Reasons To Take A Multivitamin (21 min.)

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You try to eat well. You get your steps in and work to strength train at least twice a week. And yet, even with the best of intentions, hitting every nutritional target every day feels nearly impossible.

That’s why nearly 60 percent of U.S. adults take dietary supplements, and multivitamins are by far the most popular. But with so many nutrients available individually, why do so many people still reach for a daily multivitamin? Are there real reasons to take a multivitamin, or is it just habit?

As Tyler C. Cooper, MD, MPH, Cooper Clinic Preventive Medicine Physician and Cooper Aerobics President and CEO, explains, “… supplements are not magic pills to make you feel better. That’s not their purpose. They exist to do what their name says, supplement your diet in a positive and beneficial way†.”

When it comes to multivitamins, it’s about building a nutritional foundation. Even with a healthy diet, most adults fall short on essential vitamins and minerals due to age, medical conditions, lifestyle, or medications. For example, fewer than 10% of Americans get enough vitamins D and E from food alone.

To help you understand why a multivitamin may be worth including in your daily routine, we’ve highlighted the roles of 28 key nutrients in Cooper Complete’s Original and Basic One multivitamins.

Essential Vitamins: Reasons To Take A Multivitamin†

Vitamin A (as Beta Carotene) – Immune, Skin and Eye Health†

An antioxidant that helps protect our cells from oxidative damage†. The body converts beta-carotene into vitamin A, which supports healthy immune function, vision, and skin.†

Vitamin C – Immune System and Collagen Production†

Plays a role in tissue repair and collagen formation, and helps with iron absorption from plant foods†. (Learn more about Vitamin C benefits†.)

Vitamin D3 – Bone and Immune Health†

Cooper Clinic Founder and Preventive Medicine Pioneer Kenneth H. Cooper, MD, MPH, shares, “Many patients we test at Cooper Clinic are low in vitamin D.” Vitamin D is essential for calcium absorption, strong bones, and immune function†. Most adults need a daily minimum of 50 mcg (2000 IU) of vitamin D, the amount found in Cooper Complete Original and Basic One Multivitamins.

Vitamin E – Antioxidant and Immune Support†

Helps neutralize free radicals and supports the health of the skin, brain, and immune system†. (Learn more about the benefits of vitamin E†).

B Vitamins: The Energy and Brain Support Team†

Thiamin (Vitamin B1) – Energy Metabolism†

Helps convert the food we eat into usable energy, and supports nervous system function†. Thiamin deficiency can cause weight loss, muscle weakness, short-term memory loss, and other mental symptoms. Because thiamin is stored in only small amounts and has a short half-life, regular and consistent replenishment is important†.

Riboflavin (Vitamin B2) – Cell Function and Energy†

Supports antioxidant activity and energy production†.

Niacin (Vitamin B3) – Energy and DNA Repair†

Assists in DNA repair, cholesterol management, and arthritis symptom relief†.

Vitamin B6 – Inflammatory Support†

Research conducted by The Cooper Institute^® (now the Kenneth H. Cooper Institute at Texas Tech University Health Sciences Center) showed that vitamin B6, when taken with vitamin C as part of a multivitamin, helped reduce C-reactive protein (CRP), a systemic marker for inflammation associated with increased risk of cardiovascular disease and diabetes†.

Folate – Mood, Heart, and Brain Health†

Supports mental health, cardiovascular function, and helps regulate homocysteine levels†. (Learn more about folate health benefits†.)

Vitamin B12 – Cognitive and Nerve Function†

Camron Nelson, MD, Cooper Clinic President and CEO and preventive medicine physician, notes that “In some cases of B12 deficiencies, it can affect one’s balance, neurological function and even lead to pernicious anemia.” The NIH estimates that more than 40% of older adults are affected by vitamin B12 deficiency†.

Pantothenic Acid (Vitamin B5) – Digestion and Hormone Function†

Aids digestive health and hormone production while also supporting nerve function and skin health†.

Essential Minerals: Reasons To Take A Multivitamin†

Iron – Oxygen Transport and Energy†

“Many of my female patients will be low in ferritin, which means they are iron deficient,” says Carolyn Terry, MD and Cooper Clinic preventive medicine physician. “If that’s the case, I recommend they take Cooper Complete Basic One Multivitamin with Iron or Original Multivitamin with Iron.” Iron supports red blood cell production and helps prevent fatigue†.

Iodine – Thyroid and Metabolism Function†

It is needed to convert food into energy and produce thyroid function†. Since the body does not produce iodine, it must be consumed in food and nutritional supplements, and is included in Cooper Complete Original Multivitamin.

Magnesium – Muscle, Nerve, and Vitamin D Activation†

Approximately half of all Americans are deficient in this essential mineral. Magnesium supports nerve and muscle function and activates vitamin D for optimal use in the body†. Without magnesium, vitamin D can remain stored and inactive, unable to deliver its full benefits†.

Zinc – Immune Support and Wound Healing†

This trace mineral helps fight off invading bacteria and viruses, supports vision, and aids wound healing†.

Selenium – Antioxidant and Thyroid Support†

Protects cells, supports reproduction, and helps regulate thyroid hormone metabolism†.

Chromium – Blood Sugar and Insulin Support†

This trace mineral helps support normal insulin function and the metabolism of carbohydrates, fats and proteins we eat†.

Bonus Nutrients in Comprehensive Multivitamins†

Biotin (Vitamin B7) – Hair, Skin, Nails, and Energy†

Supports healthy hair and nails, and helps convert carbohydrates, fats and proteins into energy†. Biotin is included in Cooper Complete Original Multivitamin.

Copper – Blood Vessel, Nerves and Bones†

Assists in the production of red blood cells and supports cardiovascular and skeletal health†. Cooper Complete Original Multivitamin contains 2 mg of copper, the recommended daily value.

Coenzyme Q10 (CoQ10) – Energy and Heart Support†

A powerful antioxidant that supports cardiovascular health†. Dr. Kenneth Cooper personally takes Cooper Complete Original Comprehensive Multivitamin for the 100 mg CoQ10 included in this multivitamin.

Lutein & Zeaxanthin – Vision and Skin Support†

Act as natural filters of blue light and may reduce the risk of age-related eye conditions†. (Read more about lutein and zeaxanthin.)

Lycopene – Prostate and Heart Health†

May support heart and prostate health as part of an overall healthy lifestyle†.

Phosphorus – Muscle, Nerve and Kidney Function†

The second-most plentiful mineral in the body, phosphorus, is vital for healthy bones, teeth, and cellular energy†. Cooper Complete Original Multivitamin includes 160 mg of phosphorus in each daily dose.

Potassium – Blood Pressure and Muscle Function†

Helps regulate fluid balance, muscle contractions and blood pressure†. (Learn more about potassium health benefits†.) Cooper Complete Original Multivitamin contains 400 mg of potassium, 9 percent of the daily value.

Vitamin K – Blood Clotting and Bone Strength†

Plays a key role in normal blood clotting and helps build strong bones by aiding osteocalcin production†. Cooper Complete Original contains vitamin K1 (phylloquinone). (Learn more about the benefits of vitamin K†.)

Choosing the Right Formula for You†

Different multivitamin formulations offer different nutrient levels. See the table below for a side-by-side comparison of Cooper Complete’s Original Comprehensive multivitamin and Basic One daily multivitamin.

As Dr. Tyler Cooper reminds us, supplements aren’t a replacement for healthy habits. But they can help fill in the gaps.

Compare Cooper Complete Multivitamins
Ingredient	Original	Basic One
Vitamin A (as beta carotene)	900 mcg	600 mcg
Vitamin C	500 mg	150 mg
Vitamin D3	50 mcg 2000 IU	50 mcg 2000 IU
Vitamin E	134 mg	134 mg
Vitamin K (as phytonadione)	25 mcg	—
Thiamin	3 mg	1.5 mg
Riboflavin	10 mg	2 mg
Niacin	20 mg	20 mg
Vitamin B6	10 mg	10 mg
Folate (Metafolin®, L-5-MTHF)	333 mcg DFE (200 mcg L-5-MTHF)	333 mcg DFE (200 mcg L-5-MTHF)
Vitamin B12 (as methylcobalamin)	400 mcg	400 mcg
Biotin	300 mcg	—
Pantothenic Acid	10 mg	10 mg
Iron (Ferronyl®)	18 mg	18 mg
Phosphorus	160 mg	—
Iodine	150 mcg	—
Magnesium	660 mg	200 mg
Zinc	15 mg	15 mg
Selenium	100 mcg	100 mcg
Copper	2 mg	—
Chromium	100 mcg	100 mcg
Potassium	400 mg	—
Coenzyme Q10	100 mg	—
Lycopene	10 mg	5 mg
Lutein (FloraGLO®)	6 mg	—
Zeaxanthin	0.4 mg	—

Frequently Asked Questions

Do most adults need a multivitamin?
Many adults fail to meet the recommended intake of key vitamins and minerals through their diet. A daily multivitamin can help fill common nutrient gaps, particularly for individuals with dietary restrictions or higher nutrient needs.†

Is it better to take vitamins separately or as a multivitamin?
Individual vitamins may be beneficial in certain situations, but a comprehensive multivitamin provides broad coverage in a single daily formula. This approach is often simpler and more sustainable for long-term use.†

Who might benefit from a multivitamin with iron?
Individuals who are prone to low iron levels—such as menstruating women or those with low ferritin levels—may benefit from a multivitamin that includes iron, as recommended by their physician.†

Can I take a multivitamin if I eat a healthy diet?
Yes. Even with a balanced diet, it can be challenging to consistently meet every nutrient target every day. A multivitamin helps support a strong nutritional foundation.†

Always talk with your physician or health care provider to determine which multivitamin or dietary supplement is right for your needs†.

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(Bonus: Learn ten reasons you might need other dietary supplements†. Or, learn how to compare different multivitamins to get the one that’s right for you†.)

Sources

• Centers for Disease Control and Prevention (CDC). Prevalence of Micronutrient Deficiency in the United States, 2017–2020.
• Office of Dietary Supplements, National Institutes of Health. Thiamin – Fact Sheet for Health Professionals.
• Office of Dietary Supplements, National Institutes of Health. Iodine – Fact Sheet for Consumers.
• Pharmacy Times. Study: Half of All Americans Are Magnesium Deficient.

Cooper Complete November 11, 2025