Updated: Jul 2, 2021
I mentioned on the podcast that among the six areas of focus in lifestyle medicine, nutrition is the first step towards lifestyle change. I have written an article about nutrition, particularly a whole-food, plant-based diet. In that article, I mentioned how to start and eat the colors of the rainbow.
In this article, I will discuss the food items that represent the colors of the rainbow and its benefits. This way, you will have an idea on your food choices and would be most likely to choose functional foods. Functional foods are dietary components that provide health benefits beyond basic nutrients.
We have been taught since we were kids to eat fruits and vegetables because these foods contain not only vitamins and minerals but also phytonutrients. Phytonutrients are bioactive plant-derived compounds associated with positive health effects. Phytonutrients are pleiotropic, meaning they do have multiple effects on our cells’ structure and function. And because of this, phytonutrients are helpful in preventing chronic diseases.
Not only that, anti-inflammatory plant compounds like polyphenols and other phytochemicals help offset toxicity from pollutants.
Also, a study among 12,285 Australian adults showed an increased intake of fruits and vegetables had a favorable impact on their psychological well-being. Another study in New Zealand showed that those who ate more fruits and vegetables for more than thirteen consecutive days flourished in their daily lives with high levels of well-being, intense feelings of curiosity and creativity compared with adults who ate less fruits and vegetables.
And there are numerous studies that showed intake of fruits and vegetables is associated with reducing chronic disease risk. One of them is a study which introduced the term “phytochemical index” in 2004. Phytochemical index is the percent of dietary calories from foods rich in phytochemicals. A high phytochemical index shows favorable effects on preventing weight gain, along with improved lipid levels, and lowered risk of hypertension and breast cancer.
Low Phytonutrient Intake
However, even though we know that eating fruits and vegetables is a part of a healthy diet, people continue to have a low intake of these nutrients below the recommended dietary allowance called “phytonutrient gap”.
To visualize this phytonutrient gap, a study showed that eight out of ten Americans fall short of the recommended daily allowance for each color of phytonutrients especially the purple/blue foods. Another study showed that only nine percent of American adults met the recommended daily allowance for vegetables and only twelve percent met the recommended daily allowance for fruits.
The “Eat by Color” Approach to Increase Fruit and Vegetable Intake
Although eating recommended quantities of fruits and vegetables continues to be a challenge among most people, it is much easier to adopt a qualitative color approach rather than a quantitative serving approach.
The concept of eating by colors of the rainbow seems to be an effective strategy for people in improving their diet. It can also be implemented across all ages.
For easy reference and memory, each color is associated with some general related health benefits. Each color corresponds to foods, phytonutrient content, and beneﬁts which were determined based on research publications.
Red Foods and Inflammation
Red foods are high in phytonutrients such as astaxanthin, lycopene, ascorbic acid (vitamin C), fisetin, and other classes of anthocyanins which exhibit anti-inflammatory properties and immune-modulating activities. Examples of red foods are cherries, tomatoes, red bell pepper, watermelon, grapefruit, apples, pomegranate, strawberries, cranberries, and raspberries.
Orange Foods and Reproductive Health
Orange foods share common properties with the red ones with respect to their antioxidant properties. The main difference is the carotenoids associated with orange such as beta-carotene and beta-cryptoxanthin. These carotenoids exhibit endocrine-regulating activities and have a role in fertility.
Also, a 3-year study in more than a thousand men and women showed that greater intake of dietary carotenoids in orange foods was associated with reduced risk of insulin resistance.
Examples of orange foods are carrots, pumpkin, sweet potatoes, squash, and cantaloupe.
Yellow Foods and Digestion
Yellow foods contain bioflavonoids that benefit the gastrointestinal tract and digestion. Various soluble, insoluble, and prebiotic fibers found in these foods impede the release of simple carbohydrates into the bloodstream thereby lowering the glycemic index. These foods may also provide the raw materials required as an energy substrate to be used by the gut microbiome.
Examples of yellow foods are ginger, mangoes, pineapples, bananas, and citrus fruits like lemons.
Green Foods and Cardiovascular Health
Green foods contain vitamin K, folate, magnesium, potassium, and naturally occurring nitrates and folates that benefit our cardiovascular health. Green leafy vegetables are also abundant in polyphenols which may diﬀerentially aﬀect cardiometabolic risk factors. Leafy greens (such as spinach, watercress, celery, chervil, lettuce, and rocket) and cruciferous vegetables (such as cauliflower, broccoli, and kale) are just examples of green foods. Research shows that cardiovascular disease risk could be reduced by 15.8% with “almost everyday” consumption of green leafy vegetables.
Blue-Purple Foods and Cognition
Blue-purple foods contain polyphenols, flavonoids, procyanidins, flavonols, and phenolic acids that assist with learning, cognition, memory, and mood. Flavonoids contribute to the maintenance of proper brain function and blood flow. Blueberries, blackberries, red grapes, red wine, and purple yams are just examples of blue-purple foods.
Although this article advocates to eat the colors of the rainbow, it doesn’t mean that we disregard other colors like brown and white. In fact, there are healthy brown and white foods available around us.
Brown foods contain potassium, fiber, beta-glucans, lignans, and epigallocatechin gallate which may reduce the risk of coronary heart disease and some types of cancer and maintain a healthy digestive tract. Examples of brown foods are whole wheat breads, cereals, bran, oats, barley and rye.
White foods contain glucosinolates, polyphenols, protein, fiber, B vitamins, potassium and iron. Glucosinolates provide protection against cancer. Polyphenols play an important role in managing inflammation. Examples of white foods are turnips, jicama, garlic, onion, and white beans.
Practical Ways to Get More Colorful Fruits and Vegetables
Counting colors rather than servings or calories may be more effective to engage in long-term lifestyle change. You could track your “eating by color” by creating check boxes each time you fulfill a daily requirement.
As mentioned in my previous article, one way to start a whole-food, plant-based diet is to build a meal around salads. Try incorporating each color in a salad and see if this works for you. Also, why not try adding one new fruit or vegetable every week to expand your choices?
Another way to promote higher intake of fruits and vegetables is to eat more meals at home rather than eat out. Although there are vegan, vegetarian, or farm-to-table restaurants in cities, most of them are rare in other areas. Not only will you adhere more to a whole-food plant-based diet eating at home, you will also be sure that your food is safely prepared.
Eating fruits and vegetables has numerous benefits. However, most people continue to consume less fruits and vegetables than what is recommended. That is why it is important to encourage more people to eat more of these foods. One way to do this is to associate each color with health benefits, rather than counting calories or any index. This way, people would not only remember and could relate easily to the health properties of fruits and vegetables but also sample a variety of foods in the process.
So the next time you pick any one of the fruits and vegetables, remember that it is not only bursting with color and flavor, but also contains phytonutrients that improve your health.
If you are not yet ready to go 100% on a whole-food plant-based diet or if you are interested to start, feel free to schedule a consultation. I will help and work with you to make changes at whatever pace you are comfortable with. There is a health program that might suit your needs. Or if you want to hear from me talk about Lifestyle Medicine, feel free to listen to the podcast or reach out by using the contact form below.
Minich, Deanna M. 2019. “A Review of the Science of Colorful, Plant-Based Food and Practical Strategies for ‘Eating the Rainbow.’” Journal of Nutrition and Metabolism 2019 (no data): 1–19.