acinar cell degranulation.178 A modest decrease in bicarbonate and enzyme output in response to secretin and caerulin (a CCK receptor agonist) in elderly subjects compared with their younger counterparts has been reported. However, secretin- and caerulin-mediated stimulation of sphincter of Oddi motor function and pancreatic bicarbonate, enzyme, and volume output were not significantly changed in individuals older than 60 years.179, 180 In contradistinction to human studies, animal models of pancreatic function do show significant effects of aging on trophic response to hormonal stimulation. Caerulin and secretin administration increased pancreatic weight, protein content, messenger RNA expression, enzyme concentrations, and polyamine concentrations in young and aged rats, but the magnitude of the responses was significantly greater in young rats.181 The pancreas of aged animals shows a diminished capacity to increase pancreatic lipase and amylase content in response to a high-fat or high-carbohydrate diet.182 Given the significant reserve capacity of the exocrine pancreas, the clinical significance of these observations to healthy aged individuals is questionable. Pancreatitis In about 75% of patients, acute pancreatitis does not progress beyond the stage of edema and fatty necrosis, and the disease has a mild, uncomplicated course. The incidence of acute pancreatitis in Western countries is about 10–20 cases per 100,000 per year. About half of these patients are older than 60 years, and the estimated incidence in the geriatric population is about 5–10 cases per 100,000 per year. Peak incidence in older patients varies in studies from ages 60–80 years. Little data are available for patients older than 80 years; therefore, the incidence may be underestimated in this oldest group. The prevalence is slightly higher among women, probably due to a higher incidence of gallstone-related pancreatitis. Gallstones are the most frequent etiologic factor in acute pancreatitis in the geriatric age group, being present in up to 60% of patients, with the remainder being idiopathic (25%) and other causes (surgery, drugs, trauma, and infections). In contrast, alcohol abuse is far more common in younger patients (30% vs 5% in patients older than 60 years). The mortality rate in the geriatric population is about 20%, which is twice that of the general population. Death in the elderly from pancreatitis is usually due to severe multiorgan failure. There are very little data in the literature specifically addressing the issue of chronic pancreatitis in the elderly; thus, diagnosis and management are currently based on guidelines for younger patients.183, 184 The incidence of pancreatic cancer is increasing, particularly in patients older than 65 years. Diagnosis is usually made late in the course of the disease, when curative resection is not an option. Older patients appear to have poor outcomes following surgery for pancreatic cancer. In one series of 273 patients evaluated between 1983 and 1995, 104 underwent surgical resection, with 47 patients aged 64–74 years and 19 older than 74 years.185 The highest morbidity and mortality from pancreatic resection was observed in the oldest patients (age older than 74 years), and median survival was only 11.4 months versus 25.1 months for patients aged 64–74 years. Aging and GI Immunity The elderly are relatively susceptible to infections that enter the body via the GI tract, and this raises the question of whether aging impairs