| Phytochemicals | ||||||||
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What are phytochemicals?
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. Phytochemicals have really potent antioxidant properties.
Phytochemicals have various health-promoting effects on human and some of these include:
- Antioxidant - all phytochemicals work on protecting the body from the oxidative effects of things like stress, pollution, smoking (as well as many bodily processe) by scavenging and getting rid of free radicals. The reason phytochemicals are so important is because free radicals can damage the body's DNA and thus lead to the development of cancer and serious heart problems
- Antibacterial - some phytochemicals (allicin in garlic) have an antibacterial effect, which is protective and guards against colds and flus
- Hormonal - some phytochemicals have a weak eostrogenic effect, which assist in preventing the build-up of eostrogen in the body (high eostrogen levels have some degree of influence on the rate and levels of some female cancers of the reproductive system)
Different Types of Phytochemicals
There are over 100 different types of phytochemicals, but this site will not list them all, only some of the most common and more recognisable ones will be listed.
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Alkaloids are a bitter phytochemical that occur in some plant foods. The main types of these phytochemicals are:
- Caffeine
- Theobromine
- Theophylline
Foods high in alkaloids are:
- Black tea
- Caffeine
- Cocoa
- Green tea
- Mate (a herb)
Provide cross-links or bridges that connect and strengthen the intertwined strands of collagen protein in plant foods, provide strong antioxidant effects by scavenging for free radicals, are water-soluble and create the blue/purple/dark red pigment of the skin and flesh of certain fruits and vegetables.
Foods high in anthocyanins:
- Blackberries
- Blueberries
- Dark purple grapes
- Raspberries
- Cranberries
Carotenes come in the following forms (although this list does not by any means show all the carotenes):
Beta-carotene is the more common form of the two (alpha and beta). Fruits and vegetables that are brightly coloured (dark green, orange, red and yellow) have a high content of beta-carotene.
Carotenes protect vitamin A & vitamin E from oxidation and eliminate toxins and pollutants from the body. Research has shown that carotenes offer protection against various cancers and enhance the immune system response.
Foods high in beta-carotene:
- Yellow fruits / vegetables - lemons, sweet potato, sweet yellow (banana) peppers, grapefruit
- Orange fruits / vegetables - carrots, mango, oranges, mandarin, rockmelon (cantaloupe), papaya, tomato
- Leafy green vegetables - kale, spinach, broccoli
Lutein is essential for ensuring good vision, especially as people get older. Research has shown that lutein reduces the risk of age-related macular degeneration and cataracts and may even reduce the incidence of some types of cancers.
Foods high in lutein:
- Leafy green vegetables - spinach, kale, collard greens (most highest source)
- Leafy green vegetables - broccoli, Brussels sprouts, Romaine lettuce, Swiss chard
- Fruit - kiwi fruit
A great deal of research on lycopene has shown that it reduces the risk of prostate cancer and heart disease. Lycopene is abundant in red fruits / vegetables and is the substance which gives those foods their red colouring. Lycopene appears to be released in higher concentrations from tomatoes that have been cooked in olive oil, but raw tomatoes are still very healthy.
Foods high in lycopene:
- Red fruits - tomato, watermelon, pink grapefruit
- Red vegetables - red capsicum (or red peppers)
Research on zeaxanthin has shown that this carotene also assists with reducing the risk of age-related macular degeneration, cataracts and that it may also prevent some types of cancers too. Zeaxanthin is found mainly in bright yellow foods.
Foods high in zeaxanthin:
- Yellow corn
- Winter squash
- Egg yolks
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Flavonoids are a large family of phytochemicals found in fruits and vegetables. Flavonoids, also known as bioflavonoids, act as potent antioxidants to neutralise the damage from free radicals (which cause cancer, heart disease and ageing). Flavonoids also act against allergies and inflammation, so are beneficial for conditions such as hayfever and sinusitis.
The most common flavonoids are:
Anthocyanins strengthen and encourage better collagen formation. Other research has shown that foods high in anthocyanins slow down the process of aging. Other research has proved that the anthocyanins in cranberries and blueberries prevents urinary tract infections.
Anthocyanins provide strong antioxidant effects by scavenging for free radicals, are water-soluble and create the pigment of the skin and flesh of certain fruits and vegetables.
Foods high in anthocyanins:
- Blackberries
- Blueberries
- Dark purple grapes
- Raspberries
- Cranberries
- Strawberries
Hesperidin is an anthcyanin found in citrus fruits and fruit juices that may protect against heart disease.
Foods high in hesperidin:
- Oranges and orange juice
- Grapefruit and grapefruit juice
- Lemons
- Limes
- Mandarines
- Tangelos
- Tangerines
Quercetin appears to be beneficial with allergies and inflammation of the upper and lower respiratory system. Research has shown that quercetin protects the lungs from oxidative damage due to pollution and cigarette smoke.
Foods high in quercetin:
- Fruits - apples, pears, cherries, grapes
- Green tea
- Red wine
- Vegetables - onions, garlic, kale, lettuce
Resveratrol is showing promise as an effective block against cancer of the lungs - latest research suggesting that this flavonoid may be the reason some people have a lowered risk of lung cancer. Resveratrol is mainly concentrated in the skin and pips of dark red grapes.
Foods high in reseveratrol:
- Dark red/purple grapes (inluding skin and pips)
- Dark red/purple grape juice
- Red wine (made naturally, using skin and pips)
Research shows that this interesting flavonoid is implication in lowering the incidence of cancers of the head and neck.
Foods high in tangeritin:
- Citrus fruit - grapefruit, lemons, limes, oranges, tangerines
Isoflavones are one of flavonoid phytochemicals. Isoflavones have both a weak eostrogenic and a weak anti-eostrogenic effect. Isoflavones have strong antioxidant effects on the body.
There are three types of isoflavones:
- Daidzein
- Genistein
- Coumesterol
Isoflavones block enzymes that promote tumour growth. Soy consumption is known to decrease incidence of breast, uterine and prostate cancers.
Foods high in isoflavones:
- Soy beans
- Kuszu
- Red clover (herb)
- Chickpeas
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Phenolic acid compounds may reduce the risk of heart disease and certain types of cancer.
Phenolic compounds can be found in many fruits such as: berries, prunes, red grapes and red grape juice, kiwifruit, currants, apples and apple juice, and tomatoes.
There are a few types of phenolic acids:
- Capsaicin - may help with arthritis, ulcers and psoriasis; found in chilles, peppers, capsicums
- Ellagic acid - has anti-cancer and antioxidant properties; found in red fruits and berries, pecans and walnuts
- Gallic acid - an antioxidant which has major anti-fungal and anti-viral properties; found in almost all plant foods, but especially grapes, tea, hops
- Rosemarinic acid - has antioxidant activity stronger than that of vitamin E as well as potent anti-inflammatory properties that may be useful for conditions such as arthritis and asthma; found in herbs such as rosemary, oregano, thyme, lemon balm, sage
- Tannic acid - has anti-bacterial properties; found in tea, nettle, berries
Phytoestrogens are chemicals in plants that have weak eostrogen-like activity. Phytoestrogens are part of the flavonoid class of phytochemicals.
There are two major groups of phytoestrogens:
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Phytosterols (or plant sterols) are similar in structure to cholesterol, but with a minor difference in their chemical structure.
The main phytosterol is:
- Beta-sitosterol
Phytosterols have a demonstrated ability to block cholesterol uptake and facilitate the excretion of cholesterol from the body. Phytosterols are also involved in tumour and cancer prevention.
Foods high in phytosterols:
- Corn oil
- Peanuts
- Pumpkin seeds
- Rice bran
- Soy beans
- Wheat germ
- Yams
Terpenes another largest class of phytonutrients and they function primarily as antioxidant - protecting lipids, blood & other body fluids from free radical damage (oxidisation).
Foods high in terpenes:
- Citrus fruits - lemons, limes, oranges, tangerines
- Menthol - peppermint, spearmint
Xanthophylls are xxx.
Xanthophylls come in the two forms:
- Astaxanthin
- Beta-Cryptoxanthin
Xanthophylls xxx
Foods high in Xanthophylls:
- xxx
- xxx
More information
To learn more, go to the information about Phytochemicals on the American Heart Associate web site
references
- Walker, M. Secrets of Long Life , New York, Devin-Adair Publishers, 1993.
- Dragsted, L.O., et al., Pharmacology and Toxicology , 72 Suppl. 1:116-35; 1993