Multivitamins for Teens: Necessary or Wasteful?

Teen multivitamin sales run into the hundreds of millions of dollars a year in the U.S., driven mainly by parental worry rather than measured deficiency. The underlying nutritional science is narrower than the marketing. A teenager eating a varied omnivorous diet has no clearly established cognitive or long-term health benefit from a daily multivitamin (MVI). There is a small downside: a daily pill can give false reassurance about a diet that genuinely needs attention. The real exceptions — adolescent girls with heavy menstrual bleeding, strict vegans, intensively training athletes, and teens with diagnosed absorption disorders such as coeliac disease or Crohn's — are specific enough to name.

Why Most Teens Don't Need a Multivitamin

Adolescence is a stretch of fast growth and big appetite, driven by growth spurts and hormonal change. A teen who eats enough calories from a reasonably varied diet is also taking in a lot of naturally occurring vitamins and minerals. National dietary surveys (NHANES in the U.S., similar surveys in Canada and the U.K.) consistently show that most adolescents in wealthy countries meet or exceed the recommended intake for most vitamins and minerals from food alone — with a handful of common exceptions noted below. Generic multivitamins give the same dose of every nutrient regardless of individual need; the doses that exceed what the diet already covers are largely excreted unchanged.

Who Actually Needs to Supplement

Adolescent girls have the highest risk of specific shortfalls. Iron deficiency is common after menarche because menstruation is the body's only major route for losing iron; average menstrual blood loss is around 30–40 mL per cycle, with about 10% of women losing more than 80 mL (a definition of menorrhagia, where iron loss can outpace diet). A serum ferritin (iron-storage) test is more informative than a generic MVI. Calcium and vitamin D matter most during peak bone-mass accretion — roughly ages 9–18, with the steepest gain around 11–14 (Weaver et al., 2016 NOF position statement). Teens who get fewer than three servings of dairy or fortified plant milk a day, or who live in low-sunlight climates, are the ones who should target these specifically. Folate is important for adolescent girls of reproductive age, since the neural tube closes before most pregnancies are recognised; the U.S. CDC recommends 400 mcg/day folic acid for all who could become pregnant.

Teen vegans and vegetarians face higher risk of vitamin B12 deficiency (B12 is essentially absent from plant foods) and sometimes lower iron and zinc absorption due to phytates in grains, legumes, and seeds. B12 supplementation — or reliably fortified foods — is essential for vegan teens; it is the one supplement where deficiency without action is predictable rather than speculative. Adolescent athletes training intensively have elevated needs for iron, vitamin D, and total calories — targeted testing and food planning generally serve them better than a generic MVI. The American Academy of Pediatrics has long taken the same line: routine multivitamin supplementation is not recommended for healthy children eating a varied diet.