Nutrients found in plant foods are widely referred to as phytonutrients. There are at least 5,000 known phytonutrients and probably many more.
So what does each color do for our bodies and our overall health?
Red fruits and vegetables are colored by a type of phytonutrient called “carotenoids” (including the so-called lycopene, flavones and quercetin – but the names aren’t as important as what they do). These carotenoids are found in tomatoes, apples, cherries, watermelon, red grapes, strawberries and capsicum.
These carotenoids are known as antioxidants. You may have heard this name before, but you might not remember what it means. It has something to do with “free radicals”, which you’ve probably heard of before.
Free radicals are formed naturally in our bodies as a by-product of all our usual bodily processes like breathing and moving, but they also come from exposure to ultraviolet light, smoke, air pollutants and industrial chemicals.
Free radicals are unstable molecules that can damage proteins, cell membranes and DNA in our body. This natural but harmful process is known as oxidation or oxidative stress. This contributes to aging, inflammation and disease, including cancer and heart disease.
It is important to emphasize that antioxidants “clean” the free radicals that form in our body. They stabilize free radicals so they can’t cause further damage.
Increasing antioxidants in your diet reduces oxidative stress and lowers your risk of many diseases, including arthritis, type 2 diabetes, heart disease, stroke, and cancer.
Read more: What are antioxidants? And are they really good for us?
Orange fruits and vegetables also contain carotenoids, but slightly different from red vegetables (including alpha and beta carotene, curcuminoids and others). These are found in carrots, pumpkins, apricots, tangerines, oranges and turmeric.
Alpha and beta carotene are converted to vitamin A in our bodies, which is important for healthy eyes and good eyesight. Vitamin A is also an antioxidant that can target parts of the body made of lipids (or fats), such as cell membranes.
Vitamin A targets free radicals that accumulate around our cell membranes and other areas made of lipids, reducing the risk of cancer and heart disease.
Yellow fruits and vegetables also contain carotenoids, but they also contain other phytonutrients, including lutein, zeaxanthin, meso-zeaxanthin, viola-xanthin, and others. These are found in apples, pears, bananas, lemons and pineapples.
Lutein, meso-zeaxanthin and zeaxanthin have been shown to be particularly important for eye health and may reduce the risk of age-related macular degeneration, which leads to blurring of central vision.
These phytonutrients can also absorb ultraviolet light in your eyes, acting as a sunscreen for your eyes and protecting them from sun damage.
Green fruits and vegetables contain many phytonutrients, including chlorophyll (which you probably remember from high school biology), catechins, epigallocatechin gallate, phytosterols, nitrates, and also an important nutrient known as folate (or vitamin B9). These are found in avocados, Brussels sprouts, apples, pears, green tea and leafy vegetables.
These also act as antioxidants and therefore have the benefits described above for red vegetables. But this group also has important benefits for keeping blood vessels healthy by promoting something called “vasodilation.”
These phytonutrients help make our blood vessels more elastic and flexible, allowing them to widen or dilate. This improves blood circulation and lowers blood pressure, reducing the risk of complications and diseases of the heart and other vessels.
Folate is recommended before pregnancy because it helps reduce the risk of neural tube defects (such as spina bifida) in babies. Folate aids in the development of the fetal nervous system during the first few weeks of pregnancy as it has been shown to promote healthy cell division and DNA synthesis.
blue and purple
Blue and purple products contain other types of phytonutrients, including anthocyanins, resveratrol, tannins, and others. They are found in blackberries, blueberries, figs, plums and red grapes.
Anthocyanins also have antioxidant properties and therefore provide benefits in reducing the risk of cancer, heart disease and stroke as explained in Berries and Vegetables.
More recent evidence has indicated that they may also provide improvements in memory. This is believed to do by improving signaling between brain cells and making it easier for the brain to change and adapt to new information (known as brain plasticity).
brown and white
Brown and white fruits and vegetables are colored by a group of phytonutrients known as “flavones,” which include apigenin, luteolin, isoetin, and others. These are found in foods like garlic, potatoes and bananas.
Another phytonutrient found in this color of vegetables, particularly garlic, is allicin. Allicin has been shown to have antibacterial and antiviral properties.
Most of this research is still on the lab bench and few clinical trials have been done on humans, but lab-based studies have found that it reduces microorganisms when grown under lab conditions.
Allicin has also been found in systematic reviews to normalize high blood pressure by promoting blood vessel dilation.
How can I get more vegetables in my diet?
Colorful fruits and vegetables, as well as herbs, spices, legumes and nuts provide us with a plethora of phytonutrients. Promoting a rainbow of fruits and vegetables is a simple strategy to maximize health benefits across all age groups.
However, most of us don’t eat the recommended amount of fruits and vegetables every day. Here are some tips to improve your intake:
1. when doing your fruit and vegetable shopping, include a rainbow of colors in your shopping basket (frozen varieties are absolutely fine)
two. try some new fruits and vegetables that you’ve never eaten before. The internet has tips on many different ways to cook vegetables.
3. buy fruits and vegetables of different colors that you normally eat, such as apples, grapes, onions and lettuce
4. eat the peels, as the phytonutrients may be present in the skin in greater amounts
5. don’t forget that herbs and spices also contain phytonutrients, add them to your cooking too (they make veggies more appealing too!)