The Nutritional Value of Leafy Green Vegetables
What are Leafy Greens?
Examples of leafy green vegetables include “loose” leafy greens such as kale, Swiss chard, and many kinds of lettuces. They also include other more dense veggies such as broccoli, cabbage and Brussels sprouts. There is little dispute these days that dark green vegetables should be at or near the top of the list when it comes to providing a nutritional big bang for the buck—and for their (low) calories. One cup of uncooked greens may top out at a whopping 10-20 calories, perhaps, a little higher for some of the denser veggies like broccoli.
And, in return for those few calories, you get substantial amounts of vitamins such as A, C, K, and many of the B’s including folate (B9), plus minerals such as calcium, iron, magnesium, manganese, and potassium, along with some protein, lots of fiber made up of complex carbohydrates (the “good” carbs), and antioxidant phytonutrients such as beta-carotene, lutein, and zeaxanthin, BUT little or no fat!
The greens are clearly critical actors in support of a healthy lifestyle, playing a key role in the prevention, mitigation or slowing down of excessive body weight gain, cardiovascular disease, Type II diabetes, age-related cognitive decline, macular degeneration, and other diseases including cancer.
With all of those health benefits, there is little excuse not to have the greens on your menu every single day — for breakfast, lunch, or dinner. Their versatility is key: they are suitable for smoothies at breakfast, salads at lunch, and as flavor-enhancers, sides, or main dishes at dinner. And they may be less expensive than many meats and processed foods. What more could you ask for?
So, how many kinds of edible leafy green vegetables are there? To put it simply: a lot. The U.S. Department of Agriculture lists over 60 different varieties known to be imported or grown for commercial purposes in the U.S. Many other, perhaps less well-known, varieties are grown in home gardens or gathered in the wild.
These veggies come in a wide variety of textures and flavors, from very mild to nutty to spicy/peppery, to bitter. In other words, they have the capacity to serve every palette. Generally, maximum nutritional value comes from eating them raw, but cooking them properly does not cause them to lose their benefits Raw or cooked, they are the stars of many recipes.
The leafy green vegetables are often discussed in terms of their nutrient density. In other words, the greater the multiplicity and magnitude of key nutrients, the greater the density. This is documented, in part, by the determination of Daily Values (DV), also known as Recommended Daily Intakes (RDIs). Daily Value is defined as the recommended amount of a nutrient to consume each day.
What are some of the more popular and accessible high density greens that you can easily integrate into your dietary habits? Following are a number of high-value examples:
Let’s begin with kale which is at the top of the list. A single cup of raw kale contains the following percentages of Daily Values (DV):
- Vitamin A-206%
- Vitamin K -684%
- Vitamin C -134%
- Vitamin B6 -9%
- Manganese -26%
- Calcium – 9%
- Copper – 10%
- Potassium – 9%
- Magnesium – 6%
Kale also contains 3% or more of the DV for vitamin B1 (thiamin), vitamin B2 (riboflavin), vitamin B3 (niacin), iron and phosphorus. All of these nutrients are packed into about 35 calories, along with 6 grams of carbs (2 as fiber), 3 grams of protein, and high levels of antioxidants. What little fat is present is overwhelmingly an omega-3 fatty acid (the “good” fat).
Nipping at kale’s heels is spinach. One cup of raw spinach provides:
- 181% of the DV for vitamin K
- 56% of the DV for vitamin A
- 13% of the DV for manganese
— all for under 10 calories. It, too, contains high levels of antioxidants. It is also high in folate (Vitamin B9), which may prevent neural tube defects, such as spina bifida, in the fetus during pregnancy.
Other “loose” leafy greens with good nutritional value and low calories include microgreens (which are the new, young shoots of many kinds of salad vegetables), beet, collard, and turnip greens, plus Swiss chard, and arugula, among others. Some other varieties like iceberg (head), Boston (butterhead) or Romaine lettuces may not match the aforementioned in the array and amounts of key nutrients, but they still offer nutritional value and provide variety in flavor and texture.
Some members of the leafy green family aren’t “loose” in structure like those discussed above. They are more tightly constructed and dense, but still are packed with nutrients and other important constituents. For instance, 1 cup of raw green cabbage contains:
- 22 calories
- 1 gram of protein
- 2 grams of fiber
- 85% of the DV of vitamin K
- 54% of the DV of vitamin C
- 10% of the DV for folate (vitamin B9)
- 10% of the DV for vitamin B6
- 7% of the DV of manganese
- 4% of the DVs for calcium and potassium
- 3% of the DV for magnesium.
Another example of a denser leafy green is broccoli. One cup of raw broccoli provides:
- 116% of your daily vitamin K DV,
- 135% of the DV for vitamin C and
- a good amount of folate, manganese and potassium.
- It also contains a compound called glucosinolate, as well as its by-product, sulforaphane. Sulforaphane has been shown, in whole animal and cell culture studies, to have a protective effect against some types of cancer and is being investigated as a potential prevention measure in humans.
So, now that you are armed with all this good information, there is no reason to delay assembling and serving those leafy green-containing salads, sides, or main dishes as the centerpieces of
Featured image Photo: Markus Winkler/Pexels. Some other photos courtesy of Unsplash.
“Lutein, zeaxanthin, and meso-zeaxanthin: The basic and clinical science underlying carotenoid-based nutritional interventions against ocular disease,” (Bernstein, et al. 2016), pubmed.ncbi.nlm.nih.gov/26541886)
“Salad greens: Getting the most bang for the bite,” Staying Healthy Blog, Harvard Medical School, www.health.harvard.edu/staying-healthy (Harvard Health Publishing. 2021)
“The 14 Healthiest Vegetables on Earth,” https://www.healthline.com/nutrition/14-healthiest-vegetables-on-earth (Link, 2017)
“Nutrients and bioactives in green leafy vegetables and cognitive decline,” Neurology, n.neurology.org/content/90/3/e214 (Epub 2017).
“Cruciferous Vegetables and Cancer Prevention,”National Cancer Institute, National Institutes of Health, www.cancer.gov). (2012).
“Nutritional Values For Common Foods And Products,” https://www.nutritionvalue.org/ (2021).
“The effect of green leafy and cruciferous vegetable intake on the incidence of cardiovascular disease: A meta-analysis.,” JRSM Cardiovascular Disease, journals.sagepub.com (Pollock, R.L. 2016).
“Food and Nutrient Database for Dietary Studies,” Food Surveys Research Group, Agricultural Research Service, U.S. Department of Agriculture. www.ars.usda.gov (2017-2018).
“Folic Acid Supplementation for the Prevention of Neural Tube Defects: An Updated Evidence Report and Systematic Review for the US Preventive Services Task Force,” pubmed.ncbi.nlm.nih.gov/28097361). (JAMA, 2017).
“Higher intake of fruits, vegetables or their fiber reduces the risk of type 2 diabetes: A meta-analysis,” Journal Diabetes Investig. pubmed.ncbi.nlm.nih.gov/26816602 (2016).
“Improving fruit and vegetable intake attenuates the genetic association with long-term weight gain,” American Journal of Clinical Nutrition, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6736184/
“The 13 Healthiest Leafy Green Vegetables.,” www.healthline.com/nutrition/leafy-green-vegetables (Enloe, A. 2018).
“Nutritive Values of Foods,” Home and Garden Bulletin Number 72, www.ars.usda.gov (Gebhardt, S,E, and Thomas, R.G. 2002)
Gunnars, K. 2018a. The 11 Most Nutrient-Dense Foods on the Planet. Accessed at https://www.healthline.com/nutrition/11-most-nutrient-dense-foods-on-the-planet.
Gunnars, K. 2018b. 10 Health Benefits of Kale. Accessible at https://www.healthline.com/nutrition/10-proven-benefits-of-kale