Should healthy adults be taking a daily multivitamin?
The short answer is – it’s probably not necessary.
Multivitamins sound great because they appear as a magical pill that provides you with all the vitamins and minerals you may need. They are also often marketed with claims of improving energy, sleep, and other health benefits. However, they are not a miracle solution to make up for a less-than-ideal diet. For the most part, people who are considering taking a multivitamin are already somewhat health conscious and likely consuming a fairly healthy, balanced diet that meets their requirement for most vitamins and minerals. Additionally, research has demonstrated that nutrients function differently when consumed as part of a whole food diet – rather than in supplement form. Research has also failed to demonstrate that taking a multivitamin supplement offers benefit in reducing risk of cardiovascular disease, cancer or death.
All that being said, there is certainly a time and place for nutrient supplementation. Deficiencies are common in North America and around the world and supplements may be required to treat a deficiency, particularly in individuals who exclude major food groups from their diet (i.e. vegans) and those with health conditions impairing nutrient absorption (i.e. IBD, ileostomy). In Canada, vitamin D and iron are common deficiencies, even in the general population. Many factors can influence your risk of deficiency, including restrictive diets, medications, age, and pregnancy. It can be more effective to choose a specific vitamin or mineral supplement you are deficient in than to choose a multivitamin with other unnecessary vitamins and minerals. However, you should always seek guidance from a physician or dietitian to understand if you need a supplement.
Can it be detrimental to take a multivitamin if vitamins and minerals help us maintain our health?
The saying of “too much of a good thing is a bad thing” applies here. Each vitamin and mineral has a Tolerable Upper Intake Level (UL), that indicates the maximum vitamin or mineral quantity that is not dangerous for the general population. As more of the nutrient is consumed over the UL, the more likely for your health to suffer. For example, too much calcium over time can lead to kidney stones.
Consuming the maximum quantity of a vitamin or the UL is not recommended. They are values called Recommended Daily Allowance (RDA) or Adequate Intake (AI) that are the vitamin and mineral recommended intakes for the healthy portion of society. You can look at this chart of some RDA and AI values, sourced from Health Canada.
To put it in perspective, one medium sized banana has about 0.4 mg of vitamin B6, 31% of the recommended daily intake for an adult. As well, a 1/2 cup of chopped broccoli contains 39.2 mg of vitamin C, 44% of the recommended daily intake for a male adult.
Multivitamins may be harmful, or more likely just unnecessary, as they provide the recommended amount or more of multiple vitamins in one capsule. If you are eating a healthy diet, this multivitamin could tip you into the concerning UL range. Food should be the first choice for consuming nutrients for healthy individuals!