The Plasma Cysteine/Sulphate Ratio: A Possible Clinical Biomarker

Purpose: To explore the possible manifestations of abnormal levels of either cysteine or sulphate, whether high or low, and the ratio between them, in human subjects. Design: A case–control study of the plasma cysteine and sulphate levels and cysteine/sulphate ratio in chronically ill patients. Materials and Methods: Eighty-one chronically ill patients of a nutrition clinic were suspected of having abnormal levels of sulphate and/or cysteine. Their plasma was checked to determine their cysteine and sulphate levels and cysteine/sulphate ratio. These were compared with the results of 177 controls. They were grouped according to their results, and their symptoms were listed. Results: Only one patient had a ratio within the reference range, whereas 175 of the controls did. Patients already being treated with relevant nutritional supplements at the time of testing were less likely to have a ratio over 1000. Some close relatives shared abnormal test results, but manifested different symptoms. Conclusion: Patients with chronic conditions including myalgic encephalomyelitis, irritable bowel syndrome, migraine, arthritis, multiple chemical sensitivity and depression are likely to benefit from tests for cysteine and sulphate, and from treatment designed to improve these levels. Oral fish oil, vitamin B2, pantothenate and molybdenum, and Epsom salt baths may help patients with low sulphate. Vitamins B2 and B6, zinc and magnesium, and a low protein diet may reduce high cysteine levels. N-acetyl cysteine, zinc and vitamin C may help those with low cysteine levels. Patients with abnormal levels of sulphate might be counselled against working in polluted conditions, where efficient sulphate conjugation is required, and against using pesticides. They might be advised to be cautious in their use of drugs, and possibly vaccines too. Further work is suggested, to investigate to what extent abnormalities in cysteine and sulphate levels are genetically determined, and to test the efficacy of the treatments outlined, both at improving the cysteine and sulphate levels, and health.