Kale vs. Spinach — Health Impact and Nutrition Comparison

Introduction

Spinach and kale are leafy green vegetables widely recognized for their nutritional value. At times they’re even used interchangeably in salads and other dishes. However, these two greens have distinct nutritional properties and health impacts, which will be discussed in this article.

Nutrition

The nutritional infographics in this article are presented for 100g servings of boiled spinach and kale, drained, without salt.

However, the average serving size of these greens per person is one cup, which weighs around 30g for spinach and 21g for kale.

Macronutrients and Calories

Kale and spinach are of equal density, consisting of 91% water and 9% nutrients. 

The primary macronutrient in these vegetables is carbohydrates, followed by protein. Kale is higher in carbohydrates, while spinach is richer in protein.

Macronutrient Comparison

Macronutrient breakdown side-by-side comparison

Kale

2

Protein: 1.9 g

Fats: 0.4 g

Carbs: 5.63 g

Water: 91.2 g

Other: 0.87 g

Spinach

3

Protein: 2.97 g

Fats: 0.26 g

Carbs: 3.75 g

Water: 91.21 g

Other: 1.81 g

Contains more FatsFats	+53.8%
Contains more CarbsCarbs	+50.1%

Contains more ProteinProtein	+56.3%
Contains more OtherOther	+108%

~equal in Water ~91.21g

Calories

These two leafy greens are very low-calorie foods, with kale being only a little higher in calories.

In a 100g serving, kale provides 28 calories, while spinach has 23 calories.

Carbohydrates

Kale is 1.5 times higher in carbohydrates, being 2.7 richer in net carbs. However, spinach contains 0.4g more dietary fiber per 100g serving.

A 100g serving of spinach and kale provides 3.75g and 5.63g of carbohydrates, respectively. Of this, 60% is dietary fiber, and 40% is net carbs for spinach, while in kale, these numbers are 55% for dietary fiber and 45% for net carbs.

Kale is 3 times higher in sugar.

Protein

While leafy greens are not the best source of protein, spinach is higher in this nutrient. A 100g serving of spinach and kale contains about 3g and 2g of protein, respectively.

Fats

These two leafy greens are very low in fats, containing less than 1g per 100g serving.

Fat Type Comparison

Fat type breakdown side-by-side comparison

Kale

2

Saturated Fat: Sat. Fat 0.052 g

Monounsaturated Fat: Mono. Fat 0.03 g

Polyunsaturated fat: Poly. Fat 0.193 g

Spinach

1

Saturated Fat: Sat. Fat 0.043 g

Monounsaturated Fat: Mono. Fat 0.006 g

Polyunsaturated fat: Poly. Fat 0.109 g

Contains more Mono. FatMonounsaturated Fat	+400%
Contains more Poly. FatPolyunsaturated fat	+77.1%

Contains less Sat. FatSaturated Fat

-17.3%

Vitamins

Spinach is overall richer in vitamins, being 11 times higher in folate or vitamin B9, about 3 times higher in vitamins B2 and B5, and 2 times higher in vitamin E.

Spinach also contains more vitamin B1 and vitamin B6.

At the same time, kale is 4 times richer in vitamin C and overall richer in vitamins A and K.

Vitamin Comparison

Vitamin comparison score is based on the number of vitamins by which one or the other food is richer. The "coverage" charts below show how much of the daily needs can be covered by 300 grams of the food.

Kale

3

Spinach

7

Contains more Vitamin CVitamin C	+318.4%
Contains more Vitamin AVitamin A	+30%
Contains more Vitamin KVitamin K	+65.5%

Contains more Vitamin EVitamin E	+144.7%
Contains more Vitamin B1Vitamin B1	+79.2%
Contains more Vitamin B2Vitamin B2	+237.1%
Contains more Vitamin B5Vitamin B5	+195.9%
Contains more Vitamin B6Vitamin B6	+75.4%
Contains more FolateFolate	+1023.1%
Contains more CholineCholine	+4825%

~equal in Vitamin D ~0µg

~equal in Vitamin B3 ~0.49mg

~equal in Vitamin B12 ~0µg

These leafy greens are both excellent sources of vitamin K. A 100g serving of spinach and kale covers 411% and 681% of the daily needed value for this vitamin.

Minerals

Leafy greens are an excellent source of minerals. Spinach falls in the top 16% of foods as a source of iron, while a 100g serving of kale covers 18% of the daily needed value of manganese.

Spinach is also the ultimate winner in the mineral category. It provides 5 times more magnesium, 4 times more iron, and 3 times more zinc. Spinach is richer in manganese, potassium, phosphorus, calcium, selenium, and copper.

Spinach is also an excellent source of nitrates (1).   

Kale is lower in sodium.

Mineral Comparison

Mineral comparison score is based on the number of minerals by which one or the other food is richer. The "coverage" charts below show how much of the daily needs can be covered by 300 grams of the food.

Kale

1

Spinach

9

Contains less SodiumSodium

-67.1%

Contains more MagnesiumMagnesium	+383.3%
Contains more CalciumCalcium	+88.9%
Contains more PotassiumPotassium	+104.4%
Contains more IronIron	+296.7%
Contains more CopperCopper	+11.5%
Contains more ZincZinc	+216.7%
Contains more PhosphorusPhosphorus	+100%
Contains more ManganeseManganese	+124.8%
Contains more SeleniumSelenium	+66.7%

Health Benefits

Cardiovascular Health

Consuming green leafy vegetables, including kale and Spinach, has been linked to a lower risk of cardiovascular disease and mortality (2).

A high green leafy vegetable intake may also reduce the risk of stroke, coronary heart disease, and atherosclerotic vascular disease. Spinach, in particular, is high in a phytochemical called glucosinolate, which has a strong anti-inflammatory potential (3).

Regularly using kale juice with meals can positively impact the antioxidant systems and serum lipid profiles, which can help lower the risk of coronary artery disease in people with high cholesterol levels (4).

The nitrates found in spinach are also good for heart health. They can help lower blood pressure and decrease cardiovascular disease risk (5).

Diabetes

As mentioned above, kale and spinach are low glycemic index foods, meaning the intake of these vegetables does not increase blood glucose levels rapidly.

Kale consumption has also been researched to suppress blood glucose levels after meals (6).

Spinach can be a potential dietary supplement for preventing insulin resistance as its nitrate content can increase NO status, improve lipid homeostasis, reduce inflammation, and boost endothelial function (7). 

Downsides 

Kidney Stones and Oxalates

Dietary oxalates are excreted through urine. The amount of oxalates excreted in urine is essential in calcium oxalate stone formation. Thus, continuous high amounts of oxalate intake increase the risk of developing kidney stones (8).

Spinach is very high in oxalates, providing 6.6mmol per 300g serving, whereas spinach falls in the very low oxalate category, containing only 0.1mmol oxalates in the same serving size (9).

The oxalate content of spinach can vary widely, ranging from 490 to 12576mg per 100g serving, depending on the study; however, this value is always high (10, 11).

A high oxalate content is also associated with decreased magnesium absorption (9). 

Sources

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6116056/
2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5837313/
3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5986475/
4. https://www.sciencedirect.com/science/article/pii/S0895398808600124
5. https://link.springer.com/article/10.1007/s10654-021-00747-3
6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5103670/
7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5018658/
8. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6459305/
9. https://pubmed.ncbi.nlm.nih.gov/15035687/ 
10. https://www.sciencedirect.com/science/article/abs/pii/S0889157513000902
11. https://www.researchgate.net/publication/5517631