Chapter 2 Flashcards
What percentage of cancers could be prevented?
~40%
What are the 2 most important lifestyle factors for cancer prevention?
- Avoiding tobacco
- Maintaining a healthy body weight throughout life
What is Leptin?
A hormone that helps your body maintain its weight long term. It’s produced by fat cells. Leptin resistance causes you to feel hungry and eat more even though your body has enough fat stores.
All forms of physical activity (including recreational and occupational) protect against these 3 forms of cancer.
Colon, post menopausal breast, endometrium
Vigorous physical activity prevents against this 1 type of cancer
Pre-menopausal breast
What are the physical activity guidelines in depth
75 mins vigorous/week or 150 minutes moderate. Once achieved, increase to 30 mins vigorous daily or 45-60 mins moderate daily. Children, 60 mins/day of moderate-vigrous . This provides greater protection/
Nonstarchy vegetables & fruit PROBABLY protect against these 4 cancers
Mouth, larynx, pharynx, esophagus
Limited evidence suggests that nonstarchy vegetables & fruit may reduce the risk of cancer in these 3 cancers
Lung (current/former smokers), breast (ER-), bladder
Limited evidence links a low intake of non-starchy vegetables & fruit with these 2 cancers
Colorectal & stomach
*high fiber foods, specifically whole grains, protects against colorectal
Caroteinoids, vitamin c, and isoflavone may reduce the risk of these 3 cancers
Lung, breast, colorectal
Most nutrients & phytochemicals show an ability to inhibit ________________ & promote activity of ________________
phase 1 carcinogen-activating enzymes (i.e. cytochrome p-450)
phase II carcinogen-detoxifying enzymes (i.e. glutathione s-transferase)
Nutrients/plant foods may reduce risk of cancer through these 4 mechianisms
- Epigenetics (impacting gene expression, such as tumor suppressor genes)
- Hormones like insulin (fiber sloes glucose absorption which reduces insulin secretion)
- Antioxidants (direct protection or stimulating antioxidant pathways)
- Microbiota acting on fermentable fiber/resistant starch to produce butyrate
Whats the most common Stilbene?
Resveratrol from grapes & berries
What are processed meats
Meats (often red but not always) preserved by smoking, curing, fermenting, salting, or with chemical preservatives
What are 4 possible mechanisms for the link between red meat & colorectal cancer
- Heme iron in red meat forms free radicals. It also promotes the formation of of N-nitroso compounds in the gut
- NOCs form when nitrites combine with amines from amino acids (both during the curing process and in the gut)
- Cooking meat at high temps causes production of heterocyclic amines & polycyclin aromatic hydrocarbons, both carcinogens
- Possibly gut microbiota convert protein residue and fat-stimulated bile acids from high meat diets to carcinogenic and/or proinflammatory substances
What are NOCs
N-Nitroso compounds are carcinogens that are linked to heme iron & nitrites, either during the meat curing process or in the gut
A high glycemic load is linked to this type of cancer
Endometrial
What are recommendations on fruit juice?
Limit to 2 1 serving/day, likely contributes to weight gain the same as sugary beverages (high energy, low satiety)
What are recommendations on artificial sweeteners?
Research is too mixed, make recommendations on an individual basis
What is a standard drink?
14 g ethanol = 5 oz. wine, 12 oz. beer, 1.5 oz liquor
What 2 carcinogens are found in alcohol?
- Ethanol
- Acetaldehyde (metabolite)
What 5 mechanisms link alcohol to cancer?
- Ethanol & acetaldehyde (metabolite of alcohol) are both carcinogens
- Alcohol is a solvent, which enhances dietary carcinogens into cells
- Alcohol metabolism generates ROS (reactive oxygen species, type of free radical) that can damage DNA
- Works synergistically with tobacco d/t solvent properties, increasing risk of H&N cancers
- May in crease circulating levels of estrogen, a risk for breast cancer
Alcohol increases risk for which 8 cancers?
- Mouth
- Pharynx
- Larynx
- Liver
- Colorectum
- Breast (pre & post menopause)
- Esophagus (squamous cell)
- Stomach
Calcium supplements protects against __________ cancer but increases risk for _________ cancers (limited evidence)
Colorectal (>200 mg/d)
Prostate
SELECT study
Selenium & Vitamin E Cancer Prevention trial
Linked prostate cancer w/ low levels of a-tocopherol but high dose vitamin e supplements increase risk
Links prostate cancer with low selenium levels but selenium supplementation didn’t decrease risk
VITAL study
Vitamin D & Omega-3 trial
No difference in cancer incidence/invasion among the different groups
High vitamin D in blood is likely beneficial, but results are inconsistent regarding levels & goals
2 mechanisms that link lactation with reduced risk for breast cancer:
- Amenorrhea temporarily reduced lifetime exposure to estrogen
- DNA damaged cells are eliminated through exfoliation of breast tissue & through a major apoptosis of epithelial cells at the end of lactation
Evidence suggest that the following 3 factors reduce the chance of dying early after a breast cancer diagnosis
- Physical activity before & after diagnosis
- High fiber diet before & after diagnosis
- Eating soy in the year following diagnosis & beyond
Evidence suggest that the following 3 factors increase the chance of dying early after a breast cancer diagnosis
- Body fatness before & after diagnosis
- Eating a diet high in total or saturated fats before diagnosis
Define “organic foods”
Produced using approved cultural, biological, and mechanical methods
Cannot use synthetic pesticides/fertilizers, sewage sludge, irradiation, and genetic engineering
No evidence that GMOs increase cancer risk
Pesticide residue
Generally lower in organic than conventional foods YET most still contain pesticide residue with natural ingredients. These natural ingredients also pose concern for mutagenicity.
Protective contributions in organic vs conventional produce
Organic may contain more polyphenol compounds & vitamins, however the difference is relatively small & not associated with any difference in health-related biomarkers
Switching to organic likely doesn’t lower risks associated with pesticides either
How to clean produce
Running water. Remove outer leaves of leafy vegetables. Specialty washes are no more effective than water. Dish soap and bleach may be dangerous.
Polyphenols & “anti-inflammatory” nutrients in research
More human studies needed
Isolates/extracts usually used in studies, not whole foods which doesn’t reflect bioavailability
Studies are dose-related and ? if that dose is possible to achieve through food
What are examples of prebiotics?
Inulin, inulin-type fructans, legumes, allium vegetables
What is butyrate?
A SCFA produced in the colon that shows potential anti-inflammatory & tumor-suppressive properties
It’s formed from fermentable dietary fiber, resistance starch, and B-glucans
Overall diet for reducing inflammation
Many nutrients show promise show potential. Include a variety of these (i.e. omega 3, polyphenol compounds) while avoiding red/processed meats, refined grains sugary beverages.
2 main isoflavones in soy
Genistein & Daidzein
They’re called “phytoestrogens” d/t their structure and they can bind to estrogen receptors
Soy isoflavones may also provide protective antioxidant, antiangiogenesis & epigenetic effects
Controversy with soy
Old mice studies showed that geinstein increased the growth of ER+ breast cancer cells, but it was later found that mice metabolize phtoestrogens differently than humans do.
Human studies - Asian women consume moderate amounts of soy throughout their lives and they have lower breast cancer rates. In the US, moderate soy consumption was also associated with decreased recurrence (especially in ER- cancers)
T/F: Tamoxifen (ant-estrogen medication) has no harmful interactions with soy
True
What are 3 nutrient-related interests of flaxseed
- Lignans
- Fiber content (viscous fiber, may improve insulin sensitivity)
- ALA (slowly converted to long chain omega 3 EPA & DHAs)
What are lignans?
Diet components (highest concentration is in flaxseed)
Converted by intestinal bacteria to enterolignans which is absorbable into the blood.
What is the link between lignans and reduced cancer risk?
Metanalysis showed in humans with highest serum enterolignans had lower breast cancer risk
May shift serum estrogen to a form less likely to cause cancer
May decrease IGF-1 and other cancer-related grownth factors
Evidence suggest these 3 factors decrease risk of dying early after breast cancer diagnosis
- Being physically active before & after diagnosis
- Eating a diet high in fiber before and after diagnosis
- Eating foods that contain soy in the year after diagnosis + beyond
Evidence suggest these 2 factors increase risk of dying early after breast cancer diagnosis
- Eating a diet high in total & saturated fat before & after diagnosis
- Body fatness before & after diagnosis
Body fatness increases the risk for these 8 cancers
- esophagus (adenocarcinoma)
- pancreas
- colorectum
- breast (post-menopausal)
- endometrium
- liver
- kidney
