So last week I started the rainbow series by discussing why it’s important to get a variety of fruits and vegetables (and legumes) in your diet. This week we’ll take a closer look at the red part of the rainbow. Strawberries and raspberries, tomatoes, red peppers, rhubarb, and more, but also think more widely and weirdly, red kidney beans, radicchio, or maybe try a blood orange!
Strawberries! As I touched on in the fruit roll ups recipe last week, strawberries are high in vitamin C, as well as other polyphenols. In a small study of overweight participants, consuming freeze-dried strawberries appeared to decrease oxidative stress-related inflammation as well as reduce insulin response after a meal. The study noted that the antioxidant ability of the freeze dried strawberry powder was higher before being combined with the milk based drink that was used in the study, so the antioxidant response for plain freeze dried strawberries should be even greater.1 Strawberries may also reduce oxidized LDL as well as other cardiovascular risk factors. Reductions in triglycerides and oxidized LDL were seen in participants with high lipid levels who consumed 10 grams of freeze-dried strawberries daily for six weeks.2 And the last one for strawberries specifically, some of the polyphenols and vitamin C may help reduce the risk of Alzheimer’s dementia. Just one serving of strawberries a week was associated with a 34% lower risk of developing Alzheimer’s dementia compared to participants who ate them rarely.3
Let’s talk tomatoes. First of all, one of the easiest vegetables (ok, I know it’s a fruit) to grown yourself and cherry or grape tomatoes will continue to produce for months during summer. In the nutrition thoughts of my chili post, I mentioned that lycopene, an antioxidant and carotenoid (we’ll hear more about these in the orange post too!), is more bioavailable after tomatoes are cooked so eat them raw and cooked for a wide variety of nutrients. Tomatoes have been linked to lower hypertension, reducing blood pressure in participants both with or without pharmacological hypertensives. In the study on patients with concurrent hypertensive medications, 213 mg of standardized tomato extract was given daily for one month with a reduction of about 10/4 mmHg.4 In the second study, participants with mild to moderate hypertension but not using a pharmacological intervention were given randomized doses of tomato extract for 2 months. The higher two doses, 15 and 30 mg of lycopene, both had significant reductions in systolic blood pressure, approximately 7 and 9.5 mmHg respectively.5 A single serving of sofrito (a tomato sauce with olive oil, onion, and garlic) also reduced inflammatory markers C-reactive protein and TNF-α. Surprisingly the study found the correlation with total polyphenols and β-carotene rather than lycopene.6 Tomatoes may even help protect the skin from damage from UVB light. Participants taking a tomato extract showed lower IL-6 and TNF-α upregulation after light exposure, demonstrating a reduced inflammatory response as less harm was caused by the exposure.7
FYI, watermelon also contains lots of lycopene, no cooking necessary! If you need a reason to eat watermelon (my household practically gobbles them whole in summer), it may reduce your risk of developing metabolic syndrome. In a month long study of overweight or obese participants, 2 cups of watermelon was eaten daily, while the other subjects ate low-fat cookies with the same total calorie count. The participants eating watermelon had decreases in triglycerides and LDL while HDL (the “good” cholesterol) increased. Total antioxidant capacity also increase in the watermelon group, showing an increased ability to detoxify and prevent damage within the body. Watermelon also left the participants feeling more full for longer than the low-fat cookies. There was a small reduction in both weight and blood pressure for the group eating watermelon while the cookie group rose in both measurements.8 Granted, comparing a whole fruit to a highly processed cookie isn’t really fair for a lot of reasons, but for a sweet snack, watermelon is definitely a good choice!
Chili peppers are also very red (or maybe green or orange), and full of capsaicin, the hotter, the higher the concentration. Capsaicin will have its own article in the future because there is such a wealth of research across a broad range of benefits!
Do you have a favorite red fruit, vegetable, or other plant-based food? I may have to come back to red options again in the future since there are so many wonderful things!
1. Edirisinghe, I., Banaszewski, K., Cappozzo, J., Sandhya, K., Ellis, C. L., Tadapaneni, R., Kappagoda, C. T., & Burton-Freeman, B. M. (2011). Strawberry anthocyanin and its association with postprandial inflammation and insulin. The British journal of nutrition, 106(6), 913–922. https://www.cambridge.org/core/journals/british-journal-of-nutrition/article/strawberry-anthocyanin-and-its-association-with-postprandial-inflammation-and-insulin/FED139EE31DA31AC60C82F231C82EBEA
2. Burton-Freeman, B., Linares, A., Hyson, D., & Kappagoda, T. (2010). Strawberry modulates LDL oxidation and postprandial lipemia in response to high-fat meal in overweight hyperlipidemic men and women. Journal of the American College of Nutrition, 29(1), 46–54. https://doi.org/10.1080/07315724.2010.10719816 https://www.researchgate.net/publication/44902140_Strawberry_Modulates_LDL_Oxidation_and_Postprandial_Lipemia_in_Response_to_High-Fat_Meal_in_Overweight_Hyperlipidemic_Men_and_Women
3. Agarwal, P., Holland, T. M., Wang, Y., Bennett, D. A., & Morris, M. C. (2019). Association of Strawberries and Anthocyanidin Intake with Alzheimer’s Dementia Risk. Nutrients, 11(12), 3060. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6950087/
4. Krasińska, B., Osińska, A., Krasińska, A., Osiński, M., Rzymski, P., Tykarski, A., & Krasiński, Z. (2018). Favourable hypotensive effect after standardised tomato extract treatment in hypertensive subjects at high cardiovascular risk: a randomised controlled trial. Kardiologia polska, 76(2), 388–395. https://doi.org/10.5603/KP.a2017.0215 https://www.mp.pl/kardiologiapolska/en/node/14613/pdf
5. Wolak, T., Sharoni, Y., Levy, J., Linnewiel-Hermoni, K., Stepensky, D., & Paran, E. (2019). Effect of Tomato Nutrient Complex on Blood Pressure: A Double Blind, Randomized Dose⁻Response Study. Nutrients, 11(5), 950. https://doi.org/10.3390/nu11050950
6. Hurtado-Barroso, S., Martínez-Huélamo, M., Rinaldi de Alvarenga, J. F., Quifer-Rada, P., Vallverdú-Queralt, A., Pérez-Fernández, S., & Lamuela-Raventós, R. M. (2019). Acute Effect of a Single Dose of Tomato Sofrito on Plasmatic Inflammatory Biomarkers in Healthy Men. Nutrients, 11(4), 851. https://doi.org/10.3390/nu11040851
7. Groten, K., Marini, A., Grether-Beck, S., Jaenicke, T., Ibbotson, S. H., Moseley, H., Ferguson, J., & Krutmann, J. (2019). Tomato Phytonutrients Balance UV Response: Results from a Double-Blind, Randomized, Placebo-Controlled Study. Skin pharmacology and physiology, 32(2), 101–108. https://doi.org/10.1159/000497104
8. Lum, T., Connolly, M., Marx, A., Beidler, J., Hooshmand, S., Kern, M., Liu, C., & Hong, M. Y. (2019). Effects of Fresh Watermelon Consumption on the Acute Satiety Response and Cardiometabolic Risk Factors in Overweight and Obese Adults. Nutrients, 11(3), 595. https://doi.org/10.3390/nu11030595