A radish can go from seed to plate in about a month. Under average conditions the crop matures in 3 to 4 weeks, and in cooler weather in 6 to 7 weeks. The whole plant is edible, tops included, and the root is about 95% water with 16 calories per 100 g.
The peppery bite does not exist in an uncut radish. Like other mustard-family vegetables, it holds glucosinolates, and chewing lets the enzyme myrosinase turn them into pungent isothiocyanates. In a study of eight daikon strains the main one was 4-(methylthio)-3-butenyl isothiocyanate, and allyl isothiocyanate, the compound of mustard and wasabi, was not detectable. Grated daikon held 7 times more total isothiocyanate than cut daikon.
The red skin comes from anthocyanins, and a 2023 analysis identified 46 of them in red radish. Our data lists 63 mg of anthocyanins per 100 g, all of it pelargonidin. Radishes have even been grown on the International Space Station, in two 27-day grow-outs.
Health benefits of radishes
The top findings from 18 studies, strongest evidence first
What the stars mean
- Strong. Several randomized trials, pooled in a meta-analysis, point the same way, or regulators (FDA or EFSA) have approved the claim.
- Moderate. Good randomized trials support it, but there are fewer of them, or their results vary.
- Limited. Small, short or single trials, or mixed results. Promising, but it needs confirmation.
Population and lab studies get no stars: they show a link or a mechanism, not proof.
How we rate evidence →- ★Mixed results on arteries and blood pressureSakurajima daikon, 170 g a day for 10 days, improved how well arteries widen. In 21 people with metabolic syndrome, daikon powder did not, and the top number was 9.67 mm Hg higher.
- ★More kidney stone-type crystals in urineIn 36 people, adding radish to the diet for a week raised calcium oxalate crystals in urine, with or without kidney stones. The study counted crystals, not stones.
- ★No lower oxygen use during hard exerciseIn a small study of 36 people, 100 g a day of red radish for 7 days did not lower oxygen use during exhaustive exercise.
- Population studyLinked to a lower risk of gallbladder cancerIn India, people who ate radish had 60% lower odds of gallbladder cancer than people with gallstones. Diet was recalled on a questionnaire.
- Population studyLinked to more stomach cancer with salted kimchiIn a Korean study of 136 patients and 136 controls, two kinds of salted radish kimchi went with a higher risk of stomach cancer. The authors do not blame radish alone.
All 18 studies, strongest evidence first
100 g a day of red radish for 7 days did not lower oxygen use during exhaustive exercise
Small study of 36 people. Eleven ate red radish (173 mg of nitrate a day), 11 ate watercress and 14 were a comparison group told to avoid high-nitrate foods. The radish group made more carbon dioxide at the same workload, which the authors say might hurt performance. The abstract does not say people were randomized.
A week of radish added to the diet increased calcium oxalate crystals in urine in people with and without kidney stones
Study of 36 people, 21 with kidney stones and 15 without, who ate their usual diet for a week and then added radish for a week. Crystal counts were significantly higher in both men and women. It was small and short, and it counted crystals, not stones.
Sakurajima daikon powder for 14 days did not improve artery function and raised systolic blood pressure by about 10 mm Hg in people with metabolic syndrome
Open-label randomized crossover trial in 21 patients with metabolic syndrome, who took Sakurajima daikon powder, Aokubi daikon powder and their usual diet for 14 days each. Flow-mediated dilation, a measure of how well arteries widen, did not change. Systolic pressure was 9.67 mm Hg higher than on the usual diet and a marker of oxidative stress rose. The authors say a carryover effect may have masked results.
Eating 170 g a day of Sakurajima daikon for 10 days improved a measure of artery function
First-in-human trial of Sakurajima daikon, a Japanese variety that holds about 60 times more trigonelline than other radishes and squashes, say the authors. Blood trigonelline rose and flow-mediated dilation, a measure of how well arteries widen, improved. The abstract gives no group size, and the later trial above, in people with metabolic syndrome, did not repeat the gain.
A Spanish black radish supplement for 4 weeks lowered blood levels of a test dose of acetaminophen by 40% in healthy men, which the authors read as faster liver processing
Open-label pilot study in healthy men with no comparison group; results were compared with the start of the study. Acetaminophen metabolites in urine rose 11 to 37%, blood estradiol fell 10% and the liver enzyme GGT fell. It tested a black radish supplement, not red radishes, and Standard Process Inc. sponsored it.
People who ate radish had 60% lower odds of gallbladder cancer than people with gallstones
Case-control study in India with 64 people with gallbladder cancer and 101 with gallstones (odds ratio 0.4, range 0.17 to 0.94). Diet was recalled on a questionnaire. Green chili, sweet potato and several fruits showed similar links, while cruciferous vegetables as a group did not reach significance.
Shanghai adults who ate more fruit and vegetables, including Chinese white radish, had a lower risk of mouth and throat cancer
Case-control study with 204 cases and 414 controls. After adjusting for smoking, alcohol and other factors, men in the top third of intake of these fruits and vegetables had about 30 to 50% of the risk of those in the bottom third, with a weaker link in women. Radish is not analyzed on its own, and diet was recalled from the past 10 years.
In a county with heavy coal-smoke pollution, eating radishes was linked to a lower risk of lung cancer
Case-control study in Xuanwei, China, with 498 lung cancer patients and 498 controls. Corn, buckwheat, peppers, melons and pickled vegetables also went with lower risk, while green vegetables went with higher risk (odds ratio 2.39). The authors suspect coal smoke contaminates some foods more than others, so this does not show that radish itself protects.
Two kinds of salted radish kimchi were linked to a higher risk of stomach cancer in Korea
Case-control study of 136 patients and 136 matched controls. The two kimchis were kkakduki (salted radish with red pepper) and dongchimi (radish in salty water). Total fresh vegetables went with lower risk, and the authors tie higher risk to foods rich in nitrate and in compounds formed by cooking, not to radish alone.
Wild daikon strains held about 5 times more of the compound that gives daikon its bite than the common Japanese strain
Lab study in bacteria and chemistry, not people. The compound, 4-(methylthio)-3-butenyl isothiocyanate, blocked mutations in E. coli. The common strain Aokubi held 71.0 µmol per 100 g and the wild strain Karami 363.5 µmol. Allyl isothiocyanate, the mustard and wasabi compound, was not detectable, and grated daikon held 7 times more total isothiocyanate than cut daikon.
Radish root juice lowered blood sugar by up to 33% in rats
Study in rats, not people. At 300 mg per kg of body weight, the juice cut fasting blood glucose 33.4% after 6 hours in normal rats. In a glucose tolerance test it lowered blood glucose by 15.9% in normal rats and by 23.8% and 28.3% in sub-diabetic and mildly diabetic rats.
A review of lab and animal studies found antidiabetic effects for radish, but clinical trials are missing
Review of studies from 1987 to 2017, not new data. The author suggests the effects may come from antioxidant defense, glucose uptake and less glucose absorption in the gut, and says the summary needs confirmation in clinical trials.
Rats fed Japanese radish sprouts for 21 days had lower blood glucose and insulin
Study in normal and diabetic rats fed 2.5% or 5% sprouts (kaiware daikon). In healthy rats total cholesterol and triglycerides fell but LDL cholesterol rose, and diabetic rats showed no lipid changes. These were sprouts, not roots.
Black radish juice for 6 days significantly cleared cholesterol gallstones in mice fed a gallstone-forming diet
Study in mice, not people, using juice from black radish root (Raphanus sativus var. niger), a traditional gallstone remedy in Mexico. Cholesterol and triglycerides fell and HDL rose, but gallbladder tissue still showed inflammation and liver tissue showed damage.
A fat-soluble extract of radish root stopped human cancer cells from growing and triggered cell death in lab dishes
Cell study, not people. Extracts of root, stem and leaves were compared and the root extract worked best; it contained isothiocyanates such as MTBITC, erucin and sulforaphene. The doses cannot be compared with eating radishes.
An isothiocyanate-rich radish extract reduced the metabolic activity of human colon cancer cells
Cell study with two colon cancer cell lines and non-cancer colon cells as a control. The radish extract was richest in benzyl isothiocyanate (15.35 µg/g). A cauliflower extract worked better on one of the two lines, and the authors say more experiments are needed.
Rats fed fresh or cooked radish for a long time showed signs of an underactive thyroid even with enough iodine
Study in rats, not people. Thyroid weight and thyrotropin rose while thyroid peroxidase activity and thyroid hormones fell. Radish is one of several mustard-family vegetables with this concern, and the abstract does not compare the dose with human intake.
Red radish coral sprout extract cut weight gain by 60% in mice on a high-fat diet
Mouse study plus a yeast test. Mice received 0.1% extract for 8 weeks, and their body fat was 38.3% lower than with the high-fat diet alone. It used an extract of sprouts, not the root people eat.
Who should be careful with radishes
Most people can eat radishes freely. Take a little care if one of these applies:
- Thyroid disease. Radishes hold glucosinolates, which can release thiocyanate, a compound that competes with iodine. In rats, long-term radish feeding lowered thyroid hormones even with enough iodine, but a Korean estimate put average thiocyanate intake from mustard-family vegetables below the doses that harmed animals. Ordinary servings are probably fine; mention large amounts to your doctor.
- Kidney stones. One small study of 36 people found more calcium oxalate crystals in urine during a week of added radish. It is thin evidence, but if you form stones, ask your clinician.
- Radish sprouts. The CDC advises children, older adults, pregnant women and people with weakened immune systems to avoid raw or lightly cooked sprouts of any kind, radish sprouts included. Cook them thoroughly.
How to choose, store and eat radishes
- Raw: sliced or whole, a cup (116 g) has 19 calories, 1.9 g of fiber and 17 mg of vitamin C, about 19% of the daily value. Monash University rates radish low in FODMAPs at a 75 g serving.
- Grated or cooked: grated daikon held 7 times more isothiocyanate than cut daikon in a lab test. Purdue Extension lists roasting, sautéing, steaming and braising, and no study here compares cooked and raw radish in people.
- Pickled or kimchi: in a Korean study of 136 stomach cancer patients and 136 controls, two salted radish kimchis went with higher risk. That is a link, not proof, so keep salty pickles occasional.
Choose firm, smooth, brightly colored radishes, and if the tops are attached they should be green and fresh. Cut the greens off before storing the radishes in a container in the fridge, because they keep longer that way. Residues are no reason to skip them: in USDA tests of 689 radish samples in 2020, about 59% had no detectable pesticide and 4 samples had a residue above the legal limit.
Sources
- Influence of radish consumption on urinary calcium oxalate excretion. Kumar A. Nepal Med Coll J. 2004.
- Effect of radish (Raphanus sativus Linn.) on thyroid status under conditions of varying iodine intake in rats. Chandra AK, Mukhopadhyay S, Ghosh D, Tripathy S. Indian J Exp Biol. 2006.
- Estimated dietary intake of thiocyanate from Brassicaceae family in Korean diet. Han H, Kwon H. J Toxicol Environ Health A. 2009.
- Salmonella Montevideo infections linked to raw sprouts: advice to consumers, restaurants and retailers. CDC. 2018.
- Low FODMAP shopping list. Monash FODMAP blog. 2025.
- 4-(Methylthio)-3-butenyl isothiocyanate, a principal antimutagen in daikon (Raphanus sativus; Japanese white radish). Nakamura Y, Iwahashi T, Tanaka A, et al. J Agric Food Chem. 2001.
- Dietary factors and gastric cancer in Korea: a case-control study. Kim HJ, Chang WK, Kim MK, Lee SS, Choi BY. Int J Cancer. 2002.
- Radish. Purdue Extension FoodLink.
- Pesticide Data Program annual summary, calendar year 2020. USDA Agricultural Marketing Service.
History of radishes
Nobody knows exactly where the radish began. Scientists tentatively place its origin in Southeast Asia, the only region where truly wild forms have been found, with South Asia, central China and Central Asia as secondary centers. Radishes first appear in the historical record in the 3rd century BC.
By the 1st century AD, Greek and Roman writers described small, large, round, long, mild and sharp kinds. The large, mild white form was developed in China. In the West it is mostly linked with Japanese daikon, because of Japan’s agricultural development and exports.
Radish seems to have been one of the first European crops brought to the Americas. A German botanist reported radishes of about 45 kg and 90 cm long in 1544, and the black Spanish radish is recorded in Europe from 1548.
In Oaxaca, Mexico, radishes became art. The Night of the Radishes is held every December 23, and the city grows radishes for it that are left in the ground long past a normal harvest, reaching about 50 cm in length and up to 3 kg. Carvers turn them into nativity scenes and scenes of local life, and the formal contest began in 1897. Japan’s Sakurajima radish is typically grown to about 10 kg and can reach 30 kg if left in the ground.
Radishes have also been grown in orbit. In NASA’s Advanced Plant Habitat on the International Space Station, radish plants grew for 27 days in each of two grow-outs. The same glucosinolates turned up in space-grown and ground-grown plants, and the authors report that flavor and nutrient components were comparable to Earth-grown plants.
Sources
- Radish. Wikipedia.
- Night of the Radishes. Wikipedia.
- Hasenstein KH, John SP, Vandenbrink JP. Assessing radish health during space cultivation by gene transcription. Plants (Basel). 2023.
- Hasenstein KH, Moinuddin SGA, Berim A, Davin LB, Lewis NG. Glucosinolate and sugar profiles in space-grown radish. Plants (Basel). 2025.
- Li W, Zhang Y, Deng H, et al. In vitro and in vivo bioaccessibility, antioxidant activity, and color of red radish anthocyanins as influenced by different drying methods. Food Chem X. 2023.
- Yoon W, Park M, Yoo G, Kim YS, Park HY. Bioactive compounds and health benefits of radish greens. J Agric Food Chem. 2025.
- Sasaki M, Nonoshita Y, Kajiya T, et al. Characteristic analysis of trigonelline contained in Raphanus sativus cv. Sakurajima daikon and results from the first trial examining its vasodilator properties in humans. Nutrients. 2020.
Frequently asked questions about radishes
Are radishes good for you?
They are a light, low-calorie vegetable, but the health evidence is thin. Raw radishes have 16 calories, 1.6 g of fiber and 14.8 mg of vitamin C (16% of the daily value) per 100 g, and about 95% of the weight is water. Human trials are small and mixed: 10 days of daikon improved artery function in one, while 14 days of daikon powder raised systolic blood pressure by 9.7 mm Hg in another. The links to lower cancer risk come from case-control studies, which cannot prove cause.
Are radishes low carb or keto?
Yes, they are low in carbs. Raw radishes have 1.8 g of net carbs per 100 g, from 3.4 g of carbohydrate with 1.6 g of fiber, and 1.86 g of that is sugar. A cup (116 g) has 2.1 g of net carbs, which fits most low-carb plans.
Can you eat radish leaves?
Yes, the whole plant is edible, and the tops can be used as a leafy vegetable in soups and sautés. A 2025 review says radish greens hold more polyphenols and flavonoids than the roots, but the health findings so far come from lab and animal studies. Purdue Extension advises cutting the greens off before storing radishes, because the roots keep longer.
Why are radishes spicy?
The heat forms when you cut or chew a radish. Glucosinolates in the root meet the enzyme myrosinase and turn into isothiocyanates. In eight daikon strains the main one was 4-(methylthio)-3-butenyl isothiocyanate, not the allyl isothiocyanate of mustard and wasabi. Wild strains held up to 5 times more of it than the common Japanese strain.
Are radishes good for people with diabetes?
They are low in sugar, but no human trial here tests radishes in diabetes. Raw radishes have 1.86 g of sugars per 100 g. Radish root juice lowered fasting blood glucose by 33.4% in rats and sprouts lowered glucose and insulin in rats, and a review says clinical trials are still missing. Do not swap radish products for diabetes medicine.
Are radishes good for weight loss?
No study here tested weight loss. Raw radishes have 16 calories and 1.6 g of fiber per 100 g and are 95% water, so a plate of them adds crunch cheaply. That is a swap effect for higher-calorie foods, not a proven effect of radishes. A mouse study found a red radish sprout extract cut weight gain by 60%, which says nothing yet about people.
Are radishes bad for your thyroid?
Probably not at normal amounts, but the evidence is limited. Rats fed radish for a long time showed signs of an underactive thyroid even with enough iodine. A Korean estimate put average thiocyanate intake from mustard-family vegetables, radish included, at 16.3 µmol a day, below the doses that harmed animals. If you have thyroid disease, tell your doctor how much you eat.
How many radishes can you eat a day?
No study here sets an ideal amount. Trials used 100 g a day of red radish for 7 days and 170 g a day of Sakurajima daikon for 10 days. Monash University rates radish low in FODMAPs at 75 g. If you have thyroid disease or form kidney stones, see the notes above.