In his article "Vaccinations, Inoculations and Ascorbic Acid," C. Alan B. Clemetson, MD suggests that some of the severe reactions in infants after vaccination may be due to elevated histamine levels. Elevated histamine levels in tissue cause conditions such as hay fever, allergic rhinitis, and nettle-rash. Elevated blood histamine levels, however, cause convulsions, coma, and death. Experiments with guinea pigs have shown that the injection of vaccines or toxoids raise blood histamine levels.
Dr. Clemetson says that vitamin C supplementation reduces blood histamine levels by converting histamine to hydrantoin-5-acetic acid and then to aspartic acid. Supplementation also reduces mortality rates in animals and people who have received inoculations. Conversely, studies have shown that a deficiency of vitamin C made guinea pigs (who, like humans, do not manufacture vitamin C in their bodies) more sensitive to the negative effects of histamine. J.L. Parrot and G. Richet found that significantly less histamine killed half of the guinea pigs in their experiments after 15 days on a vitamin C-deficient diet. Instead of 8 mg/kg, only 2.5 mg/kg was needed.