The Impact of Fish Oil Supplementation on Muscle Growth in Older Men

4 week n-3 PUFA supplementation will enhance daily muscle protein synthesis rates in older men on a standardized diet.

Before and after 4 weeks of n-3 PUFA supplementation

The experimental trial consists of two 5-d phases separated by 4 weeks of supplementation. Muscle protein synthesis will be determined during the last 2 d of each 5-d phase. For each phase, dietary intake will be controlled to provide an energy balanced diet containing 1.0 g of protein per kg body weight per day equally distributed over breakfast, lunch, and dinner. Participants will be instructed to refrain from vigorous-intensity physical activity (running, fast cycling, competitive sports, carrying heavy loads, etc.) and refrain from alcohol consumption for 3 d prior to and during the 2 d of measuring muscle protein synthesis. Participants will wear an accelerometer to monitor physical activity on the day before and the 2 d of measuring muscle protein synthesis. On day 3, a blood and saliva sample as well as muscle biopsy will be obtained in the fasted state and participants will then consume 150 mL deuterated water (D2O). The subsequent day (day 4), another saliva sample and muscle biopsy will be obtained to assess body water and muscle protein deuterium enrichments. An oral glucose tolerance test (OGTT) will be performed to assess insulin sensitivity. 48 h after D2O consumption, a saliva sample and the third muscle biopsy will be obtained to determine muscle protein synthesis rates.



On day 6, daily n-3 PUFA supplementation will be initiated. Participants will consume 5 g of n-3 PUFA-enriched fish oil capsules per day containing 3.5 g EPA and 0.9 g DHA. One blood sample per week will be obtained to assess blood lipid composition and plasma markers of inflammatory state. After 4 weeks of supplementation, the 5-d phase will be repeated.