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.

At the same time, lettuce is lower in sodium and richer in vitamin B5.

Both spinach and lettuce can have various beneficial effects on cardiovascular health, diabetes, and mental health.

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

While both of these leafy greens are a little sparse in nutrients, spinach is denser, consisting of 91% water. At the same time, lettuce contains 95% water.

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.

Calories

Spinach and lettuce are both very low-calorie foods; however, lettuce has fewer calories. A hundred 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.

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.

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 wins in this category, being richer in all vitamins except one. Spinach provides over three times more of the daily values needed for vitamin E, vitamin C, and folate compared to lettuce.

The one vitamin lettuce contains more of is vitamin B5.

Spinach and lettuce both completely lack vitamin D and vitamin B12.

Vitamin Comparison

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

Spinach

9

:

1

Lettuce

Contains more Vitamin A +26.6%

Contains more Vitamin E +822.7%

Contains more Vitamin C +205.4%

Contains more Vitamin B1 +11.4%

Contains more Vitamin B2 +136.3%

Contains more Vitamin B3 +93.1%

Contains more Vitamin B6 +116.7%

Contains more Folate +410.5%

Contains more Vitamin K +282.3%

Contains more Vitamin B5 +106.2%

Spinach

Lettuce

Contains more Vitamin A +26.6%

Contains more Vitamin E +822.7%

Contains more Vitamin C +205.4%

Contains more Vitamin B1 +11.4%

Contains more Vitamin B2 +136.3%

Contains more Vitamin B3 +93.1%

Contains more Vitamin B6 +116.7%

Contains more Folate +410.5%

Contains more Vitamin K +282.3%

Contains more Vitamin B5 +106.2%

Minerals

Spinach is also significantly richer in almost all minerals compared to lettuce. Based on the needed daily values of minerals, spinach provides five times more magnesium, four times more copper, and three times more iron.

Other minerals that spinach contains more of are calcium, potassium, zinc, phosphorus, selenium, and manganese. Spinach is also richer in choline.

On the other hand, lettuce contains less sodium.

Mineral Comparison

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

Spinach

7

:

1

Lettuce

Contains more Calcium +175%

Contains more Iron +215.1%

Contains more Magnesium +507.7%

Contains more Phosphorus +69%

Contains more Potassium +187.6%

Contains more Zinc +194.4%

Contains more Copper +348.3%

Contains less Sodium -64.6%

Spinach

Lettuce

Contains more Calcium +175%

Contains more Iron +215.1%

Contains more Magnesium +507.7%

Contains more Phosphorus +69%

Contains more Potassium +187.6%

Contains more Zinc +194.4%

Contains more Copper +348.3%

Contains less Sodium -64.6%

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 the 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 inside 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 central blood pressure and arterial stiffness (7).

In animal studies, lettuce has been researched to improve blood serum lipid levels, decrease liver cholesterol, and depress apparent absorption of dietary cholesterol (8).

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 and 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

1. https://www.webpal.org/SAFE/aaarecovery/2_food_storage/Processing/lacf-phs.htm
2. https://www.redalyc.org/pdf/3052/305249823014.pdf
3. https://www.sciencedirect.com/science/article/pii/S019566631500197X
4. https://www.sciencedirect.com/science/article/abs/pii/S019566631100599X
5. https://www.atkins.com/how-it-works/library/articles/low-carb-keto-vegetables
6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5986475/
7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4525132/
8. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5579650/
9. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5018658/
10. HYPOGLYCEMIC EFFECT OF SPINACH AND FENUGREEK LEAVES IN TYPE 2 DIABETICS
11. https://www.researchgate.net/publication/260875012
12. https://www.aicr.org/cancer-prevention/food-facts/spinach/
13. https://pubmed.ncbi.nlm.nih.gov/15066921/
14. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6381324/
15. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4998867/