Practice Phytochemicals.pdf

Practice 1 Phytochemicals Healthy Food Festival 1. INTRODUCTION Phytochemicals and zoochemicals are bioactive compounds found in plants and animal foods respectively that may provide health benefits but are not considered essential The interest on functional foods nutrien...

Practice 1 Phytochemicals Healthy Food Festival 1. INTRODUCTION Phytochemicals and zoochemicals are bioactive compounds found in plants and animal foods respectively that may provide health benefits but are not considered essential The interest on functional foods nutrients in the diet. began in Japan in the early 80’s. The government started programs Food rich in phytochemicals and zoochemicals are referred to to analyse food and its functions in order to improve the health of as functional foods the population after the II World War. Functional foods provide health benefits beyond those provided by its nutrients: decrease risk and/or promote optimal health. They have not been officially defined (by USDA or European legislation) 2. DEFINITION AND CLASSIFICATION OF PHYTOCHEMICALS Phytochemicals are physiologically active non-nutrient compounds found in certain plant foods (vegetables, fruits, cereal grains, plant- based beverages: tea, wine...) that provide health benefits. Phytochemicals are secondary plant metabolites essential for the plant interaction with the environment: defence against insects and microorganisms, growth regulators or pigments. Confer tastes, aromas, color and other characteristics to foods. Phytochemical consumption is associated with a decrease in risk of https://lpi.oregonstate.edu/mic/di several chronic diseases (CVD, diabetes, cancer…) due, in part, to their etary-factors/phytochemicals antioxidant and free radical scavenging effect.  About 10,000 different phytochemicals have been identified (60,000-100,000 remain unknown) Mixed diet contains 1.5 g of secondary plant metabolites The beneficial effects of phytochemicals are thought to result from the synergistic actions of multiple constituents Cancer chemoprevention with dietary phytochemicals Nature Reviews Cancer 3, 768-780 (October 2003) CLASSIFICATION OF PHYTOCHEMICALS based on physiological effect and chemical structure  CAROTENOIDS  POLYPHENOLS: FLAVONOIDS AND PHENOLIC ACIDS. RESVERATROL  PHYTOSTEROLS  PHYTO-ESTROGENS: ISOFLAVONES AND LIGNANS  GLUCOSINOLATES: SULFORAPHANE  Saponins; protease inhibitors; monoterpenes; sulphides; Color examples: Red foods provide lycopene. Yellow-green foods provide zeaxanthin. Red-purple foods: anthocyanin (blackberries and blueberries, cherries..) Orange foods: β-carotene. Orange-yellow foods provide flavonoids (other sources are: purple grapes, black tea, oregano.. Wheat…) Green foods provide glucosinolate. White-green foods provide allyl sulfides  CAROTENOIDS Food sources: widespread in fruits and vegetables (red and yellow pigments, essential for photosynthesis) Only 40-50 are significant for human nutrition. Two types: - Oxygen-free: heat-stable. e.g. alpha and beta carotene and lycopene - Oxygen-containing: heat-sensitive e.g. xanthophylls: lutein, zeaxanthin and beta-cryptoxanthin  The most important carotenoids in diets: α-carotene β-carotene Lycopene β-cryptoxanthin Lutein Zeaxanthin Carotenoids owe their name to carrots (Daucus carota) Xanthophylls (originally phylloxanthins) are derived from the Greek words for yellow (xanthos) and leaf (phyllon).  FOOD SOURCES CAROTENOIDS Apricots, cantaloupe, carrots, pumpkin a-carotene and b-carotene and sweet potato Pink grapefruit, tomatoes and lycopene, z-carotene, b-carotene, watermelon phytofluene and phytoene Mango, papaya, peaches, prunes, lutein, zeaxanthin, and b-cryptoxanthin, squash and oranges a-, b- and z-carotene, phytofluene and phytoene Green fruits and vegetables such as lutein, zeaxanthin, a- and b-carotene green beans, broccoli, brussel sprouts, cabbage, kale, kiwi, lettuce, peas and spinach  Biological activities  Provitamin A carotenoids: α-carotene, β-carotene, and β-cryptoxanthin can be converted to retinol (no vitamin A activity can be derived from lutein, zeaxanthin, and lycopene)  Antioxidant activity  Blue light filtering: lutein and zeaxanthin absorb up to 90% of blue light and help maintain optimal visual function by protecting eyes from light-induced oxidative damage Intercellular communication Immune system Randomized controlled trials have shown that high-dose β-carotene supplements do not reduce the risk of cardiovascular disease or cancer (even increases risk of lung cancer in smokers and former asbestos workers)  POLYPHENOLS Collective term for phenol derivates One of the most numerous and widely distributed (more than 8000 phenolic structures known, over 4000 flavonoids) The majority are glycosides Associated with sensory and quality of fresh and processed foods (e.g. enzymatic browning reaction of phenolic compounds) Important role in prevention of degenerative diseases, cancer and cardiovascular diseases Polyphenols o FLAVONOIDS  anthocyanidins  flavan-3-ols  flavonols  flavanones  flavones  ISOFLAVONES o PHENOLIC ACIDS: hydroxycinnamic acids (p-coumaric, caffeic, ferulic, and sinapic acids) o STILBENES: Resveratrol https://lpi.oregonstate.edu/mic/dietary- factors/phytochemicals/flavonoids  FLAVONOIDS Food sources: fruit; vegetables; chocolate; wine; tea. Fresh vegetables : 0.1% polyphenols in outer layer of fruits and vegetables Flavonoid contents of green leafy vegetables increases with ripeness Most common dietary flavonoid: Quercetin (25mg/day) Bioavailability depends on physicochemical properties. In general, flavonoids have low bioavailability due to limited absorption, Functions in plants: attracting extensive metabolism, and rapid excretion. pollinating insects; combating microbial infection and regulating cell growth  RESVERATROL A class of polyphenolic compounds called stilbenes Food sources: peanuts, grapes, red wine, and some berries. Low bioavailability Health effects: prevention and/or treatment of cancer, cardiovascular disease, and neurodegenerative diseases.  PHYTOSTEROLS Collective term for plant-derived sterols and stanols. Structurally related to cholesterol. The most abundant sterols in plants are β-sitosterol, campesterol and stigmasterol Good food sources: natural sources such as unrefined vegetable oils; whole grains, nuts and seeds; legumes. added to products such as yoghourt or margarine Biological activities: inhibition of cholesterol absorption  PHYTOESTROGENS Plant components that bind to mammalian estrogen receptors and have effects similar to endogenous estrogens ISOFLAVONES: almost exclusively in soybeans and soybean products (genistin, daidzin…). Lignans: found in a wide variety of plant-based foods, including seeds, whole grains, legumes, fruit, and vegetables Possible role in prevention of hormone-associated cancers, osteoporosis, and cardiovascular disease and menopausal symptoms  SAPONINS Rich foods source: legumes. May have beneficial effects on blood cholesterol levels, cancer, bone health and stimulation of the immune system GLUCOSINOLATES (thioglucosides) Food source: Cruciferae (cabbage, broccoli, cauliflower, turnip) Sulphoraphane: anticarcinogenic and antioxidant effects MONOTERPENES Active substances in herbs and spices: menthol (peppermint); limonene (citrus oil) Biological activity: limonene: anticarcinogen 3. PHYSIOLOGICAL EFFECTS OF PHYTOCHEMICALS Epidemiological studies suggest Major effects of phytochemicals: that constituents in plant foods anticarcinogenic effects (phytoestrogens, carotenoids..) protect against cancer and that antioxidative effects (carotenoids, polyphenols..) consumption of vegetables, fruits immunomodulatory effects (carotenoids, flavonoids, and whole cereals is associated Saponins, sulphides, phytoestrogens..) with a reduction of antimicrobial effects (sulphides, polyphenols, cardiovascular disease risk. procyanidins) However, further epidemiological cholesterol-lowering effects (Phytosterols, saponins, and experimental research is sulphides, flavonoids and lycopene..) needed. phytochemicals affecting drug metabolism CHOCOLATE Cocoa is an important source of polyphenols (12-18% total weight) Major phenolic compounds are the flavanols: catechin, epicatechin, proanthocyanidins "Flavanols are one of the most promising and exciting nutritional interventions available for helping to reduce the risk of cardiovascular disease, and a large-scale randomized trial is the next logical step in testing their effectiveness," Dr. JoAnn Manson, chief of the Division of Preventive Medicine at Harvard-affiliated Brigham and Women's Hospital Possible health benefits of chocolate Flavonoids in cocoa are thought to promote cardiovascular health by lowering cholesterol, reducing inflammation, and preventing blood clots. Flavanols support the production of nitric oxide (NO) in the endothelium that helps to relax the blood vessels and improve blood flow At high levels, cocoa flavanols have been shown to Montezuma drank large quantities improve cognition and lower the risk of diabetes of a cocoa beverage, which was Other possible beneficial effects of chocolate: anti- said to have aphrodisiac and health depressant and euphoric effects (tryptophan in chocolate); properties. The drink was reserved stimulant effects (theobromine, phenylethylamine in for the male elite, nobility and religious ceremonies. cocoa)  DARK CHOCOLATE Cocoa is an important source of polyphenols (12- Montezuma drank large 18% weight) quantities of a cocoa beverage, which was said to FLAVANOLS are the major phenolic compounds: have aphrodisiac and  Catechin health properties. The drink  Epicatechin was reserved for the male  Proanthocyanidins elite, nobility and religious ceremonies. POSSIBLE HEALTH BENEFITS OF CHOCOLATE Flavonoids in cocoa are thought to promote cardiovascular health by lowering cholesterol, reducing inflammation, and preventing blood clots. Flavanols support the production of nitric oxide (NO) in the endothelium that helps to relax the blood vessels and improve blood flow At high levels, cocoa flavanols have been shown to improve cognition and lower the risk of diabetes Other possible beneficial effects of chocolate: anti-depressant and euphoric effects (tryptophan in chocolate); stimulant effects (theobromine, phenylethylamine in cocoa)​