Phytanic acid is a branched-chain fatty acid derived from the breakdown of chlorophyll in plants. It is primarily found in certain animal fats and dairy products, as well as in some green vegetables. The body can metabolize phytanic acid, but it requires specific enzymes to do so effectively. 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 mobility issues. Proper dietary management can help control phytanic acid levels in affected individuals.