title: Dietary beta-carotene inhibits mammary carcinogenesis in rats depending on dietary alpha-linolenic acid content.
abstract: To investigate whether dietary alpha-linolenic acid (ALA) content alters the effect of beta-carotene on mammary carcinogenesis, we conducted a chemically induced mammary tumorigenesis experiment in rats randomly assigned to four nutritional groups (15 rats per group) varying in beta-carotene supplementation and ALA content. Two oil formula-enriched diets (15 %) were used: one with 6 g ALA/kg diet in an essential fatty acids (EFA) ratio of linoleic acid:ALA of 5:1 w/w (EFA 5 diet), the other with 24 g ALA/kg diet in an EFA ratio of 1:1 w/w (EFA 1 diet), both designed with a similar linoleic acid content. beta-Carotene was either added (10 mg/kg diet per d) or not added to these diets. beta-Carotene supplementation led to decreased tumour incidence and tumour growth when added to the EFA 5 diet, whereas it had no effect when added to the EFA 1 diet. The decreased tumour growth did not result from an involvement of lipoperoxidation (tumour malondialdehyde content being similar between the groups) or from an inhibition of tumour cell proliferation (as there was an unchanged S phase fraction in the tumours). We concluded that an adequate content of ALA in the diet is required to allow a protective effect of beta-carotene in mammary carcinogenesis. Whether such an interaction between ALA and beta-carotene influences the risk of breast cancer in women needs to be investigated.
authors.affiliation: Nutrition Croissance et Cancer, Université François-Rabelais de Tours, Inserm E 0211, IFR 135, 37032 Tours Cedex, France.
authors.forename: Virginie
authors.initials: V
authors.lastname: Maillard
authors.forename: Claude
authors.initials: C
authors.lastname: Hoinard
authors.forename: Khelifa
authors.initials: K
authors.lastname: Arab
authors.forename: Marie-Lise
authors.initials: ML
authors.lastname: Jourdan
authors.forename: Philippe
authors.initials: P
authors.lastname: Bougnoux
authors.forename: Véronique
authors.initials: V
authors.lastname: Chajès
mesh_terms: D000273:Adipose Tissue / Q000737:chemistry; D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage*; D002455:Cell Division / Q000502:physiology; D004032:Diet; D019587:Dietary Supplements; D005227:Fatty Acids / Q000032:analysis; D005228:Fatty Acids, Essential / Q000008:administration & dosage; D005260:Female; D008325:Mammary Neoplasms, Experimental / Q000517:prevention & control*; D051381:Rats; D017207:Rats, Sprague-Dawley; D016196:S Phase / Q000502:physiology; D017962:alpha-Linolenic Acid / Q000008:administration & dosage*; D019207:beta Carotene / Q000008:administration & dosage*
chemical_list: D000975:Antioxidants; D005227:Fatty Acids; D005228:Fatty Acids, Essential; D019207:beta Carotene; D017962:alpha-Linolenic Acid