BPK 110 Human Nutrition: Current Concepts

Transcription

1 BPK 110 Human Nutrition: Current Concepts Lecture 11a 1. Nutrition & Hypertension 2. Nutrition & Cancer

2 Learning Objectives To understand and explain what is hypertension plus its dietary and non-dietary causes To understand and explain how dietary changes including the DASH can help to reduce hypertension To understand the link between atherosclerosis and hypertension To understand and explain how hypertension can be reduced by an exercise intervention To understand and clearly describe how cancer is thought develop To understand and clearly describe how cancer is influenced positively and negatively by diet 2

3 1) Hypertension and Nutrition a) hypertension (é blood pressure): a symptom-less form of CVD ~19% of Canadians are hypertensive; males 19.7%, females 19.0% (Wilkins et al Health Reports, 2010) worldwide, 54% of strokes & 47% of coronary artery diseases attributable to hypertension (Lawes et al., Lancet, 2008) b) Hypertension Criteria BP = systolic/diastolic ratio (mm Hg/mm Hg) <120/<80 normal /85-89 high normal, /90-99 mild hypertension / moderate hypertension 180 / 110 severe hypertension

4 Pumping pressure from the heart artery Start of capillary. Fluid can cross the thinner walls. End of capillary. Fluid flows back in. Blood pressure forces the fluid across the wall at the start of the capillary. Small molecules, oxygen, glucose, amino acids, and salts move out with the water. Fluid is being forced into tissues by blood pressure. Blood proteins and cells remaining are becoming more concentrated. Blood pressure is decreasing. Blood is now so concentrated that it attracts fluid back into the capillary. Small molecules (waste products) accompany the fluid. vein The pressure that draws fluid back into the capillary is osmotic pressure.

5 1) Hypertension and Nutrition Cont c) Blood Pressure Regulation Why? to perfuse tissues with blood & supply O 2 kidneys are involved in BP regulation fxn to or fluids as needed to maintain BP & volume a normal blood volume, assuming normal arteries, helps give normal BP too BP?: kidneys help to lose H 2 0 & sodium + dilate arteries: all to BP too BP?: kidneys help to conserve H 2 0 & sodium + help constrict arteries: all to BP if obstructed & stiff as w/ arteries in atherosclerosis kidneys receive blood & perceive too BP puts into action hormones & other changes to BP

6 1) Hypertension and Nutrition Cont d) Risk factors for Hypertension: Primary Risk Factors: (i) atherosclerosis (ii) insulin resistance/type II diabetics (iii) obesity (especially central fat) = vascular resistance congestive heart failure/aneurysms/stroke also kidney damage b/c not enough blood supply Secondary Risk Factors: Heredity, Age, (2 to 5 x risk), African American Decent = H + A + AAD

7 1. Nutrition & Hypertension Cont Ø almost universal acceptance: improved diet & exercise helps control hypertension e) Salt (sodium)=direct relationship between salt intake & BP salt intake hypertension for 50% or salt sensitive group group often has/is: familial hypertension/kidney problems/ African American/ diabetic/stressed out/older conflicting results on BP prevention with dietary salt intake generally accepted best to salt to 1500 mg/d of sodium.

8 1. Nutrition & Hypertension Cont f) Weight Control, Exercise & BP? exercise with weight loss i.e. FITT = BP relaxing, stress hormones (epinephrine & norepinephrine) BP g) Alcohol & BP moderate intake = BP; intake = BP For those who drink maximum of: 2 drinks/day 1 drink/day alcoholics commonly have hypertension

9 1) Hypertension and Nutrition Cont h) Dietary Ca, Mg, K, Vit C i. Ca foods = BP; also possible in salt sensitive & salt diet mxn unclear; related to b.v. constriction ii. Potassium (K) & Magnesium (Mg) iii. Vit C: Vit C appears to give BP normal Vit C level thought to normalize BP iv) Dietary advice for maintain normal BP? Fruits K in diet associated with hypertension K prevents, corrects hypertension Mg = constrict. of arterial/capillary walls: BP fat /salt in food & Ca foods (e.g. dairy) fruits & veggies for K, Mg & Vit. C Milk

10 1) Hypertension and Nutrition Cont j) Dietary Approaches to Stop Hypertension (DASH) Table 11-5 The DASH Eating Plan 2 x (fruits & veggies)

11 2. Nutrition & Cancer a) Epidemiology and Background 1/4 US or Canadians die from cancer 20-50% of these attributed to diet cancer rates linked to: dietary fat, alcohol, intake fruits/veggies non-diet factors also related to cancer; genetics/lifestyle foods may be promoting or preventing cancer Japanese born in Japan vs. Japanese born in USA stomach & colon cancer- in USA-environment/diet?

12 Table 11-8 Factors Associated with Cancers at Specific Sites

13 2. Nutrition & Cancer Cont b) 4 Steps: General Mechanism of Cancer Development (i) Exposure to & entry of carcinogen (invisible) into normal cells. Malignant cells Normal cells (ii) Initiation by carcinogen that damages a cell s DNA; cell multiplies, passing on the damage. (iii) Promoters enhance development of tumors which may be noncancerous (benign) or cancerous (malignant) when tumor has uncontrolled cell division (iv) Cancerous tumor releases tiny clumps of cells into the bloodstream or lymph (metastasis)

14 2. Nutrition & Cancer Cont c) Diet & Cancer Reduction good diet may colon/prostate/pancreas/ breast cancers x 50% fiber diet (fruits/veggies/whole grains) = cancer rates e.g. vegetarians: cancer death rates d) Fat & Fatty Acids saturated fats: cancer rates lymph & GI organs fat vs. fat diets: fat = cancer rates in lab animals carcinogen exposure + fat diet needed to = cancer rate 30% fat recommended breast cancer thought to be unrelated to fat intake

15 2. Nutrition & Cancer Cont e) Alcohol & Smoked Meats alcohol & tobacco + intake of green & yellow veggies/fruits linked cancers of head & neck alcohol alone cancers of mouth, throat, breast, liver smoke from burning wood/charcoal/ tobacco has carcinogens, especially polycyclic aromatic hydrocarbons smoked, grilled, charbroiled or browned foods enters carcinogens into GI normally these are treated by immune system 20 yr/13 country study: diets red meat correlated with risk of colon cancer

16 2. Nutrition & Cancer Cont f) Food Energy (E) animals studies show: calories = cancer rates all combos macronutrients mxn(s) unclear: maybe adrenal hormones released with E intakes causes inflammation & (+) tumor growth Ø vegetarians have fat fiber diets & cancer rates g) Fiber & Fluid: transit time from mouth to biffy fiber = colon/rectum cancer & fluid = bladder cancer Mxn for fiber colon/rectum cancer thought to be by: + + bile excretion absorbing toxins & carrying them out of body generating beneficial hormone fragments in colon scavenging free-radical in feces stimulating body s immune system

17 2. Nutrition & Cancer Cont h) Vitamins & Minerals i) Vitamins as anti-oxidants Vit E, C, ß-carotene have cancer fighting effects (Controversy 7 for ß-carotene) ii) Vits as anti-promoters: phytochemicals Vits & minerals may act as anti-promoters; they produce mild toxins forcing body to carcinogen destroying enzymes iii) Minerals calcium diet may colon cancer

18 2. Nutrition & Cancer Cont i) How Does Cancer Develop? Cancer arises in the genes. DNA is damaged by a carcinogen. Cellular repair or self-destruction Cell loses ability to self-destruct Replicates uncontrollably Mass of abnormal tissue Cancer prevention through tumour formation 18

19 2. Nutrition & Cancer Cont j) Mxns of Cancer & Dietary Fat? Conflicting results cooking food tends to oxidize it could rectal & colon cancers fat intake may hormone secretions promoting cancers microbes in GI may convert bile to carcinogens

20 BPK 110 Human Nutrition: Current Concepts Summary Lecture 11a 1. Nutrition & Hypertension 2. Nutrition & Cancer