Inclusion Criteria:  age: ≥55 and ≤80 years BMI: ≥25.0 and ≤39.9 kg/m2; normal glucose tolerance (fasting plasma glucose <100 mg/dl and plasma glucose 2 h after a 75 g glucose challenge <140 mg/d) (control group) or impaired glucose tolerance (plasma glucose 2 h after a 75 g glucose challenge ≥140 mg/dl) (intervention groups)  Exclusion Criteria:  age: <55 and >80 years BMI: <25.0 and >39.9 kg/m2 plasma glucose 2 h after a 75 g glucose challenge <140 mg/dl treatment for T2D, except for metformin regular structured high-intensity exercise >150 min total per week significant neurological or other organ system dysfunction (e.g., progressive neuromuscular disease, unstable angina, vasculitis, certain cardiopulmonary diseases, cancer that has been in remission for <5 years, dementia, allergies to the dietary supplement) or significant ambulatory impairments (e.g., limb amputations, being wheelchair-bound) use of certain medications that are incompatible with the study procedures (e.g., certain anticoagulants) or could confound the study outcomes (e.g., anabolic steroids, metronidazole, etc) alcohol use disorder as defined by the NIAAA or use of controlled substances or smoking >20 cigarettes per week regular consumption of fish oil supplements or >2 servings of fatty fish per week x) prisoners, and persons who are unable to grant voluntary informed consent.