement group and the placebo group had the same number of cardiovascular events.

Why You Need to Do Your Own Research

Although vitamin supplements come in medicinal pill-like bottles, they aren’t regulated like drugs that are thought to be unsafe until proven otherwise. Under the Dietary Supplement Health and Education Act of 1994 (DSHEA), supplements are assumed safe until proven otherwise.

• Drugs: need to be proven safe. The FDA approves of any new drug entering the market. Manufacturers must show evidence of a drug’s safety and ability to treat a condition based on clinical trials. Once a drug makes it to the market, the FDA monitors it for doctor-reported side effects and possible problems.
• Supplements: need to be proven unsafe. Dietary supplements can be sold if they don’t contain any ingredients that pose a significant risk when used as directed. So if a vitamin supplement incorporates a food substance that’s generally recognized as safe, no worries. If manufacturers wanted to use a completely new substance, they do have to show that it’s safe, but they don’t have to perform any clinical trials. The FDA can’t stop a company from selling a supplement until someone proves that it causes harm. So don’t assume something is safe just because it’s on a shelf. Since supplements aren’t tracked as closely as drugs, their interactions, side effects, and other consequences aren’t as readily noticed.

Hidden Vitamins

We have a lot left to learn about vitamin supplements before we can tell if they’re the answer to all of our problems. We do know they’re not one-size fits all. People with certain deficiencies and conditions benefit more from supplements than healthy people with well-rounded diets.

We also know that taking excess vitamins could be harmful, especially if they’re the fat-soluble kind that your body stores. But controlling your added vitamin intake might not be as simple as controlling your supplements. Many foods, like breakfast cereals and snack bars, are fortified to contain vitamins and minerals. Pair those foods with a max-dose vitamin supplement and you could be on your way to getting too much of a good thing. The nonprofit Environmental Working Group reports that about half of American kids consume harmful amounts of vitamins because they’re added to foods.

So think twice before reaching for a second bowl of those addictive Cocoa Krispies, especially if you already took a vitamin supplement. Also, keep in mind that vitamins are good for you, but you still need to be careful and smart with all dietary choices.

Resources

Primary

American College of Physicians: Enough is Enough: Stop Wasting Money on Vitamin and Mineral Supplements

Additional

Harvard School of Public Health: Supplement Studies: Sorting Out Confusion

Compound Interest: The Chemical Structures of Vitamins

Men’s Health Adviser: Do You really Need Those Vitamin Supplements? 

Mind, Mood & Memory: Straight Talk About Vitamin and Mineral Supplements For Memory

Nursing Standard: Women Being Treated For Breast Cancer Benefit From Vitamins

Trial: Over the Counter and Under the Radar

Nature Reviews Endocrinology: Vitamin Pills May Raise Cancer Risks

New Scientist: Pills Are Pointless

Web MD: Vitamins and Minerals: How Much Should You Take?

Scientific American: Fact or Fiction?: Vitamin Supplements Improve Your Health

Live Strong: Digestion of Vitamins and Minerals

Original Internist: To E or Not to E, That is the Question

Clinician Reviews: Who Will Benefit Most From Vitamin Supplementation?

Medical Daily: Vitamin D Benefits Are Enhanced if Meal Contains Fat; Absorbing More From Supplements

Gallup: Half of Americans Take Vitamins Regularly

American Cancer Society: FDA Regulation of Drugs Versus Dietary Supplements

Environmental Working Group: How Much is Too Much?

Environmental Magazine; Over-Fortified Processed Foods

Ashley Bell

Ashley Bell communicates about health and wellness every day as a non-profit Program Manager. She has a Bachelor’s degree in Business and Economics from the College of William and Mary, and loves to investigate what changes in healthy policy and research might mean for the future. Contact Ashley at staff@LawStreetMedia.com.

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