complete guide to multivitaminsHealth & Wellness

Do You Need a Multivitamin? A Complete Guide to Supplements

Multivitamins. We see them everywhere. But have you ever wondered to yourself: Do I even need to take a multivitamin? Do they make a difference? And how do I even go about choosing one?  This article will answer these important questions as well as provide you some tips on finding the perfect supplement for your needs.


Do You Need a Multivitamin?

Do I need to take a multivitamin diagram

One of the first things to consider when deciding whether or not you even need a daily multivitamin is your diet. If you are pretty healthy and already eat a diet that includes plenty of fruits, vegetables, whole grains, protein, and healthy fats, chances are you likely already receive the nutrients that you need from your foods. In this case, studies show that a multivitamin may, in actuality, add little or no benefit to your health. Ask yourself: how does your diet compare to the diagram depicted here?

Of course, even if you do follow a well-balanced diet, sometimes your body—for various reasons—simply needs more than what your meals can provide. While the evidence is somewhat conflicting—some studies show slight benefits while others don’t—I still believe that for most people, the potential health benefits of taking a daily multivitamin outweigh the potential risks. For this reason, some physicians like to think of a daily multivitamin in terms of it being a ‘micronutrient insurance.’ Nevertheless, this next section will help you determine if taking a multivitamin, and what kind, is best for you…

How to Tell if You Need a Multivitamin

Multivitamins may benefit you if you are:

  • Over 50 years of age
  • A woman of child-bearing age who might get pregnant
  • A woman who experiences heavy bleeding during menstrual periods
  • Pregnant or breastfeeding
  • On a low-calorie diet (less than 1,600 calories/day) or have a poor appetite
  • Vegan or strict vegetarian
  • Someone who uses alcohol or tobacco heavily
  • Someone who experiences chronic diarrhea or has a disease of the liver, gallbladder, intestines or pancreas
  • Someone who has had gastric bypass surgery

But talk to your doctor first if you are:

  • Taking blood thinners: If you take warfarin (Coumadin), any supplement/food with vitamin K can lower the medication’s effectiveness. Therefore, always discuss with your doctor before starting one, as your dose may need to be adjusted or your level closely monitored.
  • A smoker: Avoid multivitamins providing large amounts of vitamin A in the form of beta-carotene because a few studies have linked these nutrients to an increased risk of lung cancer.
  • Already taking other supplements: If you consume fortified foods and drinks (those with added vitamins and minerals) or take other dietary supplements, make sure that the multivitamin doesn’t cause your intake (especially vitamin A and iron) to go above the UL value (see below).

Vitamins: How Much is Too Much?

vitamins tolerable upper limit

The Tolerable Upper Intake Level (UL) is the maximum amount of daily vitamins and minerals that you can safely take without risk of an overdose or serious side effects. This is a useful measure to refer to if you are taking multiple supplements and want to know if you are getting too much of something. The available UL for common nutrients are provided below for your reference.

Be aware that some vitamins and minerals are riskier than others. Vitamin A, D, and E are a few that you should be more cautious about. Since they are considered fat-soluble, extra amounts accumulate in your tissues rather than excreted, potentially leading to toxic levels and negative health effects. This is why it is easier to overdose on vitamin D than, say, vitamin C (which is water-soluble and gets flushed out). Therefore, be careful to never take more than the recommended UL unless instructed by a physician (eg. for correcting a deficiency). Other riskier supplements to keep in mind include iron and selenium.

Related: Vitamin D Foods & Supplements: A Definitive Guide

How to Choose a Multivitamin

Step 1 – Check the Contents

do i need a multivitamin vitamin and supplement chart

When choosing a multivitamin, try to find one tailored to your age, gender, and other characteristics (e.g., pregnancy). This is because there are important differences. For example, multivitamins for men often contain little or no iron, whereas those for seniors provide more calcium, vitamins D, and B12 than those for younger adults, and prenatal supplements generally have no vitamin A in the form of retinol. On the label of every supplement, you will find the Percent Daily Value (%DV) This will serve as one of your main guides in selecting a multivitamin:

Look for these on the label:

  • 100% of the DV for these vitamins: Vitamin D, B1 (thiamin), B2 (riboflavin), B3 (niacin), B12, and folic acid.
  • Up to 100% of the DV for these minerals: Copper, zinc, iodine, selenium, and chromium.
  • At least 100mg of magnesium.
  • Lower levels of vitamin A: Try to find one with no more than 3,000 IU. Some studies have shown that getting more than 6,000 IU of vitamin A (food + supplements) may increase your risk of fractures. Beta carotene is safe for your bones, although high doses may increase the risk of lung cancer in smokers.
  • For premenopausal women: Look for a product that provides 100% of the DV of iron.
  • For men and postmenopausal women: Choose a multivitamin without iron.
  • Don’t scrutinize the calcium: The amount in multivitamins is usually low, because calcium is simply too bulky for one pill. Therefore, depending on your diet and risk factors, you may benefit from a separate calcium supplement.

Step 2 – Check for Quality

In shopping for a multivitamin, more expensive (including ‘designer’ supplements) doesn’t necessarily mean more benefits, and standard store-brand supplements are usually just as good.

Tips for ensuring a quality product:

  1. Look for “USP Verified” on the label: The initials “USP” ensure that the supplement meets the standards for strength, quality, and purity established by the testing organization U.S. Pharmacopeia.
  2. Avoid megadoses: High-dose supplements increase your risk of building up toxic levels of nutrients in your body.
  3. Beware of extras: Don’t give in to the temptation of added herbs, enzymes, amino acids, or unusual ‘special’ ingredients. These additions usually add nothing but cost. In some instances, they may adversely interfere with medications or medical conditions. For similar reasons, ignore products that carry these terms: “high-potency,” “stress formula,” “starch-free,” “natural,” or “slow-release.”
  4. Check the expiration date: Supplements can lose potency over time, especially in hot and humid climates. If a supplement doesn’t have a date, don’t buy it.

As with all supplements, check with your doctor first before starting a multivitamin, especially if you have health problems or are taking any medications (eg. blood thinners). At your next checkup, take all of your supplements along so that your doctor can review and discuss whether you’re taking the right types and amounts.

Creating Your Daily Vitamin Regimen

Vitamin daily regimen chart

If your only supplement is the multivitamin, you can take it with any meal that’s convenient. However, if you are currently taking other supplements such as fish oil, calcium, magnesium, iron, zinc, or probiotics, refer to the diagram to determine the best time to take yours (note: vitamin D can be taken with your multivitamin during a meal):

And with that, you’re all set. Here’s to multivitamins (if you need them) and healthy living!

Phoebe Chi, MD
Phoebe Chi, MD

As a physician educator and the managing editor of Health + Inspiration, Dr. Chi aims to inspire, inform, and empower the reader community. She is the author of Being Empowered for a Healthy Heart: A personal guide to taking control of your health while living with chronic conditions, a poetry-infused health guide, and founder of Pendants for a Cause, a nonprofit organization with the purpose of raising funds to fight illness, provide care, and bring awareness to medically vulnerable populations around the world.

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36 replies »

  1. Thank you for the information. Very useful. I bought a multivitamin yesterday at an online store. Vitamin D 10000 IU. I take it once in 3 days. Will it have a bad effect?

  2. What about herbal supplements. Since there really isn’t regulation on them, we could be taking something that isn’t even in the product. I used ti take a lot of them, but it gets to be expensive Right now I am only taking flaxseed oil, elderberry and oil of oregano.
    I just checked my multi vitamin, thanks for reminder, and it expired in 2015, so that will be tossed..
    I am also taking B-12 5,000 mcg, acidophilus,and two different ones that are supposed to contain vegetables and another one with fruit. Half the time I forget to take them at all.
    That is why the multi vitamin was expired. For a long time, I thought the fountain of youth and perfect health were in exotic herbal supplements. I spent a fortune on them.

    • For herbal supplements, I usually don’t feel comfortable recommending them straight out–simply because, like you pointed out, the quality and potency of them can be so unpredictable. On top of that, those supplements can often interact with each other and with medications. But if what you are on works for you, that’s great! But I do understand how it can get expensive…

      • There’s so much information that regularly comes out abut the latest super supplements like turmeric is the rage right now. I would think that if they were plant based they would have some benefits. I mean, aren’t many medicines plant based? I’m sure if you were to use the real plant it would have more benefits, but then as you say it could interact with something else you are taking.
        Have you ever heard of Ray Kurzweil? He’s a futurist and inventor among other things. At one time he was on a regime of over 250 supplements, supposedly he is down to 150. He has some strange ideas, but he has a lot of followers.

        • Wow…250 is quite a lot! 😲

          Yes, herbal supplements can definitely be effective and powerful treatments for things. I think some docs are just hesitant to directly recommend them because the science behind them (the quality of research) is unfortunately lacking, so it’s hard to fully inform someone of their benefits and risks. But my attitude is…if it personally works for you, I think it’s great!

          Take care!

  3. Very informative kind of article, thank you.

    “You, my carrot, Brutus?” I really did not know that higher doses of beta-carotene and lung cancer have some interdependence of the negative sort…

  4. Thank you so much! This is exactly what I was looking for especially the ULs, times of day and your tip on looking at additional sources like protein shakes. I really appreciate it. A follow up question – is there a UL for fish oil and natural foods like garlic/turmeric? Those are the three I take in addition and I’m not sure what to watch out for there. Thank you so much Phoebe!

    • I’m glad this was helpful! As for fish oil, garlic, and turmeric—there is no official UL for them….however, most physicians recommend not taking more than 1,000mg of fish oil (unless instructed by a doctor.) The reason is that fish oil at doses higher than that can ‘thin the blood’ therefore potentially increasing your risk of dangerous bleeding problems.

      On that line, garlic is also known to thin the blood, therefore I would take extra caution taking those two in combination. The risk for bleeding may be minimal, and you are probably fine, but just make sure that your doctor is aware that you take those.

      I hope this helps!

      • Hi Phoebe – I was diagnosed with ulcerative colitis many years ago which has been successfully controlled with meds. Given the inherent positive aspects of fish oil and garlic, and given my circumstances, are you suggesting that I should perhaps be avoiding fish oils and garlic completely? Thx. 🙂

        • Definitely not, Colin. Depending on the person, the benefits of taking those (even in combination) may outweigh the minimal risk (that’s why some people are on blood thinners…even though there is a potential risk for bleeding). But I definitely would make sure that your doctor is aware that you are taking them, as he or she can take your overall health into consideration and and give you an official thumbs up. Hope this helps!

      • Thank you – that definitely helps! It is so nice of you to respond with so much thoughtful information. I’ve found that so rarely in clinicians (although everyone means well!) – I think everyone just has hectic lives. I hope you know it makes a *huge* difference.

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