Health authorities widely agree that a diet high in nutrient-dense fruits and vegetables is associated with a reduced risk of chronic disease. While many options for salad greens exist, experts advise prioritising variety in consumption.
Jamie Mok, a Los Angeles-based registered dietitian nutritionist, notes that 'nutrient density' – defined as nutrients per calorie – can be a factor when choosing produce. In 2014, the Centers for Disease Control and Prevention (CDC) released a study that ranked watercress as a 'powerhouse champion' with 17 nutrients per calorie, nearly double that of kale.
Mok explains that watercress is rich in vitamin K, vitamin C, and minerals such as calcium, manganese, and copper, along with beneficial phytochemicals. However, Dr Nina Cherie Franklin, a research scientist and health coach, advises against focusing on one 'best' leafy green, stating that 'eating a variety is almost always the better approach.'
Darker green vegetables are generally richer in nutrients, especially phytonutrients, compared to lighter greens. However, lighter greens like romaine and butter lettuce still provide vitamins, fibre, hydration, and beneficial plant compounds.
To enhance nutrient absorption, particularly for fat-soluble vitamins A, E, and K, Mok suggests adding healthy fats like avocado or olive oil to salads or sautéing greens. Cooking greens to approximately 71.1C can also make them safer to consume, especially if there are concerns about microorganisms such as cyclospora, E coli, or salmonella.