E module Food Carcinogens and lecture carcinogenicity
22 important questions on E module Food Carcinogens and lecture carcinogenicity
What is the link between diet and cancer?
What is a carcinogen?
- divided in genotoxic and non-genotoxic carcinogens
- based on mechanism of action underlying their contribution to cancer
What are genotoxic carcinogens?
- can eventually lead to mutations or alterations in the structure or function of DNA
- contribute to cancer
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How can genotoxic carcinogens cause DNA / chromosomal damage?
- directly
- after activation by metabolizing enzymes
What are non-genotoxic carcinogens
By which mechanisms can non-genotoxic carcinogens cause cancer?
- hormonal effects
- cytotoxicity
- cell proliferation
- epigenetic changes
What are the three main sources of food carcinogens?
- carcinogens naturally present in food
- e.g. from plants
- carcinogens formed during processing
- e.g. during heating of food
- carcinogens formed endogenously
- e.g. formation of nitrosamines in gut due to reaction between nitrite and amines
Due to the DNA damaging properties of genotoxic carcinogens, they are not considered to have a safe level of exposure. Why?
Which approach is used for the qualitative risk management of genotoxic carcinogens?
Which approach is used for non-genotoxic carcinogens?
- Tolerable daily intake (TDI) for non-avoidable non-genotoxic carcinogens
- acceptable daily intake (ADI) for avoidable non-genotoxic carcinogens
Why is it possible to derive a TDI for a non-genotoxic carcinogenic compound?
What are anticarcinogens in food?
Give examples of classes chemicals associated with anticarcinogenic potential
- Vitamins
- flavonoids
- fibers
- polyphenolic compounds
- phytoestrogens
- carotenoids
- limonene
- hydrolysis products of glucosinolates
How many changes are needed for tumor formation?
What genotoxic carcinogens are there in food? Give examples
- phytotoxins (from plants)
- alkenylbenzenes (estragole, methyleugenol)
- pyrrolizidine alkaloids
- mycotoxins (from fungi/molds)
- alfatoxin
2. Endogenously formed
- nitrosamines
3. Formed upon food processing (heating)
- PAHs: polycyclic aromatic hydrocarbons
- HCAs: heterocyclic amines (PhIP)
- acrylamide
Describe the process of endogenously formed genotoxic carcinogens. Give example
example: nitrosamines
- nitrate in veggies are converted into nitrite in the body
- the nitrate can interact with amines of fish
- together they form nitrosamines
- genotoxic carcinogenic
How are the genotoxic carcinogens Polycyclic Aromatic Hydrocarbons (PAHs) formed?
- temperature 300 - 600 degrees Celsius
How are the genotoxic carcinogens Acrylamide and PhIP formed?
- temperature < 250 degrees Celsius
How are the genotoxic carcinogens furans formed?
- in coffee, canned and jarred foods
Which genotoxic carcinogens are of high priority due to their MOE?
- Pyrrolizidine alkaloids
- acrylamide
- aflatoxin B1
- furan
What are anti-carcinogens in food
Name the mechanisms by which anti-carcinogens may reduce cancer formation
- Reduction of effects of carcinogens by modulation of biotransformation enzymes
- reduction of inflammation
- reduce oxidative/electrophilic stress
- reducing proliferative tumor cells
- reducing bioavailability
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