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Krill oil improves cognitive function in healthy elderly men, study shows

Highlights

  • Randomized, double-blind, placebo-controlled trial involving healthy elderly men
  • Krill oil activates cognitive function based on fNIS and EEG findings
  • Effective dosage is 2 g/day (providing 193 mg/day EPA and 92 mg/day DHA)
  • Treatment is well tolerated

Summary

This randomized, double-blind, placebo-controlled trial was designed to investigate the effect of krill oil on cognitive function in healthy elderly men.

For this study, researchers enrolled 45 healthy men, aged 61-72 years, retired from the Japanese business sector. The participants were randomly assigned to one of three treatment groups for 12 weeks: 2,000 mg/day of sardine oil (491 mg/day EPA; 251 mg/day DHA), 2,000 mg/day of krill oil (193 mg/day EPA; 92 mg/day DHA) or 2,000 mg/day of MCT oil (placebo; free of EPA/DHA). The daily supplements were taken in divided doses with breakfast and dinner.

At baseline, week 6 and week 12, the researchers recorded changes in the oxyhemoglobin level in the cerebral cortex using near-infrared spectroscopy (fNIS) during memory and calculation tasks. During a working memory task, an electroen­cephalogram (EEG) was simultaneously administered to measure event-related potentials, including the P300 component, which is considered to reflect cognitive processing.

A food frequency survey was completed, and body weight, blood pressure, blood chemistry, plasma fatty acids including EPA and DHA, and urinalysis measurements were taken. The participants were also instructed to avoid an excessive intake of alcohol and food, to limit strenuous exercise, and to refrain from taking supplements that contained polyunsaturated fatty acids (PUFAs) during the study.

A total of 42 participants (42/45; 93%) completed the study. Two dropouts in the krill oil group were due to gastric pain; one dropout in the sardine oil group was due to dermatitis. None of the dropouts were judged to be directly related to ingestion of the supplements.

After 12 weeks, results indicate that both krill and sardine oil supplementation significantly (P<.05) increased the oxyhemoglobin level in the cerebral cortex compared to placebo during the working memory task. During the calculation task, only krill oil supplementation resulted in a significant (P<.05) increase in the oxyhemoglobin level compared to placebo.

The differential value for P300 latency in the krill oil group was significantly (P<.05) lower than that in the placebo group. The authors note that P300 latency reflects the rate of information processing and is prolonged with aging, suggesting krill oil expedites the information processing rate and may help reduce the age-related decline in  cerebral function or help maintain such function.

These findings indicate that supplementation with marine omega-3 fatty acids (2 g/day for 12 weeks), especially krill oil, activates cognitive function in the elderly. The authors attribute the superior cognitive benefits of krill oil over sardine oil to the difference in the chemical composition of the omega-3 fatty acids. In krill oil, the majority of fatty acids are incorporated into phosphatidylcholine. By contrast, the fatty acids in sardine oil are present as triglycerides.

Reference

Konagai C, Yanagimoto K, Hayamizu K, Han L, Tsuji T, Koga Y. Effects of krill oil containing n-3 polyunsaturated fatty acids in phospholipid form on human brain function: a randomized controlled trial in healthy elderly volunteers. Clin Interv Aging. 2013;8:1247-57.

PMID: 24098072