Diet and Health

1. Chapter 11 Diet and Health Photo courtesy of the USDA

2. Introduction Infectious diseases • Bacteria, viruses, parasites, and other microbes • Vaccines and antibiotics have made them less of a risk Degenerative diseases • Lifestylediseases, or the diseases of age • Chronic, irreversible diseases characterized by degeneration of body organs

3. Introduction • Degenerative diseases far outrank infections as the leading cause of death and illness-in developed nations • Degenerative diseases occur as people age from a mixture of risk factors • Genetic predisposition • Environmental factors • Personal medical history • Lifestyle choices that in the later years can make the difference between a life of health or chronic disability

6. Lifestyle Choices and Risks of Degenerative Disease • The exact contribution diet makes to each disease is hard to estimate • Many experts believe that diet accounts for about a third of all cases of coronary heart disease • The links between diet and cancer incidence are harder to estimate • Tobacco, effects everyone’s health

7. Cardiovascular Diseases • Atherosclerosis (hardening of the arteries) • The most common form of cardiovascular disease (CVD) • Characterized by plaques along the inner walls of the arteries • Plaques damage artery walls making them rigid and narrowing the passage through them • Most people have well-developed plaques by the time they reach age 30

8. Cardiovascular DiseasesAtherosclerosis • Damage may begin from a number of factors interacting with the lining of the arteries • High LDL cholesterol • Diet high in saturated fat • Hypertension • Toxins from cigarette smoking • Elevated blood levels of the amino acid homocysteine • Or viral or bacterial infection

9. Cardiovascular Diseases • Arteries hardened and narrowed by plaques cannot expand • Blood pressure rises & damages the artery walls and strains the heart • As pressure builds the artery wall may become weakened and balloon out, forming an aneurysm • Can burst and lead to bleeding and death

10. Cardiovascular Diseases • Abnormal blood clotting is a symptom of CVD • Arterial damage, plaques in the arteries, and the inflammatory response can lead to the formation of blood clots • A clot may attach to a plaque in an artery and grow until it shuts off the blood supply to the surrounding tissue (thrombosis) • Or a clot can break loose becoming an embolus if it lodges in an artery of the heart it causes a heart attack, if it lodges in an artery of the brain, it causes a stroke • A diet that has omega-3 fatty acids (EFA) may reduce clot formation

11. Cardiovascular Diseases • Hypertension and atherosclerosis worsen CVD • A stiffened artery is strained by each pulse of blood through it (high internal pressure) • Hardened arteries cannot expand, the heart’s beat raises blood pressure • Hardened arteries also fail to let blood flow freely through the kidneys, which control blood pressure

12. Risk Factors for CVD • Age, Gender, and Family History • Men: age becomes a significant risk factor for heart disease at age 45 or older • Women: age becomes a significant risk factor after age 55 • After menopause, the rate of heart disease increases 2x-3x • Men die earlier of heart attacks than women • CVD kills more women than any other disease • Early heart disease in immediate family members is a major risk factor • The higher the LDL, the greater the risk • LDL carries cholesterol to the cells that line the arteries • HDL carries cholesterol away from the cells to the liver for other uses and disposal

14. Risk Factors for CVD • Hypertension • Chronic hypertension worsens CVD • The higher the blood pressure above normal, the greater the risk of heart attack or stroke • Hypertension injures the artery walls and accelerates plaque formation • Diabetes • A major independent risk factor for all forms of cardiovascular disease • In diabetes, atherosclerosis progresses rapidly • Obesity (especially central obesity) and Physical Inactivity • Elevates LDL cholesterol • Lowers HDL cholesterol • Worsens hypertension • Worsens diabetes

15. Reducing Risk Factors for CVD • Weight loss and physical activity • Lower LDL, Raises HDL (Sometimes) • Improve insulin sensitivity • Lower blood pressure • Routine physical activity • Strengthens muscles of the heart and arteries • Improves the heart’s response to everyday demands • Stimulates the development of new arteries to nourish heart muscle • An hour a day, as recommended by the DRI, benefits the heart

16. Increased Risk Factors for CVD Smoking • The more a person smokes, the higher the CVD risk • Smoking damages the heart and raises the blood pressure • Deprives body tissues of oxygen and increases heartbeats to deliver blood • Damages platelets making blood clots a risk • Toxins in cigarette smoke directly damage the lining of blood vessels increasing atherosclerosis risk • When people quit smoking the risk of heart disease begins to drop within a few months

17. Increased Risk Factors for CVD • Metabolic Syndromeaffects ≈47 million people in the U.S. • Central obesity • Abnormal blood lipids • Low HDL • High triglycerides • Elevated blood pressure • Elevated fasting blood glucose or insulin resistance

18. Risk Factors for CVD An Atherogenic Diet increases CVD risks • Diet high in saturated fats, trans fats, and cholesterol • Increases LDL cholesterol A diet that lowers the risk of CVD includes • Vitamins & minerals • Antioxidant phytochemicals • Omega-3 fatty acids • Viscous Fiber

20. Diet to Reduce CVD Risk • Controlling Dietary Lipids • Lowering intakes of saturated fat and trans fat lowers blood LDL cholesterol and reduces heart disease risk • Saturated fat, including trans fatty acids, should account for no more than 10% of calories • DRI recommends: the diet should contain no more that 35% of total calories from fat • Others recommend: no more than 30% of total calories from fat • Healthy people should limit cholesterol intake to 300 mg a day

21. Diet to Reduce CVD RiskRecommendations • Fish oils (omega-3 polyunsaturated fatty acids) • Lower triglycerides • Prevent blood clots • The American Heart Association recommends at least 2 servings of fish per week • Plant sources of essential fatty acids also offer benefits on the heart • Flaxseed, canola, soybean oils • Flaxseed and nuts • When diets consists mostly of unsaturated fats with abundant fish, fruits, vegetables and low fat milk blood cholesterol and the rate of death from heart disease is low

22. Diet to Reduce CVD RiskRecommendations • Fiber and Phytochemicals • The viscous (soluble) fiber of oats, barley, legumes, and pectin-rich fruits and vegetables helps to improve blood lipids • Foods rich in viscous fiber provide • Minerals to help control blood pressure • Antioxidants to help protect against LDL oxidation • Vitamins and minerals

23. Diet to Reduce CVD Risk • Alcohol (moderate consumption) • Research on middle-aged and older people who drink one or two drinks a day with no binge drinking supports the idea that moderate consumption of alcohol will reduce their CVD risk • Alcohol (heavy use) more than three drinks a day: • Elevates blood pressure • Damages heart muscle • Elevates the risk of stroke • Heart attacks among healthy young people have been associated with alcohol intoxication from heavy weekend drinking • the risks from alcohol outweigh any benefit to the heart

24. Diet to Reduce CVD Risk • Other Dietary Factors • Sterol and stanol esters • Block absorption of cholesterol from the intestine • Dropping blood cholesterol by about 7%-10% • The effect may be as powerful as some medication in lowering blood LDL cholesterol • Can reduce the absorption of some potentially beneficial phytochemicals • Pharmaceutical doses of a specific form of niacin act like a drug in lowering blood cholesterol • The “statin” drugs lower blood LDL, work best in association with a cholesterol-lowering diet and exercise

26. Nutrition and Hypertension • Chronic high blood pressure (hypertension) is the most common forms of CVD • Affects one-third of the entire U.S. adult population • For people age 65 or older, the lifetime risk of approaches 90% • Contributes to half a million strokes and over a million heart attacks each year • Ideal resting blood pressure is 120/80 • 130/85 can be considered borderline normal • In the absence of other risk factors • Above this level the risks of heart attacks and strokes rise

27. High Blood Pressure • Risk Factors • Atherosclerosis, obesity, and insulin resistance • Excess fat means miles of extra capillaries through which blood must be pumped • Age • Most people who develop hypertension do so in their 50s and 60s • Genetics • A family history of hypertension and heart disease raises the risk of developing hypertension 2x-5x • Environment Africans living in Africa have a much lower rate of hypertension than African Americans living in the U.S.

28. How Does Nutrition Affect Hypertension? • Nutrition factors for lowering blood pressure • Lower salt intake • If overweight, lose weight • Moderate alcohol use • Increase intakes of fruit, vegetables, fish, and low-fat dairy products • Reduced intake of fat • Consume calcium, potassium, magnesium • Increase physical activity

29. How Does Nutrition Affect Hypertension? • DASH (Dietary Approaches to Stop Hypertension) and other similar diets consistently improve blood pressure • Recommends significant increases in fruit and vegetable intakes • Provides 30% of its calories from fat • Emphasizes legumes over red meats • Restricts sodium • Meets other recommendations of the Dietary Guidelines for Americans

30. How Does Nutrition Affect Hypertension? A high dietary intake of salt and sodium is associated with hypertension • For people with hypertension, a lower salt (or sodium) intake often leads to a reduction in blood pressure, and reduced or no blood pressure medication • Salt-sensitive people often: have a family history of hypertension, are African American, have kidney problems or diabetes, are older, have experienced sustained psychological stress

31. How Does Nutrition Affect Hypertension? • Salt, Sodium, and Blood Pressure • People who consistently consume diets low in sodium have lower blood pressure than people with higher intakes • Recommendation: everyone should moderately restrict salt and sodium intake to DRI committee’s UL/ No more than 2,300 mg of sodium per day

32. How Does Nutrition Affect Hypertension? • Alcohol • In moderate doses, at first relaxes the peripheral arteries and reduces blood pressure • High doses raise blood pressure • Hypertension is common among people with alcoholism • Hypertension caused by alcohol leads to CVD • Alcohol may cause strokes • The Dietary Guidelines for Americans recommends moderation for those who drink alcohol • No more than one drink a day for women • No more that two drinks a day for men

33. How Does Nutrition Affect Hypertension? • Calcium, Potassium, and Magnesium • Increasing calcium often reduces blood pressure • Potassium and magnesium appear to help prevent and treat hypertension • Lowpotassium diets are associated with hypertension • Magnesium deficiency causes the walls of arteries and capillaries to constrict and may raise blood pressure

34. How Does Nutrition Affect Hypertension? • Vitamin C and other nutrients • Adequate vitamin C seems to help normalize blood pressure while vitamin C deficiency may tend to raise it • Other dietary factors that affect blood pressure • Cadmium, selenium, lead, caffeine, protein, and fat are being studied

35. How Does Nutrition Affect Hypertension? Dietary recommendations to keep blood pressure low DASH diet often reduces blood pressure A low-fat diet with abundant fruits, vegetables, and low-fat dairy products that provide the needed nutrients while limiting sodium intake If diet and exercise fail to reduce blood pressure, drugs as diuretics and other antihypertensive agents may be prescribed

36. Nutrition and Cancer • Cancer ranks second only to heart disease as a leading cause of death and disability in the U.S. • Genetics exerts a modest risk on cancer development • Lifestyle and environmental factors play a role in the development of cancer • Lack of physical activity plays a role in the development of colon and breast cancer • If everyone in the U.S. quit smoking future cancers would probably drop by a third • Another 15% may be preventable by preventing overweight and obesity

37. How Does Cancer Develop? • Cancer is really a disease of the genes • Cancer begins with one healthy cell whose genetic material sustains damage from a carcinogen (cancer-causing substance) • such as a free-radical compound, radiation or other influences • Damage to a cell’s DNA occurs every day • But most of the damage is quickly repaired if the damage cannot be repaired and the cell becomes unable to replicate its genome, the cell usually self-destructs • Occasionally, a damaged cell loses its ability to self-destruct and also loses the ability to stop reproducing • The result is a tumor

38. How Does Cancer Develop? Cancer develops through the following steps • Exposure to a carcinogen • Entry of the carcinogen into a cell • Damages to the cell’s genetic material • Cells begin to multiply out of control

39. 0 Dietary Factors and Cancer • Low rates of many cancers correlate with high intakes of fruits, vegetables, and whole grains • Under study for possible effects dietary effects on cancer are: Excess calories, diets high in certain fats, daily use of alcohol, vitamins and minerals, diets in which meat plays a dominant role • In studies with humans, evidence is mixed as to whether a diet high in fat promotes cancer • Comparisons among world populations reveal that high-fat diets often correlate with high cancer rates (direct relationship)

40. Dietary Factors and Cancer • Dietary fat tends to oxidize when exposed to high cooking temperatures • They may trigger cancerous changes in the tissues of the colon and rectum • The type of fat in the diet may be important • Some evidence implicates omega-6 polyunsaturated fatty acids promote cancer • Some evidence suggests that omega-3 fatty acids from fish may protect against some cancers

41. Dietary Factors and Cancer • Alcohol • Cancers of the head and neck correlate strongly with the combination of alcohol and tobacco use • Alcohol intake alone is associated with cancers of the mouth, throat, and breast • Alcoholism often damages the liver and effects the development of liver cancer

42. Dietary Factors and Cancer … • Smoked, Grilled, and Well-Done Meats • Red meat may be linked to an elevated risk of developing cancer of the rectum and colon • Chemical reactions during the browning of meat at high temperatures, in pan-frying, broiling, or grilling formcarcinogens in the food

43. Dietary Factors and Cancer • Fiber and Fluid • Epidemiological studies often report links between eating plenty of fruits and vegetables and a low incidence of many cancers • A theory is that a fiber-rich diet may protect against some cancers by: • Increasing stool weight, diluting the colon’s contents, stimulating bacterial fermentation, and speeding up the transit time of materials through the colon • This limits exposure of the colon walls to cancer-causing substances in the feces

44. Dietary Factors and Cancer • Bladder cancer may be related to intake of fluids • Men who drink about 10 cups of fluid a day develop substantially less bladder cancer than those drinking only about half this amount • A greater fluid intake dilutes the carcinogens that naturally form in urine and causes more frequent urination

45. Dietary Factors and Cancer • Folate deficiency seems to increase risk of cancers of the cervix and colon • Vitamin A • Helps to maintain the immune system • Identifies cancerous cell and destroys them • Vitamin D and exposure to sunshine have been suggested as protective against cancers • Except skin cancer • Calcium • Laboratory evidence suggests that a high-calcium diet may help to prevent colon cancer • Taking supplements has not been proved to prevent or cure cancer

46. Dietary Factors and Cancer … • A literature review since 1990 showed an association between colon cancer and increased dietary iron intake and highiron stores • Iron is a powerful oxidizing substance • Oxidation may damage DNA and may initiate cancer • Iron supplements are constipating • Constipation raises a person’s risk of colon cancer • Meat is high in iron • High-meat diets often directly correlate with colon cancer • If the iron and cancer link holds up the benefits of iron enrichment to iron-deficient populations must be weighed against the harm to those at risk for colorectal cancer

47. Dietary Factors and Cancer … • Foods and Phytochemicals • The phytochemicals in some fruits and vegetables are thought to be anticarcinogens • Some of these may protect against cancer by acting as mild toxins that force the body to build up carcinogen-destroying enzymes

48. Dietary Factors and Cancer Population studies find that diets lacking in green and yellow fruits and vegetables and citrus fruits correlate with cancers of many types (inverse relationship) • Some evidence suggests that a number of antioxidant nutrients and phytochemicals from a diet rich in fruits, vegetables, and whole grains may be necessary to minimize DNA damage from certain types of radiation • A low intake of fruits and vegetables may leave cells unprotected against DNA damage • Eating few cruciferous vegetables - broccoli, Brussels sprouts, cabbage, cauliflower, turnips, etc. - is common in colon cancer victims

49. Dietary Factors and Cancer • Foods that contain phytochemicals are believed to promote health and fight diseases • Such foods are called functional foods • Functional foods are any modified food or food ingredient that may provide a health benefit beyond the traditional nutrients it contains.