Radishes: Nutrients, What Research Shows and Safety

Radishes (Raphanus sativus) are root vegetables in the cabbage family (Brassicaceae, the "cruciferous" vegetables). The crisp, peppery root is eaten raw or cooked, and the leaves are sometimes eaten too. People eat radishes for crunch, flavor and a little vitamin C. This page keeps the food apart from extracts and hype, and says what the research does and does not show. The long white daikon has its own page: daikon radish.

Read this first

• Radishes are an everyday food. As with any food, an allergic reaction is possible. For trouble breathing or swelling of the face or throat, call 911. See food allergy basics and emergency signs.
• Radishes contain glucosinolates, plant compounds that give the peppery bite. A 2024 systematic review of 123 studies found most results cast doubt on the idea that cruciferous vegetables harm the thyroid in people, particularly when iodine intake is adequate. [10]
• Old folk uses for digestion and the gallbladder are traditions. We did not find human trials that test the radish root for these uses. [8]
• No vegetable here is a treatment. The honest summary: radishes are a low-calorie food with some vitamin C, and the health claims are mostly lab or observational findings.

What is in it (USDA values)

Source: USDA FoodData Central, raw radishes, SR Legacy item 169276 [1]. The per-cup figures are the per-100 g values scaled to the USDA household portion of 116 g. % Daily Value uses the FDA 2016 Daily Values; values vary with variety, ripeness and storage.

The main plant compounds are glucosinolates, sulfur-containing compounds found in radishes and other Brassica vegetables. [5] When the root is cut or chewed, they break down into isothiocyanates, which are linked to the sharp taste. One study of small Korean radishes found that glucoraphasatin (which breaks down to raphasatin) relates to pungency, but it did not fully explain why spring-grown radishes were hotter than autumn ones; the balance with sugars also seemed to matter. [6] The research on these compounds is mostly from the lab and animals; the human evidence is observational (see below). [5][7]

What research says

Eaten as food vs taken as a supplement or extract. Almost all the "benefit" findings above come from extracts, powders, cells or animals, not from people eating a few radishes. A result for a concentrated extract or powder does not transfer to the food, and a result for the food does not prove a medicine-like effect. Observational studies can show a pattern but cannot prove cause. [7]

How much is a normal serving

The USDA household portion is 1 cup of slices (116 g); a medium radish is about 4.5 g and a large one 9 g. [1] The WHO advises at least 400 g of fruits and vegetables a day for people older than 10, and the UK NHS counts 80 g of fresh, canned or frozen vegetables as one portion. [2][3] This is information, not a prescription. Cooking: glucosinolate breakdown products are affected by cooking, but we did not find a source giving radish-specific figures. [7] See fresh, frozen and canned produce.

Safety, allergy and medicines

• Allergy: the sources we read do not describe radish allergy in detail. Any food can cause an allergic reaction; for trouble breathing or swelling of the face or throat call 911. See food allergy basics and emergency signs.
• Thyroid and goitrogens: raw cruciferous vegetables contain compounds called goitrogens that, in lab studies, can affect how the thyroid takes up iodine. A 2024 systematic review found most evidence does not support harm to thyroid function in people, especially with adequate iodine. [10] One case-control study in New Caledonia found high cruciferous intake linked to thyroid cancer only among women with low iodine intake (odds ratio 1.86); it is observational and about the whole group of vegetables. [11] People with a thyroid condition or on thyroid medicine can ask their clinician. See thyroid conditions and iodine.
• Medicines: USDA lists only 1.3 µg of vitamin K per 100 g of raw radish, a small amount (1% of the Daily Value). [1] We did not find a source describing a radish-specific medicine interaction, so we make no claim either way. A pharmacist can check; see foods and medicine interactions.
• Kidney disease and potassium: USDA lists 233 mg of potassium per 100 g, about 270 mg per cup. [1] People on potassium-restricted diets can see kidney disease, potassium and oxalates; we found no source ranking radish as high or low in potassium beyond the USDA number.
• Pregnancy: Proper evidence not found in the sources we read for radish specifically. See foods in pregnancy: what official bodies advise.
• Supplements and extracts: radish seed and black radish extracts are different from the food and are not covered by safety information here. Trials of extract or powder do not tell you about the food. [8][12]

Choosing, storing and food safety

• Pick roots that are not bruised or damaged. [14]
• Rinse produce under running water, even if you will peel it; do not use soap or produce wash. Washing lowers bacteria but does not remove them all. [14]
• Refrigerate cut or perishable produce at 40°F (4°C) or below. [14]
• Trim damaged areas and discard produce that looks rotten. [14]

Related pages

• Daikon radish
• Cruciferous vegetables
• Sulforaphane and glucosinolates in cruciferous vegetables
• Thyroid conditions and iodine
• Fresh, frozen and canned produce
• Pickles and fermented vegetables vs vinegar pickles