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What is a carcinogen?  A carcinogen is a substance or agent known to cause cancer or produces an increase in incidence of cancer in animals or humans.

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Presentation on theme: "What is a carcinogen?  A carcinogen is a substance or agent known to cause cancer or produces an increase in incidence of cancer in animals or humans."— Presentation transcript:


2 What is a carcinogen?  A carcinogen is a substance or agent known to cause cancer or produces an increase in incidence of cancer in animals or humans  Carcinogens may be chemical substances; physical agents, UV radiation; or biological agents, such as certain viruses and bacteria  carcinogenic substances may be inhaled, absorbed through the skin or ingested.

3 A carcinogen can alter or damage a cell’s DNA…  A carcinogen may be the initiator — the agent that alters or damages DNA, the basic coding system of cells  It may also be promoter — encouraging out-of-control cell growth

4 The different states of the cell cycle

5 Cancer  Cancer refers to a number of diseases characterized by uncontrolled growth and spread of abnormal cells.

6 Carcinogenesis Pathogenesis of cancer is complex It is a genetic disease- either acquired genetic abnormality or inherited genetic abnormality It arises when several mutations accumulate within genome

7 Pathogenesis Acquired environmental factors chemicals,radiation,viruses Changes in genome of somatic cells Activation of growth promoting oncogenes Inactivation of cancer suppressor genes Expression all altered gene products and loss of regular gene products MALIGNANT NEOPLASM Genetic factors

8 Cancer is a global concern Cancer incidence is on the rise worldwide World Health Organization estimates that 80 per cent of cancers are caused by occupational or environmental factors, including exposure to hazardous chemicals

9 Chemicals the worst culprits Chemical substances constitute the largest group of carcinogens New chemical substances are being developed every year, often without prior testing on their potential toxic effects

10 International research tracking down carcinogenic substances International agencies such as the UN’s International Agency for Research on Cancer (IARC), are continually updating lists of known and suspected carcinogens. International Agency for Research on Cancer California’s Proposition 65

11 Natural carcinogens How much do natural plant carcinogens contribute to the incidence of cancer in human populations? The answer is still unknown, but the National Research Council has reported that excess calories pose more of a cancer threat than natural or synthetic carcinogens in food

12 The answer is still unknown. Why? The huge number and complexity of naturally occurring compounds. So far, chemists have tested only a fraction of this huge number of natural compounds particularly in food. The limitations of the process by which we test a compound to see if it causes cancer (feeding it in relatively high doses to hundreds of laboratory animals)

13 Naturally-occurring Carcinogens Aflatoxins and Ochratoxin A are natural toxins made by fungal food contaminants cause cancer in animals and humans. Safrole, which is found in sassafras tea, cinnamon, cocoa (trace), nutmeg, and other herbs and spices is a liver carcinogen in rats. Heterocyclic amines in cooked meats have been associated with stomach and other cancer formation. Aristolochic acids found in different species of the genus Aristolochia are reported as carcinogenic. Asbestos (naturally occurring silicate mineral with long, thin fibrous crystals) increases the risk of lung cancer. Tobacco smoke (lung cancer), alcohols (liver cancer).

14 Cancer prevention by phytochemicals Phytochemicals appear to have the ability to stop the conversion of a cell from healthy to cancerous at different stages. Antioxidants stop free radicals (reactive oxygen species, ROS) from harming a healthy cell Plant defenders can slow the process from precancer to cancer

15 ROS and various stages of carcinogenic process

16 Cancer protective and anticancer plants Garlic Organosulfur compounds originating from garlic inhibit carcinogen activation, boost phase 2 detoxifying processes, cause cell cycle arrest mostly in G2/M phase, stimulate the mitochondrial apoptotic pathway,

17 CURCUMA (Turmeric) Curcumin, a natural component of the rhizome of curcuma has emerged as one of the most powerful chemopreventive and anticancer agents. Its biological effects range from antioxidant, anti-inflammatory to inhibition of angiogenesis

18 Ginger It is a common condiment for various foods and beverages. Some pungent constituents (gingerol, zingerone and paradol ) present in ginger exhibit cancer preventive activity.

19 Liquorice Isoliquiritigenin (ISL), a flavonoid found in licorice, has been identified as a potent anti-tumor promoting agent

20 Ginseng root Ginsenoside 20(S)-protopanaxadiol, a metabolite of ginseng, may be applied as a potential therapeutic agent in the prevention and treatment of cancer.

21 Fenugreek A naturally occurring edible spice as an anticancer agent. The extract from the seeds of fenugreek, is cytotoxic in vitro to a panel of cancer but not normal cells.

22 Green tea Epidemiologic studies show an inverse relationship between consumption of tea, especially green tea, and development of cancers. Numerous in vivo and in vitro studies indicate strong chemopreventive effects for green tea and its constituents against cancers of various organs. (-)-Epigallocatechin-3-gallate (EGCG), the major catechin in green tea, appears to be the most biologically active constituent in tea with respect to inhibiting cell proliferation and inducing apoptosis in cancer cells.

23 Flaxseed oil Flax lignans belonging to the phytoestrogens are metabolised after ingestion into enterolignans that may offer a protection against the onset and development of hormono-dependant cancers.

24 sesame seed The mammalian lignans, which are produced by the microflora in the colon of humans and animals from precursors in foods, have been suggested to have potential anticancer effects Sesame seed, alone and in combination with flaxseed, produces mammalian lignans equivalent to those obtained from flaxseed alone.

25 Soybean It has been reported that populations consuming high levels of soybean products have both lower cancer incidence and mortality rates in the western countries. The soy isoflavones have antiproliferative effects on a variety of cancer types. Lunasin of soy is a novel seed peptide for cancer prevention. Recent studies have demonstrated a direct effect of soy saponins on cancer cells

26 Soybean Genistein is an isoflavone with oestrogenic activity that is present in a variety of soy products as a constituent of complex mixtures of bioactive compounds. Genistein can act as an oestrogen agonist resulting in proliferation of E-dependent human breast cancer tumours in vivo and its activity can be modulated by the presence of other bioactive compounds. A large, population-based, prospective cohort study provided strong evidence of a protective effect of soy food intake against premenopausal breast cancer.

27 Cruciferous vegetables Indole-3-carbinol (I3C), a naturally occurring compound found in vegetables of the Brassica genus, such as broccoli and cabbage, is a promising anticancer agent shown to induce a G(1) cell-cycle arrest in the cells of human lymph node carcinoma of prostate. Cruciferous vegetables decreased the risk of breast cancer by 40 percent.

28 Tomato Epidemiological studies have provided evidence that high consumption of tomatoes effectively lowers the risk of reactive oxygen species (ROS)-mediated diseases such as cardiovascular disease and cancer by improving the antioxidant capacity. Tomatoes are rich sources of lycopene, an antioxidant carotenoid reported to be a more stable and potent singlet oxygen quenching agent compared to other carotenoids

29 Tomato Lycopene shows an array of biological effects including cardioprotective, anti- inflammatory, antimutagenic and anticarcinogenic activities. The anticancer activity of lycopene has been demonstrated both in in vitro and in vivo tumour models.

30 Wheat germ and whole grains Tocotrienols are naturally occurring isoprenoid compounds highly enriched in palm oil, rice bran, oat, wheat germ, barley and rye. Tocotrienols have antioxidant properties as well as potent anticancer properties. Fibers in the bran is colon-protective

31 Citrus fruits Epidemiological and animal studies suggest that flavonoids (hesperidin) have a protective effect against cardiovascular diseases and some types of cancer. Limonoids are a prominent group of secondary metabolites in citrus fruit with anticancer effect

32 Spinach leaves Spinach leaves, containing several active components, including flavonoids, exhibit antioxidative, antiproliferative, and antiinflammatory properties in biological systems. Spinach extracts have been demonstrated to exert numerous beneficial effects, such as central nervous system protection and anticancer and antiaging functions. The glycolipids fraction from spinach is potentially a source of food material for a novel anticancer activity

33 Strawberry The most abundant phytochemicals are ellagic acid, and certain flavonoids: anthocyanin, catechin, quercetin and kaempferol Compounds in strawberries have demonstrated anticancer activity in several different experimental systems, blocking initiation of carcinogenesis, and suppressing progression and proliferation of tumors.

34 Change your lifestyle to be more protected It has been estimated that 30-40 percent of all cancers can be prevented by lifestyle and dietary measures alone. Try to avoid carcinogens and factors increasing cancer risk. Have more cancer protective substances and be physically active.

35 Factors increasing cancer risk Obesity. Nutrient sparse foods such as concentrated sugars and refined flour products that contribute to impaired glucose metabolism (which leads to diabetes). Low fiber intake. Consumption of excess red meat, saturated fats & the imbalance of omega 3 and omega 6 fats. Regular consumption of alcohol and tobacco

36 Types of Free Fatty Acids Saturated Saturated Fatty acids are saturated with hydrogen molecules Fatty acids are saturated with hydrogen molecules Semi-solid or solid at room temperature Semi-solid or solid at room temperature Monounsaturated (omega-9) Monounsaturated (omega-9) Fatty acid contains one double bond Fatty acid contains one double bond Liquid at room temperature Liquid at room temperature Polyunsaturated (omega-6 & omega-3) Polyunsaturated (omega-6 & omega-3) Fatty acid contains 2 or more double bonds Fatty acid contains 2 or more double bonds Liquid at room temperature Liquid at room temperature Hydrogenated Hydrogenated Industrial hardening of edible oils to make products hard at room temperature Industrial hardening of edible oils to make products hard at room temperature

37 Essential Fatty Acids (EFA) Omega-6 Dietary Sources: Omega-6 Dietary Sources: Sunflower oil, safflower oil, cottonseed oil, corn oil, & processed foods made with these oils. Omega-3 Sources: Omega-3 Sources: Cold-water fish (i.e., salmon, trout, sardines, herring), flaxseed, walnuts, pumpkin seeds, canola oil, & soybeans. Omega-9 Fatty Acids Omega-9 Fatty Acids Olives, extra-virgin olive oil, canola oil, avocadoes, sesame & almonds. Olives, extra-virgin olive oil, canola oil, avocadoes, sesame & almonds.

38 Have more cancer protective substances Vegetables, fruits, whole grains, herbs, nuts and seeds contain an abundance of phenolic compounds, terpenoids, sulfur compounds, pigments, and other natural antioxidants that have been associated with protection from and/or treatment of conditions such as cardiovascular disease and cancer.

39 Some valuable advice Enjoy fruit as a snack or dessert Add fruits to breakfast cereal Try whole-grain or multigrain toast and sandwiches Eat three different colors of vegetables with dinner Fill half of the dinner plate with vegetables Include salad with lunch

40 Some valuable advice Add sweet corn to salads Limit red meat to 3-4 serves each week (a serve of meat is 65-100 grams) Choose fish, skinless chicken, legumes, eggs or nuts on the other days Try a new vegetarian meal every week Limit processed meats Select foods low in fat Try a wide variety of vegetables and fruits.


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