In a report published in the Dec 1991 issue of American Journal of Clinical Nutrition, Harakeh and Jariwalla said they tested calcium ascorbate, a salt of vitamin C, and two thiol-based reducing agents (glutathione and N-acetyl-L-cysteine (NAC)) for their effect against the human immunodeficiency virus HIV-1 replication in chronically infected T lymphocytes.

They found that calcium ascorbate has the same magnitude of effect at reducing extracellular HIV reverse transcriptase as ascorbic acid or vitamin C does. But chronic exposure to ascorbate was necessary for HIV suppression.   NAC, but not glutathione caused less than twofold inhibition of HIV reverse transcriptase and rendered a synergistic effect (about 8-fold inhibition) when tested together with vitamin C.

Later in 1994, the researchers published another study in the June 1994 issue of Chem Biol Interact saying that "the activity of an HIV LTR-directed reporter protein made in ascorbate-treated cells was reduced to approximately 11% relative to that of untreated control," indicating that vitamin C "exerts a posttranslational inhibitory effect on HIV by causing impairment of enzymatic activity."

In 1995, Harakeh and Jariwalla reported in the Sep-Oct issue of Nutrition that "exposure to 300 micrograms/ml ascorbate (vitamin C in the form of salt) resulted in approximately 5- to 10-fold lowering of the extra-cellular RT (reverse transcriptase) titer. In contrast, no significant suppression in extracellular RT levels was seen with concentrations of AZT (an antiviral drug) in the range of 1-5 micrograms/ml." (By David Liu)