IgA is found in saliva and acts as a major barrier preventing pathogens entering the body via the oral route. As such, the level of secretory IgA has been found to correlate with resistance to some viral infections. According to two clinical studies, BC (20 g/day) increases salivary IgA levels, a factor that could feasibly increase the host's resistance to infection (Crooks et al 2006, Mero et al 2002). In the study by Crooks et © 2007 Elsevier Australia
a I, secretory IgA levels were elevated by 79% after 12 weeks of BC administration in athletes. The presence of numerous immune factors in BC further provides a theoretical basis for its use; however, little clinical investigation has been conducted to confirm its preventive effects.
In 2003, results of a randomised, double-blind, placebo-controlled trial were published, providing some support for its use as a prophylactic agent (Brinkworth & Buckley 2003). The study of 174 physically active young males compared colostrum powder (60 g/day; intact™, Numico Research Australia Pty Ltd) to concentrated whey powder over 8 weeks. During the test period, a significantly fewer proportion of subjects taking BC reported URTI symptoms than the control group; however, BC did not alter the duration of URTI once infection was established. Due to the self-reporting method used in this study, results should be viewed as preliminary and require further confirmation.
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