A recombinant plant cell, algal cell or fungal cell comprising a first exogenous polynucleotide encoding a cyclopropane fatty acid synthetase (CPFAS) and a second exogenous polynucleotide encoding an enzyme having fatty acid acyltransferase activity, said cell comprising extractable oil which contains dihydrosterculic acid and/or a fatty acid derivative thereof, wherein said fatty acid derivative comprises a cyclo-propyl group or is a branched chain fatty acid having a methyl derivative as the branch, and/or the derivative comprises 2, 4 or 6 more carbons in the acyl chain when compared to DHS, wherein the DHS or fatty acid derivative thereof is esterified in triacylglycerols in the cell, the first and second polynucleotides are each operably linked to one or more promoters that are capable of directing expression of the polynucleotide in the cell, and wherein the cell has one or more of the following features, i) at least 3% of the total fatty acid in the extractable oil in the cell is DHS and/or the fatty acid derivative thereof, ii) the CPFAS converts oleic acid to DHS in the cell with a conversion efficiency of at least 45%, iii) the ratio of oleic acid to DHS and/or fatty acid derivative thereof in the extractable oil in the cell is less than 2:1, or iv) the CPFAS comprises amino acids having a sequence as provided in any one of SEQ ID NOs:21 to 28, or an amino acid sequence which is at least 60% identical to any one or more of SEQ ID NOs:21 to 28, wherein the CPFAS is no longer than 600 amino acids in length. a first exogenous polynucleotide encoding a cyclopropane fatty acid synthetase (CPFAS) and a second exogenous polynucleotide encoding an enzyme having fatty acid acyltransferase activity, said cell comprising extractable oil which contains dihydrosterculic acid and/or a fatty acid derivative thereof, wherein said fatty acid derivative comprises a cyclo-propyl group or is a branched chain fatty acid having a methyl derivative as the branch, and/or the derivative comprises 2, 4 or 6 more carbons in the acyl chain when compared to DHS, wherein the DHS or fatty acid derivative thereof is esterified in triacylglycerols in the cell, the first and second polynucleotides are each operably linked to one or more promoters that are capable of directing expression of the polynucleotide in the cell, and wherein the cell has one or more of the following features, i) at least 3% of the total fatty acid in the extractable oil in the cell is DHS and/or the fatty acid derivative thereof, ii) the CPFAS converts oleic acid to DHS in the cell with a conversion efficiency of at least 45%, iii) the ratio of oleic acid to DHS and/or fatty acid derivative thereof in the extractable oil in the cell is less than 2:1, or iv) the CPFAS comprises amino acids having a sequence as provided in any one of SEQ ID NOs:21 to 28, or an amino acid sequence which is at least 60% identical to any one or more of SEQ ID NOs:21 to 28, wherein the CPFAS is no longer than 600 amino acids in length. i) at least 3% of the total fatty acid in the extractable oil in the cell is DHS and/or the fatty acid derivative thereof, ii) the CPFAS converts oleic acid to DHS in the cell with a conversion efficiency of at least 45%, iii) the ratio of oleic acid to DHS and/or fatty acid derivative thereof in the extractable oil in the cell is less than 2:1, or iv) the CPFAS comprises amino acids having a sequence as provided in any one of SEQ ID NOs:21 to 28, or an amino acid sequence which is at least 60% identical to any one or more of SEQ ID NOs:21 to 28, wherein the CPFAS is no longer than 600 amino acids in length.