Fifty million Americans have allergies, according to the Asthma and Allergy Foundation of America. Allergies are the result of histamine, a substance released when foreign particles invade the body and cause an immune response such as hives, sneezing and watery eyes. Vitamin C, a water-soluble vitamin your body excretes through the urine, acts as an antihistamine. Consult your physician before starting any new supplements to treat allergies, as adverse reactions can occur.
Vitamin C as an Antihistamine
Vitamin C reduces the amount of histamine in the blood. An article from the August 1992 "Journal of the American Dietetic Association" found that 2 g of ascorbic acid decreased histamine levels by 40 percent. An article from the April 1992 "Journal of the American College of Nutrition" also found that 2 g of ascorbic acid decreased histamine levels by 38 percent, and those levels did not change for four hours.
How Vitamin C Works as an Antihistamine
In the March 2011 "Journal of Evidence-Based Complementary & Alternative Medicine," researchers reported that Vitamin C works as an antihistamine by destroying the molecular structure of the imidole ring of the histamine molecule, thereby decreasing the amount of histamine in the blood. The absorption of vitamin C is highly dependent on the amount ingested. To achieve tissue saturation of vitamin C requires more than 500 mg per day. More than 2 g can cause diarrhea.
Vitamin C Deficiency
Although vitamin C toxicity is rare, since it is a water-soluble vitamin and cannot be stored, the same cannot be said about vitamin C deficiency. In the May 2004 "American Journal of Public Health," researchers assessed the occurrence of vitamin C deficiency in the U.S. among a population of 15,769 people aged 12 to 74 years, and found overall that 14 percent of males and 10 percent of females were vitamin C deficient. A deficiency in vitamin C can cause scurvy, easy bleeding, anemia, swollen joints, dry skin, weight gain and dry hair.
Foods High in Vitamin C
Fruits and vegetables high in vitamin C include oranges, green peppers, mangoes, strawberries, cantaloupe, tomatoes, broccoli, cabbage, blueberries, raspberries and fortified juices. To maximize vitamin C absorption, consume fruits and vegetables raw because vitamin C is sensitive to temperature, light and air.