Retinyl palmitate

Retinyl palmitate is an ester of retinol (vitamin A) and palmitic acid, with formula C36H60O2. It is the most abundant form of vitamin A in the human body and plays a crucial role in various biological functions.

Chemistry

Retinyl palmitate is a yellow, crystalline solid with a characteristic odor. It is insoluble in water but soluble in fats and oils. It is stable under ordinary conditions but decomposes under light or when heated to high temperatures.

Biosynthesis

In the human body, retinyl palmitate is synthesized from retinol and palmitic acid in a reaction catalyzed by the enzyme lethithin retinol acyltransferase (LRAT). This process occurs primarily in the liver, where the majority of the body's vitamin A is stored.

Biological functions

Retinyl palmitate plays a crucial role in vision. It is converted into retinal in the retina, which combines with the protein opsin to form rhodopsin, the light-sensitive pigment necessary for night vision.

In addition to its role in vision, retinyl palmitate is also involved in cell growth and differentiation, immune function, and reproduction. It is essential for the maintenance of the skin and mucous membranes, and for the growth and development of bones.

Health effects

Retinyl palmitate is generally considered safe when consumed in amounts typically found in foods. However, excessive intake can lead to vitamin A toxicity, which can cause a range of symptoms including dizziness, nausea, hair loss, and skin irritation.

There is some controversy over the safety of retinyl palmitate when applied to the skin. Some studies have suggested that it may increase the risk of skin cancer when exposed to sunlight, but these findings are not universally accepted and further research is needed.

See also

• Vitamin A
• Retinol
• Palmitic acid
• Retinal
• Rhodopsin