Keratin protein bars and shakes may increase lean body mass, study on cyclists suggests

By Adi Menayang

- Last updated on GMT

Getty Images / Dragon Images
Getty Images / Dragon Images
Supplementation of keratin—a protein derived from poultry feather—may help increase lean body mass, researchers in New Zealand suggest.

Researchers from the School of Sport and Exercise at Massey University in New Zealand looked at the effects of soluble keratin supplementation compared to casein on physically active trained cyclists.

They compared soluble keratin’s effect on body composition, blood and cardiorespiratory variables, and cycling performance.

“Total body mass and percentage body fat did not change significantly,” ​they reported in their study​, published recently in the Journal of the International Society of Sports Nutrition​.

They also found no significant change in performance measures.

“However, a significantly greater increase in bone-free lean mass occurred with keratin compared to casein,” ​they added.

“Keratin may provide a more effective alternative to casein as a protein supplement in those who wish to increase lean body mass in conjunction with an aerobic exercise program,”​ like older adults, athletes, and persons in the recovery phase of a medical intervention, they wrote.

Keratin supplier Keraplast Research LTD, a specialist in keratin for topical hair and skin care products, partially funded the study together with the university’s Doctoral Research Dissemination Grant.

Study details

Keraplast’s website lists functional keratin ingredients for use in the topical beauty space, but researchers explored its dietary supplementation potential because “[its]favorable amino acid profile suggests the potential for use as a protein source and ergogenic aid for endurance athletes, following treatment to increase digestibility,” ​they argued in their study.

Researchers recruited 15 trained male cyclists aged 18 to 50 years. The criteria for inclusion included regular participation in endurance cycling exercise at least three times per week in the three months prior to commencement of the study.

The study’s crossover design meant that one group of study participants start the supplementation period with keratin while the other with casein for four weeks, before both groups go on an eight-week ‘washout’ period and then supplementing with the other ingredient for another four weeks.

Because casein and keratin differ in their protein fractions, the amount of supplement given in each intervention was calculated as providing the desired protein content, rather than as a certain amount of supplement.

Participants consumed the two supplements in the form of protein bars (of two different flavors), and the remainder of the protein requirement in powder form, which they mixed with water to form a drink.

At the beginning and end of each trial period, participants visited a clinic so researchers could collect body composition measurements as well as cycling performance changes. During the three weeks preceding, and throughout the duration of each trial, participants were asked to refrain from taking any form of supplement, including other protein powders or bars.

Source: Journal of the International Society of Sports Nutrition
Published online,
“The effect of chronic soluble keratin supplementation in physically active individuals on body composition, blood parameters and cycling performance”
Authors: Emma M. Crum, et al.

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