6 Nutrition and Cancer Flashcards
List some dietary factors involved in the development and prevention of cancer
- Obesity
- Red and processed meat
- Saturated fat
- Alcohol
- Fruit and Vegetables
- Fibre
- Dairy and Calcium
Why is obesity commonly linked to cancer? (reason)
Due to chronic low-level inflammation
List some cancers commonly associated with obesity
- Colorectal, prostate, liver, kidney, multiple myeloma, meningioma, pancreatic, oesophageal, gastric, cardiac, gall bladder, endometrial, breast (m + f)
Describe the mechanism(s) by which obesity is linked to cancer
- Adipose tissue leads to increased levels of estrogen, which is associated with the risk of certain cancers
- Changes in circulation of certain adipokines -
> increased leptin (promotes cell proliferation)
> decreased level of adiponectin (antiproliferative effects) - Increased circulating insulin - insulin signaling through insulin receptor A; has direct oncogenic effects on cancer cells
- Increased insulin-like growth factor (IGF) 1 -
> it is a survival agent and growth factor for a diverse range of normal and malignant cells
List some cancers associated with intake of red and processed meats
Increased risk of colorectal and GI cancers
Describe the roles nitrosamines play in cured meats and cancer risk
Nitrosamines (potent carcinogens) are formed in cured meats because nitrite, and sometimes nitrate, are added to these meats during processing
- Upon consumption, nitrates can be converted into N-nitroso compounds (NOCs), which are carcinogenic
Describe how red meats are shown to promote colorectal tumorigenesis
Haem iron (present at high levels in red meats) has been shown to promote colorectal tumorigenesis by stimulating the endogenous formation of carcinogenic N-nitroso compounds
Describe why the cooking of processed meats is linked to colorectal cancer development
Processed meats are often cooked at high temperatures, which can lead to the formation of:
- heterocyclic amines (HCAs)
- polycyclic aromatic hydrocarbons (PAHs)
both of which have been linked to colorectal cancer development
List some cancers which are associated with saturated fats
Increased risk of lung, colorectal, prostate, and breast cancer
List some mechanisms by which fats promote tumourigenesis
- High fat intake results in increased production of bile acid, which is converted by intestinal bacteria into secondary bile and cytotoxic compounds:
> these compounds may enhance the proliferative activity of the colonic epithelium - High-fat diets are often associated with obesity
> high-fat-induced obesity can lead to a chronic state of low-grade inflammation - High dietary SFA intake is often synonymous with a high intake of processed and red meat
- Dietary intake of certain types of fat (Omega 3 PUFAs) is inversely correlated with the development of certain cancers
- With high-fat diets, insulin levels rise too (resulting in oncogenic effects on cancer cells)
List some cancers associated with alcohol
Alcohol has been identified as a contributory factor for several types of cancer including upper aerodigestive tract, liver, and breast
Explain the role of acetaldehyde in alcohol-related cancer risk increase
Acetaldehyde is the first metabolite of ethanol oxidation.
- Acetaldehyde has been shown to be mutagenic and carcinogenic in animal experiments
Explain the role of oestrogen in alcohol-related cancer risk
- Alcohol can increase the circulating levels of estrogen, which is linked to breast cancer
Explain the role of folate and other nutrients in alcohol-related cancer risk
- Epidemiological studies have indicated a negative association between folate intake and risk of breast cancer
- As well as a negative association between Vitamin B12 status and risk of breast cancer postulated that the lower folate and B12 levels in individuals consuming alcohol can increase cancer risk
Explain the role of alcohol and smoking in cancer-related risk
Alcohol and smoking have a synergistic effect
- High alcohol consumption can also cause cirrhosis of the liver, which can then lead to cancer
Explain the mechanisms behind the association between regular consumption of fruits + vegetables and reduced risk of cancer
- Antioxidants interact with and neutralize free radicals (aka ROS - reactive oxygen species)
- Glucosinolates and isothiocyanates - increase elimination/
metabolism of carcinogens (nitrosamines)
Explain the mechanism behind how dietary fibre is thought to protect against colorectal cancer
- Formation of short-chain fatty acids from fermentation by colonic bacteria
> these SCFAs (e.g. Butyrate) can inhibit the development of colorectal cancer - Reduction in intestinal transit time
List some cancers which are believed to have a lower risk if there is the consumption of dairy and calcium
- Bowel cancer, bladder cancer, prostate cancer
Describe the mechanism of how dairy and calcium is linked to lower risk of some cancers
- Some studies have shown the presence of sphingolipids, calcium, conjugated linoleic acid, butyric acid, and lactic acid bacteria in dairy products; which have the potential to reduce bowel cancer
- Ionised calcium or calcium phosphate may reduce colon cancer by binding to secondary bile acids and free fatty acids to form insoluble soaps, which can have a protective effect on the epithelial cells of the colon
List some advice on diet and lifestyle that can be given to patients
- Maintenance of normal body weight
- Increase intake of fruit and vegetables
- Increase intake of plant foods rich in complex carbohydrates/fiber
- Limit intake of red meat, animal fats (+ processed meats)
- Limit alcohol consumption
Describe some advice that can be given on maintenance of a normal body weight
- Physical activity according to guidelines (150min of moderate activity per week)
- Advice on energy balance, referrals to specialists/schemes when appropriate
- Important to understand that obesity is a very complex condition
Describe some advice that can be given on increasing intake of fruit and vegetables
- In UK, it is currently recommended that individuals consume a minimum of 5 portions of fruit and vegetables a day
- BUT more is better – a major review found people who regularly ate 800g of fruit + veg a day (10 portions) had a significantly lower risk of chronic diseases
o All fruit + veg (not potatoes), pulses, tinned fruit (low sugar), dried fruit (not too much – high sugar content)
Describe some advice that can be given on increasing intake of plant foods rich in complex carbohydrates/fibre
Fibre-rich foods include:
- Wholegrain breakfast cereals, wholewheat pasta, wholegrain bread and oats, barley and rye
- Fruits such as berries, pears, melon, and oranges
- Vegetables such as broccoli, carrots, and sweetcorn
- Peans, beans, and pulses
- Nuts and seeds
- Potatoes with skin
Describe some advice that can be given on limiting the intake of red meat, animal fats (+ processed foods)
The current advice says:
- Adults who eat more than 90g of red and processed meat a day should reduce their intake to 70g a fay
- Eat no more than 500g of red meat a week, and avoid processed food
