Unit 4 - Cancer and Nutrtion Flashcards
What is a genoprotective diet?
- low in harmful substances (ie: carcinogens) that may cause cancer
- sufficient in protective dietary factors (some vitamins, minerals, and possibly phytochemical components)
Why is Folate thought to be genoprotective?
Because it is involved in the production of the base thymine, which is important in DNA synthesis.
Give 3 reasons for why the role of nutrition in cancer etiology is not very well understood.
- Cancer is a complex group of diseases involving multi-step processes
- Human diet is complex → difficult to isolate specific dietary factors that can promote or protect against the pathological process of carcinogenesis
- It’s difficult to relate findings found in animal studies and apply them to humans
List and explain the 3 steps of carcinogenesis.
- Initiation: DNA mutations
- Promotion: mutation established & passed on → growth promotion of mutant cells
- Progression: Metastasis (spreading of cancer cells to other parts of the body)
T/F: All carcinogens cause cancer by acting at the “initiation phase” of carcinogenesis.
False - they do, but some act at the promotion phase as well
List 3 basic processes involved in cancer pathology at the molecular and cellular level.
- Damage to DNA (mutations)
- Expression of cancer-promoting genes
- Suppressed immunity
Explain why someone who is exposed to more environmental risk factors for cancer could have a lower overall risk for actually developing the disease.
Because if someone has very efficient DNA repair mechanisms, that may outweigh the danger of the environmental risk factors.
Why is the relationship between nutritional studies and cancer so complex? List 3 reasons.
- There are many different chemicals or substances in foods that may protect against, or promote, cancer; and these substances are often tested in isolation, not in their normal food context.
- Chronic nature of cancer development (long latency period, multi-step pathological process that could take many years)
- Applicability of animal/model studies
- Purified chemicals often tested at relatively high (non-food) concentrations
- Animals may have different metabolism for the chemical compared to humans
What is an A1 rating?
Factors that are judged to be best established to lower cancer risk (convincing evidence).
Give 2 examples of A1 level evidence.
- Avoiding overweight for colorectal, breast cancers
- Limiting alcohol for oral and esophageal cancer
What is an A2 rating?
The dietary factor has probable benefit.
Give 2 examples of A2 level evidence.
- Increasing fruit/veg intake for colorectal, lung, oral/esophageal cancers
- Limiting red meats for colorectal cancer
T/F: It has been shown that beta-carotene supplements can increase risk of cancer.
True
List one risk factor and one protective factor in terms of energy balance and cancer.
High BMI increases risk of colon, endometrial and breast cancer.
Physical activity is protective against colon and breast cancer.
There are correlations between red meat consumption and colon cancer risk. Give a co-incidental that should be considered when assessing the cancer risk of protein consumption.
Is it protein directly or another component of red meats?
Give an explanation using a co-incidental for why fat consumption might be associated with increased cancer risk.
- Is it fat directly or a higher caloric intake by those who consume more fat?
- Is it because of lipid-soluble toxins?
- Do those who consume more fat have lower fibre/plant food intake, or higher red meat consumption, or lower level of physical activity?
List the 3 types of phytochemicals and give possible benefits for each one.
- Affect hormone action/metabolism/levels (Phytoestrogens)
- Decrease formation/ Increase elimination of carcinogens (Isothiocyanates)
- Prevent oxidative damage
(Vitamin E, some flavonoids)
What are the 3 sources of phytoestrogens? Give an example of a type of food that each one can be found in.
- Isoflavones (ex: Soy)
- Coumestans (ex: Lima beans, pinto beans)
- Lignans (Flaxseed and sesame seed)
Which types of cancers are phytoestrogens thought to reduce risk for, and how are they thought to do it?
- Breast and prostate cancers
- Phytoestrogens may modulate hormones in the body and could be anti-inflammatory.
What is a synergist of drinking alcohol that contributes to increased cancer risk?
Tobacco
Which cancers does alcohol increase risk for?
- Mouth
- Esophageal
- Throat
- Breast* with heavy consumption
Criticize the correlations between carcinogens and risk (3)
- Risk is different for everyone (depends on genetics)
- Risk is often determined in experimental systems that may not be fully relevant to human metabolism
- Risk is often determined using purified compound
List 4 sources of carcinogens.
(not types of carcinogens)
- Industrial/agricultural chemicals used in food production
- Contaminants (in the air/soil or from molds)
- Food processing
- Cooking at high temperatures
What 2 carcinogens can be found in burnt meat?
- Polyaromatic hydrocarbons (PAHs)
- Heterocyclic amines (HAs)
