Vitamin C: A Comprehensive Guide to Its Health Benefits

“Vitamin C or ascorbic acid is a powerful antioxidant, supports immune health, collagen formation, and overall vitality, promoting a robust and resilient well-being”.

Prologue	Science	Benefits	Sources
Dosage	Recommendations

 

 

Introduction

The discovery of vitamin C is linked with scurvy, a nutritional deficiency condition resulting in the weakening of collagenous structures, and the importance of citrus fruits in treating and preventing it^[1,2,3]. Efforts to understand and prevent scurvy eventually led to the discovery and recognition of the importance of vitamin C in human nutrition and overall health ^[4,5].

Vitamin C is one of the essential micronutrients that supports normal metabolism and participates in many life-sustaining biochemical reactions in humans^[6,7]. Its significance is accentuated since humans cannot synthesize vitamin C because of the loss of key enzyme that is involved in its biosynthesis^[2]. It is for this reason that humans need a regular and consistent intake of vitamin C through dietary intake.

In this article, we will explore vitamin C, delving into its numerous health benefits, sources, and the science behind its remarkable impact on the body.

The Basics Science of Vitamin C

Vitamin C, chemically known as ascorbic acid (AA), has powerful reducing properties. It is a powerful antioxidant and an important enzyme cofactor^[9,10,11]. It falls in the category of water-soluble vitamins^[7,12]. The absorption of vitamin primarily occurs in the small intestine’s distal part (duodenum, jejunum, and ileum)^[13].

Unlike fat-soluble vitamins that can be stored in the body for extended periods, vitamin C, being water-soluble, is not extensively stored in significant amounts in the body^[14]. The human body does not have a specialized storage system for vitamin C. However, the body does store vitamin C in some tissues, but a limited amount in the adrenal glands, pituitary, brain, eyes, and white blood cells^[13,15].

Vitamin C has a relatively short half-life in the body and is eliminated with an elimination half-life of 10–12 hours^[16]. Only at very low plasma levels, due to low intake, is the reported half-life of vitamin C between 8 and 40 days^{[17,18,19,20]}. Because of its high elimination and low retention, especially at high doses, and no specialized storage organ, a consistent dietary replenishment of vitamin C is crucial for maintaining sustained levels in the body. The rapid excretion limits its harmful effect and makes it safe in normal doses^[7].

Vitamin C is sensitive to heat and light and can lose it biological activity at high temperature and high light exposure^[7,21]. Cooking can reduce the vitamin C content in foods, so consuming lightly cooked vegetables may help retain more of the vitamin^[22].

Health Benefits of Vitamin C

Strong Antioxidant

Free radicals are unstable molecules generated during biochemical reactions that can cause cellular damage and contribute to various diseases. Vitamin C  is a potent antioxidant^[11]. By scavenging these free radicals, Vitamin C helps neutralize free radicals and protect cells from oxidative stress^[2,3,23].

Immune System Support

Vitamin C is known for its immune-enhancing and immune-modulating properties^[24]. Scientific studies suggest that vitamin C has several beneficial effects on cellular functions of both the innate and adaptive immune system^[3,25]. Vitamin C contributes to immune defense by supporting various cellular functions of leukocytes or white blood cells (neutrophils, monocytes), including lymphocytes (B, T and NK cells) which are crucial component of our defense system against pathogenic infections^{[24,26,27,28]}.

Studies suggest that regular intake of vitamin C may reduce the severity of common colds and its duration as well^{[25,29,30,31]}. It can serve as an adjunctive or supplementary treatment in conjunction with primary therapy to alleviate common cold symptoms^[3,32,33].

Collagen Synthesis and Wound Healing

In humans, collagen is the most abundant protein, accounting for approximately one-third of the body's protein content^[34]. It is a major component of skin and various connective tissues i.e., blood vessels, bones, tendons, and ligaments, cartilage, providing them with strength, structure, and elasticity^[35].

The maintenance and healing of connective tissues is dependent on the capacity of collagen synthesis and its cross-linking^[36]. Vitamin C plays a pivotal role in the synthesis of collagen and the healing of connective tissues^{[2,6,37,38,39,40]}.

Iron Absorption

In human food, iron is supplied in two forms, heme, and non-heme. The former supplied through animal-based food, while the latter is predominantly supplied in plant-based food. Heme iron is more readily absorbed  whereas nonheme iron is absorbed less efficiently^[41,42].

Accumulating evidence suggests that vitamin C enhances the absorption of non-heme iron from plant-based foods in the gut^[43,44,45]. Consuming vitamin C-rich foods alongside iron-rich plant sources can help individuals following vegetarian or vegan diets meet their iron requirements more effectively^[46].

Sources of Vitamin C

Fruit, particularly of the citrus family, and vegetables are the rich and natural source of vitamin C^[47,48]. A diverse and balanced diet that includes a variety of fruits and vegetables is the best way to ensure an ample supply of vitamin C. Consuming five varied servings of fruits and vegetables a day can provide more than 200 mg of vitamin C^[8].

Citrus and other Fruits: Oranges, grapefruits, lemons, and limes are rich sources of vitamin C. Enjoying a variety of citrus fruits is an easy way to meet your daily vitamin C needs. Kiwi  is a powerhouse of vitamin C, providing more than the recommended daily intake in just one serving^[49,50]. Strawberries are not only delicious but also packed with vitamin C and other antioxidants^[8,51].

Vegetables: Red and green bell peppers and chilies (esp. green) are excellent sources of vitamin C^[48,52]. Cruciferous vegetables like broccoli and Brussels sprouts are not only rich in fiber but also contain significant amounts of vitamin C^[8,53].

Supplements: It's important to note that vitamin C is water-soluble  and its retention if body is limited. Vitamin C supplements are available for those who may have difficulty meeting their requirements through diet alone^[54,55,56].

Recommended Dosage

According to the intake recommendations by Food and Nutrition Board (FNB) at National Academies, the Recommended Dietary Allowance (RDA) for vitamin C varies based on factors such as age, sex, and life stage^[47]. For most normal non-smoking adults, 90 and 70 milligrams per day is recommended for male and females, respectively. Pregnant and breastfeeding women may have slightly higher RDAs (80 to 120 mg/day)^[8,47].

The maximum daily intake or Upper Tolerable Limit (UL) for vitamin C for most adults (19+), from all the dietary intakes, is typically set around 2,000 milligrams per day^[47]. This amount is safe and is unlikely to pose any risk of adverse health effects for almost all individuals in the general population.

Individual needs for vitamin C may vary depending on factors like age, smoking, illness, stress, and certain medical conditions can influence vitamin C requirements^[8,57,58,59].

It's important to note that vitamin C is water-soluble and not stored in the body for extended periods. Thus, to prevent hypovitaminosis, a consistent daily intake is necessary to maintain adequate levels^[7,12,13].

While vitamin C supplementation is generally safe and well-tolerated within recommended levels, excessive doses however are not recommended for normal individuals^[59,60]. It's advisable to consult with a healthcare provider before initiating high-dose supplementation, particularly if there are concerns about potential interactions with medications or existing health conditions.

Conclusion

Vitamin C is a versatile and indispensable nutrient with a broad spectrum of health benefits. From acting as a potent antioxidant supporting the immune system to promoting skin health, its influence on the body is profound. Ensuring a regular intake of Vitamin C through a balanced diet that includes a variety of fruits and vegetables can contribute to overall health and well-being.

As with any nutrient, moderation is key, and consulting with a healthcare professional can help tailor dietary recommendations to individual needs.

Embrace the vibrancy of Vitamin C, and let it be a cornerstone of your healthier and resilient life.

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