The concept of “eat the rainbow” highlights the consumption of a balanced diet through a colorful variety of fruits and vegetables on a daily basis. Plant-based foods provide an abundance of vitamins and minerals, which are necessary for the growth, maintenance, and repair of body tissues. Additionally, vitamins, minerals, fiber and phytonutrients aid in the prevention of chronic diseases.

Phytonutrients, also known as phytochemicals, are non-nutritive compounds that determine the pigment, flavor, and odor of plants. They provide health benefits such as boosting the immune system, detoxifying the body, reducing inflammation, improving cardiovascular health, and stimulating the death of cancer cells.

Phytonutrients act as an antioxidant, which protects the body against free radicals, a source of cell damage from unstable molecules that result from normal metabolism. Many diseases are believed to be influenced by this cell damage, or what is known as oxidative stress.

Eating a limited selection of plant-based foods not only limits your vitamins, minerals, fiber and phytonutrient intake and benefits, but also limits your gut microbiome diversity.

The gut microbiome is a collection of species like bacteria that exist by the trillions within our large intestines with the purpose to protect against illness and infections for immunity, produce essential nutrients, and regulate bowel movements. Diet has an impact on how the gut microbes change; through your current eating habits and diet patterns formed long term.

A loss in species diversity is commonly linked to multiple disease states such as irritable bowel syndrome, neuropsychiatric diseases, obesity and other metabolic diseases. Eating the rainbow may provide a way to alter the gut microbe diversity, which could improve gut function and immunity.

Phytonutrients from food are composed of the following color groups: red, orange, yellow, green, blue, purple, black, white and brown. Alongside fruits and vegetables, eating the rainbow includes whole grains, legumes, herbs, spices, nuts, seeds and tea, which are also sources of phytonutrients.

It is not necessary to consume each color every day; however, it is important to incorporate each group at least 2-3 times per week.

It’s generally recommended to eat 3-5 servings of vegetables and fruits daily. Adult women should aim for at least 30 grams of fiber per day and men 35-40 grams. 

The following count as 1 serving of fruits and vegetables:

• ½ cup cooked vegetables
• 1 cup raw leafy vegetables
• 1 medium fruit

Red plant-based foods are associated with anti-cancer, anti-inflammatory, and anti-aging benefits; and may protect the heart, liver, and brain. The main phytonutrients include lycopene, anthocyanins, fisetin and ellagic acid.

Lycopene, a carotenoid or a group of phytonutrients found in red, orange, yellow, and green plant pigments, is associated with protection against cancers of the skin, lungs, breast and prostate; eye diseases; and cardiovascular diseases.

Sources include: tomato and tomato-based products, pink grapefruit, watermelon, and guava. Cooking carotenoids in fat increases the absorption of the phytonutrient; an example would be adding olive oil to tomato sauce.

Anthocyanins are associated with protection against cancer, high blood pressure and blood clots. Sources include: red berries (raspberries, sweet cherries, strawberries, cranberries), beets, red onions, red cabbage, kidney and red beans.

Fisetin is associated with anti-cancer and anti-inflammatory benefits and may protect the skin against sun-related damages. Sources include: apples, grapes and strawberries.

Ellagic acid is found in pomegranates and is noted for assisting the liver in detoxification.

Additional sources: goji berries, plums, blood oranges, red peppers, radicchio, radishes, red potatoes, adzuki beans

Orange plant-based foods are associated with anti-cancer, anti-inflammatory, and anti-aging benefits; and may protect the heart, eyes, and immune system. The main phytonutrients are carotenoids (alpha-carotene, beta-carotene, beta-cryptoxanthin), bioflavonoids, and curcuminoids.

Carotenoids, alpha-carotene, beta-carotene, beta-cryptoxanthin, are important phytonutrients that convert into vitamin A, which is responsible for promoting cell growth, reproduction, and bone and eye health. Sources include: carrots, sweet potatoes, yams, oranges, cantaloupe, apricots, pumpkin, mango, acorn squash, butternut squash, orange peppers, papaya, and persimmon. Remember that cooking these with fat optimizes absorption.

Bioflavonoids are known to assist vitamin C with important functions such as bone, skin, and heart health. Sources include: oranges, clementines, mandarin, tangerines, nectarines, peaches, grapefruit, and yellow foods like pineapple and lemons.

Curcuminoids are an anti-inflammatory powerhouse found in the spice turmeric.

Yellow plant-based foods are associated with anti-cancer and anti-inflammatory benefits; and may protect the heart, vision, skin, and brain. The main phytonutrients are the carotenoids, lutein, zeaxanthin, and beta-cryptoxanthin. Sources include: bananas, golden delicious apples, pineapples, lemon, asian pears, starfruit, corn, yellow peppers, Yukon potatoes, summer squash, golden beets, millet, and ginger root/ginger spice. Remember that cooking these with fat optimizes absorption.

The concept of “eat the rainbow” highlights the consumption of a balanced diet through a colorful variety of fruits and vegetables on a daily basis. Plant-based foods provide an abundance of vitamins and minerals, which are necessary for the growth, maintenance, and repair of body tissues. Additionally, vitamins, minerals, fiber and phytonutrients aid in the prevention of chronic diseases.

Yellow plant-based foods are associated with anti-cancer and anti-inflammatory benefits; and may protect the heart, vision, skin, and brain. The main phytonutrients are the carotenoids, lutein, zeaxanthin, and beta-cryptoxanthin. Sources include: bananas, golden delicious apples, pineapples, lemon, asian pears, starfruit, corn, yellow peppers, Yukon potatoes, summer squash, golden beets, millet, and ginger root/ginger spice. Remember that cooking these with fat optimizes absorption.

Yellow plant-based foods are associated with anti-cancer and anti-inflammatory benefits; and may protect the heart, vision, skin, and brain. The main phytonutrients are the carotenoids, lutein, zeaxanthin, and beta-cryptoxanthin. Sources include: bananas, golden delicious apples, pineapples, lemon, asian pears, starfruit, corn, yellow peppers, Yukon potatoes, summer squash, golden beets, millet, and ginger root/ginger spice. Remember that cooking these with fat optimizes absorption.

Dark colored plant sources tend to have high levels of phytonutrients; however, white plant-based foods still provide valuable benefits such as anti-cancer and anti-inflammatory properties; and promote liver health and hormonal balance. The main phytonutrients are allicin and lignans.

Allicin is known for anti-bacterial, anti-viral, and anti-cancer properties and is found in garlic and onions.

Lignans provide anti-inflammatory and anti-cancer benefits; and may promote blood vessel health. The highest source is flaxseeds, but additional sources include sunflower seeds, tree nuts, peanuts, pumpkin seeds, sesame seeds, and tahini paste.

Additional sources: cocoa, coffee, ginger, coconut, applesauce, dates, lychee, pears, cauliflower, sauerkraut, shallots, mushrooms, potatoes, jicama, parsnips, daikon radish, celeriac, turnips, Jerusalem artichoke, oats, spelt, barley, wheat, rye, triticale, chickpeas, hummus, peas, lentils

• Make home cooked meals the majority of the week and consider meal prep for practicality.
• When preparing your shopping list, purchase at least 2-3 different varieties of fruits, vegetables, nuts, seeds, legumes and whole grain.
• Based on your budget and quality of produce in your area, opt for a combination of fresh, frozen, and canned fruits, vegetables and legumes. Keep in mind that fresh produce has the highest phytonutrient content. Watch out for added sugar and sodium in canned items.
• Your plate should consist of 50 percent vegetables, 25 percent whole grains, and 25 percent lean protein.
• Get creative with substitutions for more nutrient-dense foods, which are high in dietary fiber, vitamins, minerals, and other important nutrients, while having low saturated fat, added sugars and sodium. For example, swap frozen waffles for oatmeal with berries, nuts, and seeds; substituting white rice for black rice with a meal; or swap coffee with tea.
• Keep fruits and vegetables in your line of sight to encourage healthy snacking. Be sure to consume more non-starchy produce than starchy.
• Additionally, simple ways to introduce variety include: smoothies with fruits, vegetables, nut butters, or even tea; incorporating multiple vegetables, herbs, and spices into soups, salads, sandwiches, or casseroles; roast a pan of different vegetable varieties; create salad dressings with olive oil and garlic and/or herbs.

Chlorophyll and Metallo-Chlorophyll Derivatives. (2022, April 4). Linus Pauling Institute. https://lpi.oregonstate.edu/mic/dietary-factors/phytochemicals/chlorophyll-metallo-chlorophyll-derivatives

Eleanor Noss Whitney, & Sharon Rady Rolfes. (2018). Understanding nutrition (15th ed.). Cengage.

Heiman, M. L., & Greenway, F. L. (2016). A healthy gastrointestinal microbiome is dependent on dietary diversity.

Molecular metabolism, 5(5), 317–320. https://doi.org/10.1016/j.molmet.2016.02.005
The Institute for Functional Medicine. (2015).

Phytonutrient Spectrum Comprehensive Guide. (Version 3).

National Center for Complementary and Integrative Health. (2013, November). Antioxidants: In Depth. NCCIH. https://www.nccih.nih.gov/health/antioxidants-in-depth

Oregon State University. (2019, January 2). Carotenoids. Linus Pauling Institute. https://lpi.oregonstate.edu/mic/dietary-factors/phytochemicals/carotenoids

Santhiravel, S., Bekhit, A. E. A., Mendis, E., Jacobs, J. L., Dunshea, F. R., Rajapakse, N., & Ponnampalam, E. N. (2022). The Impact of Plant Phytochemicals on the Gut Microbiota of Humans for a Balanced Life. International journal of molecular sciences, 23(15), 8124. https://doi.org/10.3390/ijms23158124

U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020-2025. 9th Edition. December 2020. Available at DietaryGuidelines.gov.