Romaine lettuce offers a nutritional advantage over other types of green lettuce.

Image Credit: Monkey Business Images/Monkey Business/Getty Images Green lettuce is a staple among salad eaters and contains relatively high quantities of essential vitamins. Unlike some foods, green lettuce is considerably low in calories – averaging only 7 per cup – making it a boon for individuals looking to shed weight. While all four types of green lettuce are considered a healthy addition to your diet, romaine lettuce is considered the most nutritious.

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 Types

There are four primary types of lettuce: butterhead, crisphead, looseleaf and romaine. Iceberg lettuce, the least nutritious of salad greens, comes from the crisphead family and is generally recognizable by its pale green, cabbage-like appearance. Butterhead lettuce includes the Boston and bibb variants, and is generally known for its grassy green leaves and mild flavor. Looseleaf lettuce does not grow in heads. Instead, it features dark green leaves that are joined at the stem, similar in appearance to kale. Romaine lettuce, also referred to as cos, has a strong taste and crispy texture, and is commonly used in Caesar salads.

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  Vitamin A
 
Butterhead lettuce growing in soil

Image Credit: Bernhard Richter/iStock/Getty Images According to the the USDA National Nutrient Database, a leaf of romaine lettuce contains 871 International Units of Vitamin A, roughly 17 percent of the recommended daily value. By comparison, leaves of looseleaf and butterhead lettuce contained 741 and 248 IUs, respectively. Vitamin A is an essential vitamin used to promote vision health, bone growth, reproduction, cell division and a variety of respiratory, urinary and intestinal functions. Iceberg lettuce from the crisphead family contains the least vitamin A of the green lettuce types, coming in at 40 IUs per leaf.

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 Antioxidants and Other Nutrients
 
Romaine lettuce on cutting board with knife

Image Credit: Yulia Krushelnitskaya/iStock/Getty Images All four types of green lettuce contain phytonutrients, antioxidants that have been linked to preventing chronic diseases, such as heart disease and cancer. According to Colorado State University, romaine lettuce and green leaf lettuce from the looseleaf family ranked the highest in antioxidants as well as vital nutrients. According to the study, romaine lettuce contained the highest quantities of vitamin C, potassium, folic acid and lutein, while green leaf ranked the highest in vitamin K, niacin and riboflavin. Both lettuces contained more than 3,000 micrograms of beta carotene per 100 grams serving.

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 Other Factors
 
Organically grown lettuce

Image Credit: Ingram Publishing/Ingram Publishing/Getty Images While nutritional value plays an important role in helping you decide on which type of lettuce to eat, additional factors may also play a role. Buying organic offers the benefit of reducing your exposure to toxic pesticides and fertilizers that may impact the health value of your product. If possible, contact local farmers in your area and express your desire for healthy, nutritious organic lettuce.

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  references
  
      Office of Dietary Supplements: Vitamin A and Carotenoids
    
      Colorado State University: Health Benefits and Safe Handling of Salad Greens
       




  references
  
      Office of Dietary Supplements: Vitamin A and Carotenoids
    
      Colorado State University: Health Benefits and Safe Handling of Salad Greens
    




Romaine lettuce offers a nutritional advantage over other types of green lettuce.

Image Credit: Monkey Business Images/Monkey Business/Getty Images

Image Credit: Monkey Business Images/Monkey Business/Getty Images

Butterhead lettuce growing in soil

Image Credit: Bernhard Richter/iStock/Getty Images

Image Credit: Bernhard Richter/iStock/Getty Images

Romaine lettuce on cutting board with knife

Image Credit: Yulia Krushelnitskaya/iStock/Getty Images

Image Credit: Yulia Krushelnitskaya/iStock/Getty Images

Organically grown lettuce

Image Credit: Ingram Publishing/Ingram Publishing/Getty Images

Image Credit: Ingram Publishing/Ingram Publishing/Getty Images

      Office of Dietary Supplements: Vitamin A and Carotenoids
    
      Colorado State University: Health Benefits and Safe Handling of Salad Greens