It has been suggested that the gut microbiome plays an important role in the gut-brain axis, and that dysbiosis may contribute to several neurodevelopmental disorders including ADHD. (3) This is due to the gut microbiome being able to impact brain development and functioning via its direct connections with the vagus nerve, its interactions with the immune system, and by altering neurotransmitters like serotonin. Thus, a way to alter the gut microbiome could be to take a probiotic.
A randomised control trial on the introduction of strain Lactobacillus rhamnosus GG (LGG) in patients with ADHD found that children and adolescents who received LGG supplementation reported better health-related quality of life compared with the placebo group. (4) However, no significant differences in the ADHD symptom ratings were reported by parents and teachers. (4)
This is an emerging area but, as concluded by a recent review, there needs to more evidence in this area before specific recommendations can be suggested. (5)
Several studies have highlighted certain deficiencies of nutrients, mainly iron, zinc, magnesium, and vitamin B6, which are linked with ADHD symptoms. (6) It has, therefore, been proposed that addressing such deficiencies may help to reduce ADHD symptoms severity.
Research has mainly focused on iron and zinc supplementation in ADHD among children and adolescents, as papers have demonstrated that a deficiency in these two minerals was associated with impaired attention capacity and increased hyperactivity. It was also found that with additional supplementation, there was an improvement in ADHD symtoms. (6) However, a systematic review concluded that, whilst there is stronger evidence for zinc supplementation, this was still a controversial area and more controlled clinical trials are needed. (7)
Rosi, et al., (2020) reviewed 42 RCTs that included different supplementation categories and found most studies reported beneficial effects in a wide array of treatment outcome measurements. (8) For instance, 8 out of 14 studies looking at Polyunsaturated fatty acid supplementation alone found significant improvements in attention, working memory, emotional problems and behaviour as reported by parents and teachers. However, most of the studies included had different trial durations, methodologies, and outcome measures, so it was concluded that it was not possible to carry out a meta-analysis that would have provided more rigorous evidence for specific supplementation. (8) There is also the issue that some medications utilised in ADHD come with contraindications and side effects that can affect the diet, so working in MDT which involves a dietitian vital.