Phytochemical
Encyclopedia
Phytochemicals are biologically active chemical compounds that occur naturally in plants (phyto means “plant” in Greek). Phytochemicals are the molecules responsible for the color and organoleptic properties (properties affecting the organs and the senses). For example, the deep purple color of blueberries and the smell of garlic. The term is generally used to refer to those chemicals that may affect health, but are not established as essential nutrients.[1] Scientists estimate that there are about 10,000 different phytochemicals that are considered beneficial in the prevention of chronic diseases such as cancer, stroke, and heart disease. Although certain phytochemicals are available as dietary supplements, research suggests that their health benefits are best obtained through the consumption of whole foods.
may have prescribed willow tree leaves to abate fever. Salicin, having anti-inflammatory
and pain-relieving properties, was originally extracted from the bark of the white willow tree and later synthetically produced became the staple over-the-counter drug aspirin
.
There is evidence from laboratory studies that phytochemicals in fruits and vegetables may reduce the risk of cancer
, possibly due to dietary fiber
s, polyphenol antioxidant
s and anti-inflammatory
effects. Specific phytochemicals, such as ferment
able dietary fiber
s, are allowed limited health claims by the US Food and Drug Administration (FDA).
An important cancer drug, Taxol (paclitaxel
), is a phytochemical initially extracted and purified from the Pacific yew tree
.
Some phytochemicals with physiological properties may be elements rather than complex organic molecules. Abundant in many fruits and vegetables, selenium
, for example, is involved with major metabolic pathways, including thyroid hormone
metabolism and immune function. Particularly, it is an essential nutrient
and cofactor
for the enzymatic synthesis of glutathione
, an endogenous
antioxidant
.
s for a variety of diseases. Lycopene
from tomatoes, for example, has been tested in human studies for cardiovascular diseases and prostate cancer
. These studies, however, did not attain sufficient scientific agreement to conclude an effect on any disease. The FDA position reads:
"Very limited and preliminary scientific research suggests that eating one-half to one cup of tomatoes and/or tomato sauce a week may reduce the risk of prostate cancer. The United States Food and Drug Administration concludes that there is little scientific evidence supporting this claim."
Likewise, although lutein
and zeaxanthin
are suspected to inhibit macular degeneration
and cataracts, there was insufficient scientific evidence from clinical trials for such specific effects or health claims.
Interestingly, a converse example may exist in which lycopene
, a phytochemical present in tomato
es, is either unchanged in content or made more concentrated
by processing to juice
or paste
, maintaining good levels for bioavailability
.
Phytochemicals as candidate therapeutics
Phytochemicals have been used as drugs for millennia. For example, HippocratesHippocrates
Hippocrates of Cos or Hippokrates of Kos was an ancient Greek physician of the Age of Pericles , and is considered one of the most outstanding figures in the history of medicine...
may have prescribed willow tree leaves to abate fever. Salicin, having anti-inflammatory
Anti-inflammatory
Anti-inflammatory refers to the property of a substance or treatment that reduces inflammation. Anti-inflammatory drugs make up about half of analgesics, remedying pain by reducing inflammation as opposed to opioids, which affect the central nervous system....
and pain-relieving properties, was originally extracted from the bark of the white willow tree and later synthetically produced became the staple over-the-counter drug aspirin
Aspirin
Aspirin , also known as acetylsalicylic acid , is a salicylate drug, often used as an analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an anti-inflammatory medication. It was discovered by Arthur Eichengrun, a chemist with the German company Bayer...
.
There is evidence from laboratory studies that phytochemicals in fruits and vegetables may reduce the risk of cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
, possibly due to dietary fiber
Dietary fiber
Dietary fiber, dietary fibre, or sometimes roughage is the indigestible portion of plant foods having two main components:* soluble fiber that is readily fermented in the colon into gases and physiologically active byproducts, and* insoluble fiber that is metabolically inert, absorbing water as it...
s, polyphenol antioxidant
Polyphenol antioxidant
A polyphenol antioxidant is a type of antioxidant containing a polyphenolic substructure. Numbering over 4,000 distinct species, many of these compounds have antioxidant activity in vitro but are unlikely to have antioxidant roles in vivo...
s and anti-inflammatory
Inflammation
Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...
effects. Specific phytochemicals, such as ferment
Fermentation (biochemistry)
Fermentation is the process of extracting energy from the oxidation of organic compounds, such as carbohydrates, using an endogenous electron acceptor, which is usually an organic compound. In contrast, respiration is where electrons are donated to an exogenous electron acceptor, such as oxygen,...
able dietary fiber
Dietary fiber
Dietary fiber, dietary fibre, or sometimes roughage is the indigestible portion of plant foods having two main components:* soluble fiber that is readily fermented in the colon into gases and physiologically active byproducts, and* insoluble fiber that is metabolically inert, absorbing water as it...
s, are allowed limited health claims by the US Food and Drug Administration (FDA).
An important cancer drug, Taxol (paclitaxel
Paclitaxel
Paclitaxel is a mitotic inhibitor used in cancer chemotherapy. It was discovered in a U.S. National Cancer Institute program at the Research Triangle Institute in 1967 when Monroe E. Wall and Mansukh C. Wani isolated it from the bark of the Pacific yew tree, Taxus brevifolia and named it taxol...
), is a phytochemical initially extracted and purified from the Pacific yew tree
Taxus brevifolia
Taxus brevifolia is a conifer native to the Pacific Northwest of North America. It ranges from southernmost Alaska south to central California, mostly in the Pacific Coast Ranges, but with an isolated disjunct population in southeast British Columbia, most notably occurring on Zuckerberg Island...
.
Some phytochemicals with physiological properties may be elements rather than complex organic molecules. Abundant in many fruits and vegetables, selenium
Selenium
Selenium is a chemical element with atomic number 34, chemical symbol Se, and an atomic mass of 78.96. It is a nonmetal, whose properties are intermediate between those of adjacent chalcogen elements sulfur and tellurium...
, for example, is involved with major metabolic pathways, including thyroid hormone
Thyroid hormone
The thyroid hormones, thyroxine and triiodothyronine , are tyrosine-based hormones produced by the thyroid gland primarily responsible for regulation of metabolism. An important component in the synthesis of thyroid hormones is iodine. The major form of thyroid hormone in the blood is thyroxine ,...
metabolism and immune function. Particularly, it is an essential nutrient
Essential nutrient
An essential nutrient is a nutrient required for normal body functioning that either cannot be synthesized by the body at all, or cannot be synthesized in amounts adequate for good health , and thus must be obtained from a dietary source...
and cofactor
Cofactor (biochemistry)
A cofactor is a non-protein chemical compound that is bound to a protein and is required for the protein's biological activity. These proteins are commonly enzymes, and cofactors can be considered "helper molecules" that assist in biochemical transformations....
for the enzymatic synthesis of glutathione
Glutathione
Glutathione is a tripeptide that contains an unusual peptide linkage between the amine group of cysteine and the carboxyl group of the glutamate side-chain...
, an endogenous
Endogenous
Endogenous substances are those that originate from within an organism, tissue, or cell. Endogenous retroviruses are caused by ancient infections of germ cells in humans, mammals and other vertebrates...
antioxidant
Antioxidant
An antioxidant is a molecule capable of inhibiting the oxidation of other molecules. Oxidation is a chemical reaction that transfers electrons or hydrogen from a substance to an oxidizing agent. Oxidation reactions can produce free radicals. In turn, these radicals can start chain reactions. When...
.
Clinical trials and health claim status
There are currently many phytochemicals in clinical trialClinical trial
Clinical trials are a set of procedures in medical research and drug development that are conducted to allow safety and efficacy data to be collected for health interventions...
s for a variety of diseases. Lycopene
Lycopene
Lycopene is a bright red carotene and carotenoid pigment and phytochemical found in tomatoes and other red fruits and vegetables, such as red carrots, watermelons and papayas...
from tomatoes, for example, has been tested in human studies for cardiovascular diseases and prostate cancer
Prostate cancer
Prostate cancer is a form of cancer that develops in the prostate, a gland in the male reproductive system. Most prostate cancers are slow growing; however, there are cases of aggressive prostate cancers. The cancer cells may metastasize from the prostate to other parts of the body, particularly...
. These studies, however, did not attain sufficient scientific agreement to conclude an effect on any disease. The FDA position reads:
"Very limited and preliminary scientific research suggests that eating one-half to one cup of tomatoes and/or tomato sauce a week may reduce the risk of prostate cancer. The United States Food and Drug Administration concludes that there is little scientific evidence supporting this claim."
Likewise, although lutein
Lutein
Lutein is a xanthophyll and one of 600 known naturally occurring carotenoids. Lutein is synthesized only by plants and like other xanthophylls is found in high quantities in green leafy vegetables such as spinach and kale...
and zeaxanthin
Zeaxanthin
Zeaxanthin is one of the most common carotenoid alcohols found in nature. It is important in the xanthophyll cycle. Synthesized in plants & some micro-organisms, it is the pigment that gives paprika , corn, saffron, and many other plants & microbes their characteristic color.The name is derived...
are suspected to inhibit macular degeneration
Macular degeneration
Age-related macular degeneration is a medical condition which usually affects older adults and results in a loss of vision in the center of the visual field because of damage to the retina. It occurs in “dry” and “wet” forms. It is a major cause of blindness and visual impairment in older adults...
and cataracts, there was insufficient scientific evidence from clinical trials for such specific effects or health claims.
Food processing and phytochemicals
Phytochemicals in freshly harvested plant foods may be destroyed or removed by modern processing techniques, including cooking. For this reason, industrially processed foods likely contain fewer phytochemicals and may thus be less beneficial than unprocessed foods. Absence or deficiency of phytochemicals in processed foods may contribute to increased risk of preventable diseases.Interestingly, a converse example may exist in which lycopene
Lycopene
Lycopene is a bright red carotene and carotenoid pigment and phytochemical found in tomatoes and other red fruits and vegetables, such as red carrots, watermelons and papayas...
, a phytochemical present in tomato
Tomato
The word "tomato" may refer to the plant or the edible, typically red, fruit which it bears. Originating in South America, the tomato was spread around the world following the Spanish colonization of the Americas, and its many varieties are now widely grown, often in greenhouses in cooler...
es, is either unchanged in content or made more concentrated
Concentration
In chemistry, concentration is defined as the abundance of a constituent divided by the total volume of a mixture. Four types can be distinguished: mass concentration, molar concentration, number concentration, and volume concentration...
by processing to juice
Tomato juice
Tomato juice is a juice made from tomatoes. It is usually used as a beverage, either plain or in cocktails such as a Bloody Mary or Michelada.-History:...
or paste
Tomato paste
Tomato paste is a thick paste that is made by cooking tomatoes for several hours to reduce moisture, straining them to remove the seeds and skin, and cooking them again to reduce them to a thick, rich concentrate...
, maintaining good levels for bioavailability
Bioavailability
In pharmacology, bioavailability is a subcategory of absorption and is used to describe the fraction of an administered dose of unchanged drug that reaches the systemic circulation, one of the principal pharmacokinetic properties of drugs. By definition, when a medication is administered...
.
See also
- List of antioxidants in food
- List of phytochemicals in food
- NutritionNutritionNutrition is the provision, to cells and organisms, of the materials necessary to support life. Many common health problems can be prevented or alleviated with a healthy diet....
- PhytochemistryPhytochemistryPhytochemistry is in the strict sense of the word the study of phytochemicals. These are chemicals derived from plants. In a narrower sense the terms are often used to describe the large number of secondary metabolic compounds found in plants. Many of these are known to provide protection against...
- Secondary metabolites
- Superfruits
Further reading
Books- Higdon, J. An Evidence – Based Approach to Dietary Phytochemicals. 2007. Thieme. ISBN 9781588904089
- Rosa, L.A. de la / Alvarez-Parrilla, E. / González-Aguilar, G.A. (eds.) Fruit and Vegetable Phytochemicals: Chemistry, Nutritional Value and Stability. 2010. Wiley-Blackwell. ISBN 9780813803203
External links
- Phytochemicals and Cardiovascular Disease American Heart Association
- Phytochemical Database - United States Department of Agriculture
- Phytochemicals at LPI - Linus Pauling Institute at Oregon State University