When parents tell children to “eat your greens”, not all have a detailed knowledge of the health benefits. Even those most nutritionally informed are probably unaware that the consumption of green leafy vegetables could protect against psychotic episodes. Yet three papers published in quick succession by the same team suggest this could be the case.
Professor Akira Sawa of Johns Hopkins University conducted magnetic resonance spectroscopy on the brains of 81 people who had experienced their first psychotic episode in the last two years and a control group of similar ages.
The observed differences reported in JAMA Psychiatry include lower levels of glutamate, essential to signaling between brain cells, in the anterior cingulate cortex region of the brains of people with schizophrenia. The difference was just 4 percent, but statistically significant, particularly in light of past work linking glutamate deficiency to both depression and schizophrenia. Lower levels of glutathione, a larger molecule partially composed of glutamate, were found in two other brain regions.
To explore the role of these two molecules, Sawa and colleagues gave the drug L-Buthionine sulfoximine, which interferes with the conversion of glutamate to glutathione, to rats. The signaling they witnessed between brain cells resembled the over-excitation seen in people with schizophrenia.
Aiming not to induce psychosis but to prevent it, Sawa sought a drug with the opposite effects to L-Buthionine sulfoximine. Her candidate was sulforaphane, which we primarily obtain from green leafy vegetables, although you can also find it marketed in food supplements. In Proceedings of the National Academy of Sciences, he reports that cells given extra sulforaphane operate more sedately.
Rat and human brains are not the same of course, and the rats can't tell you if they are hallucinating anyway, so the next step needed to involve people. In Molecular Neuropsychiatry, Sawa describes a 30 percent rise in glutathione levels in the brains of nine volunteers after just a week on sulforaphane capsules.
Since the participants were not suffering psychosis, the study didn't test if sulforaphane reduces symptoms. However, the authors theorize glutamate is necessary to prevent psychosis, and glutathione acts as a reserve supply, making sure that in healthy brains the glutamate doesn't run out.
Co-author Professor Thomas Sedlak proposed in a statement that schizophrenia may be associated with low glutathione reserves, and expressed the hope high-sulforaphane diets might have a protective effect, similar to the one healthy diets have against heart disease. Nevertheless, any hope supplements could replace anti-psychotic drugs are a long way off being supported.
Interestingly, while marketers of sulfoximine pills proclaim a very long list of supposed health benefits – some with considerably stronger evidence than others – protecting against psychosis is not yet one of them.