D-Ascorbic Acid vs. L-Ascorbic Acid

What's the Difference?

D-Ascorbic Acid and L-Ascorbic Acid are two forms of Vitamin C that differ in their molecular structure. D-Ascorbic Acid is the synthetic form of Vitamin C, while L-Ascorbic Acid is the natural form found in fruits and vegetables. The main difference between the two is their optical rotation. D-Ascorbic Acid has a positive optical rotation, while L-Ascorbic Acid has a negative optical rotation. This means that they rotate polarized light in opposite directions. In terms of their biological activity, L-Ascorbic Acid is the active form that is readily absorbed and utilized by the body, while D-Ascorbic Acid has limited bioavailability and may not provide the same health benefits. Overall, L-Ascorbic Acid is considered the superior form of Vitamin C for its natural origin and better absorption by the body.


AttributeD-Ascorbic AcidL-Ascorbic Acid
Chemical FormulaC6H8O6C6H8O6
Optical RotationPositive (+20.5°)Negative (-20.5°)
Biological ActivityAntioxidantAntioxidant
Common NameVitamin CVitamin C
Water SolubilityHighly solubleHighly soluble
StabilityRelatively unstable in heat and lightRelatively unstable in heat and light

Further Detail


Ascorbic acid, commonly known as vitamin C, is an essential nutrient for humans. It plays a crucial role in various physiological processes, including collagen synthesis, antioxidant defense, and immune function. However, it is important to note that there are two different forms of ascorbic acid: D-ascorbic acid and L-ascorbic acid. In this article, we will explore the attributes of both forms and discuss their similarities and differences.

D-Ascorbic Acid

D-ascorbic acid is the synthetic form of ascorbic acid. It is chemically identical to L-ascorbic acid but differs in its molecular structure. D-ascorbic acid is a stereoisomer of L-ascorbic acid, meaning that it has the same chemical formula but a different spatial arrangement of atoms. This difference in structure gives D-ascorbic acid distinct properties and characteristics.

One of the notable attributes of D-ascorbic acid is its stability. Unlike L-ascorbic acid, D-ascorbic acid is more resistant to oxidation and degradation. This stability makes D-ascorbic acid a preferred choice in certain applications where long shelf life is desired, such as in the formulation of cosmetic products.

Another important aspect of D-ascorbic acid is its bioavailability. Studies have shown that D-ascorbic acid is less readily absorbed by the human body compared to L-ascorbic acid. This reduced bioavailability may limit the effectiveness of D-ascorbic acid as a dietary supplement or therapeutic agent.

Despite its lower bioavailability, D-ascorbic acid still possesses antioxidant properties. It can scavenge free radicals and protect cells from oxidative damage. However, the overall antioxidant capacity of D-ascorbic acid may be lower than that of L-ascorbic acid due to its reduced absorption and utilization by the body.

In summary, D-ascorbic acid is a stable form of ascorbic acid with lower bioavailability compared to L-ascorbic acid. While it retains some antioxidant properties, its effectiveness as a dietary supplement or therapeutic agent may be limited.

L-Ascorbic Acid

L-ascorbic acid is the natural form of ascorbic acid found in various fruits and vegetables. It is the biologically active form of vitamin C and is readily utilized by the human body. L-ascorbic acid has a specific molecular structure that allows it to interact with enzymes and receptors in the body, facilitating its absorption and utilization.

One of the key attributes of L-ascorbic acid is its high bioavailability. When consumed orally, L-ascorbic acid is efficiently absorbed by the intestines and transported to various tissues and organs. This high bioavailability ensures that the body can readily access and utilize the vitamin C it needs for optimal health.

L-ascorbic acid is also known for its potent antioxidant properties. It can neutralize free radicals, which are highly reactive molecules that can cause cellular damage and contribute to the development of various diseases. By acting as an antioxidant, L-ascorbic acid helps protect cells and tissues from oxidative stress.

In addition to its antioxidant role, L-ascorbic acid is essential for collagen synthesis. Collagen is a structural protein that provides strength and elasticity to various tissues, including the skin, bones, and blood vessels. L-ascorbic acid plays a vital role in the enzymatic reactions required for collagen production, making it crucial for maintaining healthy connective tissues.

Overall, L-ascorbic acid is the preferred form of ascorbic acid due to its high bioavailability, potent antioxidant properties, and essential role in collagen synthesis. Its natural occurrence in fruits and vegetables makes it easily accessible through a balanced diet.


In conclusion, D-ascorbic acid and L-ascorbic acid are two forms of ascorbic acid with distinct attributes. While D-ascorbic acid offers stability and some antioxidant properties, its lower bioavailability may limit its effectiveness as a dietary supplement or therapeutic agent. On the other hand, L-ascorbic acid, the natural form of vitamin C, provides high bioavailability, potent antioxidant effects, and plays a crucial role in collagen synthesis. Therefore, when considering the attributes of D-ascorbic acid and L-ascorbic acid, it is evident that L-ascorbic acid is the preferred form for optimal health and well-being.

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