Vegetarian Diet and Exocrine Pancreatic Function Using Fecal Tests: The Authors’ Reply

Abstract

In our preliminary study (1), we demonstrated that vegetarian diet alters the assessment of exocrine pancreatic function by tests of chymotrypsin activity and elastase-1 concentration, with a decreased specificity for both tests. Possible explanations for these findings have been discussed including the higher fiber intake. In addition, these indirect pancreatic function tests offer the most interesting possibility for the assessment of pancreatic adaptation to human nutrition that we are continuing to study with a more detailed analysis of the food components. The influence of soybean trypsin inhibitors has been studied both in animal and human models. Raw soybean flour containing trypsin inhibitors caused pronounced growth of the pancreas and stimulated pancreatic enzyme secretion (2). Intraduodenal instillation of raw soybeans almost abolished chymotrypsin and severely reduced (50%) tryptic activity. However, immunoreactive tryptic and chymotryptic material was increased (3). In our study (1), fecal chymotrypsin was measured by the colorimetric method (4), while pancreatic elastase-1 was determined by an immunoenzymatic assay (5). Application of soybean trypsin inhibitors therefore could influence colorimetric measurement of chymotrypsin resulting in reduced chymotrypsin activity. The immunoenzymatic assessment of fecal elastase-1, however, should not be influenced. In the case of a soy-based vegetarian diet, we would rather expect an increase of fecal elastase-1 concentration than a decrease. Dietary fiber has been shown to affect pancreatic enzyme activity in vivo and in vitro (6,7). However, the immunoenzymatic method determines fecal elastase-1 concentrations and not activity. A modified colonic microflora could produce a higher breakdown of chymotrypsin (8). Fecal chymotrypsin activity in randomly collected stool specimen of cystic fibrosis patients poorly correlates to pancreatic output measured by direct stimulation by secretin-pancreozymin test (9). In contrast, a high correlation between direct pancreatic function tests and fecal elastase-1 concentrations were found in cystic fibrosis patients and healthy subjects (10,11). The enzyme is highly specific for the pancreas and is not degraded during the intestinal passage like chymotrypsin (12). Moreover, the enzyme is stable in room temperature for 1 week (10). Therefore, bacterial degradation of pancreatic elastase-1 is rather unlikely. Selenium is an essential trace element in humans and animals, and the importance to human health is undebated (13). In severe deficiency in animals, reproductive impairment, growth depression, myopathy of heart and skeletal muscle and even pancreatic atrophy have been observed. Intake varies considerably between European countries (from 70 μg per day in Switzerland to 11 μg in Poland). Healthy Swedish vegetarians, and especially vegans, have a lower dietary selenium intake 10 to 12 μg compared to 27 to 40 μg in age-matched healthy omnivores (14). Possible involvement of selenoproteins in the human pancreatic secretory process cannot be excluded but has also not been documented. In addition, the functional consequence of a reduced intake is unclear (15). Jaroslaw Walkowiak Karl-Heinz Herzig *Poznan University of Medical Sciences †Agricultural University of Poznan, Poznan, Poland ‡A.I. Virtanen Institute for Molecular Sciences, Kuopio, Finland