In adult humans consuming a bovine whey protein concentrate, approximately 59% of IgG and IgM was detected by radial immunodiffusion from effluents from the jejunum, while 19% was detected in the ileum [202] . These estimates of digestion of immunoglobulin compare with estimates of digestion of milk proteins in adult humans which are approximately 42% complete at the end of the jejunum and 93% complete by the end of the ileum [203] , again underscoring the relative resistance of immunoglobulins to digestion in the gastrointestinal tract. Detectable immunoglobulin in stool samples of infants fed the same immune product accounted for 10% of the ingested immunoglobulin [58] . In adults fed a bovine immunoglobulin concentrate, fecal IgG was typically less than 4% of ingested dose [204] . Detectable IgG in the stool [204] , or ileal effluent samples of adults [205] , is not significantly increased by prior treatment with a proton pump inhibitor to reduce stomach acid production. However, encapsulation of the immunoglobulin product can significantly increase the IgG detectable in the stool [204] , although only low levels of IgG are detectable in the ileum of adults ingesting encapsulated immunoglobulin [205] . These studies suggest that degradation of immunoglobulins is occurring throughout the intestinal tract [202] .