Phytanic acid

Overview

Structure of phytanic acid

Phytanic acid is a branched-chain fatty acid that is derived from the phytol side chain of chlorophyll. It is a saturated 20-carbon fatty acid with three methyl branches, making it a complex lipid molecule. Phytanic acid is not synthesized by the human body and must be obtained through dietary sources, primarily from the consumption of ruminant animal fats and dairy products.

Biochemistry

Phytanic acid is metabolized in the body through a process known as alpha-oxidation, which occurs in the peroxisome. This process is necessary because the branched structure of phytanic acid prevents it from undergoing the more common beta-oxidation pathway. The initial step in alpha-oxidation involves the conversion of phytanic acid to pristanic acid, which can then enter the beta-oxidation pathway to be further broken down into acetyl-CoA units.

Clinical significance

Phytanic acid is involved in Refsum disease

The accumulation of phytanic acid in the body is associated with a rare genetic disorder known as Refsum disease. This condition is caused by a deficiency in the enzyme phytanoyl-CoA hydroxylase, which is responsible for the alpha-oxidation of phytanic acid. Symptoms of Refsum disease include peripheral neuropathy, retinitis pigmentosa, cerebellar ataxia, and hearing loss. Management of the disease involves dietary restriction of phytanic acid by avoiding foods rich in this fatty acid.

Dietary sources

Phytanic acid is primarily found in the fat of ruminant animals such as cows and sheep, as well as in dairy products. This is because ruminants have a unique digestive system that allows them to convert chlorophyll from plant material into phytanic acid. As a result, foods such as beef, lamb, and dairy products like milk, cheese, and butter are significant sources of phytanic acid in the human diet.

Related pages

• Fatty acid metabolism
• Peroxisome
• Refsum disease
• Chlorophyll