Vitamin C - The Superhero Vitamin

Vitamin C is an essential vitamin, meaning your body can’t produce it. Yet, it has many roles and has been linked to impressive health benefits. It’s water-soluble and found in many fruits and vegetables, including oranges, strawberries, kiwi fruit, bell peppers, broccoli, kale, and spinach. The recommended daily intake for vitamin C is 75 mg for women and 90 mg for men. (1)

Vitamin C, also known as ascorbic acid, is necessary for the growth, development and repair of all body tissues. It's involved in many body functions, including formation of collagen, absorption of iron, the immune system, wound healing, and the maintenance of cartilage, bones, and teeth.

Vitamin C is one of many antioxidants that can protect against damage caused by harmful molecules called free radicals, as well as toxic chemicals and pollutants like cigarette smoke. Free radicals can build up and contribute to the development of health conditions such as cancer, heart disease, and arthritis.

Vitamin C is not stored in the body (excess amounts are excreted), so overdose is not a concern. But it's still important not to exceed the safe upper limit of 2,000 milligrams a day to avoid stomach upset and diarrhea. (2)

The health benefits of Vitamin C include:

1. May reduce your risk of chronic diseases. Vitamin C is a powerful antioxidant that can strengthen your body’s natural defenses.

2. May help manage high blood pressure. In adults with high blood pressure, vitamin C supplements reduced systolic blood pressure by 4.9 mmHg and diastolic blood pressure by 1.7 mmHg, on average.

3. May lower your risk of heart disease. Vitamin C may help reduce these risk factors, which may reduce heart disease risk.

4. May reduce blood uric acid levels and help prevent gout attacks.

5. Helps prevent iron deficiency. Vitamin C supplements can help improve the absorption of iron from the diet.

6. Protects your memory and thinking as you age. Studies suggest that oxidative stress and inflammation near the brain, spine, and nerves (altogether known as the central nervous system) can increase the risk of dementia. Vitamin C is a strong antioxidant. Low levels of this vitamin have been linked to an impaired ability to think and remember.

Here are some unproven claims about vitamin C:

• Prevents the common cold. While vitamin C appears to reduce the severity of colds and recovery time by 8% in adults and 14% in children, it does not prevent them.
• Reduces cancer risk. A handful of studies have linked vitamin C intake to a lower risk of several cancers. 
• Protects against eye disease. Vitamin C has been linked to reduced risks of eye diseases like cataracts and age-related macular degeneration. 
• May treat lead toxicity. (1)

Vitamin C and Immunity:

Vitamin C contributes to immune defense by supporting various cellular functions of both the innate and adaptive immune system. Vitamin C supports epithelial barrier function against pathogens and promotes the oxidant scavenging activity of the skin, thereby potentially protecting against environmental oxidative stress. Vitamin C accumulates in phagocytic cells, such as neutrophils, and can enhance chemotaxis, phagocytosis, generation of reactive oxygen species, and ultimately microbial killing. It is also needed for apoptosis and clearance of the spent neutrophils from sites of infection by macrophages, thereby decreasing necrosis and potential tissue damage. The role of vitamin C in lymphocytes is less clear, but it has been shown to enhance differentiation and proliferation of B- and T-cells, likely due to its gene regulating effects. 

Vitamin C deficiency results in impaired immunity and higher susceptibility to infections. In turn, infections significantly impact on vitamin C levels due to enhanced inflammation and metabolic requirements. Furthermore, supplementation with vitamin C appears to be able to both prevent and treat respiratory and systemic infections. 

Prophylactic prevention of infection requires dietary vitamin C intakes that provide at least adequate, if not saturating plasma levels (i.e., 100-200 mg/day), which optimize cell and tissue levels. In contrast, treatment of established infections requires significantly higher (gram) doses of the vitamin to compensate for the increased inflammatory response and metabolic demand. (3)

Vitamin C as an antiviral: 

The suggestion that vitamin C may be beneficial in a number of viral infections is based on two concepts, namely, i) patients with acute infectious diseases have low circulating vitamin C levels (likely due to metabolic consumption) and ii) vitamin C has beneficial immunomodulating properties in patients with viral infections, predominantly by increasing the production of α/β interferons and downregulating the production of pro-inflammatory cytokines. (4)

In China’s mainland, Zhongnan Hospital is conducting a study to see how vitamin C can help with many conditions. For instance, when a person has their immune system wiped out by chemotherapy, then they often give IVs of this vitamin to rebuild immunity. (5)

References

1. https://www.healthline.com/nutrition/vitamin-c-benefits#Unproven-claims-about-vitamin-C
2. https://www.webmd.com/diet/features/the-benefits-of-vitamin-c#1
3. https://www.ncbi.nlm.nih.gov/pubmed/29099763
4. https://www.tandfonline.com/doi/full/10.1080/14787210.2020.1706483
5. https://www.powerofpositivity.com/vitamin-c-china-using-treat-covid-19/