Strictly speaking, phytochemicals are chemicals produced by plants. More than a thousand phytochemicals have been identified. Phytochemicals are non-nutritive plant chemicals that have protective or disease preventing properties for the plant.
In its current usage the term ‘phytochemical’ refers to those plant chemicals that may have health related effects for humans.. Phytochemicals are not essential for the human body to survive.
Since the 1970s, increasing numbers of research findings have found the association between what people eat and their health. During this research focus it was found that phytochemicals can help support good health – eg hundreds of studies from around the world have shown that a diet high in plant-based foods are associated with lower rates of heart disease and cancer.
There are five basic actions that phytochemicals can perform:
- Antioxidant. Almost all phytochemicals have antioxidant activity that protects our cells from free radical damage (oxidative stress), and therefore reduces the risk of developing certain types of cancer. These antioxidants include allyl sulphides (onions, leeks, garlic), carotenoids (fruits, carrots), flavonoids (fruits and vegetables), and polyphenols (tea, grapes especially grape skin).
- Hormonal action.Isoflavones can help to modulate our endocrine system. They can help reduce menopausal symptoms and osteoporosis.
- Stimulation of enzymes.Phytochemicals that stimulate enzymes include protease inhibitors (soy and beans), terpenes (citrus fruits and cherries). Some phytochemicals (indoles) stimulate enzymes that make oestrogen less effective and could reduce the risk of breast cancer.
- Interference of DNA replication.Saponins found in beans can play a role in preventing the multiplication of cancer cells by interfering with the replication of cell DNA.
- Anti-bacterial effect. Allicin (garlic) has anti-bacterial properties.
Terpenes are probably the most common of all the phytochemicals and are found in almost all plant life and have a beneficial role for the plants themselves. Terpenes in our diet help prevent certain cancers and heart disease.
The easiest way to ensure we get enough phytochemicals is to eat plenty of fresh organic whole foods. Foods that are rich in phytochemicals are: whole grains, vegetables, beans, fruits, and herbs.