High omega-6 in cooking oils interferes with vegetable omega-3

Posted: April 23, 2012

Study:	Docosahexaenoic acid synthesis from alpha-linolenic acid is inhibited by diets high in polyunsaturated fatty acids Cite Gibson R, Neumann M, Lien E, Boyd K, Tu W. Docosahexaenoic acid synthesis from alpha-linolenic acid is inhibited by diets high in polyunsaturated fatty acids. Prostaglandins, Leukotrienes and Essential Fatty Acids. Elsevier BV; 2013; 88:139-146 10.1016/j.plefa.2012.04.003
Publication:	Prostaglandins, Leukotrienes and Essential Fatty Acids, April 2012

Omega-6 can interfere with benefits of omega-3

A low dietary omega-6 to omega-3 fatty acid ratio is associated with reduced breast cancer risk. Now a new study has reported that the high omega-6 content of vegetable oils may interfere with the potentially beneficial effects of the most common vegetable omega-3 fat, alpha-linolenic acid, which is found in walnuts.

The omega-3 fatty acid alpha-linolenic acid is converted in the body to the omega-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid. These are the omega-3 fats found in abundance in fatty fish and which appear to protect against breast cancer. However, note that dietary alpha-linolenic acid above a certain threshold level results in no additional increases in circulating docosahexaenoic acid levels in both animals and humans.

The study referenced at the beginning of this article was designed to investigate the influence of the omega-6 fatty acid linoleic acid on the conversion of alpha-linolenic acid to eicosapentaenoic acid and docosahexaenoic acid. Linolenic acid is found in abundance in the omega-6 oils listed above. To conduct the study, the authors evaluated various combinations of dietary alpha-linolenic acid and linoleic acid in rats. The rats were fed one of 54 diets for three weeks. The diets varied in the percentage of energy (calories) provided by linoleic acid (0.07-17.1%) and alpha-linolenic acid (0.02-12.1%) by manipulating both the fat content and ratio of vegetable oils.

The peak circulating docosahexaenoic acid (>8% of total fatty acids) was produced by a narrow dietary range of 1 to 3% of calories from alpha-linolenic acid and 1-2% calories from linoleic acid. Circulating docosahexaenoic acid was suppressed to basal levels (approximately 2% of total fatty acids) at dietary intakes of total polyunsaturated fatty acids (alpha-linolenic acid plus linoleic acid) at levels above 3% of total calories.

The authors conclude that it is possible to enhance the docosahexaenoic acid status of rats fed diets containing alpha-linolenic acid as the only source of omega-3 fatty acids but only when the level of dietary polyunsaturated fatty acids is low.

Please see our article on how to optimize your breast cancer diet for information on what to eat during all stages of treatment and recovery.

Selected breast cancer studies

Dietary polyunsaturated fatty acids and breast cancer risk in Chinese women: A prospective cohort study Cite
Murff HJ, Shu X, Li H, Yang G, Wu X, Cai H, et al. Dietary polyunsaturated fatty acids and breast cancer risk in Chinese women: A prospective cohort study. International Journal of Cancer. Wiley; 2010; 128:1434-1441 10.1002/ijc.25703
Marine Fatty Acid Intake Is Associated with Breast Cancer Prognosis Cite
Patterson RE, Flatt SW, Newman VA, Natarajan L, Rock CL, Thomson CA, et al. Marine Fatty Acid Intake Is Associated with Breast Cancer Prognosis. The Journal of Nutrition. Oxford University Press (OUP); 2010; 141:201-206 10.3945/jn.110.128777
Omega-3 Fatty Acids for Prevention of Breast Cancer: an Update and the State of the Science Cite
Iyengar NM, Hudis CA, Gucalp A. Omega-3 Fatty Acids for Prevention of Breast Cancer: an Update and the State of the Science. Current Breast Cancer Reports. Springer Science and Business Media LLC; 2013; 5:247-254 10.1007/s12609-013-0112-1
Abstract 229: Omega-3 fattyacids strongly induce apoptosis in human breast cancer cells in vitro and in vivo via formation of reactive oxygen species and caspase 8 activation Cite
Wang P, Kang K, Yamabe N, Fukui M, Jay T, Zhu BT. Abstract 229: Omega-3 fattyacids strongly induce apoptosis in human breast cancer cells in vitro and in vivo via formation of reactive oxygen species and caspase 8 activation. Cellular and Molecular Biology. American Association for Cancer Research; 2010; 10.1158/1538-7445.am10-229
Dietary intakes of ω-6 and ω-3 polyunsaturated fatty acids and the risk of breast cancer Cite
Thiébaut AC, Chajès V, Gerber M, Boutron-Ruault M, Joulin V, Lenoir G, et al. Dietary intakes of ω-6 and ω-3 polyunsaturated fatty acids and the risk of breast cancer. International Journal of Cancer. Wiley; 2009; 124:924-931 10.1002/ijc.23980
Frequency and Type of Seafood Consumed Influence Plasma (n-3) Fatty Acid Concentrations Cite
Chung H, Nettleton JA, Lemaitre RN, Barr RG, Tsai MY, Tracy RP, et al. Frequency and Type of Seafood Consumed Influence Plasma (n-3) Fatty Acid Concentrations. The Journal of Nutrition. Oxford University Press (OUP); 2008; 138:2422-2427 10.3945/jn.108.089631
Suppression of Implanted MDA-MB 231 Human Breast Cancer Growth in Nude Mice by Dietary Walnut Cite
Hardman WE, Ion G. Suppression of Implanted MDA-MB 231 Human Breast Cancer Growth in Nude Mice by Dietary Walnut. Nutrition and Cancer. Informa UK Limited; 2008; 60:666-674 10.1080/01635580802065302
Dietary (n-3)/(n-6) Fatty Acid Ratio: Possible Relationship to Premenopausal but Not Postmenopausal Breast Cancer Risk in U.S. Women Cite
Goodstine SL, Zheng T, Holford TR, Ward BA, Carter D, Owens PH, et al. Dietary (n-3)/(n-6) Fatty Acid Ratio: Possible Relationship to Premenopausal but Not Postmenopausal Breast Cancer Risk in U.S. Women. The Journal of Nutrition. Oxford University Press (OUP); 2003; 133:1409-1414 10.1093/jn/133.5.1409
N-3 and N-6 fatty acids in breast adipose tissue and relative risk of breast cancer in a case-control study in Tours, France Cite
Maillard V, Bougnoux P, Ferrari P, Jourdan M, Pinault M, Lavillonnière F, et al. N-3 and N-6 fatty acids in breast adipose tissue and relative risk of breast cancer in a case-control study in Tours, France. International Journal of Cancer. Wiley; 2001; 98:78-83 10.1002/ijc.10130
Long-Chain n-3-to-n-6 Polyunsaturated Fatty Acid Ratios in Breast Adipose Tissue From Women With and Without Breast Cancer Cite
Bagga D, Anders KH, Wang H, Glaspy JA. Long-Chain n-3-to-n-6 Polyunsaturated Fatty Acid Ratios in Breast Adipose Tissue From Women With and Without Breast Cancer. Nutrition and Cancer. Informa UK Limited; 2002; 42:180-185 10.1207/s15327914nc422_5

Selected breast cancer studies

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