The ENRGISE (ENabling Reduction of Low-Grade Inflammation in SEniors) Pilot Study

Inclusion Criteria: * Men and women age \>70 years * Self-reported difficulty walking ¼ of a mile or climbing a flight of stairs * Walking speed \<1 meters per second and \>0.44 meters per second on the 4 meter walk at usual pace. A walking speed of \<0.44 meters per second would not be compatible with completing the 400 meter walk in 15 minutes. (In the pilot phase we explore the feasibility of recruiting at least 50% of participants who have a baseline walking speed of \<0.80 meters per second and \>0.44 meters per second) * Able to complete the 400 meter walk test within 15 minutes without sitting or the help of another person and without a walker, a cane is allowed * Blood level IL-6 \>2.5 pg/ml and \<30 pg/ml. * Willingness to be randomized to the intervention groups Exclusion Criteria: * Failure or inability to provide informed consent * Lives in a nursing home; persons living in assisted or independent housing are not excluded * Self-reported inability to walk one block * Significant cognitive impairment, defined as a known diagnosis of dementia, or a Mini-Mental State Exam (MMSE) score \<24 (\<23 for racial/ethnic minorities or participants with less than 9 years of education) * Unable to communicate because of severe hearing loss or speech disorder * Neurological conditions that are causing impaired muscle function or mobility (may include stroke with residual paresis, paralysis, neuropathy, Parkinson disease, or multiple sclerosis) * Severe rheumatologic or orthopedic diseases, e.g., awaiting joint replacement, known active inflammatory or autoimmune disease (e.g. rheumatoid arthritis, lupus, Crohn's disease, HIV) * Terminal illness with life expectancy less than 12 months * Severe pulmonary disease, requiring either steroid pills or injections * Other significant co-morbid disease that in the opinion of the field center PI would impair ability to participate in the trial, e.g. renal failure on hemodialysis, severe psychiatric disorder (e.g. bipolar, schizophrenia), excessive alcohol use (\>14 drinks per week); drug addiction; treatment for cancer (radiation or chemotherapy) within the past 1 year; or other conditions * Lives outside of the study site or is planning to move out of the area in next 1 year or leave the area for \>3 months during the next year * Exclusion criteria that apply only to those who receive losartan: * Intolerance or allergy to Angiotensin II Receptor Blockers (ARBs) * Known bilateral renal artery stenosis or liver cirrhosis * Hypotension Systolic Blood Pressure\<110 or Diastolic Blood Pressure\<60 mmHg * Serum potassium ≥5.0 mEq/L * Use of lithium salts * eGFR \<15 * Congestive heart failure with ejection fraction \< 40% * Exclusion criteria that apply only to those who receive ω-3: * Intolerance or allergy to ω-3 or fish/shellfish * Fatty fish intake \>2 servings per week on average * History of paroxysmal or persistent atrial fibrillation * To maintain blinding, those who are not eligible to receive any active treatment (ω-3 or losartan) are excluded Temporary exclusion criteria * Myocardial infarction, coronary artery bypass grafting (CABG), or valve replacement within past 6 months; * Pulmonary embolism or deep venous thrombosis within past 6 months; * Uncontrolled diabetes with recent weight loss, diabetic coma, or frequent insulin reactions; * Stroke, hip fracture, hip or knee replacement, or spinal surgery within past 4 months; * Physical therapy for gait, balance, or other lower extremity training within the past 2 months; * Severe hypertension, e.g., Systolic Blood Pressure \> 200, or Diastolic Blood Pressure\> 110 mmHg; * Hemoglobin \<10 g/dL * Participation in another intervention trial within 3 months; participation in an observational study may be permitted; * Current smoking (within 6 months), * Acute infection (urinary, respiratory, other) or hospitalization within 1 month * Exclusion criteria that apply only to those who receive losartan: * Use of Angiotensin-Converting Enzyme Inhibitor (ACEI), Angiotensin II Receptor Blocker (ARB) within 2 months * Use of aliskiren within 2 months in patients with type 2 diabetes or renal impairment with Estimated Glomerular Filtration Rate (eGFR)\<60 * Use of potassium sparing diuretics, other medications with potassium sparing properties (such as but not limited to spironolactone or eplerenone) potassium supplements, and salt substitutes containing potassium within 1 week * Transaminases \>twice upper limit of normal to exclude participants with impaired liver function * Exclusion criteria that apply only to those who receive ω-3: * Use of ω-3 within 2 months