What is the difference between vitamin A and vitamin C?

January 3, 2026 •

4 min read

According to the World Health Organization, vitamin A deficiency is a leading cause of preventable blindness in children, while a lack of vitamin C can lead to scurvy. Despite both being essential vitamins, the key difference between vitamin A and vitamin C lies in their fundamental properties and distinct roles within the body.

Quick Summary

Vitamin A is fat-soluble, crucial for vision, and stored in the body, while vitamin C is water-soluble, necessary for collagen synthesis and acts as a powerful antioxidant.

Key Points

Solubility: Vitamin A is fat-soluble and stored in the body, while vitamin C is water-soluble and needs to be replenished regularly.
Primary Function: Vitamin A is essential for healthy vision, cell growth, and immune function.
Antioxidant Role: Vitamin C is a potent antioxidant that protects cells from free radical damage and is crucial for collagen production.
Deficiency Consequences: Vitamin A deficiency can cause night blindness, while chronic vitamin C deficiency leads to scurvy.
Toxicity Differences: Excessive intake of fat-soluble vitamin A can cause toxicity, whereas water-soluble vitamin C excess is generally flushed out.
Food Sources: Vitamin A comes from animal products and colorful plants, whereas vitamin C is primarily found in fruits and vegetables.

Understanding the Fundamentals: Fat-Soluble vs. Water-Soluble

At the most basic level, the primary distinction between vitamin A and vitamin C is their solubility, which dictates how they are absorbed, stored, and used by the body. Vitamin A is a fat-soluble vitamin, meaning it is dissolved in fat and absorbed with dietary lipids. Once absorbed, it is stored in the liver and fatty tissues, which means the body can build up a reserve. Because of this storage capacity, excessive intake can lead to toxicity (hypervitaminosis A). In contrast, vitamin C (ascorbic acid) is a water-soluble vitamin. It dissolves in water, and any excess is typically flushed out of the body via urine, making regular intake essential to prevent deficiency.

Diverse Roles in Bodily Functions

Beyond their solubility, these two vitamins perform very different, yet equally vital, roles in maintaining human health. Vitamin A is most famously known for its role in vision. It is a component of rhodopsin, a protein in the eyes that allows for vision in low light conditions. Deficiency can therefore lead to night blindness. Furthermore, vitamin A supports healthy skin, mucous membranes, immune function, and reproductive health.

Vitamin C, a potent antioxidant, protects the body's cells from damage caused by harmful free radicals, which are unstable molecules linked to various diseases and aging. It is also indispensable for the biosynthesis of collagen, a protein essential for the structure of skin, tendons, ligaments, and blood vessels. This function is critical for wound healing, maintaining healthy gums, and supporting overall connective tissue integrity. Vitamin C also enhances the absorption of non-heme iron, which is found in plant-based foods.

Dietary Sources and Daily Intake

The origins of these vitamins in our diet also differ significantly. Vitamin A can be consumed in two forms: preformed vitamin A (retinoids) from animal products and provitamin A carotenoids from plant sources. The body converts carotenoids, like beta-carotene, into active vitamin A. Vitamin C, on the other hand, cannot be synthesized by humans and must be obtained directly from the diet.

Key Food Sources

Vitamin A (Retinoids): Liver, eggs, milk, cheese, and oily fish.
Provitamin A (Carotenoids): Orange and yellow fruits and vegetables like carrots, sweet potatoes, cantaloupe, and spinach.
Vitamin C: Citrus fruits (oranges, grapefruit), kiwi, strawberries, bell peppers, broccoli, and tomatoes.

Comparison Table: Vitamin A vs. Vitamin C


Feature	Vitamin A	Vitamin C
Solubility	Fat-Soluble	Water-Soluble
Storage	Stored in the liver and fatty tissue	Not stored; excess is excreted via urine
Main Function	Vision, cell growth, immune support, reproduction	Antioxidant, collagen synthesis, immune function, iron absorption
Deficiency	Night blindness, dry skin (xerophthalmia), impaired immune function	Scurvy, weakened immune system, poor wound healing, bleeding gums
Toxicity Risk	High, from excessive intake of preformed vitamin A	Low, as excess is excreted
Primary Sources	Animal products (retinoids) and colorful plants (carotenoids)	Fruits and vegetables

Deficiency and Toxicity

Due to their differing storage mechanisms, the health consequences of inadequate or excessive intake also vary. A chronic and severe lack of vitamin A can lead to serious eye problems, including blindness, and compromised immune function. Toxicity, though rare in developed countries, can occur with excessive supplementation of preformed vitamin A and lead to symptoms such as nausea, dizziness, and even liver damage.

On the other hand, vitamin C deficiency can result in scurvy, though it is uncommon in modern diets. Scurvy is characterized by fatigue, weakness, joint pain, and swollen, bleeding gums due to defective collagen production. Since the body doesn't store vitamin C, there is a very low risk of toxicity from food sources. However, extremely high doses from supplements can cause gastrointestinal discomfort.

Conclusion

While both vitamin A and vitamin C are non-negotiable for good health, they are fundamentally distinct in their chemical properties and physiological roles. Vitamin A is a fat-soluble nutrient, stored for long-term use, and is critical for eyesight and cell growth. Vitamin C is water-soluble, requires regular replenishment, and functions as a powerful antioxidant and collagen builder. Understanding these differences is key to building a balanced diet that ensures adequate intake of both vital nutrients. You can find detailed dietary intake recommendations for both vitamins from the Office of Dietary Supplements at the National Institutes of Health.

Which vitamin is right for me and my skin?

When it comes to skin care, the roles of vitamins A and C also differ. Vitamin A, often in the form of retinoids, helps with cell turnover and fights visible signs of aging like wrinkles, while vitamin C acts as a protective antioxidant and promotes collagen synthesis for firmer, brighter skin. Both are beneficial and can be used in different capacities within a skincare routine.

Frequently Asked Questions

Neither is inherently better; both are essential for different functions. Vitamin A is vital for vision and growth, while vitamin C is critical for collagen formation and immune support. A balanced diet provides both, and supplementation depends on individual needs and deficiencies.

Yes, it is safe to take vitamin A and vitamin C together. They have different functions and do not interfere with each other's absorption or efficacy. In fact, vitamin C may help protect vitamin A from oxidative damage.

Both vitamins contribute to a healthy immune system. Vitamin C is a powerful antioxidant that protects immune cells, while vitamin A is crucial for the development and maintenance of epithelial tissues, which form a protective barrier against pathogens.

Both are beneficial. Vitamin A (often as retinoids) is known for promoting cell turnover and reducing wrinkles, while vitamin C is essential for collagen synthesis, helping to improve skin firmness and brightness.

A vitamin A deficiency can lead to night blindness as one of the earliest signs. If left untreated, it can progress to more serious eye conditions like xerophthalmia and can also weaken the immune system.

A severe and prolonged vitamin C deficiency can cause scurvy. Symptoms include fatigue, weakness, joint and muscle aches, easy bruising, bleeding gums, and poor wound healing.

Foods rich in vitamin A include liver, eggs, milk, carrots, and sweet potatoes. Vitamin C-rich foods include citrus fruits, berries, bell peppers, broccoli, and leafy greens.