Do you take a daily multi-vitamin? If you read the label on a multi-vitamin supplement, you might notice that the quantity of vitamins and minerals in some multivitamin brands exceed the recommended daily value. For example, a multi-vitamin might contain 200% of the recommended daily intake or even more. This means the that supplement supplies double the recommended amount of that nutrient.
For some vitamins, like vitamin C, the %DV a multivitamin contains may be as high as 1000% of the amount recommended intake. For other nutrients, it may contain less, for example, 50% of the recommended amount you need each day. Confusing, right?
To standardize nutrition, the Food and Drug Administration gives each vitamin, mineral, and fiber a daily value (DV), the daily intake of a nutrient people need each day to avoid a deficiency of that nutrient. When you look at each vitamin and mineral in a multi-vitamin, you see a percentage corresponding to how much of the DV that vitamin supplement supplies. If a supplement contains the exact DV, then it is listed as 100% DV; if it contains twice the DV, then it is listed as 200% DV.
But don’t confuse the daily value with the amount you need for optimal health. It’s the bare minimum you require to avoid deficiency. To confuse matters, the way the government determines %DV has changed. There are now %DV for adults, infants, children, and during pregnancy since nutritional needs vary with age and increase during pregnancy. Previously, a single DV applied to all. Fortunately, most multivitamin manufacturers have updated their labels based on the new %DV but if you have a multivitamin bottle that’s a year or two old, it may still be based on old data.
Why Multivitamins Contain More Than 100% of Daily Value?
One reason multivitamin supplements may contain more than 100% of the DV is that the DV is only enough to avoid deficiency in 97% of the population. Most people can benefit from larger quantities of certain vitamins and minerals to optimize health. For example, 800 IU is the DV for vitamin D in healthy adults, but you may still have a sub-optimal vitamin D level if you take that amount. Many experts believe the average person, especially older individuals, needs at least 1000 IU of vitamin D daily and may benefit from even more.
Plus, if you’re older or obese, your risk of vitamin D deficiency is higher, and you may need a larger daily dose to keep your level in a healthy range. Therefore, multivitamin manufacturers add more of some vitamins as an extra cushion, as long there are no risks to doing so. For example, research shows people can tolerate 1,000% of the DV of vitamin C without adverse reactions. It’s also common to see several times the DV of B-vitamins in multivitamins since your body excretes the excess and there’s little risk of toxicity.
You Don’t Absorb All the Nutrients in Multivitamins
Another reason multivitamin manufacturers add more than the %DV is there are varying degrees of absorption of the vitamins and minerals from multivitamins. If you’re only getting the %DV, you might not get enough to avoid deficiency if you have absorption issues. However, most people also get vitamins and minerals from food sources.
It’s Possible to Take Too Much of Some Vitamins
Taking many times the DV of a vitamin or mineral isn’t always safe. Fat-soluble vitamins, like vitamin A, vitamin D, vitamin E, and vitamin K, can be toxic in large quantities since your body can’t excrete the excess easily. Your liver and fatty tissues store the excess. That’s why you’re less likely to see multivitamins that contain many times the %DV of fat-soluble vitamins.
Along with the risk of toxicity, taking high doses of fat-soluble vitamins can cause side effects like nausea, stomach pain, vomiting or diarrhea. Taking too many vitamins can cause harm if you mix them with other medications or supplements. For example, taking more than 100% of your daily value for selenium may decrease how well your thyroid hormone works (as per the National Institutes of Health). And taking a vitamin K supplement can interfere with blood thinning medications.
Some consumers look for multivitamins that contain more than the DV because they believe more is better but that’s not always the case, particularly with fat-soluble vitamins. That’s why it’s important to read the label and do your research before buying a multivitamin. For example, some multivitamins contain several times the DV of vitamin A, a vitamin that in high doses can cause liver damage.
Conclusion
Getting more than the DV of some vitamins and minerals is safe for some vitamins and minerals. It can be problematic, however, for fat-soluble vitamins though since it’s hard for your body to eliminate what it can’t use. However, studies show that most people can tolerate, and may benefit from, higher doses of vitamin D, and the daily upper safe limit is 4,000 IU a day. So, it’s important to check and follow a vitamin D level if your doctor recommends more than 4,000 IU per day, 5 times the %DV.
Ultimately, the goal should be to get vitamins and minerals from food sources rather than depending on a multivitamin but certain people with medical conditions or a restricted diet may benefit from one. Also, don’t use a multivitamin as an excuse to eat a junk food diet. Studies show you’ll get more health benefits from eating a nutrient-dense diet than from taking nutritional supplements.
References:
- “Should I Take a Daily Multivitamin? – The Nutrition Source.” https://www.hsph.harvard.edu/nutritionsource/multivitamin/.
- “Daily Value on the New Nutrition and Supplement Facts Labels.” 25 Feb. 2022, https://www.fda.gov/food/new-nutrition-facts-label/daily-value-new-nutrition-and-supplement-facts-labels.
- “Do Multivitamins Work? The Surprising Truth – Healthline.” 28 Jan. 2021, https://www.healthline.com/nutrition/do-multivitamins-work.
- “100% Daily Value (RDA) for Vitamins and Minerals: Is it enough?.” https://mccordhealth.com/blogs/news/100-daily-value-rda-for-vitamins-and-minerals-is-it-enough.
- “Study: Are the Nutrients in Multivitamin Supplements Absorbed?.” https://www.centrum.com/learn/articles/how-supplements-work/are-the-nutrients-in-supplements-absorbed/.
- “Daily Value on the New Nutrition and Supplement Facts Labels.” 25 Feb. 2022, https://www.fda.gov/food/new-nutrition-facts-label/daily-value-new-nutrition-and-supplement-facts-labels.
- National Research Council (US) Committee on Diet and Health. Diet and Health: Implications for Reducing Chronic Disease Risk. Washington (DC): National Academies Press (US); 1989. 11, Fat-Soluble Vitamins. Available from: https://www.ncbi.nlm.nih.gov/books/NBK218749/
- Caldera M. Common Multivitamins Contain Too Much Vitamin A? | Expanded Food and Nutrition Education Program. Uconn.edu. Published December 19, 2015. Accessed August 18, 2022. https://efnep.uconn.edu/2015/12/19/common-multivitamins-contain-too-much-vitamin-a/
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