Nutritionists will tell you to eat a rainbow of fruits and vegetables. It’s not just because it looks good on the plate. Each color represents different nutrients that our body needs.
Nutrients found in plant foods are generally called phytonutrients. There are at least 5,000 known phytonutrients, and probably many more.
So what does each color do for our body and overall health?
Red fruits and vegetables are colored by a type of phytonutrient called “carotenoids” (including those named 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 bell pepper.
These carotenoids are called antioxidants. You have heard this name before, but you may not remember its meaning. It has something to do with “free radicals”, which you’ve probably heard of.
Free radicals form naturally in our bodies as a by-product of all of our normal bodily processes, such as breathing and movement, but they also come from exposure to UV rays, smoking, air pollutants, and chemicals. industrial chemicals.
Free radicals are unstable molecules that can damage proteins, cell membranes and DNA in our body. This natural but damaging process is known as oxidation or oxidative stress. This contributes to aging, inflammation, and disease, including cancer and heart disease.
Above all, antioxidants “mop up” the free radicals that form in our bodies. They stabilize free radicals so that they do not cause further damage.
Increasing antioxidants in your diet reduces oxidative stress and lowers the risk of many diseases, including arthritis, type 2 diabetes, heart disease, stroke, and cancer.
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 into vitamin A in our body, which is important for eye health and good eyesight. Vitamin A is also an antioxidant that can target parts of your body made up of lipids (or fats) such as cell membranes.
Vitamin A targets free radicals that accumulate around our cell membranes and other areas made up of lipids, reducing the risk of cancers 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 causes blurry vision in your central vision.
These phytonutrients can also absorb UV light in your eyes, acting as sunscreen for the 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 called folate (or vitamin B9). They 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 offers significant benefits for keeping your blood vessels healthy, by promoting what’s called “vasodilation.”
These phytonutrients help make our blood vessels more elastic and flexible, allowing them to widen or dilate. This improves blood circulation and reduces blood pressure, thereby reducing our 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 helps in the development of the fetal nervous system during the first weeks of pregnancy, as it has been shown to support 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, prunes and purple grapes.
Anthocyanins also have antioxidant properties and thus offer benefits in reducing the risk of cancer, heart disease and stroke, as explained in the red fruits and vegetables section.
More recent evidence has indicated that they can also improve memory. This is thought to happen by improving signaling between brain cells and facilitating the brain’s change and adaptation to new information (called brain plasticity).
brown and white
Brown and white fruits and vegetables are colored by a group of phytonutrients called “flavones,” including apigenin, luteolin, isoetin, and others. These are found in foods such as garlic, potatoes and bananas.
Another phytonutrient found in this vegetable color, especially in garlic, is allicin. Allicin has been shown to have antibacterial and antiviral properties.
Most of this research is still in the lab and few clinical trials have been done in humans, but lab studies have shown that it reduces microorganisms when grown under lab conditions.
Allicin has also been found in systematic reviews to normalize high blood pressure by promoting dilation of blood vessels.
How can I incorporate more vegetables into my diet?
Colorful fruits and vegetables — but also 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 in all age groups.
However, most of us do not consume the recommended amount of fruits and vegetables every day. Here are some tips to improve your intake:
1. When shopping for fruits and vegetables, include a rainbow of colors in your basket. (Frozen varieties are fine.)
2. Try new fruits and vegetables that you have never eaten before. The internet offers advice on many ways to cook vegetables.
3. Buy different colors of fruits and vegetables that you normally eat such as apples, grapes, onions and lettuce.
4. Eat the peels, as phytonutrients may be present in the peel in greater amounts.
5. Remember that herbs and spices also contain phytonutrients. Add them to your kitchen too. (They also make vegetables more appealing!)
Evangeline Mantzioris, Nutrition and Food Science Program Director, Registered Dietitian, University of South Australia
This article is republished from The Conversation under a Creative Commons license.
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