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Fruits and Vegetables – The Real Thing Matters! Being Fit with Phytochemicals

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  1. Fruits and Vegetables – The Real Thing Matters!Being Fit with Phytochemicals Mollie Smith, MS, RD California State University, Fresno Department of Food Science and Nutrition

  2. Objectives • What are phytochemicals? • Where are they found? • What are the health benefits? • Are there any risks? • What are functional foods and how are they regulated? • What do we tell consumers?

  3. Definition of Phytochemicals • Biologically active chemical compounds found in plants • Not nutrients like vitamins or minerals • Believed to have health benefits especially related to heart disease and cancer

  4. Consumers often read exciting headlines about potential health benefits from eating foods that contain phytochemicals • Store shelves are overflowing with such supplements alongside functional foods whose labels often make fantastic claims for their health-promoting powers

  5. How Scientists View Phytochemicals in Foods • Some phytochemicals have profound effects on the body through actions such as • Acting as antioxidants • Mimicking hormones • Altering blood constituents in ways that may protect against some diseases

  6. Phytochemicals And Functional Foods • Some Cautions • Foods consist of thousands of different chemicals • Each has the potential of being beneficial, neutral, or harmful to the body • Some may be beneficial in some ways and harmful in others • Some chemicals may exert different effects on different people or when taken at differing doses or at different life stages

  7. Is More Better? Choose Food First Avoid Overdosing Avoid Self Prescribing

  8. Phytochemicals And Functional Foods • Research on phytochemicals is in its infancy • What is current today will likely be challenged a year from now by further studies • In most cases, the health benefits observed with intakes of certain foods cannot be ascribed to individual phytochemicals • Much less to purified supplements of them

  9. Phytochemicals And Functional Foods • Currently, the evidence is insufficient to say with any degree of certainty whether any phytochemical is effective in fighting diseases or if it is safe to consume in concentrated doses

  10. Whole Foods, Wine, and Tea • Epidemiological evidence spanning many countries indicates that deaths from cancer, heart disease, and heart attacks are less common where these foods are plentiful in the diet, where tea is a beverage, or where red wine is consumed in moderation

  11. Phytochemicals • Whole Foods, Wine, and Tea • Historically, diets containing whole grains, fruits, vegetables, herbs, spices, teas, and red wines have been reputed to possess health-promoting qualities • These foods and beverages all have something in common • Phytochemicals of the flavonoid family

  12. Flavonoids • Many flavonoids act as antioxidants • May protect against cancers and heart disease by this mechanism • More evidence is needed before any claims can be made for flavonoids themselves as the protective factor in foods • Particularly when they are extracted from foods or herbs and sold as supplements

  13. Why are antoxidants important? • free radicals are molecules missing electrons: unstable • formation of 1 free radical causes a chain reaction with many free radicals formed • antioxidants prevent formation of free radicals or break the chain reaction by becoming oxidized

  14. Antioxidants, con’t • Harmful effects from uncontrolled free radicals • oxidation of lipids in cell membrane • oxidation of DNA in cell nucleus • ? cause of cancer • ? cause of heart disease • ? inflammatory diseases • ? part of aging process

  15. Antioxidants • Because flavonoids often impart a bitter taste to food, food producers may refine away natural flavonoids to please consumers who generally prefer milder flavors • To produce white grape juice or white wine, makers remove the red, flavonoid-rich grape skins to lighten the flavor and color of the product • While greatly reducing its flavonoid content

  16. Antioxidants • Whether or not research confirms the cancer-fighting and heart-defending nature of flavonoids, consumers should seek out a variety of whole fruits, vegetables, and other plant-derived foods with their flavonoids intact in place of their more refined counterparts • Such diets are consistently associated with low rates of disease

  17. Antioxidants • Flavonoid supplements have not been proved effective or safe • As for red wine, the potential health benefits may not be worth alcohol’s immediate and substantial risk • Other sources: • Blueberries • Tea • Grapes • Vegetables

  18. Tea • Black- most often sold, fermented and more processed • Oolong- semi-fermented, heated and dried more than green tea but less than black, served in Chinese restaurants • Green- unfermented, very little processing • White- unfermented, very little processing, harvested before leaves are fully open

  19. Tea • Calorie Free • 87% of dietary flavonoids consumed • Antioxident polyphenols including flavonoids • Catechin • EGCG • Proanthocyanidins

  20. Tea’s effect on Heart Disease • Lower blood pressure • Lower cholesterol • Black tea may lower LDL cholesterol • Improved blood flow and blood vessel function

  21. Cancer • Protects against free radical damage • Decrease growth of abnormal cells • Associated with decreased risk of rectal, colon and skin cancer

  22. Other Benefits • Memory • Immune function • Oral health • Decreased risk of kidney stones • Obesity • Mostly epidemiological research and research on tea consumption, concentrated tea extracts may not be safe

  23. Antioxidants • Chocolate • Research subjects were instructed to eat three ounces of dark (bittersweet) chocolate chips • Flavonoid antioxidants from chocolate accumulate in the blood • The level of certain harmful oxidizing compounds dropped 40% • The antioxidant effects of dark chocolate may turn out to be as powerful as those of tea or red wine

  24. Chocolate • In theory, chocolate may also “thin the blood” by reducing the tendency of blood to clot • Blood clots are a major cause of heart attacks and strokes • No evidence exists to indicate that people who eat chocolate suffer fewer heart attacks or strokes than people who do not

  25. Chocolate • Chocolate consumption promotes weight gain • Three ounces of sweetened chocolate candy contain over 400 calories • A significant portion of most people’s daily calorie allowance • Chocolate contributes few nutrients save fat and sugar

  26. Antioxidants • For most people, antioxidant phytochemicals are best obtained from nutrient-dense low-calorie fruits and vegetables and calorie -free green or black tea • With chocolate enjoyed as an occasional treat

  27. Soybeans • Compared with people living in the West, Asians living in Asia suffer less frequently from: • osteoporosis • cancers, especially of the breast, colon, and prostate • heart disease • Asian women also suffer less from symptoms related to menopause

  28. Soybeans • When Asians migrate to the U.S. and adopt Western diets and habits they experience these disease and problems at the same rates as native Westerners • Among many differences between the diets of the two regions • Asians consume far more soybeans and soy products such as miso, soy drink, and tofu than do Westerners

  29. Soybeans • Soybeans contain phytochemicals known as phytoestrogens • Researchers suspect that the phytoestrogens of soy foods, their protein content, or a combination of these factors may be responsible for the health effect in soy-eating peoples • Research, though ongoing, is limited and inconsistent

  30. Soybeans • We know with certainty that phytoestrogens are plant-derived chemical relatives of the human hormone estrogen • They weakly mimic or modulate the hormone’s effects on some body tissues • They act as antioxidants

  31. Soybeans • We know that breast cancer, colon cancer, and prostate cancer are estrogen-sensitive • They grow when exposed to estrogen • It is unknown if actions of phytoestrogens may alter the course of estrogen-sensitive cancers • Results from recent breast cancer studies do not support the idea unless soy is consumed beginning in childhood

  32. Soybeans: genistein • Symptoms of menopause • Phytoestrogens may reduce risk of adult bone loss and the sensation of elevated body temperature known as “hot flashes” • A diet high in soy may offer bone protection rivaling that of hormone replacement therapy (HRT) • May not reverse bone loss but may prevent it

  33. Soybeans • Because HRT involves some serious health risks, supplements of soy are often sold to menopausal women as a “natural” alternative • Research does not support taking phytoestrogen supplements for bone mineral retention or hot flashes

  34. Soybeans • Phytoestrogen supplement use may involve some risk • While studying one soy phytoestrogen, genistein, researchers found that instead of suppressing cancer growth, high doses appeared to speed division of breast cancer cells in laboratory cultures and in mice

  35. Heart Disease • 1999: FDA approved claim that 25 gm of soy protein per day may reduce your risk of heart disease • 2000: AHA endorsed soy as a heart healthy food • Research supports LDL lowering effect of soy, better effect in divided doses • 2006: AHA reevaluating endorsement due to conflicting research

  36. Soybeans • Findings on the health effects of phytoestrogens should raise a red warning flag against taking supplements • Especially in women whose close relatives have developed breast cancer • Until more is known, a safer route to obtaining soy phytoestrogens is to include moderate amounts of soy-based foods in the diet • As generations of Asian people have safely done through the ages

  37. Make meat and poultry choices that are low fat or lean • Choose a variety of types of protein foods including fish, dry beans and peas, nuts and seeds • Consider dry beans and peas as an alternative to meat or poultry • To provide a variety of nutrients in the diet including vitamin E while keeping saturated fat and cholesterol low

  38. Flaxseed Historically, people have used flaxseed for relieving constipation or digestive distress • Currently, flaxseed and its oil are under study for potential health benefits • Contains lignans, compounds converted into biologically active phytoestrogens by bacteria that normally reside in the human intestine

  39. Flaxseed • Studies of populations suggest that women who excrete more phytoestrogens in the urine (an indicator of phytoestrogen intake from flaxseed and other sources) have lower rates of breast cancer • Animal studies show a decrease in tumors of the breast and lung when fed flaxseed

  40. Flaxseed • Studies of the direct effects of giving flaxseed to people are lacking • Some risks are possible with its use • Flaxseed contains compounds that may interfere with vitamin or mineral absorption • Thus high daily doses could cause nutrient deficiency diseases • Large quantities can cause digestive distress

  41. Flaxseed • Although no clear role has been established for flaxseed in the prevention of human cancer • Including a spoonful or two of flaxseed in the diet may not be a bad idea • Flaxseed richly supplies linolenic acid • A needed nutrient often lacking in the U.S. diet

  42. Choose most fats from sources of monounsaturated and polyunsaturated fatty acids • Keep the amount within calorie needs • Choose more fish, nuts and vegetable oils • Use lean meats and low fat dairy products • Limit saturated and trans fats • To provide essential fatty acids and vitamin E while keeping calories controlled and cholesterol and saturated fat low

  43. Tomatoes • People around the world who eat the most tomatoes, about 5 tomato-containing meals per week, are less likely to suffer from cancers of the esophagus, prostate, or stomach than those who avoid tomatoes

  44. Tomatoes • Among the phytochemical candidates for promoting this effect is lycopene • A red pigment with antioxidant activity • Found in guava, papaya, pink grapefruit, tomatoes (especially cooked tomatoes and tomato products), and watermelon