Why All The Fuss About Phytochemicals?

Phytochemicals are naturally occurring compounds in plant foods—‘phyto’ means plant—that have health benefits. These compounds are also called phytonutrients. Different foods contain different phytochemicals with varying properties. This is why eating from the rainbow (of coloured foods) is recommended.

Freshly picked lettuce, herbs, leek, zucchini, tomatoes, pears, lemons, peaches and figs

The benefits of phytochemicals

Research has indicated that phytochemicals can improve health in the following ways:

  • Destroy compounds that cause oxidative damage—some phytochemicals work as antioxidants.
  • Reduce inflammation—they are natural anti-inflammatory agents.
  • Boost our immune system.
  • Delay the aging process.
  • Protect and help repair our genes (DNA).
  • Assist in the regulation of hormones.

Where do we find phytochemicals?

Several thousand phytochemicals have been identified. Dietary polyphenols, a type of phytochemical, contribute a number of different types of active compounds including:

  • Phenolic acids e.g. hydroxybenzoic and hydroxycinnamic acids
  • Flavonoids e.g. flavonols, flavones, isoflavones, flavonones, flavanols and the anthocyanidins
  • Stilbenes
  • Lignans

Researchers continue to investigate the health properties of these compounds. The mostly widely understood phytochemicals are outlined below. Some benefits are still considered ‘potential’ rather than proven.

Phytochemical Source Benefits
Carotenoids e.g. beta-carotene and lycopene. Red, orange and green fruits and vegetables. For example: tomatoes, sweet potato, carrots, pumpkin, leafy greens and broccoli. Pistachios. Paprika and saffron. Antioxidants.

Role in improving immunity.

Potential anti-carcinogens (inhibit cancer).

Flavonoids e.g. anthocyanins and quercetin Berries, apples, citrus fruits, pecans, hazelnuts and almonds and, soybeans and soy products e.g. tofu, tempeh. May inhibit: inflammation and tumour growth; improve immunity and support detoxification processes.
(daidzein and genistein)
Soybeans and soy products. Antioxidants.

Potential anti-carcinogens (inhibit cancer).

Phenolic Acid/ Polyphenols

e.g. resveratrol

Green tea, grapes, wine, berries, citrus fruits, apples, whole grains and peanuts. Antioxidants.


May prevent cancer formation.

Indoles and Glucosinolates
and sulphur compounds
Cruciferous vegetables (broccoli, cabbage, collard greens, kale, cauliflower and Brussels sprouts), garlic, asafetida. May prevent cancer.
Isothiocyanates Cruciferous vegetables, mustard seed, wasabi. Antioxidants.

May prevent cancer.

(phytic acid)
Bran from corn, oats, rice, rye and wheat, nuts, soybeans and soy products. Antioxidants.

May prevent cancer.

e.g. limonene, sesquiterpenes
Cherries, citrus fruit peel, cumin, fennel, caraway, cinnamon, juniper, ginger, turmeric. Potential roles in preventing cancer and oxidation and, strengthening immune function.

Fill your meals and snacks with phytochemicals

  1. Eat whole foods—coloured fruits and vegetables, whole grains, legumes, nuts and seeds.
  2. Flavour your food with herbs and spices.
  3. Choose colourful and flavoursome plant foods as the foundation for meals and snacks.
  4. A variety of foods, containing different types of phytochemicals, can lead to improved health by supplying natural antioxidants, anti-inflammatory agents and compounds that help to prevent heart disease and cancer.
  5. Plant foods provide a unique balance of phytochemicals, vitamins, minerals and fibre. This balance cannot be replicated in supplements. Food is definitely your best source of nutrients.

Next week we will explore practical ways to boost the phytochemical content of your meals and snacks.


American Institute Cancer Research


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