Phytochemical

Phytochemicals are naturally occurring chemicals present in or extracted from plants.[1][2] Some phytochemicals are nutrients for the plant, while others are metabolites produced to enhance plant survivability and reproduction.[3]

The fields of extracting phytochemicals for manufactured products or applying scientific methods to study phytochemical properties are called phytochemistry.[2][3] An individual who uses phytochemicals in food chemistry manufacturing or research is a phytochemist.

Phytochemicals without a nutrient definition have no confirmed biological activities or proven health benefits when consumed in plant foods.[2] Once phytochemicals in a food enter the digestion process, the fate of individual phytochemicals in the body is unknown due to extensive metabolism of the food in the gastrointestinal tract, producing phytochemical metabolites with different biological properties from those of the parent compound that may have been tested in vitro.[4] Further, the bioavailability of many phytochemical metabolites appears to be low, as they are rapidly excreted from the body within minutes.[4] Other than for dietary fiber, no non-nutrient phytochemicals have sufficient scientific evidence for providing a health benefit.

Some ingested phytochemicals may be toxic, and some may be used in cosmetics, drug discovery, or traditional medicine.[3]

## Contents

* 1 Etymology
* 2 Definition
* 3 History of uses
* 4 Functions
* 5 Consumer and industry guidance
* 6 Effects of food processing
* 7 See also
* 8 References
* 9 Further reading
* 10 External links

## Etymology

Phytochemical derives by compounding the Ancient Greek word for plant (phytón, phyto) with chemical,[2] as first used in English for plant chemistry and organic chemistry around 1850.[5]

## Definition

Phytochemicals are chemicals produced by plants through primary or secondary metabolism.[2][6] They generally have biological activity in the plant host and play a role in plant growth or defense against competitors, pathogens, or predators.[7] As components of plants, all individual phytochemicals make up the whole plant as it exists in nature.[2][8]

Phytochemicals are generally regarded as research compounds rather than essential nutrients because proof of their possible health effects has not been established yet.[1][2][9] Phytochemicals under research can be classified into major categories, such as carotenoids[10] and polyphenols, which include phenolic acids, flavonoids, stilbenes or lignans.[9] Flavonoids can be further divided into groups based on their similar chemical structure, such as anthocyanins, flavones, flavanones, isoflavones, and flavanols.[4][9] Flavanols are further classified as catechins, epicatechins, and proanthocyanidins.[4][9] In total, between 50,000[11] and 130,000[12] phytochemicals have been discovered.

Phytochemists study phytochemicals by first extracting and isolating compounds from the origin plant, followed by defining their structure or testing in laboratory model systems, such as in vitro studies or in vivo studies using laboratory animals.[2][7] Challenges in that field include isolating specific compounds and determining their structures, which are often complex, and identifying what specific phytochemical is primarily responsible for any given biological activity.[2][7]

Further, upon consuming phytochemicals in a food entering the digestion process, the fate of individual phytochemicals in the body is unknown due to extensive metabolism in the gastrointestinal tract, producing smaller phytochemical metabolites with different biological properties from those of the parent compound, and with low bioavailability and rapid excretion.[4] Other than for dietary fiber,[13] no non-nutrient phytochemical has sufficient scientific evidence in humans for an approved health claim.[14]

## History of uses

Berries of Atropa belladonna, also called deadly nightshade, containing the toxic phytochemicals, tropane alkaloids

Without specific knowledge of their cellular actions or mechanisms, phytochemicals can be toxic or used in traditional medicine. For example, salicin, having anti-inflammatory and pain-relieving properties, was originally extracted from the bark of the white willow tree and later synthetically produced to become the common, over-the-counter drug, aspirin.[15][16] The tropane alkaloids of Atropa belladonna were used as poisons, and early humans made poisonous arrows from the plant.[17][18] Other uses include perfumes, such as the sesquiterpene santolols, from sandalwood.[19]

The English yew tree was long known to be extremely and immediately toxic to animals that grazed on its leaves or children who ate its berries; however, in 1971, paclitaxel was isolated from it, subsequently becoming a cancer drug.[7]

## Functions

The biological activities for most phytochemicals are unknown or poorly understood, in isolation or as part of foods.[2][7][9] Phytochemicals with established roles in the body are classified as essential nutrients.[1][2]

The phytochemical category includes compounds recognized as essential nutrients, which are naturally contained in plants and are required for normal physiological functions, so must be obtained from the diet in humans.[2]

Some phytochemicals are known phytotoxins that are toxic to humans;[20][21] for example aristolochic acid is carcinogenic at low doses.[22] Some phytochemicals are antinutrients that interfere with the absorption of nutrients.[23] Others, such as some polyphenols and flavonoids, may be pro-oxidants in high ingested amounts.[24]

Non-digestible dietary fibers from plant foods, often considered as a phytochemical,[13] are generally regarded as a nutrient group having approved health claims for reducing the risk of some types of cancer[25] and coronary heart disease.[26]

Phytochemical dietary supplements are neither recommended by health authorities for improving health[9][27] nor are they approved by regulatory agencies for health claims on product labels.[14][28]

## Consumer and industry guidance

While health authorities encourage consumers to eat diets rich in fruit, vegetables, whole grains, legumes, and nuts to improve and maintain health, evidence that such effects result from specific, non-nutrient phytochemicals is limited or absent.[1][2] For example, systematic reviews and/or meta-analyses indicate weak or no evidence for phytochemicals from plant food consumption having an effect on breast, lung, or bladder cancers.[29][30] Further, in the United States, regulations exist to limit the language on product labels for how plant food consumption may affect cancers, excluding mention of any phytochemical except for those with established health benefits against cancer, such as dietary fiber, vitamin A, and vitamin C.[31]

Phytochemicals, such as polyphenols, have been specifically discouraged from food labeling in Europe and the United States because there is no evidence for a cause-and-effect relationship between dietary polyphenols and inhibition or prevention of any disease.[14][32]

Among carotenoids such as the tomato phytochemical, lycopene, the US Food and Drug Administration found insufficient evidence for its effects on any of several cancer types, resulting in limited language for how products containing lycopene can be described on labels.[33]

## Effects of food processing

Phytochemicals in freshly harvested plant foods may be degraded by processing techniques, including cooking.[34] The main cause of phytochemical loss from cooking is thermal decomposition.[34]

A converse exists in the case of carotenoids, such as lycopene present in tomatoes, which may remain stable or increase in content from cooking due to liberation from cellular membranes in the cooked food.[35] Food processing techniques like mechanical processing can also free carotenoids and other phytochemicals from the food matrix, increasing dietary intake.[34][36]

In some cases, processing of food is necessary to remove phytotoxins or antinutrients; for example societies that use cassava as a staple have traditional practices that involve some processing (soaking, cooking, fermentation), which are necessary to avoid illness from cyanogenic glycosides present in unprocessed cassava.[37]

## See also

* Allelopathy
* List of antioxidants in food
* List of phytochemicals in food
* Nutrition
* Secondary metabolites

## References

1. ↑ 1.0 1.1 1.2 1.3 "Phytochemicals". Micronutrient Information Center, Linus Pauling Institute, Oregon State University, Corvallis, Oregon. 2025. http://lpi.oregonstate.edu/infocenter/phytochemicals.html.
2. ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 "Terms and nomenclature used for plant-derived components in nutrition and related research: efforts toward harmonization". Nutrition Reviews 78 (6): 451–458. June 2020. doi:10.1093/nutrit/nuz081. PMID 31769838.
3. ↑ 3.0 3.1 3.2 "Plant Metabolites: Methods for Isolation, Purification, and Characterization". Plant Metabolites: Methods, Applications and Prospects (eds Sukumaran ST et al). Singapore: Springer. 29 November 2020. doi:10.1007/978-981-15-5136-9_2. ISBN 978-981-15-5136-9. https://link.springer.com/chapter/10.1007/978-981-15-5136-9_2.
4. ↑ 4.0 4.1 4.2 4.3 4.4 "Flavonoids". Micronutrient Information Center, Linus Pauling Institute, Oregon State University, Corvallis, Oregon. February 2016. http://lpi.oregonstate.edu/mic/dietary-factors/phytochemicals/flavonoids.
5. ↑ "Phytochemical: adjective and noun". Oxford English Dictionary. 2025. https://www.oed.com/dictionary/phytochemical_adj.
6. ↑ Harborne, Jeffrey B.; Baxter, Herbert; Moss, Gerard P., eds (1999). "General Introduction". Phytochemical dictionary a handbook of bioactive compounds from plants (2nd ed.). London: Taylor & Francis. p. vii. ISBN 978-0-203-48375-6. https://books.google.com/books?id=VCITWqQS_6MC&q=vast+array.
7. ↑ 7.0 7.1 7.2 7.3 7.4 Molyneux, RJ; Lee, ST; Gardner, DR; Panter, KE; James, LF (2007). "Phytochemicals: the good, the bad and the ugly?". Phytochemistry 68 (22–24): 2973–85. doi:10.1016/j.phytochem.2007.09.004. PMID 17950388. Bibcode: 2007PChem..68.2973M. https://naldc.nal.usda.gov/download/13290/PDF. Retrieved 2017-02-10.
8. ↑ Brielmann, Harry L.; Setzer, William S.; Kaufman, Peter B.; Kirakosyan, Ara; Cseke, Leland J. (2016). "1 Phytochemicals The Chemical Components of Plants: 1.1 Introduction". Natural Products from Plants (2nd ed.). CRC Press (Taylor & Francis). ISBN 1-040-16852-3. https://books.google.com/books?id=wLxCEQAAQBAJ&pg=PP17. Retrieved 9 April 2025.
9. ↑ 9.0 9.1 9.2 9.3 9.4 9.5 Heneman, Karrie; Zidenberg-Cherr, Sheri (2008). "Publication 8313: Phytochemicals". University of California Cooperative Extension. http://anrcatalog.ucanr.edu/pdf/8313.pdf.
10. ↑ "Carotenoids". Micronutrient Information Center, Linus Pauling Institute, Oregon State University, Corvallis, Oregon. October 2023. http://lpi.oregonstate.edu/mic/dietary-factors/phytochemicals/carotenoids.
11. ↑ Afendi, Farit Mochamad; Okada, Taketo; Yamazaki, Mami; Hirai-Morita, Aki; Nakamura, Yukiko; Nakamura, Kensuke; Ikeda, Shun; Takahashi, Hiroki et al. (February 2012). "KNApSAcK Family Databases: Integrated Metabolite–Plant Species Databases for Multifaceted Plant Research". Plant and Cell Physiology 53 (2): e1. doi:10.1093/pcp/pcr165. PMID 22123792.
12. ↑ Rutz, Adriano; Sorokina, Maria; Galgonek, Jakub; Mietchen, Daniel; Willighagen, Egon; Gaudry, Arnaud; Graham, James G; Stephan, Ralf et al. (26 May 2022). "The LOTUS initiative for open knowledge management in natural products research". eLife 11. doi:10.7554/eLife.70780. PMID 35616633.
13. ↑ 13.0 13.1 "Fiber". Micronutrient Information Center, Linus Pauling Institute, Oregon State University, Corvallis, Oregon. 2025. http://lpi.oregonstate.edu/mic/other-nutrients/fiber.
14. ↑ 14.0 14.1 14.2 EFSA Panel on Dietetic Products, Nutrition and Allergies (2010). "Scientific Opinion on the substantiation of health claims related to various food(s)/food constituent(s) and protection of cells from premature aging, antioxidant activity, antioxidant content and antioxidant properties, and protection of DNA, proteins and lipids from oxidative damage pursuant to Article 13(1) of Regulation (EC) No 1924/20061". EFSA Journal 8 (2): 1489. doi:10.2903/j.efsa.2010.1489. https://efsa.onlinelibrary.wiley.com/doi/epdf/10.2903/j.efsa.2010.1489.
15. ↑ Sneader, W. (2000). "The discovery of aspirin: A reappraisal". BMJ (Clinical Research Ed.) 321 (7276): 1591–1594. doi:10.1136/bmj.321.7276.1591. PMID 11124191.
16. ↑ Landau E (22 Dec 2010). "From a tree, a 'miracle' called aspirin". CNN. http://www.cnn.com/2010/HEALTH/12/22/aspirin.history/.
17. ↑ Wink, Michael (1998). "A Short History of Alkaloids". Alkaloids: biochemistry, ecology, and medicinal applications. New York: Plenum Press. p. 20. ISBN 978-0-306-45465-3. https://books.google.com/books?id=bMCzyrAtrvYC&q=hallucinogenic++Atropa+belladonna&pg=PA20.
18. ↑ Timbrell, John (2005). The poison paradox: chemicals as friends and foes. Oxford: Oxford Univ. Pr.. pp. 2. ISBN 978-0-19-280495-2. https://archive.org/details/poisonparadoxche0000timb. "poisons used by the wife of Claudius."
19. ↑ Ellena, Jean-Claude (2022). Atlas of Perfumed Botany. Cambridge: MIT Press. pp. 12–15. ISBN 978-0-262-04673-2. https://books.google.com/books?id=yrZNEAAAQBAJ.
20. ↑ Iwasaki, S (April 1998). "Natural organic compounds that affect to microtubule functions.". Yakugaku Zasshi 118 (4): 112–26. doi:10.1248/yakushi1947.118.4_111. PMID 9564789.
21. ↑ Bjeldanes, Leonard; Shibamoto, Takayuki (2009). Introduction to Food Toxicology (2nd ed.). Burlington: Elsevier. p. 124. ISBN 978-0-08-092153-2. https://books.google.com/books?id=Lq4iw2UtDacC&pg=PA124.
22. ↑ Shaw, D (December 2010). "Toxicological risks of Chinese herbs.". Planta Medica (Georg Thieme Verlag KG) 76 (17): 2012–8. doi:10.1055/s-0030-1250533. PMID 21077025. Bibcode: 2010PlMed..76.2012S.
23. ↑ Popova, Aneta; Mihaylova, Dasha (July 2019). "Antinutrients in Plant-based Foods: A Review - 1\. INTRODUCTION". The Open Biotechnology Journal (University of Food Technologies. Bulgaria) 13 (1). doi:10.2174/1874070701913010068.
24. ↑ Halliwell, B (2007). "Dietary polyphenols: Good, bad, or indifferent for your health?". Cardiovascular Research 73 (2): 341–7. doi:10.1016/j.cardiores.2006.10.004. PMID 17141749.
25. ↑ "Health claims: fiber-containing grain products, fruits, and vegetables and cancer; Title 21: Food and Drugs, Subpart E, 101.76". U.S. Food and Drug Administration. 5 January 2017. http://www.ecfr.gov/cgi-bin/text-idx?SID=c7e427855f12554dbc292b4c8a7545a0&mc=true&node=pt21.2.101&rgn=div5#se21.2.101_176.
26. ↑ "Health claims: Soluble fiber from certain foods and risk of coronary heart disease (CHD); Title 21: Food and Drugs, Subpart E, 101.81". U.S. Food and Drug Administration. 5 January 2017. http://www.ecfr.gov/cgi-bin/text-idx?SID=c7e427855f12554dbc292b4c8a7545a0&mc=true&node=pt21.2.101&rgn=div5#se21.2.101_181.
27. ↑ "Common questions about diet and cancer". American Cancer Society. 5 February 2016. http://www.cancer.org/healthy/eathealthygetactive/acsguidelinesonnutritionphysicalactivityforcancerprevention/acs-guidelines-on-nutrition-and-physical-activity-for-cancer-prevention-common-questions.
28. ↑ "Code of Federal Regulations, Title 21, Part 101, Food Labeleing, Subpart D, Specific Requirements for Nutrient Content Claims, Section 101.54". US Food and Drug Administration. 29 July 2016. https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-101/subpart-D.
29. ↑ Aune, D; Chan, D. S.; Vieira, A. R.; Rosenblatt, D. A.; Vieira, R; Greenwood, D. C.; Norat, T (2012). "Fruits, vegetables and breast cancer risk: A systematic review and meta-analysis of prospective studies". Breast Cancer Research and Treatment 134 (2): 479–93. doi:10.1007/s10549-012-2118-1. PMID 22706630. http://eprints.whiterose.ac.uk/75579/15/Combine.pdf.
30. ↑ Smith-Warner, S. A.; Spiegelman, D; Yaun, S. S.; Albanes, D; Beeson, W. L.; Van Den Brandt, P. A.; Feskanich, D; Folsom, A. R. et al. (2003). "Fruits, vegetables and lung cancer: A pooled analysis of cohort studies". International Journal of Cancer 107 (6): 1001–11. doi:10.1002/ijc.11490. PMID 14601062. https://cris.maastrichtuniversity.nl/portal/en/publications/fruits-vegetables-and-lung-cancer-a-pooled-analysis-of-cohort-studies(e5a7f16c-9f94-461e-9454-f35522b553f5).html.
31. ↑ "Electronic Code of Federal Regulations, Title 21, Chapter I, Subchapter B, Part 101.78. Health claims: fruits and vegetables and cancer". US Government Printing Office. 9 February 2017. http://www.ecfr.gov/cgi-bin/retrieveECFR?gp=1&SID=4bf49f997b04dcacdfbd637db9aa5839&ty=HTML&h=L&mc=true&n=pt21.2.101&r=PART#se21.2.101_178.
32. ↑ Gross P (1 March 2009), New Roles for Polyphenols. A 3-Part Report on Current Regulations & the State of Science, Nutraceuticals World (republished by The Free Library), https://www.thefreelibrary.com/New+roles+for+polyphenols:+a+3-part+report+on+current+regulations+&...-a0196242906, retrieved 12 February 2017
33. ↑ Schneeman BO (9 July 2015). "Qualified Health Claims: Letter Regarding "Tomatoes and Prostate, Ovarian, Gastric and Pancreatic Cancers (American Longevity Petition)" (Docket No. 2004Q-0201)". Office of Nutritional Products, Labeling and Dietary Supplements, Center for Food Safety and Applied Nutrition, US Food and Drug Administration. https://www.fda.gov/Food/IngredientsPackagingLabeling/LabelingNutrition/ucm072760.htm.
34. ↑ 34.0 34.1 34.2 Palermo, M; Pellegrini, N; Fogliano, V (2014). "The effect of cooking on the phytochemical content of vegetables". Journal of the Science of Food and Agriculture 94 (6): 1057–70. doi:10.1002/jsfa.6478. PMID 24227349. Bibcode: 2014JSFA...94.1057P.
35. ↑ Dewanto, V; Wu, X; Adom, KK; Liu, RH (2002). "Thermal processing enhances the nutritional value of tomatoes by increasing total antioxidant activity". Journal of Agricultural and Food Chemistry 50 (10): 3010–4. doi:10.1021/jf0115589. PMID 11982434. Bibcode: 2002JAFC...50.3010D.
36. ↑ Hotz, C; Gibson, R. S. (2007). "Traditional food-processing and preparation practices to enhance the bioavailability of micronutrients in plant-based diets". The Journal of Nutrition 137 (4): 1097–100. doi:10.1093/jn/137.4.1097. PMID 17374686.
37. ↑ O L. Oke (31 December 1990). "Chapter 7: Toxic substances and antinutritional factors". Roots, tubers, plantains and bananas in human nutrition. Rome: Food & Agriculture Organization of the United Nations. ISBN 92-5-102862-1. http://www.fao.org/docrep/t0207e/T0207E08.htm#Cassava toxicity.

## Further reading

* Higdon, J. An Evidence – Based Approach to Dietary Phytochemicals. 2007. Thieme. ISBN 978-1-58890-408-9.
* 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 978-0-8138-0320-3.

## External links

* Dr. Duke's Phytochemical and Ethnobotanical Databases – United States Department of Agriculture

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