Vitamin C has been studied for decades in cardiovascular, immune system, and musculoskeletal diseases. It is a water-soluble vitamin that can only be obtained from the diet where a consistent supply is necessary to maintain normal body functions. Multifaceted, Vitamin C includes properties such as free radical scavenging and antioxidation. Despite knowledge of the importance of this vitamin, routine assessment is lacking in the general population. Current standards of parameter monitoring include only the identification of deficiency. It is unknown the prevalence of optimal (plasma levels <70 μmol/L), sub-optimal (plasma levels <50 μmol/L), and marginal (plasma levels <28 μmol/L) Vitamin C plasma levels that exist within the country. Dietary labels have also made Vitamin C an ‘optional’ inclusion on food packaging, implying there is little need for increased awareness and research. Yet, suboptimal levels may partly explain increased diagnoses of chronic diseases and must be more clearly substantiated. Residents of food deserts, recently identified as areas within the country where people have little to no access to nutritious food, are at increased risk of diminished levels plasma Vitamin C and the associations with inflammatory diseases. An examination of research, including emerging science, might better explain the need for further exploration of suboptimal and marginal Vitamin C status. The purpose of this review is to inform of the most relevant state of the science regarding the role of Vitamin C in multiple diseases, to provide evidence for re-evaluation of Vitamin C deficiency labeling and increased efforts of public health awareness.
A PUBMED/Medline database search was conducted exploring studies of associations between Vitamin C and diseases with known inflammatory and/or autoimmune components in articles published from 1994 to 2018. Keywords used included: ascorbic acid, Vitamin C, and Vitamin C hypovitaminosis. This literature review explored the multiple known properties of Vitamin C and how they related to chronic diseases that possess inflammatory components. Results identified decreased Vitamin C levels (whether plasma or leukocytic) associated with multiple disease processes such as cardiovascular disease, diabetes, Alzheimer’s disease, dementia, asthma, and others. Diseases with known inflammatory and autoimmune components were more likely to be associated with low levels of Vitamin C. Mechanisms of action varied depending on the nature of the specific disease. Inconsistent or non-existent baseline Vitamin C levels were common across multiple studies, leading to unclear benefits of supplementation.
These findings suggest both that current recommended guidelines for dietary intake may still be too low and sub-optimal/deficient people are not adequately identified prior to diagnosis. Healthcare practitioners may be better equipped to prevent disease by assessing and correcting sub-optimal levels of Vitamin C. A recommended revision to the definition of Vitamin C deficiency should include not only scurvy, but the decreased levels at which the body’s immune system may be compromised and natural defense subverted. These include the addition of identifying marginal and sub-optimal plasma Vitamin C levels as routine assessments. Recommended dietary guidelines and deficiency-state guidelines need revision to reflect the important role of this vitamin that can only be obtained from diet or supplementation. Increased public health awareness would benefit both the general population and residents identified as living in or near food deserts, where nutrition may play a significant role in disease prevention and treatment.
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