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General information on common phytochemicals in food

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  1. 1. PHYTOCHEMICALS IN FOODS Elisha Gay C. Hidalgo, RND
  2. 2. What are Phytochemicals? • Phytochemicals are chemicals found in plants. • They are chemical substances obtained from plants that are biologically active but not nutritive. • Phytochemicals (also called phytonutrients) are the powerhouse natural chemicals inside plants, which basically give the plants protection against disease and but which also have disease-preventing properties in humans too.
  3. 3. Phytochemical Evolution • These naturally occurring compounds are believed to protect plants from a variety of injurious agents, including insects and microbes, the oxygen they produce, and the UV light they capture and transform into the nutrients we need.
  4. 4. The Phytochemical Revolution • Since the 1970s, increasing numbers of studies are finding associations between the food people eat, their health, and their life expectancy. In the '70s, concerns focused on the role of dietary cholesterol in causing heart disease and cancer. • During the 1980s and 1990s, numerous laboratories began studying phytochemicals to "mine" plants for bioactive substances that might be used as medicines (nutriceuticals) or for other chemical applications. Many compounds are showing great promise as disease fighters in the body, boosting production or activities of enzymes, which then act by blocking carcinogens, suppressing malignant cells, or interfering with the processes that can cause heart disease and stroke.
  5. 5. The Phytochemical Revolution • Hundreds of studies from around the world have established that diets high in plant-based foods are associated with lower rates of cancer and heart disease, sometimes astonishingly so. • Phytochemical use comes with a caution sign, however. These compounds aren't always beneficial under all circumstances or in high doses. Certain biochemicals and vitamins, at least as provided in supplements, have been found to encourage the growth of cancer cells and their use is being discouraged in patients undergoing cancer treatments. • As they occur naturally in plant foods, phytochemicals promise to create an entirely new philosophy of "functional foods," eating not just to sustain minimal basic health but also eating to prevent disease. In the future, we may tailor our diets to include the foods that will best address our personal health problems and risks as well as maintain optimal health.
  6. 6. How do phytochemicals work? • Antioxidant - Most phytochemicals have antioxidant activity and protect our cells against oxidative damage and reduce the risk of developing certain types of cancer. Phytochemicals with antioxidant activity: allyl sulfides (onions, leeks, garlic), carotenoids (fruits, carrots), flavonoids (fruits, vegetables), polyphenols (tea, grapes). • Hormonal action - Isoflavones, found in soy, imitate human estrogens and help to reduce menopausal symptoms and osteoporosis. • Stimulation of enzymes - Indoles, which are found in cabbages, stimulate enzymes that make the estrogen less effective and could reduce the risk for breast cancer. Other phytochemicals, which interfere with enzymes, are protease inhibitors (soy and beans), terpenes (citrus fruits and cherries).
  7. 7. How do phytochemicals work? • Interference with DNA replication - Saponins found in beans interfere with the replication of cell DNA, thereby preventing the multiplication of cancer cells. Capsaicin, found in hot peppers, protects DNA from carcinogens. • Anti-bacterial effect - The phytochemical allicin from garlic has anti-bacterial properties. • Physical action - Some phytochemicals bind physically to cell walls thereby preventing the adhesion of pathogens to human cell walls. Proanthocyanidins are responsible for the anti-adhesion properties of cranberry. Consumption of cranberries will reduce the risk of urinary tract infections and will improve dental health.
  8. 8. SYNERGY: Phytochemicals work in groups • Most phytochemicals need to work with other phytochemicals to produce the desired effect on health. • The optimal combination for different types of phytochemicals is not known yet.
  9. 9. Why Is There No RDA for Phytochemicals? • Phytochemicals interact with each other in the body to produce a synergistic effect that is greater than the sum of the effect of individual phytochemicals. • Phytochemicals interact with macronutrients and vitamins and minerals. • Phytochemicals can act in different ways under different circumstances in the body. • For these reasons, no RDA for Phytochemicals can safely be established for any life stage group.
  11. 11. CAROTENOIDS: What are They?
  12. 12. • Bioactive food components in plants; found in the colorful section of the plant. • CAROTENOIDS MEASURED IN HUMANS: beta-carotene, alpha-carotene, lycopene, lutein, and beta-cryptoxanthin. • Helps prevent cancer • “Eat by the rainbow”
  13. 13. • A pigment is any substance that absorbs light. The main pigments responsible for the initiation of photosynthesis are chlorophylls and carotenoids which absorb light in different regions of the visible spectrum. And these pigments, as you already know are embedded in the thylakoid membranes of the chloroplasts.
  14. 14. • Carotenoids are yellow, orange, and red pigments synthesized by plants. The most common carotenoids in North American diets are alpha-carotene, beta-carotene, beta-cryptoxanthin, lutein, zeaxanthin, and lycopene. • Alpha-carotene, beta-carotene, and beta-cryptoxanthin are provitamin A carotenoids, meaning they can be converted by the body to retinol (vitamin A). Lutein, zeaxanthin, and lycopene have no vitamin A activity. • At present, it is unclear whether the biological effects of carotenoids in humans are related to their antioxidant activity or other non-antioxidant activities. • Although the results of epidemiological studies suggest that diets high in carotenoid-rich fruits and vegetables are associated with reduced risk of cardiovascular disease and some cancers, high-dose beta-carotene supplements did not reduce the risk of cardiovascular diseases or cancers in large randomized controlled trials. • Two randomized controlled trials found that high-dose beta-carotene supplements increased the risk of lung cancer in smokers and former asbestos workers. • Several epidemiological studies found that men with high intakes of lycopene from tomatoes and tomato products were less likely to develop prostate cancer than men with low intakes, but it is not known whether lycopene supplements will decrease the incidence or severity of prostate cancer. • Lutein and zeaxanthin are the only carotenoids found in the retinaand lens of the eye. The results of epidemiological studies suggest that diets rich in lutein and zeaxanthin may help slow the development of age-related macular degeneration and cataracts, but it is not known whether lutein and zeaxanthin supplements will slow the development of these age-related eye diseases.
  15. 15. Chemical Structure of some Carotenoids
  16. 16. Health Claims: Diets with foods rich in these phytochemicals may reduce the risk of cardiovascular disease, certain cancers (e.g. prostate), and age-related eye diseases ( cataracts, macular degeneration).
  17. 17. Food Sources • Red, orange and deep-green vegetables and fruits such as carrots, cantaloupe, sweet potatoes, apricots, spinach,pumpkin and tomatoes.
  18. 18. Cooking Tips: • Carotenoids are best absorbed with fat in a meal. Chopping, puréeing, and cooking carotenoid-containing vegetables in oil generally increases the bioavailability of the carotenoids they contain.
  19. 19. Raw foods with carotenoids, is this more beneficial than cooked?
  20. 20. FLAVONOIDS: In the News
  21. 21. Flavonoids • Flavonoids are a large family of polyphenolic compounds synthesized by plants. • Many of the biological effects of flavonoids appear to be related to their ability to modulate cell-signaling pathways, rather than their antioxidant activity. It is not yet clear how flavonoid consumption affects neurodegenerative disease risk in humans. • includes flavones, flavonols, catechins, anthocyanidins, and isoflavonoids.
  22. 22. Basic Chemical Structure of a Flavonoid: Molecular structure of theflavone backbone (2- phenyl-1,4-benzopyrone)
  23. 23. Health Claims: Diets with foods rich in these phytochemicals may reduce the risk of cardiovascular disease and cancer , possibly because of reduced inflammation, blood clotting, and blood pressure, and increased detoxification of carcinogens or reduction in replication of cancerous cells.
  24. 24. Food Sources • Berries, black and green tea, chocolate, purple grapes and juice, citrus fruits, olives, soybeans and soy products, whole wheat
  25. 25. Flavonoid Subclass Dietary Flavonoids Some Common Food Sources Anthocyanidins Cyanidin, Delphinidin, Malvidin, Pelargonidin, Peonidin, Petunidin Red, blue, and purple berries; red and purple grapes; red wine Flavanols Monomers (Catechins): Catechin, Epicatechin, Epigallocatechin Epicatechin gallate, Epigallocatechin gallateDimers and Polymers: Theaflavins, Thearubigins, Proanthocyanidins Catechins: Teas (particularly green and white), chocolate, grapes, berries, apples Theaflavins, Thearubigins: Teas (particularly black and oolong) Proanthocyanidins: Chocolate, apples, berries, red grapes, red wine
  26. 26. Flavonoid Subclass Dietary Flavonoids Some Common Food Sources Flavanones Hesperetin, Naringenin, Eriodictyol Citrus fruits and juices, e.g., oranges, grapefruits, lemons Flavonols Quercetin, Kaempferol, Myricetin, Isorhamnetin Widely distributed: yellow onions, scallions, kale, broccoli, apples, berries, teas Flavones Apigenin, Luteolin Parsley, thyme, celery, hot peppers, Isoflavones Daidzein, Genistein, Glycitein Soybeans, soy foods, legumes
  27. 27. Nutrient Interactions: • Nonheme Iron Flavonoids can bind nonheme iron, inhibiting its intestinal absorption. Nonheme iron is the principal form of iron in plant foods, dairy products, and iron supplements. The consumption of one cup of tea or cocoa with a meal has been found to decrease the absorption of nonheme iron in that meal by about 70% . To maximize iron absorption from a meal or iron supplements, flavonoid-rich beverages or flavonoid supplements should not be taken at the same time. • Vitamin C Studies in cell culture indicate that a number of flavonoids inhibit the transport of vitamin C into cells, and supplementation of rats with quercetin and vitamin C decreased the intestinal absorption of vitamin C. More research is needed to determine the significance of these findings in humans.
  28. 28. Phenolic Acids • Phenolic acids are plant metabolites widely spread throughout the plant kingdom. Recent interest in phenolic acids stems from their potential protective role, through ingestion of fruits and vegetables, against oxidative damage diseases (coronary heart disease, stroke, and cancers). Phenolic compounds are essential for the growth and reproduction of plants, and are produced as a response for defending injured plants against pathogens. The importance of antioxidant activities of phenolic compounds and their possible usage in processed foods as a natural antioxidant have reached a new high in recent years. • Includes ellagic acid, ferulic acid, caffeic acid, curcumin
  29. 29. Chemical Structure Phenol - the simplest of the phenols. Caffeic acid
  30. 30. Health Claims: Phenolic acids have mild anti-inflammatory properties and are potent antioxidants. Antioxidants help prevent cancer and injury to blood vessels. Similar to flavonoids.
  31. 31. Food Sources: Tea, Coffee, Berries, Fruits (mangoes, grapes, strawberries, apples, mangoes), potatoes, mustard, oats and soy
  32. 32. Reminder: Phenolic acids found in coffee act as antioxidants and are good. Studies show a cup or two of coffee is beneficial but too much caffeine may not be healthy.
  33. 33. PHYTOESTROGENS • Their name comes from phyto = plant and estrogen = estrus (period of fertility for female mammals) + gen = to generate. • plant-derived compounds with estrogenic activity; • These compounds in plants are an important part of their defense system, mainly against fungi. • Includes: genistein, diadzein, and lignans.
  34. 34. Chemical Structure
  35. 35. Health Claims: • Foods rich in these phytochemicals may provide benefits to bones and reduce the risk of cardiovascular disease and cancers of the reproductive tissues (e.g. breast, prostate)
  36. 36. Food Sources: • Nuts, oilseeds, soy and soy products, cereals and breads, legumes, flaxseed and whole grains.
  37. 37. Phytoestrogens and your Baby • Some researchers are most concerned about exposure of unborn fetuses and infants to high levels of phytoestrogens since development is highly controlled by hormones of the endocrine system. One study found that women eating a vegetarian diet during pregnancy have male offspring with an increased incidence of hypospadias (a birth defect in boys where the penis opening is not located in the normal position at the tip of the penis), possibly due to high maternal levels of soy isoflavones (North and Golding 2000). • Other studies show young adult men and women fed soy based formulas as infants had increased use of allergy medicines and women had longer menstrual bleeding and more discomfort during the menstrual cycle than their counterparts who were fed cow based formula (Goldman et al. 2001; Strom et al. 2001). • Some reviews express the opinion that more research is needed to answer the question of what effect phytoestrogens may have on infants, but their authors did not find any adverse effects. Multiple studies conclude there are no adverse effects in human growth, development, or reproduction as a result of the consumption of soy-based infant formula compared to conventional cow-milk formula.[While it should be noted that all infant formulas are inferior to human milk, soy formula presents no more risk than cow-milk formula.
  38. 38. ORGANOSULFUR COMPOUNDS • A member of a class of organic compounds with any of several dozen functional groups containing sulfur (S). • Includes allylic sulfur compounds, indoles, isothiocyanates, cysteine sulfoxides and gamma-glutamylcysteines.
  39. 39. Chemical Structure Some organosulfur compounds derived from garlic Some organosulfur compounds derived from the decomposition of allicin
  40. 40. Health Claims: • Foods rich in these compounds may protect against a wide variety of cancer. • Reduce risk of stroke and cardiovascular disease.
  41. 41. Food Sources: • Garlic, leeks, onions, chives, cruciferous vegetables, horseradish, mustard greens
  42. 42. Garlic Cooking Tips: • Crushing or chopping garlic releases an enzyme called alliinase that catalyzes the formation of allicin. Allicin rapidly breaks down to form a variety of organosulfur compounds. • Since cooking can inactivate alliinase, some scientists recommend letting garlic stand for ten minutes after chopping or crushing before cooking it
  43. 43. Good News for Garlic Lovers
  44. 44. What to Do in Order to Get as Much Phytochemicals as Possible • Take vegetables every day, either in salad or steamed and sautéed form. To get the optimal amount of phytochemicals, try several different types of vegetables. Eat fresh food. Don’t buy vegetables just to eat it three weeks later. Eat fruits regularly. There are also drinks and unsweetened fruit jams that contain high amounts of phytochemicals. Blueberries and blackberries contain phytochemicals as well. • Try to use olive oil, along with a few drops of lemon, to dress salads.
  45. 45. Follow the 5 a day recommendation • That is around 2 cups of fruits and 2 ½ cups of vegetables per day; • Or 2-3 servings of fruits and 3 servings of vegetables per day as per the Food Pyramid Guide for Filipinos
  46. 46. The 10 plant foods recommended by the DOH
  47. 47. To Summarize: