well sir do I have a solution for you
its almost like bipolar, except he's not at all bipolar. a med change (dosage, or actual med) could mean every day next week he's showing up at the office an hour early, AFTER getting up to hit the stairs at the gym. then he parks in some retarded spot which tends to irk my my other buddy and I who are autistic to the core and have completely unchanged routines the past decade. another change, and he might suddenly stop getting up early and start showing up to the office late 5-10 minutes every single day. the changes we see in him are personality, not focus. like he's bouncing off the walls like a happy go lucky puppy, up early and moving, or he's more quiet. ironically when he "seems" down to us, he claims "wow this is the best dose I think the dr ever wrote me, I feel so focused" but we see a dude that seems lazier, depressed, quiet, etc.
The irony is the only change we see in his a.d.d. / adhd meds from outsider perspective is MOODS. I never see any improvement in focus or getting jobs done. He usually have 100 projects 90% compete, which still makes him more effective than your typical non adhd person who has 0 or 1 project 100% complete (haha).
The healthiest I have ever seen him both from a focus standpoint, and mood, was when he stuck to a 4x/week lifting regiment with me when I was chasing my 500lb deadlift and 300lb bench. He was fatter, ate whatever he wanted, but was always lifting heavy with me. When I change up my focus to hypertrophy and cutting he gets bored, shows up half as often and I see it trickle into the rest of his life.
we are similar in our house but with other things like fiber. as of yet we still do not supplement fiber as we make a really concerted effort to get a lot of fibrous foods but coincidentally, a lot of them are like what you pointed out (broccoli and cauli, as well as a ton of brussels in our house). its so engrained in us that when we travel and have to eat out a lot I find myself craving fresh greens, good salads etc