Vitamin C Deficiency: Causes, Signs & Nutritional Support

Vitamin C deficiency occurs when the body does not receive enough ascorbic acid — a water-soluble vitamin it cannot produce or store on its own. Because humans lack a functional L-gulonolactone oxidase (GLO) gene, we depend entirely on dietary intake or supplementation to maintain adequate levels. Hypovitaminosis C is clinically defined by a plasma ascorbic acid level below 23 µmol/L (approximately 0.4 mg/dL), while a plasma level of 50 µmol/L (~0.9 mg/dL) is widely considered the threshold for adequacy.

Vitamin C deficiency matters because ascorbic acid is a critical component of both basic body-building functions and disease prevention. It is needed for the growth and repair of tissues in all parts of the body, serves as an essential cofactor for collagen biosynthesis, supports immune defense, enhances iron absorption, and functions as a potent water-soluble antioxidant.

Prolonged Vitamin C deficiency leads to scurvy — a condition that causes fatigue, inflammation of the gums, small red or purple spots on the skin, joint pain, poor wound healing, corkscrew hairs, depression, swollen and bleeding gums, loosening or loss of teeth, and anemia. Overt deficiency symptoms occur only if Vitamin C intake falls below approximately 10 mg/day for many weeks, but scurvy is fatal if left untreated. Though extremely rare today thanks to improved food supplies and supplements, Vitamin C deficiency can still occur in populations with poor diets.

Vitamin C is involved in over 300 metabolic functions in the body. Its biological activity stems from its structure as a potent reducing agent, enabling it to donate electrons and participate in a wide range of enzymatic and antioxidant processes.

Collagen and Connective Tissue

Vitamin C is essential for the production of collagen, the most abundant protein in the human body and the building block of connective tissues. It acts as a cofactor for prolyl hydroxylase and lysyl hydroxylase — the enzymes that hydroxylate proline and lysine in procollagen, required for stable collagen triple-helix formation. Without adequate Vitamin C, these enzymes cannot properly hydroxylate collagen precursors, leading to structurally defective collagen. This failure of collagen synthesis is the biochemical basis of scurvy's hallmark connective tissue breakdown.

Immune System Function

Vitamin C contributes to immune defense by supporting various cellular functions of both the innate and adaptive immune system. It helps maintain epithelial barrier function against pathogens, enhances the differentiation and proliferation of B cells and T cells, promotes phagocytosis, normalizes cytokine production, and decreases histamine levels. Vitamin C is also an immune system booster that increases white blood cell production.

Antioxidant Defense

As a water-soluble antioxidant, Vitamin C directly scavenges reactive oxygen species (ROS) in aqueous cellular compartments and plasma. It can also regenerate the antioxidant form of vitamin E at membrane interfaces. Research indicates that Vitamin C and vitamin E work synergistically, having a greater effect together than separately.

Iron Absorption

Vitamin C improves the absorption of iron from plant-based foods by reducing ferric iron (Fe³⁺) to ferrous iron (Fe²⁺) in the gastrointestinal lumen — a form more readily absorbed by intestinal mucosal cells. This is clinically relevant in the management of non-heme iron deficiency anemia.

Additional Functions

Vitamin C is vital for the healing of wounds and the repair and maintenance of cartilage, bones, and teeth. During any kind of healing process — whether from infection, injury, disease, or surgery — the body uses large amounts of Vitamin C. It also plays important roles in the production of adrenal steroids and catecholamines, metabolism of amino acids, and tissue growth and repair.

Vitamin C deficiency can affect anyone whose diet consistently lacks adequate fruits and vegetables. Because the body cannot store Vitamin C, daily intake is essential. The Recommended Dietary Allowance (RDA) is 90 mg/day for adult men and 75 mg/day for adult women. Pregnant and lactating women are recommended to increase their intake to 85 mg and 120 mg per day, respectively.

Smokers are at elevated risk and are recommended to increase their Vitamin C consumption by 35 mg per day, regardless of sex. Populations with limited access to fresh produce, individuals on highly restrictive diets, and people recovering from surgery or illness — when the body uses large amounts of Vitamin C — may also be particularly vulnerable.

The best food sources of Vitamin C include citrus fruits, red and green peppers, kiwifruit, broccoli, strawberries, and Brussels sprouts. However, Vitamin C is water-soluble and susceptible to heat — cooking can reduce Vitamin C content significantly, with up to 50 percent lost through boiling. To maximize dietary intake, eating fruits and vegetables raw or lightly steamed is advisable.

Mean intakes from food and beverages are 105.2 mg/day for adult males and 83.6 mg/day for adult females in the U.S., meeting the RDA for most nonsmoking adults. When dietary intake is insufficient, supplementation may help maintain adequate levels.

Take one (1) tablet, one (1) to three (3) times daily with meals, or as directed by a health care professional. Store in a cool, dry place and away from direct light.

Each tablet provides 1,000 mg of Vitamin C (as ascorbic acid) and 50 mg of Rose hips. This product is gluten free, dairy free, soy free, and grain free.

It is worth noting that high doses of Vitamin C (amounts greater than 2,000 mg/day) are not recommended, as they may lead to gastrointestinal discomfort including stomach upset and diarrhea, and, although rarely, kidney stones. The Tolerable Upper Intake Level (UL) set by the Institute of Medicine for adults is 2,000 mg per day. People with hemochromatosis, G6PD deficiency, or a predisposition to kidney stones should consult a healthcare professional before supplementing with high-dose Vitamin C.