Spinach vs. Lettuce — Health Impact and Nutrition Comparison
Summary
Spinach is nutritionally superior to lettuce, providing more protein, carbohydrates, fats, and almost all vitamins and minerals. Specifically, it contains 4 times more vitamin K, 5 times more folate, and 3 times more vitamin C than lettuce. With regard to minerals, spinach provides 3 times more manganese and iron.
Although both lettuce and spinach have low levels of sodium, lettuce contains fewer amounts compared to spinach.
Both spinach and lettuce can have various beneficial effects on cardiovascular health, diabetes, and mental health.
Table of contents
Introduction
Leafy greens are often considered to be “superfoods” associated with maintaining good health. But do all leafy greens provide the same beneficial nutrients? This article will compare spinach and lettuce to see which of these vegetables is the healthier option.
Classification
Lettuce, or Lactuca sativa, belongs to the Asteraceae family and the Lactuca genus. This family is also known as the daisy or sunflower family and includes other vegetables, such as chicory, endive, and globe artichoke.
Spinach (Spinacia oleracea) is a part of the Amaranthaceae family and the Spinacia genus. Other vegetables in this family include garden beets and chards. The pseudocereal quinoa is also part of this family.
Appearance
Lettuce and spinach have easily distinguishable characteristics. Spinach has small, rounded triangular leaves in darker green, while lettuce leaves are much larger, wrapping each other to form a rosette.
Taste and Use
Spinach, being denser, has a stronger flavor, getting more robust as it is cooked. Lettuce, on the other hand, has a very mild taste and almost no scent.
Both of these greens can be used raw as part of a salad or cooked, boiled, and steamed.
Varieties
The same vegetable can have different textures, tastes, and nutrition depending on the variety.
There are three main groups of spinach leaves: savoy, semi-savoy, and smooth-leafed. Savoy spinach, also known as curly-leaf spinach, is usually crispy and easier to cook with. The Regiment and Bloomsday are two of the most popular cultivars belonging to this group.
Smooth-leafed spinach, as the name suggests, has unwrinkled leaves, making them easier to clean. Some of the most popular varieties in this group are Space and Red Cardinal spinach.
Last but not least, semi-savoy spinach has characteristics of both groups, making them undemanding in both cooking and cleaning. The most popular varieties of semi-savoy spinach are Tyee and Catalana.
Different varieties of lettuce leaves are also based on their texture. The most widely used types of lettuce are looseleaf lettuce, Romaine or cos, and iceberg or crisphead.
Both lettuce and spinach can come in a variety of different shades of not only green but also red. Red spinach and red lettuce are high in compounds called anthocyanins which give these vegetables several health-beneficial properties.
Nutrition
The nutritional values below are presented for raw spinach and raw lettuce. Cooking methods can alter the nutritional composition of foods.
Macronutrients and Calories
The average serving size for both of these vegetables is one cup. For spinach, one serving weighs 30g, while one cup of shredded lettuce is equal to 36g.
While both of these leafy greens are a little sparse in nutrients, spinach is denser, consisting of 91% water, while lettuce contains 95% water.
Macronutrient Comparison
Calories
Spinach and lettuce are both very low-calorie foods; however, lettuce has fewer calories.
A 100-gram serving of spinach contains 23 calories, while the same serving size of lettuce provides only 15 calories.
Protein and Fats
Spinach is richer in both protein and fats when compared to lettuce.
Both spinach and lettuce provide low levels of all essential amino acids.
As can be seen from the fat type comparison chart below, while the fat content found in leafy greens is very low, most of this fat consists of favorable polyunsaturated fatty acids, containing minimal amounts of saturated fats.
Spinach and lettuce naturally contain no cholesterol, as they are plant-based products.
Fat Type Comparison
Carbohydrates
Spinach has a higher level of carbohydrates than lettuce. Consequently, spinach contains almost two times more dietary fiber.
The small amounts of sugars found in lettuce consist of glucose and fructose. In addition to these two, spinach also contains low levels of sucrose and galactose.
Vitamins
Spinach is the winner in the vitamin category, as it contains significantly higher levels of almost all vitamins.
Although both lettuce and spinach are great sources of vitamin K and vitamin A, spinach provides around 4 times more vitamin K and slightly more vitamin A. Moreover, spinach is a great source of folate, containing around 5 times the amount in lettuce, as well as vitamin C, containing around 3 times more than in lettuce.
Some other vitamins prevalent in both at lower quantities include vitamin B6, vitamin B2, vitamin B1, and vitamin E.
Spinach and lettuce both completely lack vitamin D and vitamin B12.
Vitamin Comparison
Minerals
Spinach is significantly richer in almost all minerals compared to lettuce.
Specifically, spinach is a great source of manganese and iron, containing around 3 times the amounts found in lettuce.
Spinach also contains adequate amounts of magnesium, potassium, copper, and calcium. Compared to lettuce, spinach provides 6 times more magnesium, 4 times more copper, and 3 times more potassium and calcium.
Although both lettuce and spinach have low levels of sodium, lettuce contains fewer amounts compared to spinach.
Mineral Comparison
Glycemic Index
As lettuce and spinach both contain low levels of available carbohydrates, consuming enough of these vegetables to calculate an exact glycemic index is exceedingly difficult. For this reason, the glycemic index values for lettuce and spinach have not yet been calculated.
However, these leafy greens are considered to have low glycemic index values.
Acidity
The pH value of spinach falls in the range of 5.50 to 7.18, depending on its state and cooking method. This makes the acidity of spinach slightly acidic to neutral. Frozen spinach has a more neutral acidity, while fresh spinach is relatively more acidic (1).
Fresh lettuce is similarly slightly acidic, with pH values ranging from 5.9 to 6.2. These values can differ depending on the season the vegetable is grown in. Lettuce grown in winter is somewhat more acidic than lettuce grown in the summer (2).
The potential renal acid load, or PRAL, is an alternative way of measuring the acidity of foods. The PRAL value demonstrates how much acid or base the given food produces in ide the organism.
The PRAL value for spinach is -11.8, while this value for lettuce is -3.1. This shows us that spinach is more alkaline-forming compared to lettuce.
Weight Loss & Diets
Leafy greens are famed for their important role in weight loss diets, and spinach and lettuce are no exceptions. While both are very low in calories, lettuce contains fewer calories.
Between these two vegetables, lettuce is the better choice for low-calorie, low-fat, and low-carb diets.
Spinach is rich in compounds called thylakoids. Thylakoids in spinach have been found to reduce hunger, increase satiety and reduce cravings for palatable food in overweight women (3).
Eating low-energy-dense salad, such as lettuce, before the main course has been studied to reduce meal energy intake (4).
Lettuce and spinach contain no notable amount of starch and are low in sugars. For these reasons, both of these leafy greens can be consumed on keto and Atkins diets (5).
Naturally, these vegetables are also a great addition to paleo and Mediterranean diets.
Health Impact
Health Benefits
We all hear about how good leafy vegetables can be for our health. In this section, we will delve into some of these beneficial effects.
Cardiovascular Health
Most studies have suggested that the intake of leafy greens, spinach and lettuce, particularly, has strong cardiovascular health benefits, potentially reducing the risk of fatal and nonfatal myocardial infarction, stroke, and overall cardiovascular mortality (6).
The high content of nitrates found in spinach may also contribute to beneficial hemodynamic effects, improving vascular health by decreasing arterial blood pressure and arterial stiffness (7).
In animal studies, lettuce has been researched to improve blood serum lipid levels, decrease liver cholesterol, and depress the apparent absorption of dietary cholesterol, which may have an important role in atherosclerosis prevention (8).
In summary, both spinach and lettuce offer cardiovascular benefits as part of a healthy diet. However, spinach stands out for its higher nutrient density, particularly in potassium, antioxidants, and dietary nitrates, which contribute to its greater potential in supporting heart health and reducing the risk of CVD. Incorporating a variety of leafy greens, including spinach and lettuce, into your diet can contribute to overall cardiovascular wellness.
Diabetes
We have already stated that spinach and lettuce are low in sugars and have low glycemic index values. In addition, these leafy greens have certain properties that may contribute to the prevention of diabetes.
Nitrates found in spinach have been researched to ameliorate insulin resistance by improving nitrate status and blood lipid levels, relieving inflammation, and enhancing protective endothelial function (9).
Spinach leaves also demonstrate hypoglycemic qualities by decreasing blood glucose levels after a meal (10).
Red lettuce, high in polyphenols and antioxidants, has been researched to have anti-diabetic qualities, potentially reducing hyperglycemia and improving insulin sensitivity (11).
Cancer
There is probable evidence that foods high in dietary fiber, such as spinach, decrease the risk of breast cancer (12). Studies have also shown that raw salad vegetables may protect against breast cancer (13).
There is probable evidence that non-starchy vegetables reduce the risk of aerodigestive cancers, such as mouth, pharynx, larynx, esophageal, lung, stomach, and colorectal cancers (12).
Mental Health
Research has shown that mental well-being responds in a dose-depends fashion to increases in both the quantity and the frequency of the vegetables consumed (14).
Downsides and Risks
Leafy green vegetables have very few downsides to be aware of, especially when washed well and consumed in moderation.
Spinach and Medication
Green leafy vegetables and spinach, in particular, contain high levels of vitamin K. Several blood thinners, such as warfarin, function by inhibiting the role of vitamin K in the creation of blood clots. Due to this, some have recommended being careful when consuming high levels of spinach while on these medications.
However, available evidence does not support the advice to modify dietary habits when starting therapy with vitamin K antagonists (15).
References
- https://www.webpal.org/SAFE/aaarecovery/2_food_storage/Processing/lacf-phs.htm
- https://www.redalyc.org/pdf/3052/305249823014.pdf
- https://www.sciencedirect.com/science/article/pi /S019566631500197X
- https://www.sciencedirect.com/science/article/abs/pii/S019566631100599X
- https://www.atkins.com/how-it-works/library/articles/low-carb-keto-vegetables
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5986475/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4525132/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5579650/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5018658/
- HYPOGLYCEMIC EFFECT OF SPINACH AND FENUGREEK LEAVES IN TYPE 2 DIABETICS
- https://www.researchgate.net/publication/260875012
- https://www.aicr.org/cancer-prevention/food-facts/spinach/
- https://pubmed.ncbi.nlm.nih.gov/15066921/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6381324/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4998867/
Infographic
Carbohydrate type comparison
Comparison summary table
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| Lower in Sugar |
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| Lower in price |
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| Rich in minerals |
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| Rich in vitamins |
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| Lower in Sodium |
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| Lower in Saturated Fat |
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| Lower in Cholesterol | Equal | ||
| Lower in Glycemic Index | Equal | ||
All nutrients comparison - raw data values
| Nutrient | |
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Opinion |
| Net carbs | 1.43g | 1.57g |
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| Protein | 2.86g | 1.36g |
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| Fats | 0.39g | 0.15g |
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| Carbs | 3.63g | 2.87g |
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| Calories | 23kcal | 15kcal |
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| Fructose | 0.15g | 0.43g |
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| Sugar | 0.42g | 0.78g |
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| Fiber | 2.2g | 1.3g |
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| Calcium | 99mg | 36mg |
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| Iron | 2.71mg | 0.86mg |
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| Magnesium | 79mg | 13mg |
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| Phosphorus | 49mg | 29mg |
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| Potassium | 558mg | 194mg |
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| Sodium | 79mg | 28mg |
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| Zinc | 0.53mg | 0.18mg |
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| Copper | 0.13mg | 0.029mg |
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| Manganese | 0.897mg | 0.25mg |
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| Selenium | 1µg | 0.6µg |
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| Vitamin A | 9377IU | 7405IU |
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| Vitamin A RAE | 469µg | 370µg |
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| Vitamin E | 2.03mg | 0.22mg |
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| Vitamin C | 28.1mg | 9.2mg |
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| Vitamin B1 | 0.078mg | 0.07mg |
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| Vitamin B2 | 0.189mg | 0.08mg |
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| Vitamin B3 | 0.724mg | 0.375mg |
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| Vitamin B5 | 0.065mg | 0.134mg |
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| Vitamin B6 | 0.195mg | 0.09mg |
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| Folate | 194µg | 38µg |
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| Vitamin K | 482.9µg | 126.3µg |
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| Tryptophan | 0.039mg | 0.009mg |
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| Threonine | 0.122mg | 0.059mg |
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| Isoleucine | 0.147mg | 0.084mg |
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| Leucine | 0.223mg | 0.079mg |
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| Lysine | 0.174mg | 0.084mg |
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| Methionine | 0.053mg | 0.016mg |
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| Phenylalanine | 0.129mg | 0.055mg |
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| Valine | 0.161mg | 0.07mg |
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| Histidine | 0.064mg | 0.022mg |
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| Saturated Fat | 0.063g | 0.02g |
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| Monounsaturated Fat | 0.01g | 0.006g |
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| Polyunsaturated fat | 0.165g | 0.082g |
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Which food is preferable for your diet?
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| Low Fats diet |
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| Low Carbs diet |
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| Low Calories diet |
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| Low Glycemic Index diet | Equal | |
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.
- Spinach raw - https://fdc.nal.usda.gov/fdc-app.html#/food-details/168462/nutrients
- Lettuce - https://fdc.nal.usda.gov/fdc-app.html#/food-details/169249/nutrients
All the Daily Values are presented for males aged 31-50, for 2000-calorie diets.