Cooking methods, carcinogens, and diet-cancer studies

Pluchea lanceolata attenuates cadmium chloride induced oxidative stress and genotoxicity in Swiss albino mice

Cadmium intoxication induces lipid peroxidation and causes oxidative damage to various tissues by altering antioxidant defence system enzymes. At 24h after treatment with a single intraperitoneal dose of cadmium chloride (5 mg kg−1), Swiss albino mice showed a significant increase in the levels of malanodialdehyde and xanthine oxidase (P<0.001), and a concomitant depletion of renal glutathione, catalase (P<0.001) and other antioxidant enzymes. CdCl2 also led to a simultaneous increase in micronuclei formation (P<0.001) and chromosomal aberrations (P<0.05) in mouse bone marrow cells. Oral pre-treatment with Pluchea lanceolata extract at doses of 100 and 200 mg kg−1 for 7 consecutive days before CdCl2 intoxication caused a significant reduction in malanodialdehyde formation and xanthine oxidase activity (P<0.001). A significant restoration of the activity of antioxidant defence system enzymes such as catalase, glutathione peroxidase (P<0.05), glutathione-S-transferase and glutathione reductase (P<0.001) was observed. A significant dose-dependent decrease in chromosomal aberrations and micronuclei formation was also observed (P<0.05). The results indicate that pre-treatment with P. lanceolata attenuates cadmium chloride induced oxidative stress and genotoxicity by altering antioxidant enzymes and reducing chromatid breaks and micronuclei formation.

Diversity of dietary patterns observed in the European Prospective Investigation into Cancer and Nutrition (EPIC) project

OBJECTIVE

To describe the diversity in dietary patterns existing across centres/regions participating in the European Prospective Investigation into Cancer and Nutrition (EPIC).

DESIGN AND SETTING

Single 24-hour dietary recall measurements were obtained by means of standardised face-to-face interviews using the EPIC-SOFT software. These have been used to present a graphic multi-dimensional comparison of the adjusted mean consumption of 22 food groups.

SUBJECTS

In total, 35 955 men and women, aged 35-74 years, participating in the EPIC nested calibration study.

RESULTS

Although wide differences were observed across centres, the countries participating in EPIC are characterised by specific dietary patterns. Overall, Italy and Greece have a dietary pattern characterised by plant foods (except potatoes) and a lower consumption of animal and processed foods, compared with the other EPIC countries. France and particularly Spain have more heterogeneous dietary patterns, with a relatively high consumption of both plant foods and animal products. Apart from characteristics specific to vegetarian groups, the UK 'health-conscious' group shares with the UK general population a relatively high consumption of tea, sauces, cakes, soft drinks (women), margarine and butter. In contrast, the diet in the Nordic countries, The Netherlands, Germany and the UK general population is relatively high in potatoes and animal, processed and sweetened/refined foods, with proportions varying across countries/centres. In these countries, consumption of vegetables and fruit is similar to, or below, the overall EPIC means, and is low for legumes and vegetable oils. Overall, dietary patterns were similar for men and women, although there were large gender differences for certain food groups.

CONCLUSIONS

There are considerable differences in food group consumption and dietary patterns among the EPIC study populations. This large heterogeneity should be an advantage when investigating the relationship between diet and cancer and formulating new aetiological hypotheses related to dietary patterns and disease.

Fried foods: a risk factor for laryngeal cancer?

The role of fried foods on laryngeal cancer risk was investigated in a case-control study from Italy and Switzerland on 527 cases and 1,297 hospital controls. A significant increased risk was found for high consumption of fried meat, fish, eggs and potatoes, with odds ratios of 1.6, 3.1, 1.9 and 1.9, respectively.

Inhibitory effect of Emblica officinalis on the in vivo clastogenicity of benzo[a]pyrene and cyclophosphamide in mice

Benzo[a]pyrene (B[a]P) and cyclophosphamide (CP) are potent carcinogens/mutagens. Effect of Emblica officinalis extract administration on the in vivo genotoxicity of B[a]P and CP was studied using bone marrow chromosomal aberration and micronucleus induction tests in mice. Three doses (50, 250 and 500 mg/kg body weight) of the plant extract were administered orally for 7 consecutive days prior to the administration of single dose of mutagens (B[a]P 125 mg/kg oral; CP 40 mg/kg i.p.). It was found that administration of 250 and 500 mg/kg of E. officinalis extract significantly inhibited the genotoxicity of B[a]P as well as CP in both the assay systems. Administration of 50 mg/kg of the plant extract had no inhibitory effect. Vitamin C, a major constituent of E. officinalis when administered at dose level of 9 mg/kg b.w. (the approximate estimated amount present in the highest dose of plant extract, i.e. 500 mg) for 7 days did inhibit chromosomal aberrations and micronuclei induction, but not in a significant manner. Effect of administration of the abovementioned effective doses (250 and 500 mg/kg oral for 7 days) of plant extract and vitamin C (9 mg/kg oral for 7 days) on the hepatic activation and detoxification enzymes was also studied. Significant induction in the levels of glutathione content (GSH) and of antioxidant and detoxification enzymes viz., glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione-S transferase (GST) resulted from plant extract treatment to animals. On the other hand, cytochrome P 450 level was significantly decreased in the plant-extract-treated animals. There was no significant change in cytochrome P 450, GSH contents and activities of enzymes on treatment with vitamin C. The data indicate that the possible mechanism of inhibition by plant extract is mediated by its modulatory effect on hepatic activation and disposition processes.

The synergistic effects of vanillin on recombination predominate over its antimutagenic action in relation to MMC-induced lesions in somatic cells of Drosophila melanogaster

The wing Somatic Mutation And Recombination Test (SMART) in Drosophila melanogaster was used to study the modulating action of vanillin (VA) in combination with the alkylating agents mitomycin C (MMC), methylmethanesulphonate (MMS) and the bifunctional nitrogen mustard (HN2). Two types of treatments with VA and each of the three genotoxins were performed: chronic co-treatments of three-day-old larvae of the standard cross as well as post-treatments after acute exposure with the genotoxins. This allowed the study of the action of VA not only in the steps that precede the induction of DNA lesions but also in the repair processes. The overall findings from the co-treatment series suggest that ingestion of VA with MMS or MMC can lead to significant protection against genotoxicity; but this is not the case with HN2. Antioxidant activity, suppression of metabolic activation or interaction with the active groups of these two alkylating agents could be mechanisms by means of which VA exerts its desmutagenic action. In contrast, when evaluated in the post-treatment procedure, VA causes two antagonistic effects on the genotoxicity of MMC: (i) synergism on recombination (172.8%) and (ii) protection against mutation (79.0%). Consequently, both activities together lead to a considerable increase in mitotic recombination. In spite of being separate events, recombination and gene mutation are correlated during mitosis since the fate of a DNA lesion depends on the repair pathway followed. Our results may suggest that VA is a modifying factor that blocks the mutagenic pathway and consequently directs the MMC-induced lesions into a recombinational repair. Furthermore, VA did not modify the genotoxicity when administered after treatments with HN2 or MMS. Therefore, the major finding of the present study, namely the co-recombinagenic activity of VA on MMC-induced lesions, seems to be related to the type of induced lesion and consequently to the repair processes involved in its correction.

Dietary chemoprevention of clastogenic effects of 3,4-benzo(a)pyrene by Emblica officinalis Gaertn. fruit extract

Dietary supplementation with extract of fruit of Emblica officinalis Gaertn. (a rich source of vitamin C) to mice in vivo significantly reduced the cytotoxic effects of a known carcinogen, 3,4-benzo(a)pyrene. Age-matched Swiss albino mice were fed by gavaging the fruit extract daily for 28 days. From day 9, one dose of the carcinogen was given on alternate days up to a total of eight doses. On day 29, all mice were transferred to normal diet. Control sets received the extract alone, the carcinogen alone and olive oil alone. All mice were sacrificed at 12 weeks and 14 weeks after the end of the experiment. Chromosome preparations were made from bone marrow after the usual colchicine-hypotonic-fixative-air drying-Giemsa staining schedule. Cytogenetic end points screened were the frequencies of chromosomal aberrations and of damaged cells induced. The cytotoxic effects were significantly lower in the mice given the fruit extract with the carcinogen than in those given the carcinogen alone.

Lack of aberrant crypt promotion and of mutagenicity in extracts of cooked casein, a colon cancer-promoting food

Dietary casein cooked at 180 degrees C promotes the growth of aberrant crypt foci and colon cancer in rats initiated with azoxymethane. We speculated that promotion was due to a product that could be extracted by a solvent, such as 5-hydroxymethyl-2-furaldehyde (HMF), with tumor- promoting activity or the carcinogenic heterocyclic aromatic amines (HAA). This hypothesis was tested by extracting cooked casein with solvents and water. The extracts were then 1) assayed by high-performance liquid chromatography for HMF and HAA, 2) measured for mutagenicity on a frame-shift-sensitive strain of Salmonella typhimurium, and 3) fed for 100 days to azoxymethane-initiated rats to test the promoting effect on aberrant crypt foci. Data show that 1) no HMF or HAA was detected in cooked casein, 2) no mutagenicity was detected on strain TA98, with or without metabolic activation, and 3) promotion was not associated with the extracts but with the cooked casein residue. Therefore the promotion by cooked casein would not appear to be associated with a product that can be extracted by solvents.

Antimutagens and anticarcinogens in foods

The role of dietary factors in the prevention of major chronic diseases, cancer in particular, is under intensive investigation by many laboratories around the world. Evidence from epidemiological studies and tests in laboratory animals suggests that food consumed by the general population contains certain ingredients that may have a role in reduction of the incidence of cancer. It has been observed that a number of regular food components, belonging to different chemical groups, do possess cancer preventive and/or beneficial outcomes for some other diseases; these chemicals, therefore, are frequently collectively known as 'chemopreventers'. The mode of action of most chemopreventers is still unknown, although it appears that many of them are antioxidants, and as such, they may scavenge free radicals, formed either during the preparation of food, or by biological processes in the body. As free radicals damage lipids, proteins, cell membranes and DNA, their removal could prevent development of certain chronic diseases, particularly cancer or atherosclerosis. This review summarizes recent developments in the search for beneficial effects of regular food ingredients in prevention of cancer.

Prevention of adverse effects of food browning

Amino-carbonyl interactions of food constituents encompass those changes commonly termed browning reactions. Such reactions are responsible for deleterious post-harvest changes during processing and storage and may adversely affect the appearance, organoleptic properties, nutritional quality, and safety of a wide spectrum of foods. A growing area of concern is nutritional carcinogenesis, in which nutritionally linked cancer has been associated with amino-carbonyl reaction products. Specific practical and theoretical approaches to prevent adverse effects of food browning include: (1) modification and removal of primary reactants and endproducts in the browning reaction; (2) prevention of deleterious browning reactions through the use of antioxidants; (3) blocking of in vivo toxicant formation from browning products by means of dietary modulation; (4) accurate estimation of low levels of browning products in whole foods and their removal through antibody complexation; and (5) stimulation of inactivation in vivo toxicants from browning products by use of amino acids and sulfur-rich proteins.

Latitudinal variation of digestive tract cancers in the US and China

Latitude influences the availability of fresh fruits and vegetables (which are associated with cancer protection) and the use of food preservation methods (which are associated with increased cancer). Such dietary differences might be reflected in the frequency of death from cancer of the digestive tract. Female mortality rates for states and provinces of the US and China, both of which cover a wide latitude range, were chosen to investigate latitude- and time-related changes. Mortality for cancer of the stomach, liver, and rectum did increase with latitude in both nations, which is consistent with the hypothesis. Exceptions were cancer of the colon and esophagus; these cancers had a variable association with latitude and did not decline markedly in the US by 1970-1979 as did mortality rates from cancer of the other digestive tract sites. Increased refrigeration and improved transportation, both of which result in increased consumption of fresh fruits and vegetables, and decreased use of older food preservation methods may be responsible for the US decline in mortality rates from stomach, liver, and rectal cancers.