This takes me back. Around 25 years ago I was struggling with candida and having exhausted the medical route I started to see a colonic irrigationist and nutritionist. (I was completely desperate). She drastically cut foods I could eat in an attempt to starve the candida (and me. I was rake thin due to this).
Of the many and varied tests, pills and potions she administered, one was a hair analysis. The results showed high levels of mercury but given I have no fillings there was no explanation for it. Then, by complete chance, I met a guy who imported fish and he told me that tuna typically contained high levels of mercury. Despite the fact I consider fish to be the food of the devil, during this period I used to virtually live on jacket potatoes with tuna mayo (I used to carry around a ‘healthy’ taste-free mayonnaise. The lengths we go to). I stopped eating tuna and did nothing about the mercury and I’m still here.
I agree with the others. Heavy metal poisoning is real but enters dubious waters once it navigates into alternative ground. Anxiety and insomnia are typical TMS fare. Is your friend amenable to a TMS approach?