Fish Oils and Metabolic Syndrome

Metabolic syndrome is defined by symptoms such as abdominal obesity, dyslipidemia, and high blood sugar levels. “MS prevalence has increased significantly over the last years, reaching pandemic proportions worldwide” (4). In 2019 the Mayo clinic reported that up to one-third of American adults have metabolic syndrome, and this number is expected to increase. Metabolic syndrome is associated with obesity and insulin resistance.

Risk factors for metabolic syndrome:

  • Age
  • Obesity
  • Diabetes
  • Inactive Lifestyle

Studies have found that a diet including fish oil rich in omega-3 (EPA and DHA) can help address the causes of metabolic syndrome and might improve some obesity-associated metabolic syndrome features such as insulin resistance, hypertension, and dyslipidemia.

Despite the various benefits of fish oil, your patients likely are not getting enough in their diet. Even when including patients who use supplements, most American’s do not consume enough of these essential fatty acids (1).

What does the research say?

  • A meta-analysis of fish oil studies concluded that “among participants with metabolic disorders, fish oil supplementation could reduce the risk of insulin resistance by 47%” (4).
  • A study of 39 adults compared the effects of a lifestyle modification program with and without fish oil supplementation of 3g of fish oil per day (3). The fish oil group showed a significant decrease in waist circumference and reduction in metabolic syndrome markers. Both groups showed a decrease in blood triglycerides but only the fish oil group saw a reduction in blood glucose. The authors contribute a 29% resolution of metabolic syndrome to omega-3 supplementation.
  • A long term study followed 3504 individuals over a period of 6 years. At the beginning of the study period, all individuals were free of metabolic syndrome and known cardiovascular disease. Compared with those eating fish less than once per week, men who ate fish daily were 40% as likely to develop metabolic syndrome. “Similarly, metabolic syndrome risk was halved for men in the top decile of n-3 fatty acid intake when compared with those in the bottom decile” (6). The results for women were similar but less significant.

Various animal studies have also shown impressive results:

  • In rats fed high fat diets, replacing linoleic acid – a source of omega 6 – with omega 3 fatty acids prevented the development of insulin resistance, especially in liver and skeletal muscle (2).
  • A diet rich in omega 3 showed increased rate of glycolysis and increased glycogensis compared to a diet rich in omega 6 (2).
  • Supplementing with EPA/DHA was shown to help prevent obesity, dyslipidemia, and insulin resistance while improving glucose tolerance and restoring insulin sensitivity (2).

Potential mechanisms could explain the association between fish oil supplements and insulin sensitivity. Nutraceuticals and functional food ingredients are beneficial to insulin resistance and dyslipidemia through decreasing 7a–hydroxylase, 3-hydroxy-3-methylglutaryl-CoA, very low-density lipoprotein. Lee et al. also suggested that polyunsaturated fatty acid-based dietary supplements could improve biomarkers related metabolic syndrome. It is well recognized that Insulin sensitivity/resistance is associated with metabolic syndrome tightly. The main signs of metabolic syndrome are visceral obesity, hypertension, evaluated fasting serum triglyceride level, impaired fasting glucose, insulin resistance, or pre-diabetes. Adiposity increases the risk of diabetes and reduces insulin sensitivity through the fat tissue release inflammatory markers, insulin-like growth factors (IGF), sCD163 and adipokines. Thus, it is biologically plausible that fish oil supplementation could improve insulin sensitivity among people with metabolic disorders.” (4)


1. Papanikolaou, Y., Brooks, J., Reider, C., & Fulgoni, V. L., 3rd (2014). U.S. adults are not meeting recommended levels for fish and omega-3 fatty acid intake: results of an analysis using observational data from NHANES 2003-2008. Nutrition journal, 13, 31.

2. Poudyal, H., Panchal, S. K., Diwan, V., & Brown, L. (2011). Omega-3 fatty acids and metabolic syndrome: effects and emerging mechanisms of action. Progress in lipid research, 50(4), 372–387.

3. Lidiana de Camargo Talon, Erick Prado de Oliveira, Fernando Moreto, Kátia Cristina Portero-McLellan, & Roberto Carlos Burini. (2015) Omega-3 fatty acids supplementation decreases metabolic syndrome prevalence after lifestyle modification program. Journal of Functional Foods,Volume 19, Part B, Pages 922-928,ISSN 1756-4646, Retrieved from:

4. Gao, H., Geng, T., Huang, T., & Zhao, Q. (2017). Fish oil supplementation and insulin sensitivity: a systematic review and meta-analysis. Lipids in health and disease, 16(1), 131.

5. Souza, D. R., Pieri, B., Comim, V. H., Marques, S. O., Luciano, T. F., Rodrigues, M. S., & De Souza, C. T. (2020). Fish oil reduces subclinical inflammation, insulin resistance, and atherogenic factors in overweight/obese type 2 diabetes mellitus patients: A pre-post pilot study. Journal of diabetes and its complications, 34(5), 107553.

6. Baik, I., Abbott, R. D., Curb, J. D., & Shin, C. (2010). Intake of fish and n-3 fatty acids and future risk of metabolic syndrome. Journal of the American Dietetic Association, 110(7), 1018–1026.

7. Lorente-Cebrián, S., Costa, A. G., Navas-Carretero, S., Zabala, M., Martínez, J. A., & Moreno-Aliaga, M. J. (2013). Role of omega-3 fatty acids in obesity, metabolic syndrome, and cardiovascular diseases: a review of the evidence. Journal of physiology and biochemistry, 69(3), 633–651.