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:
- Protect DNA from damage
- Block DNA replication in cancerous cells
- Control regulatory genes
- Regulate hormones
- Fight inflammation that promotes cancer
- Alter chemical structure of carcinogens, making them less harmless
- Cut off blood supply to tumors
- Convert malignant cells to healthy cells
- Trigger death of cancer cells (apoptosis)
- Stimulate production of anticancer enzymes
- Block or reduce tumor growth
How Can We Get More Phytochemicals?
We can increase intake of and absorption of phytochemicals by:
- Eating an adequate amount of plant-based food
- Eating a wide variety of foods (Image 1), and
- Eating fresh plant foods or minimally processed where possible
Summary of Phytochemicals with Known Anti-Cancer Properties
| Phytochemical | Example | Common Sources |
| Alkaloids | Solanine | Potato and tomato |
| Caffeine | Tea and coffee | |
| Quinine | Bitter tonic | |
| Alpha-tomatidine | Green tomato | |
| Allyl sulfides | Allicin | Onion, garlic, leeks, and chives |
| Glucosinolates | Isothiocyanates | Brussel sprouts, cabbage, turnips, mustard greens, radishes |
| Indoles | Broccoli, cabbage, and cauliflower | |
| Phenolic acid | Ellagic acid | strawberries, raspberries, blackberries, cherries, and walnuts |
| Phenylindanes | Coffee | |
| Flavanoids | Anthocyanins | Black beans, red and purple berries, grapes, apples, plums, cabbage |
| Flavanols | Epigallocatechin gallate (EGCG) | Tea |
| Quercetin | Yellow and red onions, red grape juice, apples, cranberries, and asparagus | |
| Isoflavones (phytoestrogens) | Genistein, and Daidzein | Soybean |
| Phytosterols | β-sitosterol | Rice bran, wheat germ, peanuts, corn oils, and soybeans |
| Stigmasterol | In the lipid component of soybean, calabar bean, and rape seed | |
| Terpenes | Taxol | Citrus fruits, tea, thyme, cannabis, and Spanish sage |
| Carotenoids | Carotenes (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 zeaxanthin | Yellow, orange and dark green vegetables. | |
| Saponins | Glycyrrhizin | Roots of the liquorice plant |
