Ascorbic acid, more commonly known as vitamin C, is a water-soluble vitamin that humans need to ingest on a regular basis. Unlike most animals, humans cannot make their own vitamin C. To the general public, it is probably one of the more familiar vitamins but many people may be unaware of the ways it is used by the body and its effect on the hormone cortisol.
Vitamin C has a wide array of functions. The Linus Pauling Institute reports that this vitamin is needed for the body to create the collagen which is part of blood vessels, tendons, muscles, bones and skin. Vitamin C is an antioxidant which helps to protect against “free radicals” -- atoms, ions or molecules thought to be involved in degeneration and disease; it affects the digestion of cholesterol, and is involved in the synthesis of norepinephrine, a chemical in the brain.
Cortisol is a steroid hormone secreted by the adrenal glands in response to stress or when the level of cortisol in the blood is low. The body uses cortisol to increase blood sugar. Cortisol also aids in the metabolism of fat, protein and carbohydrates, and can decrease bone formation. It prevents the release of inflammatory substances, and is used medically to treat Addison’s disease, rheumatoid arthritis and allergies.
Elevated cortisol levels are a factor in suppressing the immune system, and research is being conducted to determine if vitamin C supplementation can boost immune system function by reducing cortisol levels. At the Dalhousie University in Nova Scotia, researchers have studied the effect of vitamin C supplementation on human subjects subjected to exercise-heat stress. The authors state: “Prolonged physical exertion and environmental heat stress may elicit postexercise depression of immune cell function, increasing upper respiratory tract infection (URTI) susceptibility.” They found that vitamin C was more effective than a placebo in reducing cortisol levels. A study in Germany measured the response of human subjects to stress testing -- public speaking and mental arithmetic -- using both vitamin C and a placebo. This study found that vitamin C supplementation decreased measures of stress and that the subjects’ elevated cortisol levels recovered more quickly. In a study reported in the October 2001 “International Journal of Sports Medicine,” marathoners who received vitamin C supplements showed decreased cortisol levels.
Considerations and Warnings
While vitamin C and cortisol do interact, the research implications are still unclear. The Linus Pauling institute -- although Pauling himself recommended very high doses of vitamin C -- states that adult men and women should consume at least 400 mg of vitamin C daily. This is the equivalent of ten servings or five cups of fruits and vegetables, so the Institute suggests supplemental vitamin C in two separate 250 mg doses, taken morning and evening. It is unwise to self-medicate with vitamin C or any other supplement for a specific condition, and if you have questions or concerns, you should discuss them with your health care professional.
- “International Journal of Sports Medicine”: Vitamin C Supplementation Attenuates the Increases in Circulating Cortisol, Adrenaline and Anti-Inflammatory Polypeptides Following Ultramarathon Running, Peters EM, Anderson R, Nieman DC, Fickl H, Jogessar V. October 2001
- “International Journal of Sports Physiology Performance” Vitamin C Supplementation and Salivary Immune Function Following Exercise-Heat Stress. Carrillo AE, Murphy RJ, Cheung SS December 2008
- “Psychopharmacology (Berlin)”: A Randomized Controlled Trial of High Dose Ascorbic Acid for Reduction of Blood Pressure, Cortisol, and Subjective Responses to Psychological Stress, Brody S, Preut R, Schommer K, Schürmeyer TH January 2002
- http://lpi.oregonstate.edu: Oregon State University Linus Pauling Institute Micronutrient Center: Vitamin C; Jane Higdon, PhD, Victoria J. Drake, PhD November 2009