This piece was written by one of our contributors; registered nutritionist; Ghazal.
Should healthy adults take multivitamin supplements?
The short answer is…you’re probably wasting your money! Paradoxically, most people who consider taking multivitamin supplements are health-conscious individuals who are already consuming a healthy, balanced diet (in line with the Eatwell Guide) that meets their requirement for most vitamins and minerals. It is also becoming increasingly clear that food is more than the sum of its parts and that nutrients function better when consumed as part of a whole food rather than pills.
Having said that, supplementation with specific nutrients may be necessary in those who are excluding major food groups from their diet (e.g. vegans and vegetarians), and in certain groups of population, such as pregnant women and young children. Supplementation with vitamin D during autumn/winter, is also recommended for all individuals living in the UK, and all year round in certain at risk groups.
While the most common reason for taking supplements is to “improve” or “maintain” good health (1), current research suggests that multivitamin supplements confer no benefit in reducing risk of cardiovascular disease ( e.g. heart attack and stroke), cancer or death rates (2,3).
But are they safe?
Most multivitamin supplements purchased from reputable sources in the UK, are unlikely to cause any adverse effects, if taken in the correct doses and not in addition to interacting medications/supplements. Taking the correct dose is especially important when it comes to ‘fat-soluble’ vitamins: A, D, E, K. Risk of toxicity is lower with ‘water-soluble’ vitamins as we pee out most of the excess. This is not the case with ‘fat-soluble’ vitamins that can accumulate in the body and cause toxicity. Also, “multivitamin” supplements commonly contain minerals such as iron and selenium which in excess, can be harmful. In other words, too much of a good thing can be a bad thing!
If, however, you stick to the instruction on the label, and ensure that the nutrient profile of other supplements you take does not overlap with those in your multivitamin supplement, you are likely to be on the right track! Having said that, a study that looked at 67 different multivitamins found that most of these supplements, supplied less than the recommended 400 IU vitamin/d for vitamin D (4). As such depending on the composition of the supplement, additional supplementation with vitamin D may be necessary. Also, as our requirements for vitamin/minerals vary depending on gender, age (among other factors), it is best to choose a supplement specifically designed for your gender and age group.
Those taking medications (especially warfarin) should check with their doctor before starting any supplement as it may interact with the medication, increasing or decreasing its efficacy or lead to harmful side effects.
Clearly, consuming a balanced and varied diet is the best way of obtaining vitamins and minerals. Multivitamin supplementation can be useful in those with inadequate micronutrient intake, however, as the name implies, they are intended to supplement the diet, and should not take the place of a balanced diet.
References
1. Bailey RL, Gahche JJ, Miller PE, Thomas PR, Dwyer JT. Why US adults use dietary supplements. JAMA Intern Med. 2013;173(5):355–61.
2. Macpherson H, Pipingas A, Pase MP. Multivitamin-multimineral supplementation and mortality: A meta-analysis of randomized controlled trials. Am J Clin Nutr. 2013;97(2):437–44.
3. Kim J, Choi J, Kwon SY, McEvoy JW, Blaha MJ, Blumenthal RS, et al. Association of multivitamin and mineral supplementation and risk of cardiovascular disease: A systematic review and meta-analysis. Circ Cardiovasc Qual Outcomes. 2018;11(7):1–14.
4. Moon RJ, Curtis EM, Cooper C, Davies JH, Harvey NC. Vitamin D supplementation : are multivitamins sufficient ? 2019;1–3.
