Immune Modulation

Vitamin C

Vital vitamin

Vitamin C is a water-soluble dietary vitamin essential for human life. Orally it is used help reduce the risk of upper tract respiratory infections, reduce lipid levels (LDL and TAGs) in those with high cholesterol, reduce blood pressure in those with hypertension, helps prevent atrial fibrillation after cardiac surgeries, reduces post-operative pain, lowers concentrations of blood levels of lead and improves the markers of anemia in patients on hemodialysis.

Vitamin C is found in high concentrations in the pituitary and adrenal glands and the corpus luteum (endocrine structure in female ovaries that is involved in the production of progesterone estradiol and inhibin A). Vitamin C is also found in skeletal muscle, the brain and liver.

Even though the human body cannot make vitamin C, it is a critical factor for human health for many reasons:

  • ability to donate electrons
  • potent antioxidant
  • co-factor for a family of biosynthetic and gene regulatory enzymes
  • contributes to immune defense by supporting various cellular functions of both the innate and adaptive immune system
  • supports epithelial barrier function and cellular mechanisms against pathogens
  • needed for apoptosis and clearance of the spent neutrophils from sites of infection by macrophages, thereby decreasing necrosis and potential tissue damage
  • enhances differentiation and proliferation of B- and T-cells
  • deficiency results in impaired immunity and higher susceptibility to infections
  • Rapidly consumed as the body reacts to infectious states
  • prevents and treat respiratory and systemic infections
  • For those who are obese, have diabetes, or part of the aging population, vitamin C supplementation can favourably modulate inflammation and the immune response to infection.

Sources of Vitamin C

The recommended daily dietary allowance for vitamin C is 90mg for males and 75mg for females. Supplementation of 500mg per day may reduce the incidence of upper respiratory tract infection. Vitamin C is found naturally in foods:

  • Oranges and other citrus fruits
  • Kiwi
  • Bell peppers
  • Wild violet flowers
  • Acerola
  • Rose hips

 

Can you take too much?

Adverse events are more common when oral doses above 2000mg are taken daily. Nausea, vomiting, diarrhea, abdominal cramps and increased likelihood of kidney stones in those susceptible have been reported. This is different for injectable vitamin C.

Large amounts of vitamin C can increase false reporting on laboratory blood analysis like those for liver, kidney and glucose tests. Ask your doctor when to stop the supplementation before your tests.

What are signs I don’t have enough?

Signs of deficiency can be vague; fatigue is the common first symptom. Sustained deficiency over three to five months may result in bleeding of the gums, loose teeth, hyperkeratosis (rough patches or thickened layers of skin), and hemorrhages into the muscles of the arms and legs and deficiency of collagen in the joints.

References:

See also

Carr AC, Maggini S. Vitamin C and Immune Function. Nutrients. 2017 Nov 3;9(11):1211. doi: 10.3390/nu9111211. PMID: 29099763; PMCID: PMC5707683.

Carr AC, Vissers MC. Synthetic or food-derived vitamin C–are they equally bioavailable? Nutrients. 2013 Oct 28;5(11):4284-304. doi: 10.3390/nu5114284. PMID: 24169506; PMCID: PMC3847730.

Cerullo G, Negro M, Parimbelli M, Pecoraro M, Perna S, Liguori G, Rondanelli M, Cena H, D’Antona G. The Long History of Vitamin C: From Prevention of the Common Cold to Potential Aid in the Treatment of COVID-19. Front Immunol. 2020 Oct 28;11:574029. doi: 10.3389/fimmu.2020.574029. PMID: 33193359; PMCID: PMC7655735.

Monograph for Vitamin C. Natural Medicine Database. Accessed Oct. 20, 2021 https://naturalmedicines.therapeuticresearch.com/databases/food,-herbs-supplements/professional.aspx?productid=1001