title: Effect of dietary calcium on the colonic luminal environment.
abstract: Dietary supplementation with calcium may prevent the development of colorectal cancer. This mechanism may be related to fatty acid and bile salt chelation in the small bowel forming non-toxic calcium-soap compounds. Calcium may also act locally or systemically on the colonic mucosa. Faecal concentrations of free fatty acids and free bile acids were measured in 17 Sprague-Dawley rats (weighing 472 (39 g)) whose daily calcium intake had been trebled by enriching the chow and adding calcium lactate (24 g/l) to the drinking water. Mean (SEM) faecal concentrations of free bile acids were 33% less than in 19 controls (1.23 (0.15) v 1.82 (0.20) mg/g; p less than 0.001), whereas free fatty acid concentrations were 117% higher (14.68 (3.59) v 6.76 (2.41) mg/g; p less than 0.02). The 'direct' effect of calcium was assessed by organ culture of rat colonic explants in three different concentrations of calcium. Crypt cell production rate (measured by a stathmokinetic technique), which was (mean (SEM)) 4.80 (0.23) cells/crypt/h in control medium (Ca2+ = 2.14 mmol/l), fell by 43% when calcium concentration was doubled (p less than 0.05) and by a further 43% when the concentration was trebled (p less than 0.02). Calcium binds free fatty acids but not free bile acids intraluminally. Calcium has a direct antitropic action on colonic crypts.
authors.affiliation: University Department of Surgery, Southmead Hospital, Bristol.
authors.forename: G V
authors.initials: GV
authors.lastname: Appleton
authors.forename: R W
authors.initials: RW
authors.lastname: Owen
authors.forename: E E
authors.initials: EE
authors.lastname: Wheeler
authors.forename: D N
authors.initials: DN
authors.lastname: Challacombe
authors.forename: R C
authors.initials: RC
authors.lastname: Williamson
mesh_terms: D000818:Animals; D001647:Bile Acids and Salts / Q000378:metabolism*; D002118:Calcium / Q000097:blood; D002136:Calcium, Dietary / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D003106:Colon / Q000187:drug effects*; D003110:Colonic Neoplasms / Q000517:prevention & control; D046508:Culture Techniques; D005230:Fatty Acids, Nonesterified / Q000378:metabolism; D005243:Feces / Q000737:chemistry; D007413:Intestinal Mucosa / Q000187:drug effects; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012004:Rectal Neoplasms / Q000517:prevention & control
chemical_list: D001647:Bile Acids and Salts; D002136:Calcium, Dietary; D005230:Fatty Acids, Nonesterified; D002118:Calcium