It is well known that Vitamin C nutrition is essential for prevention of scurvy in human and most animals, but the roles of Vitamin C and other constituents of citrus juice are now known to have many other important roles in health.
Many of the article’s cited studies have been carried out in humans or in animals other than cats, dogs and horses. References to human inflammation and immunity in the paper do have important potential implications for animals (except perhaps those that synthesize their own vitamin C).
THE MAIN POINTS MADE IN THIS ARTICLE
- The immune system’s role is to protect the individual against pathogenic organisms, including bacteria, viruses, fungi, and parasites. Thus, in order to provide effective protection, the immune system has evolved to include many different cell types and communicating molecules and multiple functional responses.
- Individuals with weakened immune systems are at increased risk of becoming infected and of infections being more serious, even fatal.
- Inflammation is an essential and normal component of the innate immune response. In general, inflammation acts to create an environment that is hostile to pathogens. It initiates pathogen killing, and it causes changes in the metabolism of the host.
- Loss of the regulatory processes involved in the resolution of inflammation can result in excessive, inappropriate or ongoing inflammation that can cause irreparable damage to host tissues leading to pathology and disease.
- Inflammation is an important component of a wide array of human (and animal) conditions, including classic chronic inflammatory diseases like rheumatoid arthritis, inflammatory bowel diseases, allergy and asthma, which are all controlled or treated with varying degrees of success with anti-inflammatory medications. Inflammation is also involved in human cardiovascular diseases, metabolic diseases, neurodegenerative disorders and cognitive decline; in many cancers; and in ageing.
- The relationship between inflammation and oxidative stress is bidirectional: oxidative stress induces inflammation, and inflammation induces oxidative stress. Hence, agents that act to reduce oxidative stress, such as vitamin C, can also be anti-inflammatory.
- Vitamin C is an essential nutrient that acts primarily as a water-soluble antioxidant. The European Food Safety Authority permits claims of “contributes to the normal function of the immune system” for vitamin C.
- Vitamin C also has anti-inflammatory effects, in part because of its role as an antioxidant, and also has roles in several aspects of immunity. Vitamin C also has a role in sustaining the integrity of immunological barriers, including the skin and internal mucosal linings, for example, of the intestinal tract.
The full paper is available online at https://doi.org/10.3389/fimmu.2021.712608