Phytanic acid metabolism in health and disease

► 3-Methyl branched-chain fatty acids can be oxidized by α- and/or ω-oxidation. ► The mechanism, enzymology and subcellular localization of α-oxidation has largely be resolved. ► The peroxisomal membrane is a semi-permeable membrane allowing the transport of some, but not all substrates and products of α-oxidation. ► The enzymology of the phytanic acid ω-oxidation has largely been resolved. ► Stimulation of ω-oxidation by bezafibrate reduces the accumulation of phytanic acid in Refsum mice.