Arugula vs Spinach – Key Differences

Read on to learn how arugula and spinach compare against each other in terms of nutritional value, nitrate content, taste, uses, and more.

Nutrition Facts

The arugula vs spinach chart below shows you the calorie count and nutrient content of each leafy green in its raw, uncooked form. A value highlighted in bold means that a 100-gram serving of the food covers at least 10 percent of the Daily Value (DV) for the nutrient in question. (Source: USDA, see Reference 1)

Both of these leafy greens are low in calories and loaded with vitamin K, which supports bone and cardiovascular health, and folate, which is used to form red blood cells. Both spinach and arugula also contain significant amounts of magnesium, manganese, vitamin C and beta-carotene, with each providing at least 10 percent of the daily value (DV) for these nutrients. The main difference is that spinach generally contains much higher levels of nutrients than arugula, with one notable exception: arugula contains 60 percent more calcium than spinach. In addition to keeping your bones strong and healthy, calcium enables your blood to clot, your muscles to contract, and your heart to beat.

Nitrate Content

Not only are arugula and spinach packed with beneficial nutrients, they both also contain exceptionally high levels of nitrates. However, while both are rich in these controversial compounds, arugula clearly beats out spinach in terms of nitrate levels. An analysis based on 2000 samples of arugula and 7000 samples of spinach found that on average, arugula contained 75 mmol of nitrate per kg, whereas spinach contained only 17 mmol of nitrate per kg (2).

The nitrates in arugula and spinach are not thought to be harmful as such, but they can be converted into nitrites and further into carcinogenic nitrosamines, which has raised questions about the safety of diets high in nitrate-rich leafy green vegetables like arugula and spinach. However, a meta-analysis published in the peer-reviewed scientific journal Nutrients could not find a positive correlation between a high intake of plant-based nitrates and risk of gastric cancer, probably because the health benefits of eating green leafy vegetables outweigh the disadvantages (3, 4).

Taste

One of the most striking differences between arugula and spinach is that arugula tastes much stronger than spinach. The flavor of arugula can be described as peppery or mustardy with a hint of nuttiness. The pungent flavor of arugula comes from its high concentration of glucosinolates. These sulfur-containing compounds function as precursors to isothiocyanates, phytochemicals that have been extensively researched for their potential anti-cancer benefits.

Compared with arugula, spinach generally has a mild flavor. The large, more mature leaves tend to have a more bitter flavor than baby spinach because they usually contain higher levels of oxalates, which are bitter-tasting phytochemicals. In addition to contributing to the flavor profile of this leafy green, the oxalates in spinach can also adversely affect the nutritional benefits of spinach by limiting calcium absorption (5).

Culinary Uses

Because of its sharp, peppery flavor, arugula can be used both as a herb and as a lettuce in mixed salads that also contain milder greens. As an ingredient, spinach is more versatile because of its mild flavor. The sturdy texture of mature spinach makes it perfect for cooked dishes, such as soup and omelets, whereas the tender, mild-flavored baby spinach can also be used in raw recipes such as salads and smoothies.

In smoothies, baby spinach pairs particularly well with mango (try, for example, this spinach, mango and apple smoothie). If you have a masticating or cold-press juicer which processes greens like spinach or kale with ease, you may also want to try making some nutrient-packed spinach juice, which you can then incorporate into smoothies, or use as a coloring for homemade pasta dough.

Storage

Both arugula and spinach, whether it's regular spinach or baby spinach, are best stored in ziplock bags or plastic containers in the fridge. Storing arugula or spinach out of the fridge will lead to a rapid loss of nutrients and an increase in the nitrate content of the food (6, 7).

Before putting spinach or arugula in the fridge, some people recommend washing and drying the leaves, and then wrapping the leaves in paper towels before transferring them to the bags or containers. The paper towels are supposed to help keep the greens from getting slimy by absorbing excess moisture

If you think you won't be able to use up all that fresh arugula or spinach in your fridge before its goes bad, you can also freeze the leaves for later use. Just keep in mind that both arugula and spinach lose their texture when frozen and thawed, so you won't be able to use them for dishes like salads later on. However, they work fine in stir-fries, omelets and as pizza topping.

When freezing arugula or regular spinach, it is best to blanch your greens first in order to protect their nutritional value, color and flavor. To blanch spinach or arugula, boil or steam the leaves for two minutes, then immediately transfer to a large bowl filled with ice water for two minutes to stop the cooking process. Baby spinach can also be frozen without blanching.

References

1. USDA National Nutrient Database for Standard Reference (Release 28, released September 2015, slightly revised May 2016). USDA Database.
2. D. Hobbs et al (2013). The effects of dietary nitrate on blood pressure and endothelial function: a review of human intervention studies. Nutrition Research Reviews, 26: 210-222.
3. P. Song et al (2015). Dietary Nitrates, Nitrites, and Nitrosamines Intake and the Risk of Gastric Cancer: A Meta-Analysis. Nutrients, 7(12): 9872-9895.
4. Marina Cavaiuolo and Antonio Ferrante (2014). Nitrates and Glucosinolates as Strong Determinants of the Nutritional Quality in Rocket Leafy Salads. Nutrients, 6(4): 1519-1538.
5. S. Noonan and G. Savage (1999). Oxalate content of foods and its effect on humans. Asia Pacific Journal of Clinical Nutrition, 8(1), 64-74.
6. S. Pandrangi and L. LaBorde (2004). Retention of Folate, Carotenoids, and Other Quality Characteristics in Commercially Packaged Fresh Spinach. Journal of Food Science, 69(9).
7. Chung et al (2004). Changes in nitrate and nitrite content of four vegetables during storage at refrigerated and ambient temperatures. Food Additives and Contaminants, 21(4):317-22.