Do you have a child with ADHD or an autism spectrum disorder? You may have already heard of vitamins B or D to alleviate certain symptoms. A new meta-analysis published in 2025 looked into the question. However, not all patients respond the same way.
Vitamins B and D, what effects on autism and ADHD?
The researchers analyzed 12 studies involving 652 people with autism spectrum disorder (ASD) and 10 studies involving 852 people with attention deficit hyperactivity disorder (ADHD). In total, 787 participants received vitamins and 717 made up the control groups.
ASD is notably characterized by difficulties in social interactions and communication, as well as restricted interests and repetitive behaviors. ADHD, for its part, combines difficulty paying attention, impulsivity and, in some people, hyperactivity.
On the ASD side, it is mainly the B vitamins, notably vitamins B6, B9 and B12, which seem to have had an effect. The researchers observed an improvement in certain emotional aspects and a reduction in stereotypical behavior, with an effect size of 0.42.
For ADHD, the results are different. Vitamin D has been associated with a reduction in certain behavioral problems as well as improved attention in children monitored.
Real, but modest, effectiveness
However, should we see these vitamins as a new solution against autism or ADHD? The results do not allow us to go that far.
Concretely, the researchers observed a moderate overall benefit from supplementation, with a standardized difference of 0.41 compared to the control groups. This result therefore suggests a possible effect, but far from a spectacular effect. Especially since vitamin D has not shown a significant effect on ASD symptoms. Multivitamin preparations also did not differ significantly from the control groups.
Another point is worth keeping in mind: the studies analyzed were very different from each other. The doses used, the duration of supplementation and the tools used to measure symptoms varied greatly. This diversity could partly explain the very high heterogeneity observed by the researchers, at 92%.
These results therefore do not call into question the usual treatment of autism or ADHD. Vitamins B and D could possibly supplement them in certain people, but they are not intended to replace educational, psychological support or drug treatment when necessary.
The right reflex: talk to your doctor
For families, this study above all provides food for thought. If a deficiency is suspected, an assessment can be discussed with the doctor to determine if supplementation is necessary.
The objective is then to adapt the intake to the situation of each person, rather than systematically taking supplements. Individualized supplementation can be considered with a health professional, in particular to choose the appropriate supplement, dose and duration.
These results therefore remain interesting, but they do not mean that all people with autism or ADHD need vitamins B or D. Supplementation must above all respond to an identified need.