By Phoebe Chi, MD, MPH
Multivitamins. Have you ever wondered if taking one makes a difference? Whether you even need one? And if you take several supplements, how much should you take of each…and when? In this post I will answer these important questions as well as provide you some tips on finding the perfect supplement for your needs.
– Step 1 –
Determine Your Need
One of the first things to consider when deciding whether or not you 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 below?
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…
Do You Fall into These Groups?
◊ Consider taking a multivitamin 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.
◊ Be CAUTIOUS if you are:
- 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).
How Much is Too Much?
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.
– Step 2 –
Choose Your Multivitamin
Check the Contents
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:
◊ What to look for 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.
Below is a sample label. Would this supplement be right for you?
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:
- 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.
- Avoid megadoses: High-dose supplements increase your risk of building up toxic levels of nutrients in your body.
- 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.”
- 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.
– Step 3 –
Make Your Daily Regimen
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 below 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 healthy living!