Depression can lead to permanent brain damage

Brain damage from too much selenium

SOUTHAMPTON. A lot helps a lot, thinks the medical layman; the dose makes the poison, the doctor knows.

Nevertheless, immunologists around Dr. William Rae from the University Hospital in Southampton puzzled for a long time what led to a progressive visual and memory impairment in a woman over the age of 50 (JAMA Neurol; online July 2nd, 2018).

Her visual acuity was extremely limited, and she could no longer see any numbers in the Ishihara color test.

50 times higher selenium value

The FLAIR imaging revealed pronounced leukoencephalopathy, but the EEG was normal. The usual laboratory tests also remained inconspicuous: there was no evidence of an infection or a metabolic disorder.

Vitamin B12 and folic acid levels were in the normal range, as were the concentrations of other vitamins as well as minerals and trace elements such as zinc, copper and magnesium.

The immunologists also examined the woman for autoimmune encephalopathy; various antibody analyzes also gave no evidence of this. Genetic analyzes for hereditary diseases, to which the clinical picture could fit, also turned out negative.

The woman's advice to take selenium supplements on a regular basis then led her on the right track. The doctors then determined the selenium level - at 5370 micrograms per liter, it was around 50 times higher than the norm (63–158 μg / l).

Taken long and many selenium tablets

The patient admitted that she had been taking over-the-counter selenium supplements for a long time. Most of the time, she only took one 200 microgram tablet a day.

Six months before she was admitted to the clinic, she increased the dose to six to eight tablets (1200–1600 micrograms) per day. She assumed that selenium supported her immune system.

The information sounded reasonably plausible: In a blood sample taken a year before the event, the selenium levels of 193 micrograms per liter were only slightly above the normal range.

The doctors around Rae advised immediate selenium withdrawal, whereupon the symptoms receded with falling selenium levels. Two years later, the woman no longer had any symptoms that could be traced back to the selenium intoxication, and the selenium level was only slightly increased at 170 micrograms per liter.

The MRI showed hardly any changes in the white matter, but pronounced brain atrophy was now recognizable, which the doctors attributed to the intoxication.

No effects of selenium in prevention studies

Memory and vision problems with selenium poisoning have already been observed several times, according to Rae and co-workers, but no leukoencephalopathy has been described with such intoxication so far.

Of course, the doctors cannot clearly prove that the symptoms were primarily or exclusively caused by selenium. It is possible that the selenium tablets were also contaminated with other substances, but this could no longer be checked.

In addition, the woman did not show all the typical signs of selenium poisoning, such as hair loss or nail growth disorders. In the absence of other explanations and due to the extremely high selenium levels and the decrease in symptoms after the supplementation was stopped, the doctors assume that both the symptoms and the leukoencephalopathy were caused by the excessive consumption of selenium tablets.

In Germany, too, selenium is often offered over-the-counter in doses of 200 micrograms per tablet. The essential trace element is said to be good for skin and hair as well as the immune system.

For a long time selenium was also thought to have cancer and cardiovascular preventive effects. However, this could not be proven in large studies.

Since dietary supplements are very popular in the population, doctors are increasingly confronted with damage from such agents, write the doctors around Rae.

So it can't hurt to ask specifically about supplements when you have puzzling symptoms and findings.