The Fate of Major Royal Jelly Proteins during Proteolytic Digestion in the Human Gastrointestinal Tract

Royal jelly (RJ) is a beehive product with a complex composition, major royal jelly proteins (MRJPs) being the most abundant proteins. Cell culture and animal studies suggest various biological activities for the full-length/native MRJPs. In the field of apitherapy, it is assumed that MRJPs can positively affect human health. However, whenever RJ is administered orally, the availability for assimilation in the gastrointestinal tract is a prerequisite for MRJPs to have any effect on humans. We here show that MRJPs vary in resistance to pepsin digestion with MRJP2 being most stable and still present as full-length protein after 24 h of digestion. In the intestinal phase, using trypsin and chymotrypsin, MRJPs are rapidly digested with MRJP2 again showing longest stability (40 min), suggesting that MRJPs can reach the small intestine as full-length proteins but then have to be resorbed quickly if full-length proteins are to fulfill any biological activity.