A nucleic acid molecule selected from the group consisting of a) nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO: 1 or 3, or a complement thereof; b) nucleic acid molecule which encodes a polypeptide comprising the amino acid sequence of SEQ ID NO: 2 or 4, or a complement thereof; c) nucleic acid molecule comprising a nucleotide sequence which is at least 75 % identical to the entire nucleotide sequence of SEQ ID NO: 1, or a complement thereof wherein said nucleic acid molecule encodes a fatty acid desaturase protein having an activity of catalyzing the formation of a double bond at position ω3, Δ12 and Δ15 of the fatty acid; d) a nucleic acid molecule encoding a polypeptide comprising an amino acid sequence which is at least 80 % identical to the amino acid sequence of SEQ ID NO: 2 wherein said nucleic acid molecule encodes a fatty acid desaturase protein having an activity of catalyzing the formation of a double bond at position ω3, Δ12 and Δ15 of the fatty acid; e) a nucleic acid molecule comprising a nucleotide sequence which is at least 95 % identical to the entire nucleotide sequence of SEQ ID NO: 3, or a complement thereof, wherein said nucleic acid molecule encodes a fatty acid desaturase protein having an activity of catalyzing the formation of a double bond at position Δ12 of the fatty acid, and f) a nucleic acid molecule encoding a polypeptide comprising an amino acid sequence which is at least 95 % identical to the amino acid sequence of SEQ ID NO: 4 wherein said nucleic acid molecule encodes a fatty acid desaturase protein having an activity of catalyzing the formation of a double bond at position Δ12 of the fatty acid. a) nucleic acid molecule comprising the nucleotide sequence of SEQ ID NO: 1 or 3, or a complement thereof; b) nucleic acid molecule which encodes a polypeptide comprising the amino acid sequence of SEQ ID NO: 2 or 4, or a complement thereof; c) nucleic acid molecule comprising a nucleotide sequence which is at least 75 % identical to the entire nucleotide sequence of SEQ ID NO: 1, or a complement thereof wherein said nucleic acid molecule encodes a fatty acid desaturase protein having an activity of catalyzing the formation of a double bond at position ω3, Δ12 and Δ15 of the fatty acid; d) a nucleic acid molecule encoding a polypeptide comprising an amino acid sequence which is at least 80 % identical to the amino acid sequence of SEQ ID NO: 2 wherein said nucleic acid molecule encodes a fatty acid desaturase protein having an activity of catalyzing the formation of a double bond at position ω3, Δ12 and Δ15 of the fatty acid; e) a nucleic acid molecule comprising a nucleotide sequence which is at least 95 % identical to the entire nucleotide sequence of SEQ ID NO: 3, or a complement thereof, wherein said nucleic acid molecule encodes a fatty acid desaturase protein having an activity of catalyzing the formation of a double bond at position Δ12 of the fatty acid, and f) a nucleic acid molecule encoding a polypeptide comprising an amino acid sequence which is at least 95 % identical to the amino acid sequence of SEQ ID NO: 4 wherein said nucleic acid molecule encodes a fatty acid desaturase protein having an activity of catalyzing the formation of a double bond at position Δ12 of the fatty acid.