Of 31 consecutive Brazilian patients (mean age, 67.5 years) with Parkinson's disease, all were found to have evidence of riboflavin deficiency, as assessed by plasma FAD concentrations and the erythrocyte glutathione-reductase activation coefficient. In contrast, only 3 of 10 patients with dementia had evidence of riboflavin deficiency. Nineteen of the patients with Parkinson’s disease were treated with 30 mg of riboflavin 3 times a day for 6 months and at the same time eliminated all red meat from their diet. After three months, all patients showed improved motor capacity; during the following three months, five patients continued to improve, while the others maintained their previous level of improvement. The average motor capacity increased from 44% to 71% after six months (p < 0.001).

Comment: This study demonstrates that riboflavin deficiency is common in Brazilian patients with Parkinson’s disease and suggests that riboflavin supplementation may improve their clinical condition. The mechanism of action of riboflavin may involve preventing glutathione depletion or improving mitochondrial energy metabolism. Whether or not the elimination of red meat from the diet played a role in the improvement is not known. The digestion of red meat releases hemin, a potential neurotoxin.

Coimbra CG, Junqueira VBC. High doses of riboflavin and the elimination of dietary red meat promote the recovery of some motor functions in Parkinson's disease patients. Braz J Med Biol Res 2003;36:1409-1417.