You know that greens are good for you. That fact has likely been drilled into your head from an early age.
But what greens should you be going for most often? A plethora of options are available, and the nutritional differences between say, butterhead lettuce and romaine lettuce, are far from common knowledge. No worries—we're here to help. We've ranked nine of the most popular greens by their nutritional value, so you'll know what sort of foliage you should be feeding on most frequently.
*All nutrition data comes from nutritiondata.self.com. All data is based on the raw, uncooked version of the green
Kale. Most people hadn't even heard of the stuff 10 years ago, but now it's hailed as the quintessential superfood. Not only is it frequently used as a base for salads or bowls, but it's also a frequent ingredient in smoothies and cold-pressed juices. Kale belongs to the "Brassica" family of vegetables, which also includes broccoli, cauliflower and Brussel sprouts. Kale has built a reputation as a nutrient-packed wonder food, buy do the nutrition facts really back that up? In short—yes.
A hundred grams of kale contains 50 calories, .7 grams of fat, 43 mg of sodium, 447 mg of potassium, 10 grams of carbohydrate, 3.3 grams of protein and 2 grams of dietary fiber. It also serves up an astronomical amount of vitamin K—1,021% the recommended daily value (RDV), to be exact. Vitamin K plays a critical role in bone health and wound healing. It may also provide protection against conditions like heart disease, Alzheimer's, prostate cancer and osteoporosis. No need to worry about the high dosage, either. According to the Linus Pauling Institute, "there is no known toxicity associated with high doses" of dietary vitamin K.
One-hundred grams of kale also contains a whopping 308% the RDV of vitamin A and 200% of the RDV of vitamin C. Vitamin A helps cells reproduce normally and effectively. Additionally, it aids in good vision and is needed for proper development of an embryo and fetus (making it especially important for women who are pregnant or are expecting to become pregnant). Vitamin C has great benefits for eye health, as it reduces the risk of cataracts, promotes healthy ocular blood vessels and slows the progression of age-related macular degeneration. Vitamin C also helps the body synthesize collagen, a protein crucial for building healthy skin and tissue, and it may play a role in preventing vascular disease.
One hundred grams of kale also contains significant amounts (at least 10% of the RDV) of calcium, copper, manganese, and vitamin B-6. Kale is also high in a compound known as sulforaphane, which has been found to have potent cancer-fighting capabilities. When it comes to leafy greens, kale deserves its reputation.
Spinach is a nutritional powerhouse. There's a reason it was Popeye's favorite food.
One hundred grams of spinach contains 23 calories, .4 grams of fat, 79 mg of sodium, 558 mg of potassium, 3.6 grams of carbohydrate, 2.9 grams of protein and 2.2 grams of dietary fiber. It also serves up a whopping 604% of the RDV of vitamin K and 188% of the RDV of vitamin A. It includes significant amounts (at least 10% of the RDV) of vitamin E, riboflavin, vitamin B-6, folate, calcium, iron, magnesium and manganese.
In terms of overall essential vitamins and minerals, kale edges out spinach for the number one spot. But that's more of a testament to kale than it is a knock on spinach, because spinach is packed with plenty of beneficial nutrients. One area where spinach does win out over kale is folate content. One hundred grams of spinach contains 49% of the RDV of folate, while 100 grams of kale contains 7% of the RDV. Folate—also referred to as folic acid or vitamin B9—is crucial for proper brain function and plays a big role in mental and emotional health. It also helps produce the body's genetic material, an especially important job during infancy, adolescence and pregnancy.
Baby spinach refers to spinach that's been harvested during an early stage of growth (typically between 15 and 35 days after planting). Baby spinach leaves are smaller and more tender than mature spinach leaves. Some research has found that baby spinach is more concentrated in certain nutrients (vitamin C, carotenoids, flavonoids) than mature spinach, but other studies have found the opposite. The soil and climate in which the spinach is grown seems to have a significant impact on the nutrient levels in spinach, so we can't say definitively whether baby spinach or mature spinach is the better nutritional option. For optimal health, it might be best to include both varieties in your diet.
3. Swiss Chard
Swiss Chard might not be as popular as the other greens on this list, but its nutritional profile could make it a future favorite of many health-conscious Americans.
One hundred grams of Swiss chard contains 19 calories, 1.6 grams of fat, 213 mg of sodium, 379 mg of potassium, 3.7 grams of carbohydrate, 1.8 grams of protein and 1.6 grams of dietary fiber. It's got even more vitamin K than an equivalent amount of kale, coming in with 1,038% of the RDV. It's also high in vitamin A at 122% of the RDV. Additionally, it's a significant source (at least 10% of the RDV) of vitamin C, iron, magnesium and manganese. Swiss chard has hearty leaves similar to kale, but many people find it possess a milder, more palatable flavor.
4. Green Leaf Lettuce
In terms of overall nutrition, kale, spinach and Swiss chard stand above conventional lettuce varieties.
However, lettuce is still plenty healthy. Perhaps the healthiest common variety is green leaf lettuce. One hundred grams of green leaf lettuce contains 15 calories, .2 grams of fat, 28 mg of sodium, 194 mg of potassium, 2.8 grams of carbohydrate, 1.4 grams of protein and 1.3 grams of dietary fiber. It's quite high in vitamin A (148% of the RDV) and vitamin K (217% of the RDV). It also contains a significant amount (at least 10% of the RDV) of vitamin C, folate and manganese.
5. Romaine Lettuce
Though green leaf lettuce might edge out romaine lettuce in terms of overall nutrition, romaine lettuce is no slouch. It's also one of the most popular greens included in the rinsed, ready-to-eat salad packages you find in your local supermarket. According to the Academy of Nutrition and Dietetics, "the darker the leaves, the more nutrient-rich the lettuce." So it's no surprise that romaine lettuce is healthier than a variety like iceberg lettuce, which features mostly white leaves.
One hundred grams of romaine lettuce contains 17 calories, .3 grams of fat, 8 mg of sodium, 247 mg of potassium, 3.3 grams of carbohydrate, 1.2 grams of protein and 2.1 grams of dietary fiber. It's quite high in vitamin A (174% of the RDV) and vitamin K (128% of the RDV). It also packs a significant amount (at least 10% of the RDV) of vitamin C and folate.
Arugula—also known as "rocket" or "rucula"—is a peppery-tasting green that's popular in Mediterranean cuisine.
A 100-gram serving of arugula contains 25 calories, .7 grams of fat, 27 mg of sodium, 369 mg of potassium, 3.7 grams of carbohydrate, 2.6 grams of protein and 1.6 grams of dietary fiber. It's quite high in vitamin K (136% of the RDV). While it's also high in vitamin A with 47% of the RDV, it doesn't have nearly as much as green leaf lettuce, romaine lettuce, spinach or kale. One hundred grams of arugula also contains a significant amount (at least 10% of the RDV) of vitamin C, folate, calcium, magnesium and manganese.
7. Butterhead Lettuce
Also commonly referred to as "Boston lettuce" or "bibb" lettuce, butterhead lettuce is known for its tender, smooth leaves and mildly sweet flavor. One hundred grams of butterhead lettuce contains 13 calories, .2 grams of fat, 5 mg of sodium, 238 mg of potassium, 2.2 grams of carbohydrates, 1.3 grams of protein and 1.1 grams of dietary fiber. It's quite high in vitamin K (128% of the RDV) and vitamin A (66% of the RDV). It also contains a significant amount of folate (18% of the RDV). Butterhead lettuce's mild sweet flavor and smooth texture make it a great choice for salads.
Like kale, cabbage is a member of the Brassica family of vegetables. It's known for its densely leaved heads and firm texture when ripe.
A hundred grams of cabbage contains 25 calories, .1 grams of fat, 18 mg of sodium, 170 mg of potassium, 5.8 grams of carbohydrate, 1.3 grams of protein and 2.5 grams of dietary fiber. It's very high in vitamin C (61% of the RDV) and vitamin K (95% of the RDV). It also contains a significant amount of folate (11% of the RDV). While cabbage in its simple form is nutritious, sauerkraut might be even more beneficial. Sauerkraut is pickled cabbage. Sauerkraut is incredibly high in probiotics, the "good bacteria" that live inside the gut. Scientists are finding that the gut microbiome (the collection of bacteria inside the gut) can have a massive impact on overall health, and probiotics can help keep your microbiome at an optimal (or near-optimal) condition.
9. Iceberg Lettuce
Iceberg lettuce has long been a staple of fast-food restaurants thanks in part to its mild, unoffensive flavor. However, Chik-fil-A recently banned it from their menus. McDonald's also recently stopped using iceberg lettuce in their salads. Why? Because they both determined that consumers desired more flavorful, nutritious greens. "[Iceberg lettuce] is at the bottom of the salad food chain," David Farmer, Chik-fil-A's vice president of menu strategy and development, told Business Insider. "There is no nutritional value in iceberg lettuce."
While that's not entirely true, iceberg lettuce doesn't pack the same amount of nutrients as the other types of lettuce on this list. Why? One reason is because it grows in tight, dense heads. This limits the amount of sunlight that the inner leaves receive, which in turn limits the amounts of nutrients they contain. That's why iceberg lettuce leaves are usually so much whiter than other types of lettuce leaves. This phenomenon means that iceberg lettuce is mostly water, even more so than other lettuce varieties. But to say that is has "no nutritional value" is inaccurate. Though it does not stand up to kale, iceberg lettuce contains its fair share of useful nutrients.
A 100-gram serving of iceberg lettuce contains 14 calories, .1 grams of fat, 10 mg of sodium, 141 mg of potassium, 3.2 grams of carbohydrate, .9 grams of protein and 1.2 grams of dietary fiber. It also includes a significant amount (at least 10% of the RDV) of vitamin A and vitamin K. Along with celery, parsley and thyme, iceberg lettuce is one of the richest sources of a compound called apigenin. A 2007 review published in the International Journal of Oncology concluded that apigenin has been shown to "possess remarkable anti-inflammatory, antioxidant and anti-carcinogenic properties."
So iceberg lettuce certainly does have nutritional value—just not as much as the other greens on this list. The issue with iceberg lettuce comes when it's the only type of green you eat on a consistent basis. When you do that, you miss out on the more nutrient-packed greens. Unfortunately, this type of eating pattern describes many Americans. According to a 2016 analysis by MarketWatch, Americans eat more iceberg lettuce than kale, romaine and spinach combined.
RELATED: Is Iceberg Lettuce Good For You?
The important thing to remember about greens—and food in general, really—is that variety equals balance. By including a variety of these veggies in your diet, you'll ensure that you get a wide range of nutrients and antioxidants and reap the full benefits greens can offer.
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