Although lettuce contains a lot of fiber, water, and vitamins, there are circumstances and health conditions in which it can be problematic. Not because it is bad, but because the body reacts differently in certain cases.

Why Does Lettuce Have Such a Good Reputation?

Lettuce is low in calories, meaning it contains little energy but a lot of volume. In 100 grams, it has on average only around 15 calories, while more than 90% is water. This is one of the reasons people like to include it in diets and light meals.

It also contains fiber. These are the parts of plants that the body cannot fully digest, but they help with digestion and the feeling of fullness. Research from 2020–2024 shows that adequate fiber intake reduces the risk of constipation and regulates digestion. For the average adult, the recommended daily intake is about 25 to 30 grams of fiber, and lettuce contributes a small but regular part to this.

Where Problems Start: The Invisible Danger on The Leaves

One of the biggest problems with lettuce is that we eat it raw. This means it is not heat-treated, so any harmful microorganisms are not destroyed. Lettuce leaves grow close to the ground and are often in contact with water, soil, and fertilizers.

Over the past 20 years, according to European and American agencies, there have been several notable outbreaks of infections connected to lettuce. In 2020, there was a series of gastrointestinal infections in Europe, where the common factor was packaged salad. In 2025, similar reports again highlighted that labels such as "washed" or "ready to eat" do not guarantee complete safety. The word "contamination" refers to the pollution of food by microorganisms that can cause disease. This can happen already in the field, during harvesting, packaging, or transport.

Why This Is Especially Dangerous for Some People

A healthy person with a strong immune system often recovers from infection without major complications. It is quite different for people with a weakened immune system. The immune system is the body’s defense mechanism that protects us from infections. If it does not function optimally, the body has more trouble fighting even minor threats.

Research from 2020–2023 shows that those over 65 years, chronic patients, pregnant women, and people recovering from serious illnesses or surgeries are up to three times more at risk of complications from foodborne infections. In these people, even a mild infection can cause prolonged weakness, dehydration, or even hospitalization.

Digestion and Lettuce: Why It Causes Bloating

Many people notice that lettuce makes them gassy. Bloating means a feeling of fullness and pressure in the abdomen, often due to gas. In healthy people, this is usually just an inconvenience. For some, however, it becomes a serious problem. People with so-called irritable bowel syndrome (meaning the bowel is more sensitive and reacts more quickly with pain, cramps, or diarrhea) often tolerate raw leafy vegetables less well. Research from 2021 showed that for these people, raw lettuce is one of the more common triggers of problems.

Interestingly, even a short heat treatment, for example quick braising, can reduce these problems by up to 50%, as the fibers partially soften and become easier to digest.

Kidneys, Stones, and Lettuce

For people who have kidney problems or have had kidney stones, caution is often advised with certain vegetables. Kidney stones are hard formations that develop from minerals in urine. Some types of leafy vegetables contain substances that can contribute to stone formation in sensitive individuals. This does not mean that lettuce is forbidden, but that intake must be adjusted and individual recommendations always followed.

According to 2025 data, in Europe around 10% of people will have kidney stones at least once in their lifetime, and recurrence is very common if the diet is not adjusted.

Industrial Processing: Why Packaged Lettuce Is Not Always (the) Best

Many people think that packaged lettuce is safer because it is washed. But the truth is more complex. Industrial washing uses large quantities of water, in which microorganisms can spread from one leaf to another. If a mistake occurs in the process, the risk actually increases. In 2020, analyses showed that in some cases there were more bacteria in packaged lettuce than in fresh head lettuce washed at home.

Folk Wisdom: How Lettuce Was Once Eaten

Our grandparents did not eat lettuce every day and almost never in winter. It was a seasonal food, picked from the garden and washed just before use. They often poured a warm dressing over it or lightly blanched it, something experts now recommend again. Folk practice always emphasized freshness, moderation, and listening to one's body. If lettuce caused problems, they replaced it or prepared it differently.

How Lettuce Can Remain Part of the Diet Even for the Sensitive

If you do not want to give up lettuce completely, there are simple and inexpensive measures. Fresh head lettuce is generally safer than packaged. Washing it under running cold water just before use reduces the risk of contamination. For sensitive digestion, it's wise to eat less lettuce or give it light heat treatment. This is not a step backward, but an adjustment that makes things easier for the body.

Key Points to Remember

Lettuce is healthy, but not neutral. For most people it is an excellent choice, but for some it requires caution. The problem is not in the lettuce itself, but in who eats it, how much, and how.

When you tailor your diet to suit yourself, you don't follow trends, but listen to your own body. This is a principle that folk wisdom has emphasized for centuries and is now also confirmed by science.