If you want to eat lettuce, that no longer just means iceberg. In our modern grocery landscape, there are many options available, including romaine, red-leaf lettuce, butter lettuce, beet greens, bok choy, and bitter varieties. Sometimes, the choice comes down to personal preference. However, if you are trying to meet your daily serving of 2.5 cups of vegetables—or you are rethinking your salad choices amid the US cyclospora outbreak—you might have questions about which greens to prioritize.
Health authorities widely agree that a diet high in nutrient-dense fruits and vegetables is associated with a reduced risk of chronic disease. But which greens provide the most value? “Nutrient density,” defined as the “nutrients per calorie” of a food, can be a helpful factor when shopping for produce, notes Jamie Mok, a Los Angeles–based registered dietitian nutritionist.
In 2014, the Centers for Disease Control and Prevention released a study attempting to help people better understand nutrient density via a ranking system that declared watercress a powerhouse champion, with 17 nutrients per calorie—almost twice the nutrient density as kale. Regarding its taste, Mok notes, “It’s a very light, delicate flavor.”
This doesn’t mean you should opt for watercress and ban other greens from your crisper. While watercress grabbed the CDC’s top spot, many other cruciferous greens, like green or Napa cabbage, also offer significant health benefits. “Cruciferous vegetables contain a group of compounds called glucosinolates,” as well as vitamin C, vitamin K, and fiber, explains Mok. “These are sulfur-containing compounds that have antioxidant activity.” Researchers believe glucosinolates support cancer prevention.
Rather than focusing on only the most nutrient-dense greens, experts advise prioritizing variety. Even the fruits and vegetables that scored lower on the CDC’s ranking, such as iceberg lettuce, contribute to your overall intake. “I don’t encourage people to focus on finding one ‘best’ leafy green,” says Dr. Nina Cherie Franklin, a research scientist and health coach who goes by “That Salad Lady.” “Eating a variety of greens is the best way to ensure you get a broad spectrum of nutrients.”
Many people believe that darker greens are healthier than lighter ones. Experts say that in terms of nutritional content, this is true—the rich hunter green of kale trumps the pallid hues of iceberg lettuce. “Darker green vegetables are generally richer in nutrients, especially phytonutrients,” a kind of bioactive antioxidant-like compound, says Franklin. However, she adds, “Lighter greens are far from nutritionally empty. Romaine, butter lettuce, endive, and other lettuces still provide vitamins, fiber, hydration, and beneficial plant compounds.”
For instance, one cup of shredded cabbage will net you about 2g of fiber and 28mg of vitamin C, but no vitamin A. A cup of spinach contains 1g of fiber, 9mg of vitamin C, and 16mcg of vitamin A. That means easy staples that include various vegetables are a good option, including boxed mesclun mix, which contains different leafy greens such as mustard greens and arugula. “There is no single point at which greens suddenly stop being nutritious,” Franklin notes.
To maximize the benefits of your greens, consider your preparation methods. Some nutrients are fat-soluble, particularly vitamins A, E, and K, says Mok. Adding healthy fats like avocado, olive oil, or eggs to salad greens can help your body absorb these essential vitamins. Additionally, pairing iron-heavy greens like spinach with foods rich in vitamin C, such as citrus, bell peppers, or tomatoes, can significantly improve iron absorption.
Cooking also reduces the volume of greens, making it easier to consume larger quantities; two cups of raw leafy vegetables are the equivalent of a 1-cup vegetable serving. Furthermore, heating greens to about 160F (71C) can make them safer to consume, particularly if you are concerned about risks posed by microorganisms like cyclospora, E. coli, or salmonella. “Washing raw produce can reduce dirt and some contamination, but no home-washing method can guarantee the removal of every organism,” says Franklin. “Cooking is more effective at eliminating pathogens.”
Proper storage is essential to keep your greens fresh and safe. “For whole, unprocessed greens that you’re not planning to use right away, I generally recommend storing them unwashed,” says Franklin. “Cutting, bruising, or otherwise damaging the leaves can also shorten their useful life.” She suggests using a container that allows for some airflow. “A regular plastic bag can also work when used properly,” she says, recommending that you place a slightly damp paper towel inside the bag to help “manage humidity without allowing the greens to become soggy.” The report also notes that up to 9% of foodborne illnesses caused by pathogens in the US are linked to leafy greens. The report also notes that costing the nation more than $5bn to address, according to research from the Ohio State University, this looks like an estimated 2.3m illnesses annually. The report also notes that “Watercress is rich in vitamin K, vitamin C, minerals like calcium, manganese, copper and lots of phytochemicals, which are beneficial compounds that we find in plants,” says Mok, who grew up eating watercress in Chinese soups her mother made. The report also notes that “Wash your hands and preparation surfaces, discard damaged leaves, rinse loose greens thoroughly under running water and dry them with a clean cloth, paper towel or a salad spinner.”. The report also notes that the physical attributes of leaves make them susceptible to harboring disease, says Kristin Krokowski, a commercial horticulture educator at the University of Wisconsin–Madison, when it comes to waterborne pathogens like cyclosporiasis. The report also notes that says Krokowski: “There’s lots of little places for the cyclospora to attach, and the fact that they’re heads – multiple layers of leaves – allows for space in between the leaves, the leaves of leafy green vegetables are bumpy. The report also notes that and there’s more places to hide.”, so water isn’t evaporating quickly. The report also notes that and another thing to actually eat them in a timely manner; we’ve all felt guilt over limp lettuce and slimy mesclun, it’s one thing to stock up on leafy greens at the store.
