Spinach vs Arugula - Health impact and Nutrition Comparison

Introduction

We all know that leafy vegetables are good for our health but are some greens better than others? This article will compare two of these greens, arugula and spinach, to see what nutritions they provide us with and how it impacts our bodies.

Classification

Arugula has many names, including salad rocket, garden rocket, eruca, rucola, colewort and, scientifically, Eruca vesicaria, Eruca sativa or Brassica eruca. It belongs to the Eruca genus and the Brassicaceae family. Arugula shares this family with broccoli, cauliflower, cabbage, Brussel sprouts and many others.

Spinach or Spinacia oleracea belongs to the Spinacia genus and the Amaranthaceae family. This family also includes vegetables, such as garden beets and chard, as well as pseudocereal quinoa.

Appearance

Arugula and spinach are easy to differentiate from each other by appearance. Spinach has smaller rounded triangular leaves, while leaves of arugula are pinnate shaped with lobes on each side.

Arugula leaves also tend to be darker in colour when compared to spinach.

Taste and Use

Arugula is believed to have originated from the Mediterranean region, Morocco, Portugal, Lebanon and Syria. It’s either eaten in the raw form by itself like in Turkey, Egypt, Brazil and Cyprus as a side dish or as an ingredient. For example, it is often added to pizza in Italy. Spinach, on the other hand, comes from ancient Persia. In a raw, fresh form it is used in burgers and salads, often to replace lettuce.

Arugula is famous for its peppery and slightly bitter taste. Spinach, however, has a much milder flavour, becoming more robust as it is cooked.

Varieties

Based on the cultivar, the nutritional and physical properties of these greens can change.

The three main types of spinach are savoy, semi-savoy and smooth-leafed spinach. Savoy spinach is also known as curly-leaf spinach. This variety usually has crispier leaves and is easier to cook with. The most popular varieties of savoy spinach are Regiment and Bloomsdale.

Semi-savoy spinach, as the name suggests, is somewhere in between savoy and smooth spinach. It has crispier leaves when compared to smooth-leafed spinach, but is easier to clean than savoy spinach. The two common types of semi-savoy spinach are Tyee and Catalana.

And finally, the most popular varieties of smooth-leafed spinach are Space and Red Cardinal spinach.

Arugula also has a wide variety of cultivars with differing appearances, tastes and nutritional values. The two primary commercially available groups of arugula are wild and common arugula. Wild arugula tends to have a stronger taste.

Some of the widely known common varieties of arugula are Astro, Sylvetta and Apollo.

Nutrition

The nutritional values are presented for raw arugula and spinach.

Macronutrients and Calories

As can be easily seen in the visual nutrition comparison below, these foods have very similar nutritional content. Macronutrient structure is nearly the same. Both arugula and spinach consist of 91% water, spinach being only a little denser.

However, these two vegetables have a drastically different average serving size. One serving size of arugula is considered to be one leaf, weighing only 2g, whereas one average serving size of spinach is one cup, equal to 30g.

Calories

Arugula and spinach are very similar in calorie content, both being very low in calories.

A 100g serving of arugula contains 25 calories, only 2 more calories when compared to spinach.

Protein and Fats

Leafy vegetables are not particularly rich in most macronutrients. However, spinach contains a little more protein when compared to arugula.

The protein quality in both of these vegetables is high, as they contain some levels of all essential amino acids.

Arugula and spinach are very low in fats. Having said that, arugula has a slightly higher content of fats. The predominant fats found in these greens are polyunsaturated fatty acids.

Naturally, arugula and spinach contain no cholesterol.

Carbohydrates

Arugula and spinach contain nearly the same amount of carbohydrates. However, arugula is higher in sugar, while spinach contains more dietary fiber.

The little sugar content of spinach is made up of sucrose, glucose, fructose and galactose.

Vitamins

There are relatively serious differences in vitamin content. Arugula contains 5 times more Vitamin B5, while spinach has around 3 times more Vitamin A, E and K.

Spinach is the winner in this category, as it contains significantly higher levels of all vitamins except for vitamin B5. These include vitamin A, vitamin C, vitamin E, vitamin K, vitamins B1, B2, B3, B6 and folate.

Spinach and arugula are both completely absent in vitamin B12 and vitamin D.

Minerals

Most minerals appear in approximately the same amounts. It’s important to mention though that both are quite high in potassium, calcium and magnesium.

That being said, spinach is relatively richer in iron, potassium, magnesium, copper, zinc, manganese, selenium and choline.

Arugula, on the other hand, is higher in calcium and phosphorus. Arugula is also lower in sodium.

Nitrates

Leafy green vegetables are rich in natural compounds called dietary nitrates, which are said to be responsible for various beneficial effects of these greens, such as improving vascular functions (1, 2).

Arugula is over four times richer in dietary nitrates when compared to spinach (2). 

The nitrate content can be found in different amounts depending on the seasonal period. Studies have shown the nitrate content of leafy green vegetables to be higher in autumn (3),

Glycemic Index

An exact number has not yet been calculated for the glycemic index of arugula and spinach. However, dark green leafy vegetables are said to have a low glycemic index due to their low sugar content (4).

One study has shown spinach consumption to lower the glycemic response of a meal, while another found that spinach only improves insulin sensitivity but has no effect on blood glucose levels (5, 6). 

Acidity

The pH value of arugula is estimated to be around 6.9, making the acidity of arugula neutral (7).

Spinach, however, has a slightly more acidic pH value that can fall anywhere from 5.38 to 7.18, depending on the cooking method (8).

An alternative way of looking at the acidity of foods is the potential renal acid load or the PRAL value. This value demonstrates how much acid or base the given food produces inside the organism.

The PRAL value of arugula and spinach are -7.9 and -11.8, respectively. This shows us that spinach is more base-producing when compared to arugula.

Weight Loss & Diets

Green leafy vegetables famously fit well into weight loss diets.

Arugula and spinach are no exceptions, being low calorie foods. A hundred gram serving of these vegetables provides 25 calories or less. Green leafy vegetables are also a good source of dietary fiber and micronutrients.

Between the two vegetables, spinach is the preferred choice during low calorie, low fats and low carb diets. However, both arugula and spinach are low in calories, fats and carbohydrates.

Green leafy vegetables, especially spinach, are rich in a compound called thylakoid. Thylakoid has been found to reduce hunger and cravings for palatable foods and increase satiety in overweight women (9). This means that eating spinach or arugula before a meal can help reduce overeating.

Health Impact

Health Benefits

In addition to the nutrients stated above, these leafy vegetables are also rich in antioxidants and phytonutrients, such as carotenoids, phenolic acids and flavonoids. Due to these and other compounds, arugula and spinach have certain favourable impacts on health.

Both foods are very healthy and nutritious. However, spinach appears to be part of more scientific studies.

Cardiovascular Health

An inverse association has been found between the intake of green leafy vegetables, such as arugula spinach, and cardiovascular disease and mortality (10).

Green leafy vegetable consumption may also decrease the risk of atherosclerotic vascular disease, coronary heart disease and stroke (11).

Dietary nitrate may also contribute to the management of high blood pressure (12). Overall, dietary nitrate has been studied to reduce morbidity and mortality (2).

Diabetes

As mentioned above, both spinach and arugula are low glycemic index foods containing few sugars.

An extract of arugula leaves exhibited antidiabetic effects on cells that were responsive to insulin, which may prove useful for the treatment of type 2 diabetes (13).

Spinach consumption can help control metabolic syndrome, due to its high level of antioxidants (14).

Cancer

A compound found in arugula, called erucin, has been found to have the potential to prevent cancer by inhibiting the division of tumour cells (15).

Spinach has been researched to help protect against colorectal, breast, bladder, lung and prostate cancers (16, 17).  

Downsides and Risks

Vitamin K and Drugs

Green leafy vegetables, especially spinach, are very high in vitamin K. There has been some concern, that due to this fact, these vegetables may interact negatively with certain blood-thinners, such as warfarin, which work by inhibiting the blood clotting function of vitamin K. However, available evidence does not support the advice to modify dietary habits when starting therapy with vitamin K antagonists (18).

Summary

The foods are not radically different, having similar calories, macronutrient content and glycemic index, however, spinach contains 3 times more vitamins A, E and K, as well as more iron, potassium and magnesium. This makes spinach a better choice in terms of nutrition.

While arugula and spinach both have numerous beneficial effects on health, spinach has been studied more extensively in the area of health.

Sources.

1. https://www.sciencedirect.com/science/article/abs/pii/S0891584914004407
2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6116056/
3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5412236/
4. https://www.ars.usda.gov/plains-area/gfnd/gfhnrc/docs/news-2013/dark-green-leafy-vegetables/
5. https://www.researchgate.net/profile/Arvind_Singh56/post/What_is_the_pharmacological_effects_of_spinach_on_diabetes/attachment/5b9c98f7cfe4a76455f35cd7/AS%3A670996461780992%401536989431109/download/full-text-14.pdf
6. https://www.researchgate.net/publication/270676832
7. http://www.nphsystem.guide/vegetable_values.htm
8. https://www.webpal.org/SAFE/aaarecovery/2_food_storage/Processing/lacf-phs.htm
9. https://www.sciencedirect.com/science/article/pii/S019566631500197X
10. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5837313/
11. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5986475/
12. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4525132/
13. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6130626/
14. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5534315/
15. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4065051/
16. https://www.aicr.org/cancer-prevention/food-facts/spinach/
17. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3209415/
18. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4998867/