Watercress vs Spinach - Health impact and Nutrition Comparison
Spinach contains four times more dietary fiber than watercress.
Spinach contains 21.5 times more folate, five times more zinc, and 15 times more iron. It is also richer in most of the B complex vitamins, vitamins A, E, and K, magnesium, potassium, zinc, copper. Notably, watercress is five times richer in vitamin B5, as well as vitamins C and B1, calcium, and phosphorus.
Spinach has been known worldwide for centuries; therefore, its health effects are well studied.
Table of contents
- Macronutrients and Calories
- Glycemic Index
- Weight Loss & Diets
- Health Impact
- Health Benefits
- Downsides and Risks
Leafy green vegetables or leafy greens, salad greens, or simply greens are well known for their beneficial health impact on our bodies. Besides introducing the main nutritional differences between spinach and watercress, this article will also provide information about their impact on host health.
Spinach (Spinacia oleracea) belongs to the Spinacia genus, Chenopodioideae subfamily, and Amaranthaceae family. Most species in this family are annual or perennial herbs or subshrubs.
Watercress or yellowcress (Nasturtium officinale) belongs to the Nasturtium genus and the Brassicaceae family. Brassicaceae or Cruciferae is commonly known as the mustard, the crucifer, or the cabbage family. Most plants in this family are herbaceous plants, and some are shrubs.
Spinach has simple, ovate to triangular leaves that vary in size.
Watercress is regarded as a weed in some regions and an aquatic vegetable or herb in others. It has pinnately compound leaves.
Taste and Use
Spinach is mainly said to be originated from ancient Persia and was known as a Persian vegetable. It is used both raw, in salads and burgers, and sauteed as a side dish.
Watercress was first cultivated in the United Kingdom. It is best eaten raw as it loses a proportion of its health benefits when cooked. However, it’s still a useful ingredient in cooked dishes, such as soups, stews, and stir-fries.
Raw spinach has a mild, slightly sweet taste and is more acidic and robust when cooked. Watercress has a pungent, spicy, and peppery taste.
Spinach is divided into three main types: savoy, semi-savoy and flat-leafed. Savoy spinach has very wrinkled leaves that grow pretty low and take the cold better than the other types of spinach. Its popular varieties are Bloomsdale and Regiment.
Semi-savoy spinach grows more upright than savoy spinach; therefore, it stands up a bit straight. Its leaves are much less wrinkled, which makes washing them easier. It is also disease and bolt-resistant. Indian summer, Tyee, Catalina belong to this type.
The smooth-leafed spinach has a smooth surface that makes it pretty easy to clean. This spinach is usually sold canned or frozen; nonetheless, it can be sold fresh too. Space spinach and Red Carnival belong to the flat-leafed spinach.
There are also alternative spinach varieties such as New Zealand and Malabar spinach.
In addition to traditional watercress, there are similar plant species that have a bit different flavor and texture. Garden Cress (Lepidium sativum) has a spicier flavor, like horseradish. Upland Cress (Barbarea verna) has thinner stems and a more delicate flavor, while Korean Watercress is more bitter and crunchy.
The nutritional values are presented for raw spinach and raw watercress.
Macronutrients and Calories
Spinach and watercress have very similar nutritional contents. Spinach contains a little bit more protein and carbohydrates.
Both spinach and watercress consist of 94% water, spinach being only a little denser in nutrients.
The average serving size of spinach and watercress is one cup, equal to 30g for spinach and 34g for watercress.
Both spinach and watercress are low-calorie foods.
A 100g serving of spinach provides 23 calories, and watercress provides only half of that.
Protein and Fats
Leafy vegetables are not generally rich in macronutrients, yet spinach is slightly richer in proteins.
Both vegetables contain some amounts of all essential amino acids, making their protein quality high.
Spinach and watercress are very low in fats, spinach being only slightly higher in fats.
The predominant fats are polyunsaturated fats, which are considered to be healthy.
There is no cholesterol in these vegetables.
As said before, they are not particularly rich in carbs; however, spinach contains three times more total carbs and four times more dietary fiber: spinach contains 3.63g of carbs (from which 2.2g is fiber), whereas watercress contains 1.29g (from which 0.5g is fiber).
Vitamin content difference in these vegetables is vast. Spinach contains 21.5 times more folate or vitamin B9, three times more vitamins A and B3, whereas watercress has almost five times more vitamin B5.
Watercress has more vitamins B1 and C, while spinach has higher levels of vitamins B2, B3, B6, vitamin A, vitamin E, and vitamin K.
Both spinach and watercress are absent in vitamin B12 and vitamin D.
Spinach is richer not only in vitamins but in minerals as well.
Spinach has 15 times more iron, five times more zinc, and nearly four times more magnesium than watercress.
Spinach is also richer in potassium, copper and contains higher levels of sodium.
Watercress contains more calcium and phosphorus.
Leafy green foods are a rich source of inorganic nitrate. Nitrates stimulate the production of nitric oxide that regulates muscle blood flow and participates in mitochondrial respiration.
Spinach is over two times richer in nitrates compared to watercress (1).
Depending on the season, the nitrate content differs. According to studies, the nitrate content of leafy greens is higher in autumn (2).
Spinach and watercress are non-starchy dark green leafy vegetables with low glycemic index values (3).
Dark green leafy vegetables are considered to be superfoods or powerhouse foods. Due to having a low glycemic index, they are good for patients with diabetes. (4).
Spinach's pH value can be anywhere from 5.38 to 7.18.
Watercress has a pH value ranging between 5.88 to 6.18 (5).
The pH values can change depending on the greens’ growing conditions and processing methods.
The PRAL (potential renal acid load) value is another way of looking at the acidity of the foods based on how much acid is produced in the organism from the given food.
The PRAL value of spinach is -11.8, while the PRAL value of watercress is -5.7. The more negative PRAL value of spinach shows that it’s more base-producing.
Weight Loss & Diets
A 100g serving of spinach provides 23 calories, while watercress provides 11 calories, making it a better choice for low-calorie diets. Between these two, watercress is also a better choice for low-carb and low-fat diets.
Both greens are low in carbs, fats, and calories, making them a great choice for weight loss diets, such as keto, Atkins, and Mediterranean diets.
Non-starchy greens are also part of the “Cruise” and “Consolidation” phases of the Dukan Diet.
Leafy green vegetables are consumed during the anti-inflammatory diet. They are high in natural antioxidants, polyphenols, carotenoids, and vitamins, which protect cells from free-radical damage and reduce inflammation (6).
Structures found in plants named thylakoids are shown to reduce appetite and help in the weight loss journey. The mechanisms behind these effects are thylakoids increasing and reducing levels of some hormones related to the appetite and desire to eat and preventing a drop in blood sugar after meals, helping you feel full for longer (7).
Both spinach and watercress are rich in minerals, vitamins, antioxidants, nitrates, fiber, and other compounds, mainly showing favorable impacts on health.
Many studies have reported inverse associations of leafy green vegetables with cardiovascular disease outcomes. Increasing the intake of leafy greens may provide significant cardiovascular health benefits due to the number of nutrients and phytochemicals they contain (8).
Inorganic dietary nitrate from the greens is converted to nitrite and NO in vivo. The NO leads to the widening of blood vessels and lowers both systolic and diastolic blood pressures, thus fighting against hypertension. NO also has protective effects on the heart by attenuating cardiac hypertrophy and fibrosis (9).
Several studies have shown that increasing the daily intake of leafy vegetables could significantly reduce the risk of type 2 diabetes due to its high concentrations of β carotene and vitamin C, both of which confer antioxidant properties (10).
The low glycemic index and high magnesium level are also effective in preventing and treating type 2 diabetes. High magnesium lowers glucose intolerance and insulin resistance (11).
There is limited data on the influence of vegetable consumption on obesity and metabolic health. Consumption of greens is associated with positive metabolic outcomes, including reduced visceral and liver fat (12).
Prospective and retrospective studies suggest that carotenoids may reduce the risk of certain cancers. The low intake of carotenoids is associated with an increased risk of lung cancer (13).
Xanthophyll carotenoids were found to reduce cell viability through apoptosis (cell death) induction in the human prostate cancer cells (14).
Dietary fiber also has its role here. It helps to keep the microbiome (community of microbes living in the digestive tract) healthy, and a healthy microbiome has been linked with a lower risk of cancer (15).
Vitamins as well partake in lowering the risks of cancer; for example, people with low folate levels have a higher risk of breast, pancreatic, and colon cancer (15).
More than half of the women in menopausal transition or postmenopausal age have the risk of osteoporosis, which can be diagnosed after sudden and unexpected bone fractures.
Due to their high magnesium, calcium, and vitamin K levels, leafy greens help prevent the disease by maintaining normal storage levels of those minerals (16, 17).
Carotenoids from green vegetables, mainly lutein and zeaxanthin, play a major role in eye health. They show antioxidant effects and absorb near-to-UV blue light (18).
Consumption of leafy greens lowers the chances of eye diseases, such as night blindness and age-related macular degeneration, and reduces the chances of eye cancer.
Downsides and Risks
Spinach is one of the highest oxalate-containing foods: 755mg in 1/2 cup (15g). Similarly, watercress also has a high oxalate content, but its level is not dangerously high.
High oxalate is the primary cause of kidney stone formation, and people with kidney stones or at high risk of kidney stones should exclude spinach from their diets and lower the level of consumed watercress (19, 20, 21).
Vitamin K and Drugs
A relatively high amount of vitamin K can be found in leafy greens. Vitamin K participates in coagulation (blood clotting), while Warfarin (Coumadin) does the exact opposite - it makes your blood clot more slowly. Therefore, some researchers suggest if you take warfarin, to make sure that consumed vitamin K is about the same every day. There’s a risk of bleeding (if you consume less) or making blood clots (if you consume more) (22).
- Oxalate in Food
Fat Type Comparison
Comparison summary table
|Lower in Sugar|
|Lower in Sodium|
|Lower in Saturated Fat|
|Lower in price|
|Rich in minerals|
|Rich in vitamins|
|Lower in Cholesterol||Equal|
|Lower in glycemic index||Equal|
All nutrients comparison - raw data values
|Vitamin A RAE||160µg||469µg|
Which food is preferable for your diet?
|Low Fats diet|
|Low Carbs diet|
|Low Calories diet|
|Low glycemic index diet||Equal|