What are Phytochemicals?

Phytochemicals are non-nutritive bioactive compounds in plants. Over 10000 phytochemicals have been isolated and more than 150 studied in depth.

How Do Phytochemicals Prevent Cancer?

The role of phytochemicals in plants is to provide protection from attack by fungus, bacteria, insects, animals, and diseases. However, they provide several benefits in the human diet such as protection from cancer. Phytochemicals help us fight cancer using one or more of the following mechanisms:

  1. Protect DNA from damage
  2. Block DNA replication in cancerous cells
  3. Control regulatory genes
  4. Regulate hormones
  5. Fight inflammation that promotes cancer
  6. Alter chemical structure of carcinogens, making them less harmless
  7. Cut off blood supply to tumors
  8. Convert malignant cells to healthy cells
  9. Trigger death of cancer cells (apoptosis)
  10. Stimulate production of anticancer enzymes
  11. Block or reduce tumor growth

How Can We Get More Phytochemicals?

We can increase intake of and absorption of phytochemicals by:

  1. Eating an adequate amount of plant-based food
  2. Eating a wide variety of foods (Image 1), and
  3. Eating fresh plant foods or minimally processed where possible

Image 1. Eating a rainbow of food colors will increase your chances of getting a variety of phytochemicals in adequate amount

Summary of Phytochemicals with Known Anti-Cancer Properties

PhytochemicalExampleCommon Sources
AlkaloidsSolaninePotato and tomato
 CaffeineTea and coffee
 QuinineBitter tonic
 Alpha-tomatidineGreen tomato
Allyl sulfidesAllicinOnion, garlic, leeks, and chives
GlucosinolatesIsothiocyanatesBrussel sprouts, cabbage, turnips, mustard greens, radishes
 IndolesBroccoli, cabbage, and cauliflower
Phenolic acidEllagic acidstrawberries, raspberries, blackberries, cherries, and walnuts
FlavanoidsAnthocyaninsBlack beans, red and purple berries, grapes, apples, plums, cabbage
FlavanolsEpigallocatechin gallate (EGCG)Tea
 QuercetinYellow and red onions, red grape juice, apples, cranberries, and asparagus
Isoflavones (phytoestrogens)Genistein, and DaidzeinSoybean
Phytosterolsβ-sitosterolRice bran, wheat germ, peanuts, corn oils, and soybeans
 StigmasterolIn the lipid component of soybean, calabar bean, and rape seed
TerpenesTaxolCitrus fruits, tea, thyme, cannabis, and Spanish sage
CarotenoidsCarotenes (e.g., alpha-carotene, beta-carotene, and lycopene)Yellow-orange fruits e.g., carrots, tomatoes, pumpkins, and peppers, and dark green and yellow vegetables
 Xanthophyll e.g., lutein and zeaxanthinYellow, orange and dark green vegetables.
SaponinsGlycyrrhizinRoots of the liquorice plant
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Courtney Simons
Courtney Simons
Courtney Simons is a food science professor. He holds a BS degree in food science and a Ph.D. in cereal science from North Dakota State University.