Vitamin C: Unveiling Its History, Functions, and Impact on Health

Vitamin C, also known as ascorbic acid, is a water-soluble vitamin that is essential for various biological processes in the human body.

It is renowned for its role in supporting the immune system, promoting healthy skin, and acting as a powerful antioxidant.

Let’s delve into the fascinating world of vitamin C, exploring its history, functions, recommended daily intake, sources, and factors influencing its absorption.

What is Vitamin C?

Vitamin C is a micronutrient that cannot be synthesized by the human body and must be obtained through diet or supplements.

It is found in numerous fruits and vegetables, with citrus fruits, strawberries, bell peppers, and broccoli being notable sources.

Vitamin C plays a vital role in collagen synthesis, iron absorption, and protection against oxidative stress.

History of Vitamin C

The history of vitamin C dates back to the 18th century when it was recognized that consuming fresh fruits and vegetables could prevent scurvy, a disease characterized by weakness, gum disease, and fatigue.

In the early 20th century, Albert Szent-Györgyi, a Hungarian biochemist, isolated and identified ascorbic acid, earning him a Nobel Prize.

This discovery laid the foundation for understanding the importance of vitamin C in human health.

Main Functions of Vitamin C

Vitamin C is involved in various biological processes that are vital for overall health and well-being.

Here are the main functions of vitamin C.

Collagen Synthesis

One of the primary functions of vitamin C is its role in collagen synthesis.

Collagen is a protein that forms the structural framework of many tissues in the body, including the skin, tendons, ligaments, and blood vessels.

Vitamin C is necessary for the hydroxylation of proline and lysine amino acids, a process crucial for the formation of stable collagen fibers.

Adequate vitamin C levels support the maintenance and repair of connective tissues, promoting skin elasticity, wound healing, and overall tissue integrity.

Antioxidant Activity

Vitamin C acts as a powerful antioxidant in the body, helping to protect cells from damage caused by harmful free radicals.

Free radicals are unstable molecules that can lead to oxidative stress, which contributes to various chronic diseases and accelerates the aging process.

As an antioxidant, vitamin C neutralizes free radicals, preventing oxidative damage to cells, tissues, and DNA.

It also regenerates other antioxidants, such as vitamin E, enhancing their effectiveness.

Immune System Support

Vitamin C plays a critical role in supporting the immune system.

It enhances the function of various immune cells, including white blood cells, which help defend the body against pathogens.

Vitamin C promotes the production and activity of immune system components, such as antibodies and cytokines, which are involved in immune responses.

It also aids in the proper functioning of the skin’s barrier function, acting as a defense against pathogens.

Iron Absorption

Another important function of vitamin C is its ability to enhance the absorption of non-heme iron from plant-based sources.

Non-heme iron is not as readily absorbed as heme iron found in animal-based foods. Vitamin C forms a complex with non-heme iron, converting it into a more easily absorbable form.

This interaction increases the uptake of iron from the intestines into the bloodstream, supporting optimal iron levels and helping prevent iron deficiency anemia.

Neurotransmitter Synthesis

Vitamin C plays a role in the synthesis of certain neurotransmitters, including norepinephrine and serotonin.

These neurotransmitters are involved in mood regulation, stress response, and cognitive function.

Vitamin C helps convert dopamine to norepinephrine and tryptophan to serotonin, supporting proper neurotransmitter balance and function.

Wound Healing

Vitamin C is crucial for the process of wound healing. It aids in the production of collagen, which forms the framework for new tissue growth.

Vitamin C also supports the synthesis of new blood vessels necessary for delivering oxygen and nutrients to the wound site.

Additionally, it enhances the function of immune cells involved in tissue repair, promoting efficient wound healing and reducing the risk of infection.

Protection against Chronic Diseases

Adequate vitamin C intake has been associated with a lower risk of various chronic diseases, including cardiovascular disease, certain types of cancer, and age-related macular degeneration.

As an antioxidant, vitamin C helps reduce oxidative stress and inflammation, both of which contribute to the development of chronic diseases.

Its ability to regenerate other antioxidants further enhances its protective effects.

Recommended Dietary Allowance (RDA) of Vitamin C

The recommended daily intake of vitamin C varies depending on age, sex, and life stage.

For most adults, the RDA is around 75-90 milligrams per day, while pregnant and breastfeeding women may require slightly higher amounts.

However, it’s important to note that individual needs may vary based on factors such as health conditions, stress, and lifestyle choices.

Vegan and Animal Sources of Vitamin C

Vegan/vegetarian sources

Vitamin C is found abundantly in various fruits and vegetables, making it accessible to both vegans and non-vegans.

Citrus fruits like oranges and grapefruits, strawberries, kiwi, papaya, and mangoes are excellent vegan sources.

Among vegetables, bell peppers, broccoli, Brussels sprouts, and leafy greens such as spinach and kale are rich in vitamin C.

Animal sources

For non-vegans, certain animal sources like liver and other organ meats also contain vitamin C, although the levels are lower compared to plant-based sources.

Non-Genetic Factors that Affect Vitamin C Absorption

Several factors can influence the absorption of vitamin C.

Smoking, alcohol consumption, certain medications like aspirin and oral contraceptives, and medical conditions such as gastrointestinal disorders may decrease vitamin C levels in the body.

Additionally, cooking and storage methods can affect the vitamin C content in food, as it is sensitive to heat and oxygen exposure.

Genetic Factors that Affect Vitamin C Absorption

Genetic variations can influence the absorption and utilization of vitamin C in the body.

These variations often involve specific genes that are responsible for transporting and metabolizing vitamin C.

Understanding the genetic factors that affect vitamin C absorption can shed light on individual differences in vitamin C requirements and help optimize dietary recommendations.

Here are some key genetic factors that play a role in vitamin C absorption:

SLC23A1 and SLC23A2 Genes

The SLC23A1 and SLC23A2 genes encode proteins called sodium-dependent vitamin C transporters (SVCTs), which are responsible for transporting vitamin C into cells.

Variations in these genes can affect the efficiency of vitamin C absorption.

Certain single nucleotide polymorphisms (SNPs) in the SLC23A1 gene, such as rs6596473 and rs33972313, have been associated with altered vitamin C levels in the blood.

These variations may influence the activity of the SVCT1 transporter and affect vitamin C uptake in specific tissues.

Similarly, SNPs in the SLC23A2 gene, including rs33972313 and rs6053005, have been linked to variations in plasma vitamin C levels.

These genetic variations can impact the activity of the SVCT2 transporter, affecting the absorption and distribution of vitamin C in the body.

Check your 23andMe, Ancestry DNA raw data for SLC23A1 and SLC23A2 gene variants

GSTT1 and GSTM1 Genes

Glutathione S-transferases (GSTs) are enzymes involved in the metabolism of various compounds, including vitamin C.

The GSTT1 and GSTM1 genes encode two important GST enzymes.

Certain individuals may carry genetic variations that result in the absence (null genotype) of GSTT1 or GSTM1 enzymes.

Studies have suggested that individuals with the GSTT1 null genotype may have lower plasma and tissue vitamin C levels, potentially indicating reduced vitamin C absorption or altered metabolism.

Check your 23andMe, AncestryDNA raw data for GSTT1 and GSTM1 gene variants

Other Genetic Variations

Additional genetic variations in genes related to vitamin C metabolism and antioxidant defense mechanisms may also impact an individual’s response to vitamin C intake.

For example, variations in the SOD2 (superoxide dismutase 2) gene, which encodes an antioxidant enzyme, have been associated with variations in plasma vitamin C levels.

It’s important to note that the influence of these genetic variations on vitamin C absorption and metabolism can be complex and may vary among individuals and populations.

Multiple genes, each with different variations, can collectively contribute to the overall genetic influence on vitamin C absorption.

Understanding an individual’s genetic profile related to vitamin C absorption may have implications for personalized nutrition recommendations.

Genetic testing and interpretation by healthcare professionals or genetic counselors can provide valuable insights into an individual’s unique genetic factors and help tailor dietary strategies to optimize vitamin C absorption and utilization.

Here’s an SNP table showcasing some of the genetic variations associated with vitamin C absorption and metabolism. You can upload your DNA raw data here and check which variations you have.

Gene	SNP Variation	Function/Impact
SLC23A1	rs6596473	Associated with altered vitamin C levels
SLC23A1	rs33972313	Affects the activity of the SVCT1 transporter
SLC23A2	rs33972313	Linked to variations in plasma vitamin C levels
SLC23A2	rs6053005	Influences activity of SVCT2 transporter
GSTT1	Null genotype	Potentially lower plasma and tissue vitamin C
GSTM1	Null genotype	Potential impact on vitamin C metabolism
SOD2	Various variations	Associated with variations in plasma vitamin C

Vitamin C Deficiency

Vitamin C deficiency can result from a diet lacking in vitamin C-rich foods, limited food access, certain health conditions that impair absorption, and smoking, which increases vitamin C requirements.

Effects of vitamin C deficiency: Scurvy

Inadequate intake of vitamin C can lead to deficiency, which manifests as scurvy. This condition is characterized by fatigue, weakness, joint pain, impaired wound healing, gum disease, and skin problems.

Takeaways

Vitamin C is an essential nutrient with a rich history and multifaceted functions in the body.

Its impact on collagen synthesis, immune function, antioxidant defense, and iron absorption underscores its significance for overall health.

By understanding the recommended intake, sources, and factors influencing absorption, individuals can ensure adequate vitamin C levels and mitigate the risks of deficiency.

References

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2. Schleicher RL, Carroll MD, Ford ES, Lacher DA. Serum vitamin C and the prevalence of vitamin C deficiency in the United States: 2003-2004 National Health and Nutrition Examination Survey (NHANES). Am J Clin Nutr. 2009;90(5):1252-1263. doi:10.3945/ajcn.2008.27016
3. Padayatty SJ, Katz A, Wang Y, et al. Vitamin C as an antioxidant: evaluation of its role in disease prevention. J Am Coll Nutr. 2003;22(1):18-35. doi:10.1080/07315724.2003.10719272
4. Lykkesfeldt J, Michels AJ, Frei B. Vitamin C. In: Erdman JW, Macdonald IA, Zeisel SH, eds. Present Knowledge in Nutrition. 11th ed. Wiley-Blackwell; 2018:313-327.
5. Wang Y, Mackenzie B, Tsukaguchi H, et al. Human vitamin C (L-ascorbic acid) transporter SVCT1. Biochem Biophys Res Commun. 2000;267(2):488-494. doi:10.1006/bbrc.1999.1986