Why Does Lettuce Turn Red

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By Oluwaseun Bamisile


Do you ever wonder why lettuce turns red? This article provides comprehensive explanations and insights into this fascinating phenomenon.

I shall begin this article by examining several reasons lettuce may develop reddish parts. Then, we will discuss if it is safe to consume lettuce that appears reddish.

Following that, I will provide tips to prevent this vegetable from turning red.

Finally, our FAQ section answers common questions related to this article’s topic.

Reasons Lettuce Becomes Reddish

Reasons Lettuce Becomes Reddish

Lettuce can turn red for several reasons. Moreover, this color change is typically related to the specific type of lettuce and various environmental factors.

Here’s a detailed explanation of why this vegetable may turn red.

1. Lettuce Variety

Lettuce is a diverse plant species with numerous cultivars and varieties. These varieties can differ significantly in terms of color, texture, flavor, and growth habits.

The color of lettuce leaves is often determined by the variety grown. Some lettuce varieties, such as red leaf lettuce, red romaine lettuce, and red butterhead lettuce, naturally appear red or purple.

These varieties have been selectively bred for their unique color traits. Red leaf lettuce, for example, typically has vibrant red or purple-tinted leaves with a green base, as stated by medicinenet.com.

2. Oxidation

According to culinary nutritionist Laura M. Ali, another reason lettuce becomes reddish is due to oxidation. Oxidation in lettuce typically refers to enzymatic browning.

It is a chemical reaction that occurs when enzymes in the plant tissue come into contact with oxygen from the air. Enzymatic browning is responsible for the discoloration of fruits and vegetables when cut, bruised, or exposed to air.

In lettuce, the enzyme primarily responsible for this browning reaction is polyphenol oxidase.

3. Exposure To Ethylene Gas

Lettuce can turn red when exposed to ethylene gas, as established by brightly.eco. Ethylene is often referred to as the “ripening hormone.”

Furthermore, it involves various physiological processes related to fruit ripening and plant development. Fruits such as apples, bananas, and tomatoes release ethylene gas as they ripen.

Thus, when lettuce is close to or stored alongside ethylene-producing fruits or vegetables, it may appear reddish.

4. Temperature

Temperature plays a crucial role in the coloration of lettuce leaves. Cooler temperatures, especially during the growing season, can stimulate the production of anthocyanin pigments.

This is often observed in the fall when temperatures drop, and many red lettuce varieties develop deeper red or purple colors. To give more detail, cold temperatures activate the genes responsible for anthocyanin synthesis, as stated by ncbi.nlm.nih.gov.

This results in increased pigment production, causing reddish leaves or stems. Nonetheless, anthocyanins are known for their antioxidant properties.

This can help protect plant tissues from damage caused by environmental stressors, UV radiation, and free radicals.

5. Maturity and Growth Stage

The color of lettuce leaves can change as the plant matures, as hinted by flourishingplants.com. Young leaves may have a different color than older leaves on the same plant.

This variation in coloration is often related to the distribution of anthocyanin pigments in different plant tissues. Also, it occurs because the plant generates chlorophyll and carotenoids.

Chlorophyll is responsible for green coloration. Meanwhile, carotenoids impart yellow hues, and, subsequently, pink tones.

However, with plant maturation, the production of carotenoids increases while chlorophyll production decreases.

Is Red Lettuce Safe To Eat?

Some varieties of lettuce, like red leaf lettuce, red romaine lettuce, and red butterhead lettuce, are naturally red or purple. These varieties are safe to eat, just like their green counterparts.

They are nutritious and commonly used in salads, sandwiches, and various culinary dishes. Similarly, green lettuce may develop reddish parts due to various factors.

These color changes are generally safe and do not indicate spoilage or a safety concern. However, veganfoundry.com suggests cutting off the reddish part of the lettuce as they may not taste great.

Unless your lettuce shows signs of decay, like sliminess or odors, you don’t have any problem.  

How To Prevent Lettuce From Turning Red

How To Prevent Lettuce From Turning Red

While some lettuce varieties are genetically red, there are several steps you can take to prevent green lettuce from turning red. Here are some tips and steps to do that.

1. Select Green Varieties

When aiming to prevent lettuce from becoming reddish, your first step is to choose naturally green lettuce varieties. These varieties include iceberg lettuce, romaine lettuce, green leaf lettuce, and butterhead lettuce.

Furthermore, they have been selectively bred for their green leaf coloration. When purchasing them, read the variety descriptions and labels carefully to ensure you are selecting green lettuce varieties.

2. Store In Airtight Container

Tastingtable.com suggests storing your lettuce in an airtight container to prevent it from turning red. This method is particularly effective for maintaining the freshness and appearance of lettuce.

Besides, airtight containers create a sealed environment that minimizes the exposure of lettuce to oxygen from the surrounding air. Oxygen is one of the primary factors that can lead to the oxidation of certain compounds in lettuce.

This can contribute to the red or purple coloration of the vegetable, as discussed in the previous section.

3. Keep Away From Ethylene-producing Fruits

Keeping lettuce away from ethylene-producing fruits or vegetables is an effective strategy to prevent it from becoming reddish. Ethylene is a natural plant hormone that plays a significant role in the ripening and maturation of certain fruits and vegetables.

These include tomatoes, apples, melons, pears, avocados, and bananas. When lettuce is exposed to ethylene gas produced by these items, it can undergo physiological changes, including color alterations.

While lettuce is not a fruit, it is sensitive to ethylene gas.

4. Pest and Disease Management

Regularly inspect your lettuce plants for signs of pest infestations and diseases. Common pests for lettuce include aphids and snails, while diseases like downy mildew and powdery mildew can affect lettuce leaves.

Promptly address any issues to prevent stress-related color changes.

5. Reduced Temperature

Ncbi.nlm.nih.gov says lower temperatures slow down enzymatic browning reactions in vegetables, including lettuce. Enzymatic browning is a natural process that occurs when enzymes in the lettuce tissue come into contact with oxygen from the air.

This process can cause the breakdown of certain compounds in the lettuce, resulting in color changes. By reducing the temperature, you slow down the enzymatic reactions responsible for color alteration.

Savorysuitcase.com recommends a temperature between 32°F (0°C) and 40°F (4°C). This temperature range helps maintain the freshness of your lettuce, preventing texture damage.

Frequently Asked Questions

1. Is Lettuce Safe To Eat When It Turns Pink?

It is generally safe to eat lettuce when it appears reddish or pink. Unless your lettuce shows signs of decay, like sliminess or odors, it is edible.  

2. Does All Lettuce Turn Red?

No, not all lettuce exhibits reddish parts. Red lettuce varieties, such as red leaf lettuce and red romaine lettuce, have naturally red or purple leaves.

However, green lettuce varieties can also turn red under specific conditions, but it’s not a universal occurrence.

3. Can You Eat Lettuce Raw

Yes, you can eat lettuce raw. Furthermore, it is commonly consumed in its raw form in various dishes.

Lettuce is a leafy green vegetable that is often used as a base for salads and as a crisp, refreshing addition to sandwiches, wraps, and burgers. Eating lettuce raw is not only safe but also a nutritious way to enjoy this vegetable.

4. Does Red Lettuce Taste Different From Green Lettuce?

The taste of reddish lettuce can vary depending on the variety. According to thrivecuisine.com, green lettuce is milder in taste compared to its red counterpart.

However, taste preferences are subjective

5. Is Red Lettuce As Nutritious As Green Lettuce?

Red lettuce is nutritionally similar to green lettuce. It contains essential vitamins, minerals, and antioxidants.


Lettuce becomes reddish due to a mix of various factors. Some types of lettuce are naturally red due to their genes.

However, the transformation of green lettuce into shades of red or purple is primarily influenced by external conditions. Factors such as ethylene gas exposure and temperature variations can trigger this color change.

Understanding why lettuce may become reddish helps us maintain and store them better.

So, whether it’s naturally red or turns red due to environmental influence, this vegetable teaches us the dynamics of plants and adds variety to our meals.

I hope this article has provided you with valuable information. If you found it helpful, please consider sharing it with your friends and family on social media.

Additionally, you can explore our Food page for more articles on similar topics.

References And Further Reading

  1. brightly.eco – Is Red Lettuce Safe to Eat? A Registered Dietitian’s Answer Might Surprise You
  2. veganfoundry.com – My Lettuce Is Red: Is It Safe To Eat?
  3. tastingtable.com – Here’s Why Your Lettuce Is Turning Red
  4. garden.eco – Why Does Lettuce Turn Red?
  5. flourishingplants.com – Lettuce Turning Red or Pink: We Explain Why & Are They Bad
  6. eatingwell.com – Why Does Lettuce Turn Pink?
  7. gfloutdoors.com – Lettuce Turning Red: 3 Common Reasons
  8. quora.com – Why does lettuce get “rusty red”? Is it okay to eat it?

About the Author

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Oluwaseun Bamisile

Oluwaseun is the Lead Content Editor at Ilifeguides.com. He holds a National Diploma in Computer Science (currently studying part-time for his Higher National Diploma). An internet geek with a love for automobiles, he writes relationship articles, travel guides, and general life hacks on the site.

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