The purpose of this study is to determine whether omega-3 fatty acid supplementation influences muscle protein synthesis rates in young and older adults.

Loss of muscle mass is a normal consequence of aging. The decline in muscle mass is estimated to be 0.2-0.5% per year from 60 years old onwards in healthy subjects with the decline worsened by chronic illness, poor appetite and diet, and reduced physical activity in the elderly. Increased morbidity is demonstrable with as little as a 5% loss of muscle mass - therefore, treatments that can prevent or slow the progression of muscle loss with aging are much desired.

A major cause for loss of muscle mass in advanced age appears to be an impaired ability to stimulate the synthesis of muscle protein in response to increased levels of amino acids (the building blocks of proteins) and insulin as occurs after eating because of low-grade inflammation and insulin resistance in muscle of old persons. We propose that long-chain omega-3 polyunsaturated fatty acids (fish oil) slow the loss of muscle mass because fish oil has anti-inflammatory properties and increases the sensitivity of muscle protein synthesis to insulin and amino acids. We will test this by studying the effect of fish oil supplementation on the muscle protein synthesis process in young and older adults.

Inclusion Criteria:

• Body mass index (BMI) < 30 kg/m2;
• Age 18-45 yr; or
• Age 65-85 yr

Exclusion Criteria:

• Those taking medications known to affect substrate metabolism or medications that may confound the findings from our study (synthetic steroids, glucocorticoids etc.);
• Those with evidence of significant organ system dysfunction (e.g. diabetes mellitis, cirrhosis, hypo- or hyperthyroidism; hypertension);
• Body mass index > 30 kg/m2
• Age <18 yr, 45-65 yr or > 85 yr
• Those performing >1.5h of exercise/wk