A good friend for almost two decades also writes a blog Cort Johnson (HealthRising) and is attending the National Institute of Health ME/CFS conference and giving regular reports on his notes (the above link goes to one of them). Several of them caught my eye — today, I will look at the report of high uranium levels being detected in ME/CFS patients.
Early hair analysis results highlight increased mercury and uranium (!) levels associated with decreased selenium levels. The sample size is small, however….The NIH ME/CFS Conference II: Lipkin’s Possibilities, Prusty’s Big Idea, Oh’s Search and Ron Davis on ALWAYS Moving Forward, Apr 15, 2019
Then came a preliminary but really weird finding – elevated levels of mercury (not so weird) and high levels of uranium (really weird) associated with low selenium levels in the hair analyses of a significant subset of patients. Both the mercury and uranium issues derive from low selenium levels. Selenium, interestingly, also plays a role in the conversion of T4 to T3 in the thyroid. (Chris Kressler recommends getting your selenium levels tested and, in general, using
dietary methods (not selenium supplementation) to safely
increase selenium levels in hypothyroidism.)
I have selenium as one of my core recommendations – which the above reinforces. The reasons that I cite on earlier posts (see prior link for more studies)
- 78% of IBS patients examined showed selenium insufficiency ,
- Low selenium is associated with hypothyroidism 
- FM has lower selenium levels 
- Selenium supplement improved the condition of CFS rats 
Uranium and mercury is frequently found in trace amount in drinking water , as well as in human placenta  and US children . It appears, for reasons not currently understood, that the body retains more of those two minerals when it is short of selenium. (“Significant pairwise correlations were observed for a number of metals.” ) Some additional interesting studies:
- “Our results suggested that asthma prevalence in the Chinese adults was positively associated with urinary chromium, chromium, selenium, molybdenum, cadmium, and uranium, ” 
- Impacts of selenium supplementation on soil mercury speciation, and inorganic mercury and methylmercury uptake in rice (Oryza sativa L.). “As a result, inorganic Hg (mercury) was reduced by >48%, 18%, and 80% in root, stem, and grain “
- Selenium, total mercury and methylmercury in sardine: Study of molar ratio and protective effect on the diet. 
- “the selenium content in canned sardine samples is enough to provide a protective effect on the Hg species. “
Preferred sources are from food (a list here) but not that malabsorption does occur with gastrointestinal condition (i.e. microbiome dysfunction).
Selenium Toxicity does occur with supplements — so the safest course is to get measured and under medical supervision for supplementation.
The source of the outbreak was identified as a liquid dietary supplement that contained 200 times the labeled concentration of selenium. Of 201 cases identified in 10 states, 1 person was hospitalized. The median estimated dose of selenium consumed was 41 749 μg/d (recommended dietary allowance is 55 μg/d). Frequently reported symptoms included diarrhea (78%), fatigue (75%), hair loss (72%), joint pain (70%), nail discoloration or brittleness (61%), and nausea (58%). Symptoms persisting 90 days or longer included fingernail discoloration and loss (52%), fatigue (35%), and hair loss (29%). The mean initial serum selenium concentration of 8 patients was 751 μg/L (reference range, ≤125 μg/L). The mean initial urine selenium concentration of 7 patients was 166 μg/24 h (reference range, ≤55 μg/24 h).Acute Selenium Toxicity Associated With a Dietary Supplement 2010