Fueling Facts: Eat the Rainbow

If you haven’t heard the phrase “Eat the Rainbow” from your SHIFT Registered Dietitian, then you have likely heard it somewhere else. What does this phrase mean, exactly? Why is it important to consume a variety of fruits and vegetables in your diet? In this month’s Fueling Facts, we explore the nutritional benefits of eating fruits and vegetables across the rainbow and provide recipes to help you add more variety to your meals this summer!

fruit & vegetable basics

Research clearly shows an association between fruit and vegetable intake with a decreased risk of chronic diseases, including hypertension, coronary artery disease, stroke, type 2 diabetes, certain eye diseases, dementia, osteoporosis, and potentially cancer.¹ Newer research also correlates fruit and vegetable consumption with an increase in psychological well-being.² Although many benefits can be attributed to the micronutrients (vitamins and minerals) and fiber in fruits and vegetables, some outcomes are linked to their respective phytonutrients.

Phytonutrients are natural compounds found in plants that protect them from bugs, germs, sun, and other threats. Phytonutrients also give fruits and vegetables their colors. Scientists predict there to be over 4,000 phytonutrients,³ and research continues to uncover phytonutrients’ numerous benefits to human health. Phytonutrients are commonly touted for their antioxidant properties,⁴ but new research suggests additional functions that benefit human health and lower disease risk.⁵

Examples of phytonutrient categories and subcategories include antioxidants, flavonoids, phytochemicals, flavones, isoflavones, catechins, anthocyanidins, isothiocyanates, carotenoids, allyl sulfides, polyphenols.³ Let’s take a deeper look into specific phytonutrients by color.

RED Fruits & Vegetables

Red foods tend to be higher in phytonutrients that provide antioxidant and anti-inflammatory benefits. Lycopene and anthocyanins are among the most studied.

• Lycopene is a powerful antioxidant concentrated in red fruits and vegetables, such as tomatoes and watermelon. It is associated with decreased risk of prostate cancer and protection against heart attacks.⁶ Lycopene in tomatoes is also shown to reduce inflammation and lower blood cholesterol.⁷

• Anthocyanins are found in red produce, such as strawberries, and support heart health and healthy blood pressure.⁶ One 2017 study shows strawberry intake is associated with reduced inflammation and oxidative stress for individuals with osteoarthritis.⁸

How to Eat More Red Foods

With watermelon, tomatoes, strawberries, raspberries, peppers, and cherries in-season during the summer months, now is the time eat them! Try our watermelon gazpacho recipe for an easy appetizer with a lycopene boost.

orange Fruits & vegetables

Orange fruits and vegetables share similar antioxidant concentrations with red fruits and vegetables. The primary difference in orange foods is their concentration of carotenoids, specifically beta-carotene, which are the phytonutrients that actually give orange foods their color.⁹

• Beta-Carotene converts to vitamin A within the body and promotes healthy vision, skin, and a strong immune system.⁶ Research also continues to uncover the benefits of beta-carotene in foods, such as carrots and sweet potatoes, for reproductive health as well as to highlight its association with a decreased risk of breast cancer.¹⁰

How to Eat More Orange Foods

Seasonal orange fruits and vegetables, such as apricots, oranges, peaches, nectarines, mangoes, and bell peppers, are easy to pair with a lean protein for a balanced snack. You can also try grilled peaches with a touch of whipped cream as a lighter dessert this summer.

YELLOw Fruits & vegetables

While there is crossover between many orange and yellow foods, phytonutrients specifically present in yellow fruits and vegetables are associated with digestive health benefits. The prebiotic fibers found in many yellow fruits and vegetables also contribute to the gastrointestinal benefits. For more information about prebiotics, refer to our Gut Microbiome: The Basics blog.

• Gingerols – It is widely known that phytonutrients in ginger are helpful for a variety of gastrointestinal disorders, ranging from nausea to irritable bowel syndrome.^11,12

• Hesperidin is a flavonoid with powerful antioxidant properties and is found in many citrus fruits. Hesperidin functions to increase blood flow and is shown to protect against gastric ulcers^9,13 and to reduce risk of esophageal and gastric cancers.¹⁴

How to Eat More Yellow Foods

Yellow foods, such as pineapple and bananas, can be easily added to smoothies or a breakfast meal for a touch of sweetness. Grilled summer squash can also add yellow to your plate as a flavorful summer side.

GREEN Fruits & Vegetables

Green vegetables, such as leafy greens, have long been connected to cardiovascular health. Findings from a meta-analysis indicate that 15.8% of cardiovascular risk could be reduced by consuming leafy greens “almost every day.”¹⁵ There are multiple mechanisms involved in this process, but it is clear that phytonutrients play a role.

• Lutein is an antioxidant found in green foods, such as kale, spinach broccoli, lettuces, and artichokes, that promotes good vision and healthy skin. Higher dietary intake and blood concentrations of lutein is also associated with more optimal cardiometabolic health.¹⁶

• Zeaxanthin is a carotenoid found in leafy greens, such as spinach, broccoli and kale. It gives green vegetables their color and protects against cataracts.¹⁷

How to Eat More Green Foods

Salads are one of the most obvious and easiest ways to incorporate leafy greens (e.g., lettuces, Swiss chard, spinach, arugula, and kale) into your daily nutrition. Try this spinach strawberry salad for summer or, alternatively, try blending greens into a smoothie for an easy, on-the-go breakfast.

BLUE-PURPLE Fruits & Vegetables

Blue-purple foods, such as red grapes and blueberries, contain high concentrations of anthocyanins and resveratrol. These plant compounds are linked to stabilized mood and improved cognition.¹⁸

• Anthocyanins are also present in many blue foods, such as blueberries. A 2017 randomized controlled trial found subjects with higher blueberry intake made fewer repetition errors on verbal recall tests, indicating a possible association between blueberry intake and improved mental acuity.¹⁹

• Resveratrol is a powerful antioxidant found in red grapes and is associated with increased antiaging properties and nitric oxide production, which promotes blood flow and lowers blood pressure.⁶

How to Eat More Blue-Purple Foods

Many blue-purple foods, such as grapes, blueberries, plums, and blackberries, can be eaten on their own or paired with a lean protein for a balanced snack. Purple cabbage can be made into a tangy slaw used to top your weekly tacos. Try these fish tacos with cabbage for your next ‘Taco Tuesday.’

White Vegetables

Many white vegetables, especially garlic and mushrooms, contain cancer protective agents (e.g., anthoxanthins, sulforaphane, and allicin), and are linked to antimicrobial and anti-inflammatory benefits.^6,20

• Research suggests that allicin, found in garlic, may contribute to reduced cholesterol and blood pressure. Recent studies reveal potential enhanced immunomodulatory and anti-inflammatory benefits of aged garlic when compared to raw garlic.²⁰

How to Eat More White Foods

In recent years, cauliflower has emerged as a healthy alternative to many carbohydrate-based products, such as pizza crusts and rice. While cauliflower should not completely replace whole grains in the diet, occasionally incorporating these products can help increase your white vegetable intake. For example, try these tofu cauliflower rice bowls for your next weeknight meal.

key takeaways

Fruits and vegetables provide fiber, energy, and complex carbohydrates to fuel you throughout the day. Beyond this, however, specific phytonutrients provide additional health benefits relative to their color group. We recommend aiming for five servings of fruits and vegetables daily with added focus toward incorporating a variety of colors. If you are more ambitious, try aiming for 10 different fruits and vegetables throughout your week. Here are three simple ideas for getting fruit and vegetable variety into your fueling routine:

• Add vegetables to your breakfast. Add sautéed peppers, onions, spinach, etc., to your morning eggs to start the day with three different colored vegetables.
• Liven up your lunch. Try out a vegetable wrap with a leafy green or aim to double the vegetable amount on your sandwich or bowl by adding a new variety (e.g., tomato, lettuce, cucumber, banana peppers).
• Make vegetables the main. When cooking at home, try new vegetable entrée recipes, and instead have your protein as a “side.” For example, this lemon asparagus salad or this black bean avocado cucumber salad would make a fantastic main entrée paired with 3-6 ounces of lean protein.

Questions about how to implement a greater variety of phytonutrients into your diet? Reach out to our Registered Dietitians, Rachel Klomstad (Rachel.klomstad@shiftlife.com) and Lauren Munson (Lauren.munson@shiftlife.com), for more individualized recommendations.

In Real Health,

Rachel Klomstad & Lauren Munson

SHIFT Registered Dietitians

references

1. Boeing H, Bechthold A, Bub A, et al. Critical review: vegetables and fruit in the prevention of chronic diseases. Eur J Nutr. 2012;51(6):637-663. doi:10.1007/s00394-012-0380-y
2. Mujcic R, J Oswald A. Evolution of Well-Being and Happiness After Increases in Consumption of Fruit and Vegetables. Am J Public Health. 2016;106(8):1504-1510. doi:10.2105/AJPH.2016.303260
3. What are phytonutrients? Have A Plant. https://fruitsandveggies.org/stories/what-are-phytochemicals/. Accessed July 7, 2022.
4. Banudevi S, Swaminathan S, Maheswari KU. Pleiotropic Role of Dietary Phytochemicals in Cancer: Emerging Perspectives for Combinational Therapy. Nutr Cancer. 2015;67(7):1021-1048. doi:10.1080/01635581.2015.1073762
5. Minich DM, Bland JS. Dietary management of the metabolic syndrome beyond macronutrients. Nutr Rev. 2008;66(8):429-444. doi:10.1111/j.1753-4887.2008.00075.
6. https://foodrevolution.org/blog/eating-the-rainbow-health-benefits/
7. Valderas-Martinez P, Chiva-Blanch G, Casas R, et al. Tomato Sauce Enriched with Olive Oil Exerts Greater Effects on Cardiovascular Disease Risk Factors than Raw Tomato and Tomato Sauce: A Randomized Trial. Nutrients. 2016;8(3):170. Published 2016 Mar 16. doi:10.3390/nu8030170
8. Schell J, Scofield RH, Barrett JR, et al. Strawberries Improve Pain and Inflammation in Obese Adults with Radiographic Evidence of Knee Osteoarthritis. Nutrients. 2017;9(9):949. Published 2017 Aug 28. doi:10.3390/nu9090949
9. Minich DM. A Review of the Science of Colorful, Plant-Based Food and Practical Strategies for “Eating the Rainbow” [published correction appears in J Nutr Metab. 2020 Nov 28;2020:5631762]. J Nutr Metab. 2019;2019:2125070. Published 2019 Jun 2. doi:10.1155/2019/2125070
10. Chen H, Shao F, Zhang F, Miao Q. Association between dietary carrot intake and breast cancer: A meta-analysis. Medicine (Baltimore). 2018;97(37):e12164. doi:10.1097/MD.0000000000012164
11. Marx W, McCarthy AL, Ried K, et al. The Effect of a Standardized Ginger Extract on Chemotherapy-Induced Nausea-Related Quality of Life in Patients Undergoing Moderately or Highly Emetogenic Chemotherapy: A Double Blind, Randomized, Placebo Controlled Trial. Nutrients. 2017;9(8):867. Published 2017 Aug 12. doi:10.3390/nu9080867
12. Nikkhah Bodagh M, Maleki I, Hekmatdoost A. Ginger in gastrointestinal disorders: A systematic review of clinical trials. Food Sci Nutr. 2018;7(1):96-108. Published 2018 Nov 5. doi:10.1002/fsn3.807
13. Elshazly SM, Abd El Motteleb DM, Ibrahim IAAE. Hesperidin protects against stress induced gastric ulcer through regulation of peroxisome proliferator activator receptor gamma in diabetic rats. Chem Biol Interact. 2018;291:153-161. doi:10.1016/j.cbi.2018.06.027
14. Bae JM, Kim EH. Dietary intakes of citrus fruit and risk of gastric cancer incidence: an adaptive meta-analysis of cohort studies. Epidemiol Health. 2016;38:e2016034. Published 2016 Jul 25. doi:10.4178/epih.e2016034
15. Pollock RL. The effect of green leafy and cruciferous vegetable intake on the incidence of cardiovascular disease: A meta-analysis. JRSM Cardiovasc Dis. 2016;5:2048004016661435. Published 2016 Aug 1. doi:10.1177/2048004016661435
16. Leermakers ET, Darweesh SK, Baena CP, et al. The effects of lutein on cardiometabolic health across the life course: a systematic review and meta-analysis. Am J Clin Nutr. 2016;103(2):481-494. doi:10.3945/ajcn.115.120931
17. Abdel-Aal el-SM, Akhtar H, Zaheer K, Ali R. Dietary sources of lutein and zeaxanthin carotenoids and their role in eye health. Nutrients. 2013;5(4):1169-1185. Published 2013 Apr 9. doi:10.3390/nu5041169
18. Yang J, Xiao YY. Grape phytochemicals and associated health benefits. Crit Rev Food Sci Nutr. 2013;53(11):1202-1225. doi:10.1080/10408398.2012.692408
19. Miller MG, Hamilton DA, Joseph JA, Shukitt-Hale B. Dietary blueberry improves cognition among older adults in a randomized, double-blind, placebo-controlled trial. Eur J Nutr. 2018;57(3):1169-1180. doi:10.1007/s00394-017-1400-8
20. Baiba J Grube, Elizabeth T. Eng, Yeh-Chih Kao, Annette Kwon, Shiuan Chen, White Button Mushroom Phytochemicals Inhibit Aromatase Activity and Breast Cancer Cell Proliferation, The Journal of Nutrition, Volume 131, Issue 12, December 2001, Pages 3288–3293, https://doi.org/10.1093/jn/131.12.3288
21. Ryu JH, Kang D. Physicochemical Properties, Biological Activity, Health Benefits, and General Limitations of Aged Black Garlic: A Review. Molecules. 2017;22(6):919. Published 2017 Jun 1. doi:10.3390/molecules22060919