Effects of rumenic acid rich conjugated linoleic acid supplementation on cognitive function and handgrip performance in older men and women

• 6 wk. of rumenic acid rich (RAR) CLA supplementation had no effect on grip strength or fatigue in older adults.
• 6 wk. of RAR CLA supplementation had no effect on cognitive function in older women.
• 6 wk. of RAR CLA supplementation had a potential effect on cognitive function in older men.
• The effects of RAR CLA on hand joint discomfort were inconclusive in men and women.

The purpose of this study was to investigate the effects of 8 weeks at 6 g per day of RAR CLA versus placebo on cognitive function and handgrip performance in older men and women. Sixty-five (43 women, 22 men) participants (mean ± SD; age = 72.4 ± 5.9 yrs; BMI = 26.6 ± 4.2 kg·m− 2) were randomly assigned to a RAR CLA (n = 30: 10 men, 20 women) or placebo (PLA; high oleic sunflower oil; n = 35: 12 men, 23 women) group in double-blind fashion and consumed 6 g·d− 1 of their allocated supplement for 8 weeks. Before (Visit 1) and after supplementation (Visit 2), subjects completed the Serial Sevens Subtraction Test (S7), Trail Making Test Part A (TMA) and Part B (TMB), and Rey's Auditory Verbal Learning Test (RAVLT) to measure cognitive function. The RAVLT included 5, 15-item auditory word recalls (R1–5), an interference word recall (RB), a 6th word recall (R6), and a 15-item visual word recognition trial (RR). For handgrip performance, subjects completed maximal voluntary isometric handgrip strength (MVIC) testing before (MVICPRE) and after (MVICPOST) a handgrip fatigue test at 50% MVICPRE. Hand joint discomfort was measured during MVICPRE, MVICPOST, and the handgrip fatigue test. There were no treatment differences (p > 0.05) for handgrip strength, handgrip fatigue, or cognitive function as measured by the Trail Making Test and Serial Seven's Subtraction Test in men or women. However, RAR CLA supplementation improved cognitive function as indicated by the RAVLT R5 in men. A qualitative examination of the mean change scores suggested that, compared to PLA, RAR CLA supplementation was associated with a small improvement in joint discomfort in both men and women. Longer-term studies are needed to more fully understand the potential impact of RAR CLA on cognitive function and hand joint discomfort in older adults, particularly in those with lower cognitive function.