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Spinach vs Lettuce - Health impact and Nutrition Comparison

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Spinach
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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 flavour, 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

Different varieties of the same vegetable can alter in texture, taste and nutrition.

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, which make 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 of the 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

Cooking methods can alter the nutritional composition of foods. The nutritional values below are presented for raw spinach and raw lettuce.

Macronutrients and Calories

While both of these leafy greens are a little sparse in nutrients, spinach is more dense, 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 that 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 favourable polyunsaturated fatty acids, containing very small amounts of saturated fats.

Being plant-based products, spinach and lettuce naturally contain no cholesterol.

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.

Minerals

Spinach is also significantly richer in almost all minerals compared to lettuce. Based on the needed daily values of minerals, spinach provides 5 times more magnesium, 4 times more copper and 3 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.

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 calories, low fats and low carbs 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 the intake of leafy greens, spinach and lettuce, in particular, to have 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, have 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 raw salad vegetables may protect against breast cancer (13).

There is also probable evidence that non-starchy vegetables reduce the risk of aerodigestive cancers, such as mouth, pharynx and larynx, oesophagal, lung, stomach and colorectal cancers (12).

Mental Health

Research has shown that mental well-being 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 ability of vitamin K to create 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).

Summary

In conclusion, 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.

Sources.

  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. https://www.researchgate.net/profile/Arvind_Singh56/post/What_is_the_pharmacological_effects_of_spinach_on_diabetes/attachment/5b9c98f7cfe4a76455f35cd7/AS%3A670996461780992%401536989431109/download/full-text-14.pdf
  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/
Article author photo Victoria Mazmanyan
Profession: Yerevan State Medical University
Last updated: May 26, 2021

Infographic

Spinach vs Lettuce infographic
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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
:
Contains more Iron +215.1%
Contains more Calcium +175%
Contains more Potassium +187.6%
Contains more Magnesium +507.7%
Contains more Copper +348.3%
Contains more Zinc +194.4%
Contains more Phosphorus +69%
Contains less Sodium -64.6%
Iron Calcium Potassium Magnesium Copper Zinc Phosphorus Sodium 102% 30% 50% 57% 44% 15% 22% 11%
Iron Calcium Potassium Magnesium Copper Zinc Phosphorus Sodium 33% 11% 18% 10% 10% 5% 13% 4%
Contains more Iron +215.1%
Contains more Calcium +175%
Contains more Potassium +187.6%
Contains more Magnesium +507.7%
Contains more Copper +348.3%
Contains more Zinc +194.4%
Contains more Phosphorus +69%
Contains less Sodium -64.6%

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
:
Contains more Vitamin C +205.4%
Contains more Vitamin A +26.6%
Contains more Vitamin E +822.7%
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 Vitamin K +282.3%
Contains more Folate +410.5%
Contains more Vitamin B5 +106.2%
Vitamin C Vitamin A Vitamin E Vitamin D Vitamin B1 Vitamin B2 Vitamin B3 Vitamin B5 Vitamin B6 Vitamin B12 Vitamin K Folate 94% 563% 41% 0% 20% 44% 14% 4% 45% 0% 1208% 146%
Vitamin C Vitamin A Vitamin E Vitamin D Vitamin B1 Vitamin B2 Vitamin B3 Vitamin B5 Vitamin B6 Vitamin B12 Vitamin K Folate 31% 445% 5% 0% 18% 19% 8% 9% 21% 0% 316% 29%
Contains more Vitamin C +205.4%
Contains more Vitamin A +26.6%
Contains more Vitamin E +822.7%
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 Vitamin K +282.3%
Contains more Folate +410.5%
Contains more Vitamin B5 +106.2%

Vitamin and Mineral Summary Scores

The summary score is calculated by summing up the daily values contained in 300 grams of the product. Obviously the more the food fulfills human daily needs, the more the summary score is.
Vitamin Summary Score
181
Spinach
75
Lettuce
Mineral Summary Score
41
Spinach
13
Lettuce

Macronutrients Comparison

Macronutrient comparison charts compare the amount of protein, total fats, and total carbohydrates in 300 grams of the food. The displayed values show how much of the daily needs can be covered by 300 grams of food.
Protein
17%
Spinach
8%
Lettuce
Carbohydrates
4%
Spinach
3%
Lettuce
Fats
2%
Spinach
1%
Lettuce

Comparison summary table

Pay attention to the most right column. It shows the amounts side by side, making it easier to realize the amount of difference.
Spinach Lettuce
Lower in Sugar ok
Lower in price ok
Rich in minerals ok
Rich in vitamins ok
Lower in Sodium ok
Lower in Saturated Fat ok
Lower in Cholesterol Equal
Lower in glycemic index Equal

Which food is preferable for your diet?

ok
ok
is better in case of low diet
Spinach Lettuce
Low Calories diet ok
Low Fats diet ok
Low Carbs diet ok
Low glycemic index diet Equal

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Comparison summary

Which food is lower in Sugar?
Spinach
Spinach is lower in Sugar (difference - 0.36g)
Which food is cheaper?
Spinach
Spinach is cheaper (difference - $0.3)
Which food is richer in minerals?
Spinach
Spinach is relatively richer in minerals
Which food is richer in vitamins?
Spinach
Spinach is relatively richer in vitamins
Which food contains less Sodium?
Lettuce
Lettuce contains less Sodium (difference - 51mg)
Which food is lower in Saturated Fat?
Lettuce
Lettuce is lower in Saturated Fat (difference - 0.043g)
Which food contains less Cholesterol?
?
The foods are relatively equal in Cholesterol (0 mg)
Which food is lower in glycemic index?
?
The foods have equal glycemic indexes (32)

All nutrients comparison - raw data values

Nutrient Spinach Lettuce Opinion
Calories 23 15 Spinach
Protein 2.86 1.36 Spinach
Fats 0.39 0.15 Spinach
Vitamin C 28.1 9.2 Spinach
Carbs 3.63 2.87 Spinach
Cholesterol 0 0
Vitamin D 0 0
Iron 2.71 0.86 Spinach
Calcium 99 36 Spinach
Potassium 558 194 Spinach
Magnesium 79 13 Spinach
Sugar 0.42 0.78 Spinach
Fiber 2.2 1.3 Spinach
Copper 0.13 0.029 Spinach
Zinc 0.53 0.18 Spinach
Starch 0 Lettuce
Phosphorus 49 29 Spinach
Sodium 79 28 Lettuce
Vitamin A 9377 7405 Spinach
Vitamin E 2.03 0.22 Spinach
Vitamin D 0 0
Vitamin B1 0.078 0.07 Spinach
Vitamin B2 0.189 0.08 Spinach
Vitamin B3 0.724 0.375 Spinach
Vitamin B5 0.065 0.134 Lettuce
Vitamin B6 0.195 0.09 Spinach
Vitamin B12 0 0
Vitamin K 482.9 126.3 Spinach
Folate 194 38 Spinach
Trans Fat 0 0
Saturated Fat 0.063 0.02 Lettuce
Monounsaturated Fat 0.01 0.006 Spinach
Polyunsaturated fat 0.165 0.082 Spinach
Tryptophan 0.039 0.009 Spinach
Threonine 0.122 0.059 Spinach
Isoleucine 0.147 0.084 Spinach
Leucine 0.223 0.079 Spinach
Lysine 0.174 0.084 Spinach
Methionine 0.053 0.016 Spinach
Phenylalanine 0.129 0.055 Spinach
Valine 0.161 0.07 Spinach
Histidine 0.064 0.022 Spinach
Fructose 0.15 0.43 Lettuce

References

The source of all the nutrient values on the page (excluding the main article the sources for which are presented separately if present) is the USDA's FoodCentral. The exact links to the foods presented on this page can be found below.

  1. Spinach - https://fdc.nal.usda.gov/fdc-app.html#/food-details/168462/nutrients
  2. 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.

Data provided by FoodStruct.com should be considered and used as information only. Please consult your physician before beginning any diet.