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April 1990

Are High-Protein Diets Effective in McArdle's Disease?

Author Affiliations

Department of Medicine
Department of Neurology University of Chicago School of Medicine 5841 S Maryland Ave Chicago, IL 60637

Arch Neurol. 1990;47(4):383-384. doi:10.1001/archneur.1990.00530040023014

To the Editor.  —Recent articles have held forth hope that certain metabolic myopathies might undergo improvement with proper dietary therapy.1-3 In particular, the simple expedient of a high protein diet has appeared to be remarkably effective in the disparate disorders of McArdle's disease,1 debrancher deficiency,2 and acid maltase deficiency.3 With respect to McArdle's disease, a single patient, described by Slonim and Goans, demonstrated marked improvement after consuming a high protein diet.1 Indeed, 45 minutes after a high protein (25% to 35%) meal, his exercise tolerance improved 400%. Over a 3-year period, the patient also experienced a decrease in muscular atrophy and an increase in exercise tolerance. The investigators discussed the possibility that increased availability of branched-chain amino acids (BCAAs) contributed to the improvement by serving as an alternative energy source for exercising muscle. To focus on this possibility, we studied the functional and metabolic muscle