Dark leafy greens are not everyone’s cup of tea. Collard greens, kale and turnip greens, for example, can taste bitter, especially when not handled in a way to alleviate some of that bitterness. However, spinach is a dark leafy green, less bitter than most, and still packs the nutritional punch of other dark leafy greens. Spinach contains more calcium than any other leafy green (245 milligrams per 1 cup cooked spinach). However, some things are not always what they seem.

While the Nutrition Facts label on a bag of spinach may show that it is a good source of calcium, it is also high in oxalates. Oxalates, or oxalic acid, is a compound that binds to calcium and inhibits the body’s ability to absorb it. Therefore, only about 5% (or approximately 12 milligrams) of spinach’s calcium is actually absorbed, which isn’t great when you’re trying to get in the recommended 1,000 to 1,300 milligrams of calcium each day. The oxalates in spinach also aren’t great for people who are prone to forming calcium oxalate stones, the most common type of kidney stones. Limiting oxalate-rich foods may help lower the chances of forming new stones. 

All of this is not to say that spinach isn’t good for you. Spinach is rich in potassium, folate, iron, vitamins K, A, and C, dietary fiber and carotenoids. It’s a powerhouse; just not a big source of calcium. That’s why it’s important to eat a variety of foods in all the food groups, including dairy, vegetables, fruit, protein and grains. 

Source: 
USDA FoodData Central. Cooked spinach.