A small number of people with Asthma also have food intolerance – the most common culprits are sulfites and salicylates.. Asthma can increase the risk of migraine (Asthma Allergy Network). Having both may increase susceptibility.
ADHD and migraine can co-occur (CHADD). Some people with ADHD may have other conditions that can be associated with food intolerance in susceptible people.
General guidelines for ADHD and diet can be found at CHADD here Chadd is a CDC.gov ADHD recommended resource
Around 80% of people with ME/CFS experience chronic daily headaches or migraine Some benefit from a food intolerance diet, as discussed by health professionals in some parts of this video 14- When even food triggers your symptoms, what can you eat? 22:04
Resources for ME/CFS
Myalgic encephalomyelitis (or encephalopathy)/chronic fatigue syndrome: diagnosis and management https://www.nice.org.uk/guidance/ng206
Patient Toolkit https://www.cdc.gov/me-cfs/toolkit/index.html