In 2002, Ohguro et al. found that rats fed 10 grams of sodium glutamate (97.5% sodium glutamate and 2.5% sodium ribonucleotide) added to a 100 gram daily diet for as little as 3 months had a significant increase in amount of glutamic acid in vitreous, had damage to the retina, and had deficits in retinal function (27).
Ohguro et al. also documented the cumulative effect of damage caused by daily ingestion of MSG.
Other reports of toxic effects of monosodium glutamate on the retina have come from studies at the University of Pecs, Hungary, where the neuroprotective effects of PACAP in the retina have been studied (28,29).
27. Ohguro H, Katsushima H, Maruyama I, et al. A high dietary intake of sodium glutamate as flavoring (Ajinomoto) causes gross changes in retinal morphology and function. Exp Eye Res. 2002;75(3):307-15.
28. Babai N, Atlasz T, Tamas A, et al. Search for the optimal monosodium glutaamte treatement schedule to study the neuroprotective effects of PACAP in the retina. Ann N Y Acad Sci. 2006;1070(July):149-155.
29. Szabadfi K, Atlasz T, Horvath G, et al. Early postnatal enriched environment decreases retinal degeneration induced by monosodium glutamate treatment in rats. Brain Res. 2009;1259(March):107-12.
49. Potts AM, Modrell RW, Kingsbury C. Permanent fractionation of the electroretinogram by sodium glutamate. Am J Ophthalmol. 1960;50(Nov): 900-907.
50. Freedman JK, Potts AM. Repression of glutaminase I in the rat retina by administration of sodium L-glutamate. Invest Ophthalmol. 1962;1(Feb):118-121.
51. Freedman JK, Potts AM. Repression of glutaminase I in rat retina by administration of sodium L-glutamate. Invest Ophthal. 1963;2(June):252-258.
52. Potts AM. Selective action of chemical agents on individual retinal layers. In: Graymore CN, ed. Biochemistry of the retina. New York: Academic Press; 1965:155-161.
53. Hamatsu T. Experimental studies on the effect of sodium iodate and sodium L-glutamate on ERG and histological structure of retina in adult rabbits. Acta Soc Ophthalmol Jpn. 1964;68(11):1621-1636. (Abstract)
54. Hansson HA. Ultrastructure studies on long-term effects of MSG on rat retina. Virchows Arch [Zellpathol]. 1970;6(1):1-11.
55. Cohen AI. An electron microscopic study of the modification by monosodium glutamate of the retinas of normal and "rodless" mice. Am J Anat. 1967;120(2):319-356.
56. Olney JW. Glutamate-induced retinal degeneration in neonatal mice. Electron-microscopy of the acutely evolving lesion. J Neuropathol Exp Neurol 1969;28(3):455-474.
57. Hansson HA. Scanning electron microscopic studies on the long term effects of sodium glutamate on the rat retina. Virchows Arch ABT B (Zellpathol). 1970;4(4):357-367.
58. Arees E, Sandrew B, Mayer J. MSG-induced optic pathway lesions in infant mice following subcutaneous injection. Fed Proc. 1971;30(2):287Abs (Abstract # 521).