Krill oil shown to boost signaling pathway associated with muscle growth in study

By Hank Schultz

- Last updated on GMT

Krill oil boosts muscle growth signaling in study
A new pilot study has found that krill oil supplementation stimulates mTOR signaling in resistance-trained subjects, boosting its potential application as a sports nutrition ingredient.

According to the Journal of Cell Science​, the mTOR (or the mammalian target of rapamycin) signaling pathway integrates both intracellular and extracellular signals and serves as a central regulator of cell metabolism, growth, proliferation and survival. Discoveries that have been made over the last decade show that the mTOR pathway is activated during various cellular processes, such as insulin resistance or tumor formation, and is deregulated in human diseases such as cancer and type 2 diabetes.

Looking for mTOR effects

The new study, published in the Journal of Nutrition and Metabolism​, looked at krill oil supplementation in a double-blind, placebo-controlled study design. The researchers were investigating krill oil’s effect on mTOR signaling as a measure of how it affects muscle growth and recovery after resistance exercise.

The research team consisted of individuals associated with Avoca, a Rimfrost/Olympic Seafood AS subsidiary, two researchers from Increnovo, a Milwaukee-based contract research organization and a faculty member from the University of Wisconsin, Madison. One of the researchers, Dr Ralf Jäger, PhD of Increnovo, said the benefits of krill oil, and omega-3s in general, in aiding in the recovery from exercise is an area of continued study.

More research needed on effects of omega-3s on exercise

“In athletes, krill oil has been shown to improve post-exercise immune function (2 g/d for six weeks) and diminished post-exercise oxidative damage during recovery (1 g/d for six weeks); however, failed to improve exercise performance (cycling time trial and total run time in a 2,000 meter test),” ​Jäger told NutraIngredients-USA.

“The lack of performance benefits of krill oil supplementation in previous sports studies might have been based on a lack of an accompanying controlled challenging training protocol optimizing krill oil’s benefits on recovery, as muscle recovery after an exercise bout might influence training adaptations,”​ he said.

Fish oil supplementation in combination with or without resistance exercise resulted in increased strength and functional ability in older adults; however, potential long-term benefits of omega-3 PUFA supplementation on muscle hypertrophy and performance in young healthy subjects undergoing a controlled resistance training program are currently unknown,”​ he said.

Dr Jäger is also a co-holder of a patent ​on the use of krill oil extract to increase muscle growth.

Possible effects of astaxanthin inclusion

The researchers noted that in addition to the beneficial molecules of EPA and DHA, krill oil also includes the potent antioxidant carotenoid astaxanthin. This molecule has been shown to have some beneficial effects in attenuating muscle breakdown during resistance exercise and has shown to boost performance in a time trial test with cyclists.

The researchers did admit that the amount of astaxanthin contained in the krill oil dosage used is far below what has been studied in the past (0.5 grams as opposed to 4 grams). But they speculated that the phospholipid nature of krill oil might boost the absorption of the astaxanthin in the material as it does for the EPA and DHA that is present.

Study details

The researchers recruited 21 healthy, resistance trained males 18 to 30 yeas of age. Eighteen subjects, evenly divided between the krill oil and placebo groups, completed the eight week test. The krill oil group received 3 grams of krill oil (supplied by Rimfrost) daily, whereas the others received olive oil placebos. The krill oil dosage delivered 240 mg of DHA and 393 mg of EPA as well as the small amount of astaxanthin. 

The subjects participated in a specified weight training regime that included strength (higher weight, lower reps) and endurance (lower weight, higher reps) phases. Power output, lean body mass and other markers were measured.

A cultured tissue assay comparing the mTOR signaling activation effects of krill oil to soy-derived phosphatidylcholine also formed part of the publication.

“The main findings of the study were compared to baseline, krill oil increased exercise-induced gains in lean body mass. Also, while krill oil consists of 90+% choline containing phospholipids, and soy-derived phosphatidylcholine is inactive, krill oil is able to activate the key muscle building pathway, the mTOR pathway,”​ Jäger said. 

Source: Journal of Nutrition and Metabolism
Volume 2018, Article ID 7625981,
The Effects of Krill Oil on mTOR Signaling and Resistance Exercise: A Pilot Study
Authors: Georges J, Sharp MH, Lowery PR, et al.

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