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04/19/23Oklahoma Cooperative Extension Service
Diet and Health Guidelines to Lower Risk of Cancer
Presented by Janice Hermann, PhD, RD/LD
OCES Adult and Older Adult Nutrition Specialist
CancerCancer second leading cause of death in the
United StatesCancer not a single disorder
Many typesDifferent characteristicsOccur in different body locationsTake different coursesRequire different treatments
Cancer DevelopmentGenes work together to regulate cell division
and ensure new cells are replicas of parent cells
Process allows:Body to growReplace dead cellsRepair damaged cells
Cancer DevelopmentCancer develops from mutations in genes
regulating cell divisionMutations inhibit genes that ordinarily monitor
and correct errorsAffected cells lose ability to stop cell division
Result is an abnormal mass of cells
Cancer DevelopmentAn abnormal mass of cells is called a tumor
BenignTumors that stop growing without intervention or can be
surgically removedMost often pose no threat to health
MalignantTumors that multiply out of controlThreaten surrounding tissues and health
How Cancer DevelopsAs a malignant tumor grows, blood vessels
form to supply the tumor with nutrients Eventually, the tumor invades more and more
healthy tissue and may metastasizeMalignant cancers are described by:
LocationSizeExtent of growthIf spread to surrounding lymph nodesIf spread to distant sites in the body
Cancer Development
Cancer DevelopmentGenetic FactorsImmune FactorsEnvironmental FactorsPhysical ActivityDietary Factors
Cancer InitiatorsCancer PromotersProtective Factors
Cancer DevelopmentGenetic factors
All cancers have a genetic component in that a mutation causes abnormal cell growth
Some cancers have a genetically inherited component as wellExample: someone with a family history of color cancer
has a greater risk of developing colon cancer than someone without a genetic predisposition; however, this does not mean that they will develop colon cancer
Cancer DevelopmentImmune factors
A healthy immune system recognizes foreign cells and destroys them
Theorized an ineffective immune system may not recognize tumor cells as foreign, thus allowing unchecked cell growthAging affects immune function, and incidence of cancer
increases with ageDiseases that weaken the immune system can increase
cancer risk
Cancer DevelopmentEnvironmental Factors
Environmental factors known to cause cancer:Exposure to radiation and sunlightWater and air pollutionSmoking
Cancer DevelopmentPhysical Activity
Lack of physical activity may play a role in the development of some types of cancerPeople whose lifestyles include regular, vigorous physical
activity have the lowest risk of colon cancerPhysical activity may also protect against breast cancer
by reducing body weight and by other mechanisms unrelated to body weight
Cancer DevelopmentDietary Factors
Estimates are 1/3 of cancers attributed to nutrition
Cancer InitiatorsSome dietary factors may initiate cancer development
Cancer PromotersOther dietary factors may promote cancer development
once it has startedProtective Factors
Still other dietary factors may protect against cancer development
Diet and Cancer StudiesEpidemiological studies try to identify relationships
between the diet of population groups and incidence of specific cancers
Diet complexity makes identifying relationships difficultThousands of chemicals in a dietDiets contain initiators, promoters and protective factorsChanging one factor in the diet may change others, making
identifying individual factors difficultMany cancers have a long latency period, thus diet at
initiation or promotion may not be the same as at diagnosis
Dietary Factors: Cancer InitiatorsPesticides
Some pesticides may be carcinogenic at extremely high doses, however, they are safe at the levels permitted on fruits and vegetables
The benefits of eating fruits and vegetables are far greater than any potential risk
Food additivesThose approved for use in foods are not
carcinogenic
Dietary Factors: Cancer Initiators
AlcoholAlcohol associated with increased risk of mouth,
esophageal and breast cancerMouth and esophageal cancer are especially increased if
alcohol is combined with smoking
Dietary Factors: Cancer Initiators
Alcohol If alcohol intake causes liver cirrhosis, there is an
increased risk of liver cancerMalnutrition associated with alcoholism is also
likely to be important in the increased risk for certain cancers
Thus, potential benefits of moderate alcohol intake for cardiovascular disease must be weighed against potential risks
Dietary Factors: Cancer InitiatorsFood preparation methods
Cooking meat, poultry, and fish at high temperatures and smoking meat causes carcinogens to form on food surfaces which have been related to colon, breast and stomach cancerHigh heat cooking methods such as grilling, broiling, and
barbecuing Healthier cooking methods include roasting,
broiling, poaching, steaming, stewing, braising and microwaving
Fruits and vegetables appear to provide a protective effect
Dietary Factors: Cancer InitiatorsFood preparation methods
Large amounts of salt-cured and salt-pickled foods have been related to stomach, colon and bladder cancersSodium and potassium nitrates used in salting, pickling,
and curing processesNitrates can be converted into nitrite, which can form
potential carcinogens nitrosamines Diets with high amounts of fruits and vegetables
contain vitamin C and phytochemicals can retard conversion of nitrites to nitrosamines
Dietary Factors: Cancer Promoters
High fat dietsHigh dietary total fat and saturated fat may be
related to increased risk of breast, colon, endometrial and prostate cancerOmega-3 fatty acids however, may be protective
Thus same dietary fat advice applies to cancer protection as to heart diseaseReduce total fat and saturated fatIncrease omega-3 fatty acids
Dietary Factors: Cancer Promoters
High fat dietsMay increase cancer risk by increasing:
ObesityBile acid productionEstrogen levels
Because fat is calorie dense it is difficult to distinguish between the effects of high dietary fat, and total calories
Dietary Factors: Cancer Promoters
High calorie intakeIn most epidemiologic studies, a positive
association has been seen with high calorie intake and promotion of breast, colon and endometrial cancer
Increased risk may be due to:Excess calories themselvesWeight gain due to excess caloriesHigh fat intake that often supplies excess calories
Dietary Factors: Cancer Promoters
Obesity may increase risk of colon, endometrial and breast cancerIncreased risk may be due to:
Extra weightAdipose tissue production of estrogenExtra caloriesHigh fat intake that often supplies excess calories and
contributes to weight gainProtective effect of physical activity related to
breast and colon cancer may be due in part to helping to control obesity
Dietary Factors: Cancer PromotersProtein
Excessive muscle meat sources of protein have been related to increased risk of colon and prostate cancer
Not know if increased risk due to:Protein levelFat contentFat typeIncreased calories from fatOther factor such as being low in fiber, antioxidants and
phytochemicalsFurther research needed
Dietary Factors: Cancer PromotersProtein
In general tumor development is:Suppressed by diets that contain protein below that
required for optimal growthEnhanced by protein levels two to three times the
amount required
Dietary Factors: Protective Factors Fruits, vegetables, whole grains and legumes
Epidemiological studies show a link between diets with plenty of fruits, vegetables, whole grains and legumes and reduced incidence oral cavity, esophagus, stomach, colon and lung cancer
Compounds in these foods that may help lower cancer risk:Dietary fiberVitamin CVitamin EPhytochemicalsLow fat
Dietary Factors: Protective FactorsFruits, vegetables whole grains and legumes:
FiberFiber-rich diets may protect against colon cancer
In the intestine bile can be converted into potential cancer causing substances. Soluble fibers can bind bile acids and increase their excretion
Insoluble fibers absorb water making a larger, softer stool which can dilute potential cancer causing substances
A larger, softer stool moves through intestine faster so colon exposed to cancer causing substance for less time
Foods high in fiber are typically lower in fat, which may also help protect against colon cancer by reducing bile acid production
Dietary Factors: Protective FactorsFruits, vegetables, whole grains and legumes:
Antioxidants Fruits, vegetables, whole grains and legumes also
contain antioxidant nutrients that may protect against cancerAntioxidants stop free radical oxidation which may help
to prevent cell and tissue damage that can promote cancer
Possible these nutrients have many other effects in the body which lower cancer risk
Dietary Factors: Protective FactorsFruits, vegetables, whole grains and legumes:
PhytochemicalsFruits, vegetables, whole grains and legumes also
contain phytochemicals that may protect against cancerSome function antioxidants, protecting against harmful
cell damage from oxidationOthers lower cancer risk in different ways such as
activating enzymes that destroy carcinogens
Dietary Factors: Protective Factors
Fruits, vegetables, whole grains, and legumesBecause it is not known which specific substances
in fruits, vegetables, whole grains and legumes help to lower cancer and whether it is the substances themselves or their presence in food, the best recommendation is to eat a variety of these foods.
Best to get these nutrients from foods not supplements.
Dietary Factors: Protective Factors
CalciumCalcium may have a role in lowering colon cancer;
however, more research is neededIn the meantime, adequate calcium is known to
be important for growth and bone development
Cancer Development
Evidence suggests millions of cases of cancer could be prevented by changes in:DietWeight controlPhysical activitySmoking
Consequences of CancerNonspecific effects of cancer include:
Anorexia and reduced food intakeMetabolic alterationsTissue wasting and weight loss
Anorexia, tissue wasting, weight loss and fatigue typify cancer cachexiaOccurs in as many as 80% of people with cancer
Consequences of CancerAnorexia and Reduced Food Intake
Major contributors to wastingWith cancer body may not be able to respond to
reduced nutrient intake and nutrient stores are rapidly depleted
Without adequate energy and nutrients, the body is poorly equipped to:Maintain immune defensesSupport organ functionAbsorb nutrientsRepair damaged tissues
Consequences of CancerAnorexia and Reduced Food Intake
Factors contributing to anorexia and reduced food intake:Chronic nausea and early satiety
People with cancer frequently experience nausea and a premature feeling of fullness after eating small amounts of food
FatiguePeople with cancer often tire easily and lack the energy to prepare
and eat meals If cachexia develops, these tasks become even more difficult to
handle
Consequences of CancerAnorexia and Reduced Food Intake
Factors contributing to anorexia and reduced food intake:Pain
People in pain may have little interest in eating, particularly if eating makes pain worse
Mental stressA cancer diagnosis can cause distress, anxiety, and depression, all
of which may reduce appetiteFacing and undergoing cancer treatments causes additional
psychological stress
Consequences of CancerAnorexia and Reduced Food Intake
Factors contributing to anorexia and reduced food intake (cont.):Effects of cancer therapies
Therapies for cancer (including medications, chemotherapy radiation therapy, surgery, and bone marrow transplants) can affect food intake by causing nausea, vomiting, altered taste perceptions, food aversions, inflammation of the mouth and esophagus, dry mouth, mouth sores, difficulty swallowing, intestinal cramping, diarrhea, and constipation
Consequences of CancerAnorexia and Reduced Food Intake
Factors contributing to anorexia and reduced food intake (cont.):Obstructions
A tumor may partially or completely obstruct a portion of the GI tract, causing complications such as nausea and vomiting, early satiety, delayed gastric emptying, and bacterial overgrowth
Some patients with obstructions are unable to tolerate oral diets
Consequences of CancerMetabolic Alterations
Metabolic changes can also exacerbate wastingIncreased protein turnover, but reduced muscle protein
synthesisIncreased gluconeogenesis, further straining supply of body
proteinsIncreased triglyceride breakdown, but decreased fat synthesisMany develop insulin resistance
Metabolic alterations help explain why people with cancer fail to regain lean body mass or maintain healthy body weights even when receiving adequate energy and nutrients
Consequences of CancerTissue Wasting
Weight loss often evident at time cancer diagnosedFactors contributing to wasting
Anorexia and reduced food intakeMetabolic alterationsCytokines released by both tumor and immune cells
induces a hypermetabolic, catabolic stateDiversion of nutrients to support tumor growth result in
lower energy and nutrients available to healthy tissuesSevere tissue wasting, often seen in the later stages
of cancer, may be ultimate cause of death
Cancer TreatmentsPrimary medical treatments for cancer are:
SurgeryChemotherapyRadiation Therapy
Aim is to remove cancer cells, prevent further tumor growth, and alleviate symptoms
Medical treatments can effect nutritional status
Cancer TreatmentsSurgery
Performed to remove tumorsCan affect nutritional status
Acute metabolic stress caused by surgery raises protein and energy needs and can exacerbate wasting
Surgery may also contribute to pain, fatigue, anorexia and reduced food intake
Blood loss further contribute to nutrient losses
Cancer TreatmentsChemotherapy
Used to inhibit tumor growthInterfere or prevent cell divisionAffect rapidly growing cancer cells
Unfortunately, most of these drugs can effect normal cells (especially rapidly dividing cells, such as those in the GI tract, skin and bone marrow) and can effect nutritional status due to:AnorexiaNauseaMalabsorptionDiarrhea
Cancer TreatmentsRadiation Therapy
Bombarding cancer cells with radiation induces formation of reactive oxygen species, such as superoxide and hydroxyl radicals, which can damage cellular DNA and cause cell death
Radiation can effect normal cells and can effect nutritional status Radiation to head and neck may damage salivary glands and
taste buds, causing dry mouth and altered tasteRadiation to lower abdomen can cause radiation enteritis,
inflammation of the small intestine, causing nausea, vomiting, diarrhea, and malabsorption
Cancer TreatmentsBone Marrow Transplants
Replace bone marrow destroyed by chemotherapy or radiation
Primary treatment for leukemiaCan substantially effect nutritional status
After bone marrow is destroyed, immune function is suppressed, increasing the risk of foodborne illness
Effects of transplant include anorexia, dry mouth, inflamed mucous membranes, altered taste, and diarrhea
Patients often unable to consume adequate food and may require nutritional support
Cancer TreatmentsMedications to combat anorexia and wastingMedications sometimes prescribed to
stimulate the appetite and promote weight gain
Cancer TreatmentsAlternative therapies
60 to 80% of cancer patients combine complementary and alternative medicine (CAM) approaches with standard treatment
Many people do not discuss their use of complementary and alternative medicine approaches with their physicians
Cancer TreatmentsAlternative therapies
Dietary supplements and herbal remedies among most frequently used CAM
Many supplements can be used without risk; however, others may have adverse effects or interfere with conventional treatmentsSt. John’s wort can reduce effectiveness of some
anticancer drugsAntioxidant supplementation may interfere with
chemotherapy and radiation treatment
Nutritional TherapyObjectives of medical nutrition therapy are to:
Minimize tissue wasting and weight lossProtein and energy needs are considerable to prevent
tissue wasting and weight loss.Correct nutritional deficienciesHelp people maintain their strength and immune
functionProvide a diet that can be tolerated and enjoyed
despite the complications of illness
Nutrition TherapyNutrition therapy depends on the type and
severity of cancer, side effects of treatment and patient’s nutritional status
In addition, factors may interfere with eating
Nutrition TherapyEnteral (tube) and parenteral (intravenous) nutrition
supportTube feedings and intravenous nutrition not routinely
recommended for adequately nourished or mildly malnourished people with cancer who are able to eat
However, these approaches help to maintain nutrition status when anorexia persists or when a patient is severely malnourished and is about to undergo aggressive cancer therapy
Each case is decided individually
Nutrition TherapyNutrition support for bone marrow transplants
People undergoing a bone marrow transplant routinely receive total parenteral nutrition (TPN) before and after the transplant because the GI tract is severely compromised by the preparatory procedure
When GI function return, the patient begins to receive foods orally along with TPN, whenever possible
As oral intake improves, TPN is gradually tapered off