Kale vs. Spinach — Health Impact and Nutrition Comparison
Summary
Kale is somewhat higher in calories and carbohydrates due to net carbs, while spinach is richer in protein and dietary fiber.
Spinach is a better source of both vitamins and minerals, containing 11 times more folate or vitamin B9, about 3 times more vitamins B2 and B5, 5 times more magnesium, 4 times more iron, and 3 times more zinc.
However, kale is 4 times richer in vitamin C and overall richer in vitamins A and K.
Spinach contains 66 times more oxalates, an increased intake of which leads to the formation of calcium oxalate kidney stones.
Table of contents
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.
Classification and Appearance
Kale belongs to the Brassica family of vegetables, which includes other members like broccoli, cauliflower, and Brussels sprouts. Conversely, Spinach is part of the Amaranthaceae family, which also includes beets and chard.
Kale leaves are usually darker, with a bluish-green or even purplish hue. They are curly or frilly, with a central rib running down the middle. Spinach leaves are typically bright, vibrant green with a more oval or heart-shaped appearance. They are also thinner and more delicate than kale leaves.
Taste and Use
Kale has a more bitter and earthy taste than spinach, which has a milder and sweeter flavor. Spinach has a softer texture than kale, which can be tough and fibrous.
However, kale can be massaged or cooked to make it more tender.
Both spinach and kale are versatile vegetables that can be used in a variety of dishes. Spinach is commonly used in salads, sandwiches, and smoothies, while kale is often used in soups, stews, and stir-fries.
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
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
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
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
Glycemic Index
There are no specific glycemic index values measured for kale and spinach. However, these values are considered to be low, as kale and spinach are rich in dietary fiber and relatively low in net carbs.
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
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6116056/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5837313/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5986475/
- https://www.sciencedirect.com/science/article/pii/S0895398808600124
- https://link.springer.com/article/10.1007/s10654-021-00747-3
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5103670/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5018658/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6459305/
- https://pubmed.ncbi.nlm.nih.gov/15035687/
- https://www.sciencedirect.com/science/article/abs/pii/S0889157513000902
- https://www.researchgate.net/publication/5517631
Infographic
Comparison summary table
|
|
||
| Lower in Sugar |
|
||
| Lower in Saturated Fat |
|
||
| Rich in minerals |
|
||
| Lower in Sodium |
|
||
| Lower in Glycemic Index |
|
||
| Lower in price |
|
||
| Lower in Cholesterol | Equal | ||
| Rich in vitamins | Equal | ||
All nutrients comparison - raw data values
| Nutrient | |
|
Opinion |
| Net carbs | 3.63g | 1.35g |
|
| Protein | 1.9g | 2.97g |
|
| Fats | 0.4g | 0.26g |
|
| Carbs | 5.63g | 3.75g |
|
| Calories | 28kcal | 23kcal |
|
| Sugar | 1.25g | 0.43g |
|
| Fiber | 2g | 2.4g |
|
| Calcium | 72mg | 136mg |
|
| Iron | 0.9mg | 3.57mg |
|
| Magnesium | 18mg | 87mg |
|
| Phosphorus | 28mg | 56mg |
|
| Potassium | 228mg | 466mg |
|
| Sodium | 23mg | 70mg |
|
| Zinc | 0.24mg | 0.76mg |
|
| Copper | 0.156mg | 0.174mg |
|
| Manganese | 0.416mg | 0.935mg |
|
| Selenium | 0.9µg | 1.5µg |
|
| Vitamin A | 13621IU | 10481IU |
|
| Vitamin A RAE | 681µg | 524µg |
|
| Vitamin E | 0.85mg | 2.08mg |
|
| Vitamin C | 41mg | 9.8mg |
|
| Vitamin B1 | 0.053mg | 0.095mg |
|
| Vitamin B2 | 0.07mg | 0.236mg |
|
| Vitamin B3 | 0.5mg | 0.49mg |
|
| Vitamin B5 | 0.049mg | 0.145mg |
|
| Vitamin B6 | 0.138mg | 0.242mg |
|
| Folate | 13µg | 146µg |
|
| Vitamin K | 817µg | 493.6µg |
|
| Tryptophan | 0.023mg | 0.04mg |
|
| Threonine | 0.085mg | 0.127mg |
|
| Isoleucine | 0.114mg | 0.152mg |
|
| Leucine | 0.133mg | 0.231mg |
|
| Lysine | 0.114mg | 0.182mg |
|
| Methionine | 0.018mg | 0.055mg |
|
| Phenylalanine | 0.097mg | 0.134mg |
|
| Valine | 0.104mg | 0.168mg |
|
| Histidine | 0.04mg | 0.066mg |
|
| Saturated Fat | 0.052g | 0.043g |
|
| Monounsaturated Fat | 0.03g | 0.006g |
|
| Polyunsaturated fat | 0.193g | 0.109g |
|
Which food is preferable for your diet?
|
|
|
| Low Fats diet |
|
|
| Low Carbs diet |
|
|
| Low Calories diet |
|
|
| Low Glycemic Index diet |
|
People also compare
Vitamins & Minerals Daily Need Coverage Score
Comparison summary
References
All the values for which the sources are not specified explicitly are taken from FDA’s Food Central. The exact link to the food presented on this page can be found below.
- Kale - https://fdc.nal.usda.gov/fdc-app.html#/food-details/169238/nutrients
- Spinach - https://fdc.nal.usda.gov/fdc-app.html#/food-details/168463/nutrients
All the Daily Values are presented for males aged 31-50, for 2000-calorie diets.