Kohlrabi (called su hào in Vietnamese) is a nutritious cruciferous vegetable rich in fiber, vitamins, and minerals. For most people, it’s a healthy addition to meals. However, there are specific situations where eating it — especially in large amounts or raw — may be best avoided or limited. Cleveland Clinic

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🛑 1. People with Sensitive Digestion or Stomach Issues

Kohlrabi is high in fiber and complex carbohydrates. While this supports digestion for many, it can cause gas, bloating, abdominal discomfort, or diarrhea in people with sensitive guts — especially if eaten raw or in large quantities. Cleveland Clinic+1

• Individuals with chronic stomach issues (e.g., gastritis, functional dyspepsia) may experience irritation from raw kohlrabi.

• Children and some older adults can have difficulty digesting raw, fibrous vegetables.
  Tip: Cooking kohlrabi can make it easier to digest. TUOI TRE ONLINE

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🧠 2. People with Thyroid Conditions

Kohlrabi belongs to the cruciferous vegetable family, which contains compounds called goitrogens. These substances can interfere with thyroid hormone production by affecting how the body uses iodine, an essential element for thyroid function. Lao Động

• Those with hypothyroidism or other thyroid disorders may need to limit raw kohlrabi intake.

• Cooking kohlrabi reduces the goitrogenic compounds and may make it safer for people with thyroid issues. Lao Động

Important: Most healthy people with normal thyroid function don’t need to avoid cruciferous vegetables entirely; moderation is key. Báo điện tử Dân Trí

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🤢 3. People Who Experience Digestive Discomfort with Raw Vegetables

Even without a diagnosed condition, some individuals simply find raw kohlrabi — or other cruciferous vegetables — harder to tolerate. Common symptoms include:

• Bloating

• Gas

• Mild abdominal pain

This is due to the high fiber and complex sugar content that ferments in the gut. Cleveland Clinic

Tip: Try lightly cooking or steaming su hào to reduce these effects. Cleveland Clinic

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⚠️ 4. Rare Allergies or Sensitivities

Although uncommon, some people may have an allergy or intolerance to kohlrabi or other Brassica (cruciferous) vegetables. Possible reactions include:

• Itching

• Swelling

• Breathing discomfort
  (rare, but possible) fitelo.co

If allergic symptoms occur after eating su hào, avoid it and consult a healthcare provider.

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When Kohlrabi Is Still Safe to Eat

✔ Most people with normal digestion and thyroid health can enjoy kohlrabi as part of a balanced diet.
✔ Cooking reduces potential digestion issues and the goitrogen effect for those worried about thyroid health.
✔ Kohlrabi provides fiber, vitamin C, potassium, and other beneficial nutrients. Cleveland Clinic

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Quick Practical Tips Before Eating Kohlrabi

🍽 Cook it (steamed, boiled, stir-fried) if you have a sensitive stomach or thyroid condition. Lao Động
🥗 Introduce gradually if you’re not used to high-fiber foods. Cleveland Clinic
📆 Moderation works better than large amounts eaten raw every day. Báo điện tử Dân Trí

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Summary — Who Should Avoid Kohlrabi

➡️ People with sensitive digestion or gastrointestinal disorders
➡️ Individuals with thyroid dysfunction or hypothyroidism
➡️ Young children or those with weak digestive systems
➡️ Anyone who experiences discomfort after eating raw cruciferous vegetables Cleveland Clinic+1

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