The other day, a good friend of mine told me that when it comes to vegetables, they only eat spinach because it is the only vegetable that they can stand to eat. While it’s great that they are at least eating vegetables – most of us don’t eat enough – that got me thinking about why variety is so important for fruit and vegetable intake. If you want to learn why it’s actually bad to only ever eat the same vegetable or same fruit day after day, keep on reading. If you prefer to listen to this article, click here.
I know that you love apples, but you really should mix it up - let me explain why.
Let’s talk about produce.
Vegetables – and all plant foods really – have very unique nutritional profiles. The differences in their colors, textures, growing conditions, and more all contribute to this. Even vegetables that look similar and can be used interchangeably in the kitchen, like spinach and kale for instance, are not identical in terms of their chemistry.
The uniqueness of each plant food is a huge bonus, because where one plant food may be lacking, another plant food can pick up the slack and vice versa. One way to think about this is to compare different fruits and vegetables to members on a basketball team. A power forward like Tim Duncan is really important for defending the team, but without a shooting guard like Manu Ginobili, the team will not make it to the championship.
I don't actually know anything about basketball, but I promise that the analogy makes sense.
Just as the players on a basketball team have unique strengths, so do plant foods. Limiting yourself to just one or a few vegetables on a regular basis means that you are missing out on the value that comes from playing with a strong team. This value translates to specific health outcomes, which I will get into next.
Let’s first look at cancer prevention.
Cancer is a devastating disease that I'm sure most if not all of you have encountered either personally or through loved ones. Diet is not a cure all, but it has been shown to play a key role in cancer prevention. Interestingly, specific foods are linked to a reduced risk of cancer at specific anatomical sites. Here are just a few examples:
Cruciferous vegetables, common ones being broccoli, cabbage, and Brussels sprouts, are linked to a reduced risk of colorectal cancer and ovarian cancer.
Apples are linked to a reduced risk of cancer in the lungs (see this article, and this one).
Lycopene from tomatoes has been shown to lower prostate specific antigen (PSA) levels, which is a biomarker for prostate cancer. Studies also show that a greater intake of lycopene is correlated with a lower risk of developing prostate cancer and having less aggressive forms of the disease. Pro tip: cooking tomatoes and including oil in the dish greatly increases the bioavailability of the lycopene, so our bodies actually absorb more lycopene from something like tomato sauce relative to fresh tomatoes.
Soy intake from foods like edamame and tofu is linked to a lower risk of breast cancer (see this article, and this one).
From these examples, you can see why eating a variety of fruits and vegetables matters for protecting your body against various types of cancer, and why eating just one class of fruit or vegetable could help you out in one area but leave you vulnerable in another.
Aside from cancer, there are other health outcomes against which certain fruits and vegetables have also been shown to be effective.
One example is the link between berries and brain function. Research on berries supports the hypothesis that these darkly pigmented fruits can actually slow down cognitive decline (see this article, and this one). By the way, the research shows that this benefit comes from both fresh and frozen berries; if fresh berries are just too expensive but you still want to up your intake and get those cognitive benefits, know that you are not losing out on any health benefits of you choose more economically friendly frozen berries. Personally, I tend to buy frozen berries since they are much cheaper and at a lower risk of spoiling.
This same group of flavonoid-rich foods has also been studied extensively in the context of heart health, and these plant foods have been shown to prevent atherosclerosis and reduce the risk of heart attack and stroke. Here's another example: yellow, orange, and red-colored fruits and vegetables like guavas, carrots, pumpkins, and red bell peppers, rich in carotenoids, are important for protecting eyesight.
Okay, so I think that by now you have a good idea about why varying the fruits and vegetables that you eat each day is so so so important for staying healthy.
Now, let’s talk about synergy.
Another reason to not limit yourself to just 1 or 2 of your favorite veggies is because plant foods actually have synergistic powers – the unique phytonutrients contained inside each plum, each pepper, and each mango actually work together to improve your health in a greater way than either of them could just on their own. To go back to the earlier basketball analogy, having all 5 players on the court is far more advantageous than having just the star player trying to do all the work. Take a look at this graph.
Liu 2004.
It shows the antioxidant activity of various fruits on their own and in combination. Oranges are on the bottom, but their effect is certainly not zero. Next is apples, then concord grapes, and blueberries are on top of the other fruits. But, look at which line of the graph surpasses them all – the line corresponding to the mixture of all four fruits together. There is a clear additive effect, and this is believed to contribute to the anticancer effect of plant foods.
Now, you may be wondering about how much of each type of fruit and vegetable you should be eating to get all of these wonderful health benefits.
The USDA Dietary Guidelines actually gives some guidance on this. Within the guidelines, there is an example of how to divide your intake between food groups for a 2000 calorie diet.
USDA Dietary Guidelines 2020-2025.
The recommendation is that every day, you should aim to consume 2 portions of fruits and 2.5 portions of vegetables. Remember that this is a general guideline, and the actual amount will vary from person to person. Now, I’m sure that you already know that you should eat fruits and vegetables every day, but, did you know that there is actually a break down of how often you should eat specific types of vegetables? This is a less well known feature of the guidelines. For the same 2000 calorie diet, it is recommended that over the course of a week 1.5 servings of vegetables be of the dark green variety, while 5.5 servings are red/orange, 1.5 are legumes, 5 are starchy, and 4 are from any category, so that can include mushrooms, onions, green peppers, etcetera. There isn’t the same breakdown for fruit, but the principle of having fruits of different colors and textures is valid too.
Apple filling does not count.
Even if you do have a favorite vegetable, you can try adding other things to it by making something like a spinach, bell pepper, garlic, and lemon sautée instead of having just spinach. When you make salads, don't limit yourself to just lettuce and tomato - add radishes, cucumbers, olives, nuts, and whatever else delights your palate. When you have fruits, feel free to combine them into a fruit salad. Getting creative in this way not only boosts the health benefits that you get from each meal, but it also add layers of flavor to your meals.
Your goal should be to, as they say, “eat the rainbow.”
And use your imagination - get creative!
Have any fun ideas for plant food combos? Comment them down below!
If you learned anything new or think that someone you care about could benefit from this information, share this article, and subscribe to the blog for regular updates on commonly asked nutrition questions.
Enjoy today!
References:
Devore, E. E., Kang, J. H., Breteler, M. M. B., Grodstein, F. (2012). Dietary intakes of berries and flavonoids in relation to cognitive decline. Annals of Neurology, 72(1):135-143.
Fabiani, R., Minelli, L., Rosignoli, P. (2016). Apple intake and cancer risk: a systematic review and meta-analysis of observational studies. Public Health Nutrition, 19(14):2603-17. doi: 10.1017/S136898001600032X. Epub 2016 Mar 22. PMID: 27000627.
Hu, J., Hu, Y., Hu, Y., Zheng, S. (2015). Intake of cruciferous vegetables is associated with reduced risk of ovarian cancer: a meta-analysis. Asia Pacific Journal of Clinical Nutrition, 24(1):101-9. doi: 10.6133/apjcn.2015.24.1.22. PMID: 25740748.
Le Marchand, L., Murphy, S. P., Hankin, J. H., Wilkens, L. R., Kolonel, L. N. (2000). Intake of flavonoids and lung cancer. Journal of the National Cancer Institute, 92(2), 154-60. doi: 10.1093/jnci/92.2.154. PMID: 10639518.
Liu, R. H. (2004). Potential Synergy of Phytochemicals in Cancer Prevention: Mechanism of Action. The Journal of Nutrition, 134(12), 3479S–3485S.
Messina, M. (2016). Impact of Soy Foods on the Development of Breast Cancer and the Prognosis of Breast Cancer Patients. Forschende Komplementarmedizin, 23(2):75-80. doi: 10.1159/000444735. Epub 2016 Apr 12. PMID: 27161216.
Miller, M. G., Hamilton, D. A., Joseph, J. A., Shukitt-Hale, B. (2018). Dietary blueberry improves cognition among older adults in a randomized, double-blind, placebo-controlled trial. European Journal of Nutrition, 57(3):1169-1180.
National Institutes of Health. (2017). Office of Dietary Supplements - Vitamin A. Nih.gov. https://ods.od.nih.gov/factsheets/VitaminA-HealthProfessional/
Raventós, R. M. PREDIMED Study Investigators. (2014). Inverse association between habitual polyphenol intake and incidence of cardiovascular events in the PREDIMED study. Nutrition, Metabolism and Cardiovascular Diseases, 24(6):639-47. doi: 10.1016/j.numecd.2013.12.014. Epub 2014 Jan 22. PMID: 24552647.
Rienks, J., Barbaresko, J., Nöthlings, U. (2017). Association of Polyphenol Biomarkers with Cardiovascular Disease and Mortality Risk: A Systematic Review and Meta-Analysis of Observational Studies. Nutrients, 9(4):415.
Rowles, J. L., Ranard, K. M., Smith, J. W., An, R., & Erdman, J. W. (2017). Increased dietary and circulating lycopene are associated with reduced prostate cancer risk: a systematic review and meta-analysis. Prostate cancer and prostatic diseases.20(4):361-77. doi:10.1038/s41391-017-0005-x
Tse, G., Eslick, G. D. (2014). Cruciferous vegetables and risk of colorectal neoplasms: a systematic review and meta-analysis. Nutrition and Cancer, 66(1):128-39. doi: 10.1080/01635581.2014.852686. Epub 2013 Dec 16. PMID: 24341734.
U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020-2025. 9th Edition. December 2020.
Wei, Y., Lv, J., Guo, Y., Bian, Z., Gao, M., Du, H., Yang, L., Chen, Y., Zhang, X., Wang, T., Chen, J., Chen, Z., Yu, C., Huo, D., Li, L. China Kadoorie Biobank Collaborative Group. (2020). Soy intake and breast cancer risk: a prospective study of 300,000 Chinese women and a dose-response meta-analysis. European Journal of Epidemiology.
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