Effects of Omega-3 Fatty Acid Supplementation and Physical Training on Metabolic Health

The degree of insulin resistance in an individual can be monitored by several means including blood concentrations of insulin, triglycerides, HDL-C, and eventually glucose. In particular, the ratio of triglycerides to HDL-C reflects the severity of insulin resistance's impact on liver-mediated lipoprotein transport and may be a sensitive measure of early insulin resistance when fasting glucose levels are still in the normal range (compensated by higher output of insulin). High triglycerides and low HDL-C indicate poor metabolic health and increased risk of fatty liver and atherosclerotic cardiovascular diseases.

Two diet and lifestyle strategies that have shown therapeutic promise are 1) supplementation with omega-3 fatty acids and 2) aerobic exercise training. Omega-3 fatty acids can prevent the development of insulin resistance but have not been successful in reversing established insulin resistance. Importantly, omega-3 fatty acids are effective for improving the ratio of triglycerides to HDL-C in blood and reducing the amount of fat in the liver. Aerobic exercise has demonstrated greater success for reversing established insulin resistance, but it is not known if and to what degree supplementation with omega-3 fatty acids could potentiate its therapeutic efficacy and vice versa regarding dyslipidemia. Both omega-3 fatty acids and exercise lead to increased blood concentrations of beneficial oxygenated lipid compounds (termed oxylipins) that regulate inflammatory and metabolic processes (including insulin resistance) linked to the development of NAFL.

In preparation for studies of people in poorer metabolic health, the investigators will conduct a pilot and feasibility study of relatively inactive younger adults with low dietary intake of omega-3 fatty acids to assess whether increased aerobic physical activity combined with omega-3 supplementation leads to greater improvements in blood concentrations of triglycerides, HDL-C, and their ratio, as well as concentrations of oxylipins in the blood. The investigators will also assess whether a less studied omega-3 fatty acid, called DPA, may have effects above and beyond those conferred by EPA and DHA (which are concentrated in prescription omega-3 fatty acid products).