Nutritional evaluation of rapeseed protein compared to soy protein for quality, plasma amino acids, and nitrogen balance--a randomized cross-over intervention study in humans.

Background & Aims: Plant proteins such as rapeseed have received little attention for human nutrition due to their high level of antinutritive compounds. Today, newer technologies can eliminate such compounds. The present intervention study aimed to evaluate nutritional and physiological properties of two manufactured canola proteins with special focus on their bioavailability in humans.

Methods: 28 healthy male subjects (ø 25 years) consumed 30.0 g protein (canola protein isolate--CPI, canola protein hydrolyzate--CPH or soy protein isolate--SPI) in a randomized, double-blind, cross-over study. Blood samples were regularly drawn over the 8-h postprandial period and a 24-h urine sample was collected.

Results: True digestibility of the canola proteins determined in a separate rat assay showed 93.3% for CPI and 97.3% for CPH. In humans, consumption of either 30.0 g canola protein or soy protein mixed in a drink led to significant increases in plasma amino acids after 62.3 and 83.6 min, respectively. While the CPH produced an earlier response compared to CPI and SPI, total amino acid response (AUC for 8 h) was comparable between all interventions. The nitrogen balance between the three proteins tested showed no statistical differences.

Conclusions: High digestibility of rapeseed protein was found in rats. In humans, this is the first intervention study showing rapeseed protein (both isolate and hydrolyzate) as having a high nutritional quality and can be considered to be as efficient as soy protein for a postprandial amino acid response. This trial was registered at ClinicalTrials.gov Identifier: NCT01481584.