Dietary supplements are extremely popular, and multivitamins can seem particularly appealing for their potential to cover multiple possible nutritional issues. But do you really need supplements? Do multivitamins actually help? Should you take a multivitamin every day? Contrary to common marketing practices, we do not believe that multivitamins are a worthwhile expense, as they can be (at best) a waste of money or (at worst) cause dangerous nutrient toxicities.
Multivitamins typically claim to provide 100% or more of the Recommended Daily Value (%DV) of the nutrients listed on their labels. (Note: just because it’s listed on the label, doesn’t mean it’s really in the bottle! Read our blog about choosing supplements for more info on this topic.) If you are eating a variety of foods, your diet is certainly providing more than 0% of these nutrients. There’s a good chance that it’s providing the vast majority of them.
Multivitamins are often thought of as “insurance policies” for individuals who fall outside of these three categories—a way to ensure that nutrition needs are being met. And while this isn't typically a dangerous approach, it's certainly not a cost-effective one. Looking more closely at the contents of a multivitamin can help you determine just how expensive (and potentially unnecessary) such an insurance policy it is.
Deficiencies of water-soluble vitamins are incredibly rare in the developed world. Not only do most foods contain water-soluble vitamins, but many foods are fortified with them, too. Water-soluble vitamins cannot be stored in the body, so any excess water-soluble vitamin you consume is excreted. If you’ve ever wondered why your urine is bright yellow after taking a multivitamin, you can blame that on the excess riboflavin (B2), which is yellow in color (flavinis from the Latin word for yellow). Fun fact: it also glows under a black light!
Though water-soluble vitamins are not stored in tissues, constant supplementation can still result in unnecessarily high levels of these vitamins. In fact, InsideTracker dietitians have found that InsideTracker users who report taking a multivitamin often have excessively high levels of vitamin B12. While excessive intake of water-soluble vitamins is not clinically harmful, it’s simply unnecessary.
Unlike water-soluble vitamins, fat-soluble vitamins are stored in the body. Because of this, it is very possible to reach toxic levels of these vitamins with continuous excessive intake. And toxicity from certain vitamins, like vitamin A, have very serious side effects. Supplementing with fat-soluble vitamins therefore is not recommended unless there is an observed deficiency.
Ideally, these vitamins will instead come from foods, as the body can better regulate their absorption and the risk of toxicity is much lower. Vitamin D is unique, however—while there are some food sources of vitamin D (fortified dairy and non-dairy milks, some fish), the body typically produces vitamin D in the skin as a result of sun exposure. Vitamin D deficiency, like other fat-soluble vitamins, can easily be checked with a blood test. Based on your level, you may need to take a corresponding supplemental dosage to improve your levels. Our philosophy at InsideTracker is always "test, don’t guess," to ensure you're giving your body what it needs.
Similar to fat-soluble vitamins, minerals accumulate in the body and are therefore not required every day. Because of this, it is possible to take reach toxic, dangerous levels of these minerals if they are taken in too high a dose. Some groups of people, however, like post-menopausal females, may have a more difficult time reaching their needs of certain nutrients, as the recommended intake of calcium increases with to protect bone integrity and prevent osteoporosis. In these cases, targeted supplementation (read: not from a multivitamin) may be warranted.
One trace mineral in particular is often given prominence on supplement shelves: iron. Iron is the most common nutrient deficiency in the United States, largely due to the very high iron requirement in premenopausal women that many struggle to reach. Accordingly, iron supplementation is relatively common, particularly in women who do not consume sufficient iron from food sources. Men, on the other hand, do not experience iron deficiency at the same rate. Even still, iron is very often included in multivitamin supplements targeted to men. This decision by supplement companies can have detrimental effects: excess levels of iron can be harmful, as it can deposit itself in the soft tissues of the muscles, organs, brain, and joints.
So, in general, though supplementation of trace minerals can be critically important for some groups, unnecessary supplementation of these minerals (even that from a multivitamin) can have deleterious effects.
Many think of a multivitamin as an insurance policy—something to cover all nutritional bases. But the truth is that you likely don't need everything that's in such a supplement, making a multivitamin more comparable to wasting money on "incidentals"—items that you don't really need and didn't intend to pay for. Plus, the dosages found in multivitamins are often not even high enough to fix a deficiency if one is present. For example, the level of vitamin D that is commonly included in multivitamins is much lower than is necessary to increase your vitamin D level if it is low.
If you aren’t sure which nutrients you should be focusing on, Test. Don’t guess. InsideTracker blood tests include a range of vitamins and minerals to assess whether your diet is meeting your needs. It includes personalized optimized zones for each marker based on your age, gender, activity level, and ethnicity, so you can tell exactly where your blood levels stand. You’ll also get recommendations for the exact dosages of supplements if your blood work shows they are required.