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Ever heard of “eating the rainbow” of vegetables and fruit? Nature’s pigments are amazing at protecting plants—and us! Each plant color offers a different health benefit, so you need variety. If you are a gardener, consider growing plants from each color category, as each one offers unique benefits for your health.
Mom knows best: eating your veggies improves your health! She would tell you to eat your carrots to see better and she’s right. Orange (and yellow) vegetables and fruits can indeed help keep your eyes healthy thanks to all the vitamin A that they contain.
“Since the 1970’s, an abundance of evidence has demonstrated that people who eat a lot of fruit and vegetables are healthier and seem to be protected from chronic disease,” says Beverly Clevidence, a nutritionist with the U.S. Agricultural Research Service’s Food Components and Health Laboratory since 1984.
That’s because they house a variety of vitamins, minerals, antioxidants, and phytochemicals—not to mention fiber. (Not sure what antioxidants and phytochemicals do? Basically, antioxidants work to fight cellular damage, while phytochemicals can help stimulate immune function, improve heart health, and reduce inflammation.) In other words, there’s a lot of goodness packaged in pretty, colorful plants!
Study after study has confirmed that people who eat more fruits and vegetables, particularly more deeply colored varieties, have less heart disease, cancer, diabetes, osteoporosis, and age-related neurological decline.
“Something must be responsible, so scientists set out to find out what,” says Clevidence. There’s a lot at stake. Chronic diseases, responsible for 70 percent of American deaths, currently afflict 40 percent of Americans and 80 percent of older Americans. Half the nation’s elders suffer from two or more chronic health conditions. With the population of elders rising dramatically and the incidence of chronic diseases increasing among children, it’s no wonder researchers are eager to learn why eating fruits and vegetables confers so many health-protecting benefits.
The Power of Pigments
If you happen to be a gardener, you can’t help but notice that the seed catalogs have been exploding with colorful new vegetable varieties. Coral, burgundy, and deep-purple carrots. Lettuce in shades of fuchsia, bronze, and burgundy. Purple-, magenta-, black,- pink-, and deep yellow-fleshed potatoes. Orange, purple, and near-black tomatoes. Orange, purple and chartreuse cauliflower. Bright yellow, orange, brown, and purple bell peppers.
Increasingly, researchers around the world have begun to focus on pigments, the beautiful colors we appreciate in flowers, fruits, and foliage. Scientists define pigments as light-harvesting molecules. Each pigment selectively absorbs certain bandwidths of visible light and reflects the others. The reflected wavelengths are the colors we see.
The first plant pigment—chlorophyll—arguably the most important molecule on Earth—appeared at least 2.5 billion years ago. The photosynthetic reactions it initiates produce all the food and the all the oxygen that sustains the animal life on the planet.
Some pigments work with chlorophyll as photosynthetic accessory pigments. Pigments serve higher plants as signaling agents, attracting pollinators to their flowers and seed-dispersing animals to their ripe fruits.
But pigments also protect plants from excessive, tissue-damaging solar radiation and assault from free radicals, protect them from environmental stress, defend against attacks by microbes, insects and animal predators, heal damaged tissues, serve as growth regulators, and probably act in many other ways still undiscovered.
Plants: The Master Chemists
“Plants are the master chemists,” says Mary Ann Lila, who directs the Plants for Human Health Institute at North Carolina State University. “Because plants can’t move around, they have to manufacture what they need, not merely to grow, but to defend, protect, and heal themselves. It makes sense that the compounds plants produce in response to stress would help a human under similar circumstances.”
Increasingly, scientists have begun to focus on the health-promoting benefits of pigments, the light-harvesting molecules plants manufacture that selectively absorb certain bandwidths of visible light and reflect the others.
Why not simply extract the pigments and put them into pills?
“Well, there’s a lot of research heading in that direction,” says James Joseph, a neuroscientist and senior researcher at the Tufts University Human Nutrition Research Center on Aging in Boston. “But when you start taking these things apart, the compounds don’t act like they do in the whole food. In fact extracts can even produce the opposite effect, especially in high doses.”
“If you take something out of a plant and put into a pill, it’s more expensive, probably less effective, and possibly dangerous,” says retired USDA ethnobotanist James A. Duke, author of 30 books and a huge phytochemical (chemicals plants have manufactured naturally) database, and an authority on medicinal plants. “Plus it’s not occurring with its natural synergists. Most phytocompounds work together, with synergistic or additive effects.
Get a Variety of Colorful Fruits and Vegetables
Remember how your mom said eat your carrots for eyesight? It’s true. Carrots contain carotenoids (including beta carotene) which help guard against eye disease. Add yellow and orange vegetables to your shopping list! The same things go for red, dark green, purple, blue, and dark red!
“You can’t overdose on vegetables,” Duke says. “Variety is the key. Get the most variety of colorful fruits and vegetables you can the most cheaply.”
He also encourages consumers to “graze in the field,” learning to identify and eat weeds and other plants from the wild. “Wild plants have to produce more [protective compounds] to protect themselves, and they pass that protection along to you and me.”
The more we clearly connect the health benefits of pigments, the more acceptable nutritional approaches to human health will become to the medical community. Clevidence adds, “Meanwhile, we just do the science and report what we learn, building our knowledge base brick by brick.”
“For now, we should apply what we know, and the message is not sexy: ‘Eat more fruits and vegetables. Eat a little fat, from any source, with green and yellow vegetables. Steam, microwave, or add red and purple vegetables to soup so you don’t pour those water-soluble anthocyanins (pigments) down the drain.”
Chart: Color Categories and Health Benefits
See a chart listing each colorful vegetable and how they are healthy. Specifically, this chart summarizes the main classes of plant pigments (light-harvesting molecules that plants manufacture), the roles they play in plant health, the foods rich in each pigment class, and its potential value to human health.
When you are buying (or growing) vegetables and fruit, consider choosing from each color category, as each one offers unique benefits for your health.
Roles in plants
Foods rich in these pigments
Potential value to humans
harvest light; initiate photosynthesis
help deactivate carcinogens
Carotenoids (fat-soluble: eat with a little fat)
attract pollinators and seed dispersers
accessory photosynthetic pigment in periods of low light, absorbs excess light energy, antioxidant roles, substrate for hormones
Anthocyanins (water-soluble: don’t throw out cooking water)
attract pollinators and seed dispersers
repel predators, protect cells from damage by excess light, improve plant tolerance to stress such as drought, UV-B, and heavy metals, resist disease, scavenge free radicals.
purple vegetables (onions, cabbage, potatoes), red, blue & purple berries, black beans
prevent, forestall, possibly even reverse age-related cognitive declines and neuro-degenerative diseases; improve night vision and other vision disorders, protect against heart disease, insulin resistance, cancer; promote wound healing
Betalains (water-soluble, never co-occur with anthocyanins)
beets (red and yellow), chard, spinach, fruit of prickly-pear cactus
antioxidant, may protect against heart disease, various cancers, ulcers, liver damage
There’s a lot at stake …
Just over a quarter of Americans eat the current USDA recommendation of three servings of vegetables a day, and most experts call for nine servings to get the maximum benefits.
Children ages two to 18 eat even less: dark green or orange vegetables make up only eight percent of the veggies children eat and fried potatoes account for nearly half.
Margaret Boyles is a longtime contributor to The Old Farmer’s Almanac. She wrote for UNH Cooperative Extension, managed NH Outside, and contributes to various media covering environmental and human health issues. Read More from Margaret Boyles