Phytanic acid is a branched-chain fatty acid that is primarily derived from the diet, particularly from animal fats and certain plant sources. It is formed from the breakdown of chlorophyll in plants and is found in foods like dairy products and certain fish. The body metabolizes phytanic acid through a specific pathway involving the enzyme alpha-oxidation. In humans, excessive accumulation of phytanic acid can lead to a rare genetic disorder known as Refsum disease. This condition affects the nervous system and can cause symptoms such as vision problems and hearing loss. Proper metabolism of phytanic acid is essential for maintaining overall health and preventing such disorders.