The colourful secret about phytonutrients

Learn the mystery behind the vibrant colours of fruits and vegetables and a healthy life

basket full of colourful fruits and vegetablesMother Nature knows that we use all our senses to select our foods—her bounty provides us with an incredible array of beautiful, fragrant and tasty foods and herbs.

We’re still naturally drawn to bright colours, delicious flavours and wonderful aromas. But beyond the sensory appeal, foods and herbs contain thousands of phytonutrients—natural plant compounds that have far-reaching effects on our health.

The world of phytonutrients

Phytonutrients are chemical compounds that appear naturally in all plant foods. Different plant foods provide different phytonutrients, which is why it’s so important to eat a wide variety.

The best known phytonutrients are carotenoids, flavonoids, and isoflavones. Carotenoids include yellow, orange, and red pigments in fruits and vegetables. Flavonoids are reddish pigments, found in red grape skins and citrus fruits, and isoflavones can be found in peanuts, lentils, soy, and other legumes.

Another phytonutrient, resveratrol, found in red wine, has cancer-fighting properties. Resveratrol is a potent antioxidant [more potent than vitamin C], which acts synergistically with vitamin C to enhance the effect of both. It also prevents the formation of blood clots and promotes the formation of new dendrites in the brain.

Phytonutrients provide a range of health benefits. These health benefits are due to the presence of certain pigments present in fruits and vegetables, which gives these foods their peculiar vibrant red, yellow, green and other rich colours.

While almost all plant foods contain health-promoting phytochemicals, the following are the most common food sources of these: soy, tomato, broccoli, garlic, flaxseeds, citrus fruits, melons like cantaloupe, watermelon, pink grapefruit, blueberries, sweet potatoes, chilli peppers and legumes like beans and lentils.

Apart from these, green tea, red grapes, papaya, carrots, kale, nuts and seeds, eggplant, cabbage, brussel sprouts, onions, apples, cauliflower, dried apricots, pumpkin, squash, spinach, mangoes, and shiitake mushrooms also contain phytonutrients.

Phytonutrients come in many forms. Some are natural pigments that give plant foods their beautiful hues, while others, like sulphur compounds in onion or garlic, are responsible for strong odours and flavours.

Varied benefits

According to a new American research, choosing different coloured fruits and vegetables will increase your phytonutrient intake, thereby lowering the risk of heart diseases, cancer and diabetes.

Many phytonutrients act as powerful antioxidants. Oxidation is a process that occurs in the body naturally as part of everyday metabolism and exposure to air and sunlight. Oxidation needs to be kept in check, since too much oxidative stress on the body can cause damage to body cells and tissues. And phytonutrients play a key role in this.

Apart from serving as antioxidants, phytonutrients enhance immune response, enhance cell-to-cell communication, repair DNA damage caused by smoking and other toxic exposures and detoxify carcinogens.

While these phytonutrients make plants attractive to look at or delightful to eat, many protect the plant from heat, sunlight or pests. When we consume fruits, vegetables and herbs, these phytonutrients then work in our body to keep us healthy.

Just as humans suffer from the harmful UV rays of the sun, plants need to protect themselves too. For example, as tomatoes ripen in the heat of the sun, they produce more and more lycopene—the pigment that not only gives tomatoes their deep red colour, but also acts as an antioxidant to protect the plant from harmful ultraviolet rays.

Now, when we eat tomatoes or any other antioxidant-rich fruits or vegetables, they reap similar benefits in our body. The lycopene and other antioxidant phytonutrients in the tomato help protect the body’s cells by bolstering the body’s antioxidant defence system.

A shade of difference

Not all phytonutrients are colourful. There are phytonutrients that have a strong odour like the strong-smelling glucosinolates found in broccoli, cauliflower and horseradish. These help keep the plant healthy by deterring pests. When we eat them, these same compounds keep us healthy by helping break down and detoxify potentially harmful substances. Other fragrant plant foods like herbs, spices and teas are also rich in phytonutrients.

The diversity of plant foods and the unique makeup of each herb, spice, tea, fruit or vegetable supply us with literally thousands of these beneficial, health-promoting phytonutrients in the diet. So what matters is not just eating more servings, but eating a wide range of plant foods.

So, when you can, mix your plant foods together in the same dish or meal. There is some evidence that when eaten together, combinations of plant foods—like a mixed fruit salad or a spicy mixed vegetable curry—might deliver a stronger antioxidant punch than when eaten alone.

How colourful is your diet?

Foods are divided into seven colour groups, each representing a predominant phytonutrient.

  • RED: Tomatoes and tomato products, pink grapefruit and watermelon.
  • RED/PURPLE: Grapes, berries, plums, cherries, pomegranate.
  • ORANGE: Carrots, mangos, cantaloupes, pumpkin, winter squash, and sweet potatoes.
  • ORANGE/YELLOW: Citrus fruits, pineapple and papaya
  • YELLOW/GREEN: Leafy greens like spinach and lettuce, yellow corn, avocado, green peas, green beans, green peppers, yellow peppers, cucumber, kiwi, honeydew melon.
  • GREEN: Broccoli, brussels sprouts, cabbages, cauliflower and kale.
  • WHITE/GREEN: Garlic, onions, leeks and asparagus

Adapted from: “What Color is Your Diet?” by David Heber with S. Bowerman; HarperCollins/Regan Books, 2001

Susan Bowerman
Susan Bowerman, MS, RD, CSSD, is the assistant director of the UCLA Center for Human Nutrition and a registered dietician and a board-certified specialist in sports dietetics. She is the co-author of What Color is Your Diet.


  1. has any scientific organization experimented with the spectro-analysis of fruits and vegetables to grade their ranking of benefits in antioxidants and phytonutrients? Knowing the strength of the colors these fruits and vegetables emit and possess could be the hidden secrets of cures to all ailments and diseases.


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