What Is Vitamin C? Benefits, Sources & How It Works

If you've ever wondered "what is Vitamin C," you're asking about one of the most essential and most studied nutrients in human biology. Vitamin C — also known as ascorbic acid — is a water-soluble vitamin that the body cannot produce on its own due to a genetic mutation in the L-gulonolactone oxidase (GLO) gene. That means every milligram must come from food or supplementation.

Vitamin C is a potent antioxidant and a cofactor for many enzymes involved in biological functions including immune system support, collagen biosynthesis, carnitine and catecholamine metabolism, and dietary iron absorption. It exists in two main forms: ascorbic acid (AA) and dehydroascorbic acid (DHA), with the L-enantiomer (L-ascorbic acid) being the biologically active form in humans.

The best dietary sources of Vitamin C are fruits and vegetables — especially citrus fruits, red and green peppers, kiwifruit, broccoli, and strawberries. Because Vitamin C is water-soluble and heat-sensitive, up to 50 percent can be lost through cooking, so eating produce raw or lightly steamed helps maximize intake.

Understanding what is Vitamin C really means understanding how deeply it is woven into your body's daily operations. As an antioxidant, Vitamin C scavenges reactive oxygen species (ROS) in aqueous environments and may regenerate other antioxidants such as vitamin E. Research suggests it helps diminish lipid peroxidation and reduce biomarkers of oxidative damage.

Vitamin C is also essential for collagen biosynthesis — the protein required for wound healing, skin integrity, and the structural framework of blood vessels, bones, and cartilage. Without adequate Vitamin C, prolyl and lysyl hydroxylase enzymes cannot properly hydroxylate collagen precursors, which is the biochemical basis of scurvy's connective tissue breakdown.

On the immune front, research shows Vitamin C contributes to both innate and adaptive immunity. It supports epithelial barrier function against pathogens, enhances phagocytosis, promotes the differentiation and proliferation of B cells and T cells, normalizes cytokine production, and decreases histamine levels. Plasma concentrations of Vitamin C decline rapidly during viral infections, underscoring its active role in immune defense.

Vitamin C also enhances iron absorption from plant-based foods by reducing ferric iron (Fe³⁺) to the more absorbable ferrous form (Fe²⁺) in the gastrointestinal tract — a clinically relevant function for anyone relying on non-heme iron sources.

If you have questions about how Vitamin C fits into your own wellness routine, our naturopath is available for a free consultation.

The scientific literature on Vitamin C is vast. Here are some of the key areas where evidence is strongest:

Common Cold

A Cochrane review of 30 placebo-controlled trials involving over 11,000 participants found that regular Vitamin C supplementation does not reduce common cold incidence in the general population. However, it may modestly reduce cold duration — by about 8% in adults and 14% in children — and severity. The benefit appears more pronounced in people under severe physical stress, such as marathon runners and military personnel.

Immune Function

More than half a century of research has shown Vitamin C to be a crucial player in immune cell function, including antimicrobial and natural killer cell activities, lymphocyte proliferation, and chemotaxis. Mechanistic evidence is well-established; however, human clinical evidence demonstrating that supplementation above adequate intake meaningfully improves immunity in non-deficient individuals is limited.

Antioxidant Defense

Multiple human trials demonstrate that Vitamin C supplementation raises antioxidant capacity and reduces biomarkers of oxidative damage, though clinical endpoints such as disease prevention show more mixed results. The evidence base is substantial, mechanistically well-characterized, and supported by peer-reviewed systematic reviews.

Age-Related Macular Degeneration (AMD)

The AREDS and AREDS2 studies demonstrated that a supplement formula including 500 mg Vitamin C alongside vitamin E, zinc, and copper may reduce progression to advanced AMD by 25% over five years in some patients. This is one of the few nutritional supplements with demonstrated benefit in eye disease, though the effect cannot be attributed to Vitamin C alone.

Nature's Sunshine Vitamin C Time Release is designed to deliver Vitamin C's benefits throughout the day. Each tablet includes a special coating that slows absorption until the nutrients reach the intestines — an important design feature because intestinal absorption of ascorbic acid is dose-dependent, and absorption falls to about 50 percent or less at doses above 1 g/day. By releasing the nutrient gradually, a time-release format may help the body utilize more of each serving.

This formula blends ascorbic acid with a base of Rose hips extract, acerola extract, Rutin, Lemon bioflavonoids, and Hesperidin complex — a completely natural product with no sugar, starch, artificial colorings, or flavorings. It is also vegan and non-GMO.

The product highlights include supporting the immune system, fighting free radicals, nourishing the tissues, and assisting in the production of collagen.

Because the body cannot make or store Vitamin C, virtually everyone needs a steady daily supply. This product may be especially relevant for:

• Anyone seeking immune support — Vitamin C's role in immune cell function is one of the most well-documented in nutritional science.
• People looking for antioxidant defense — especially those concerned about environmental oxidative stress or wanting to support skin health through collagen synthesis.
• Individuals who eat limited fresh fruits and vegetables — cooking, freezing, and processing significantly reduce Vitamin C content in food.
• Those under physical stress — research suggests the benefits of regular Vitamin C supplementation on cold duration are more pronounced in people exposed to severe physical exertion.
• People who want plant-based support — this vegan, non-GMO formula is built on a base of whole-food extracts including Rose hips and acerola.

The RDA for Vitamin C is 90 mg/day for adult men and 75 mg/day for adult women, with smokers recommended to add 35 mg/day. The Tolerable Upper Intake Level (UL) is set at 2,000 mg/day for adults.

Take one tablet daily with a meal.

The time-release coating is designed to slow absorption until the nutrients reach the intestines, helping your body utilize Vitamin C gradually throughout the day rather than in a single burst.