Horseradish: a hot condiment the trials barely touch

The strongest human result with horseradish in it comes from a tablet. In a 6-month double-blind trial in 217 German women with recurrent cystitis, pills of 200 mg nasturtium herb plus 80 mg horseradish root lowered the risk of a new urinary infection by a factor of 0.64 against placebo (95% CI 0.42 to 0.97). The maker of the product sponsored the trial, it stopped early because recruitment stalled, and the gap had gone by day 360. It says nothing about the spoonful next to your roast beef. As a food, horseradish turned up in one trial we found. Twenty-two young men ate a brunch with 8.3 g of it, and over 4 hours their energy expenditure, appetite and later intake did not differ from placebo. Heart rate fell and diastolic blood pressure rose in that trial at p values of 0.048 and 0.049, but these were secondary results among five spices tested, and the abstract gives no sizes, so they may well be chance.

The numbers, per 3.5 oz (100 g)

As people eat it, per 3.5 oz (100 g)

How much is actually in it

• UK tables list raw horseradish root at 580 mg potassium, 120 mg calcium and 6.2 g fiber per 3.5 oz (100 g). — - (n = -) Evidence E source
  Per 100 g raw: 62 calories, 580 mg potassium, 120 mg calcium, 2.0 mg iron, 6.2 g NSP fiber, 8 mg sodium

What a real portion looks like

• US dietary survey data count one tablespoon of horseradish as 15 g and a sandwich serving of horseradish sauce as 16 g. — - (n = -) Evidence E source
  1 tbsp horseradish 15 g, unspecified 5 g, sauce 16 g per sandwich
• In a survey of 250 Moscow medical students, cauliflower, radishes, kale and horseradish were each in the diet of only 7.8 to 14.9 percent of the students. — 250 medical students aged 21 to 27, Moscow region (n = 250) Evidence C source
  7.8 to 14.9% for cauliflower, radishes, kale and horseradish

What cooking and storage change

• Prepared horseradish in the USDA table carries 420 mg sodium per 3.5 oz (100 g), against 8 mg in raw root in UK tables. — - (n = -) Evidence E source
  Sodium 420 mg/100 g prepared vs 8 mg/100 g raw, vitamin C 24.9 vs 120 mg

What it does to your health

• In a randomized crossover trial in 22 young men, adding 8.3 g of horseradish to a meal did not change energy expenditure, appetite or energy intake over 4 hours. — 22 normal-weight young men, single brunch meal, 4 h follow-up (n = 22) Evidence B source
  No significant effect on diet-induced thermogenesis, appetite (P>0.85), ad libitum intake (P=0.63)
• In the same trial of 22 young men, a meal with 8.3 g of horseradish slightly lowered heart rate and raised diastolic blood pressure compared with placebo, at borderline significance. — 22 normal-weight young men, single meal (n = 22) Evidence B source
  Heart rate lower (P=0.048), diastolic blood pressure higher (P=0.049), sizes not given in abstract
• In a 6-month double-blind RCT in 217 women with recurrent cystitis, tablets of nasturtium herb plus 80 mg horseradish root cut the risk of a new urinary infection by 36 percent against placebo. — 217 women with recurrent uncomplicated cystitis, 57 German practices, 6 months prophylaxis (n = 217) Evidence B source
  Risk of first recurrence x0.64 (95% CI 0.42 to 0.97), p = 0.033

Safety, limits and interactions

• Contact allergy to allyl isothiocyanate, the pungent compound of horseradish and mustard, was confirmed in 2 of 259 Danish patients tested for suspected food-related dermatitis. — 259 patients with suspected contact dermatitis from vegetables and food, Denmark, 1994 to 2003 (n = 259) Evidence C source
  0.8% positive patch test, 16.6% doubtful reactions
• In a crossover trial in 46 adults, allyl isothiocyanate from mustard and cabbage raised DNA strand breaks in blood cells 3 hours after eating, but the change was gone by 6 hours. — 46 adults, 10 days per treatment plus acute dose on day 11 (n = 46) Evidence B source
  % tail DNA at 3 h: 8.3 AITC and 8.0 mustard/cabbage vs 3.2 control, back to 5.7 vs 4.2 at 6 h
• Over 6 months in the same trial, women on the nasturtium and horseradish tablets had 3.7 adverse events on average against 3.0 on placebo, a difference that was not significant. — 217 women with recurrent cystitis, 6 months (n = 217) Evidence B source
  3.7 +/- 4.5 vs 3.0 +/- 3.2 adverse events per patient, p = 0.651

What people believe that the data does not support

• The EU did not authorize the claims that horseradish enhances renal water elimination or acts as a diuretic. — - (n = -) Evidence E source
  Status Non-authorized
• The EU did not authorize the claim that horseradish root supports respiratory health. — - (n = -) Evidence E source
  Status Non-authorized

Who this works differently for

• Among 80 older women, those with a poorer sense of smell showed less preference for pungent foods such as horseradish. — 80 free-living women aged 65 to 93, New Haven (n = 80) Evidence C source
  Lower preference for pungency with lower olfactory perception, size not given

What is still unknown

• No study in our corpus measured how horseradish affects absorption of nutrients or how cooking and storage change its compounds, and the USDA retention table has no entry for it. — - (n = -) Evidence E source
  0 records for axes 2 and 3

The bottom line

Raw root looks rich on paper: UK tables give 580 mg potassium, 120 mg calcium and 6.2 g fiber per 3.5 oz (100 g). A tablespoon is 15 g in US survey data, about a seventh of those numbers. The jar is a different product. Prepared horseradish in the USDA table carries 420 mg sodium per 3.5 oz (100 g), against 8 mg in raw root, and 24.9 mg vitamin C against 120 mg. Buy it for the heat and count it as a salty condiment. The EU looked at claims that horseradish works as a diuretic and that it supports the respiratory system, and authorized neither. Non-authorized means the evidence did not reach the bar. We found no study of how cooking or storage changes horseradish, and the USDA retention table has no entry for it. For caution, the allergy data is about its pungent compound, allyl isothiocyanate, which mustard shares. Among 259 Danish patients patch-tested for suspected food-related dermatitis, 2 reacted clearly to it and 43 gave doubtful reactions. In 46 adults, the same compound from mustard and cabbage raised DNA strand breaks in blood cells 3 hours after eating, and the difference had disappeared at 6 hours. That trial used no horseradish. In the cystitis trial, women on the tablets had 3.7 adverse events on average over 6 months against 3.0 on placebo, a difference that did not reach significance. We found nothing on pregnancy or on interactions with medicines, which leaves those questions unanswered. Among 80 women aged 65 to 93, a weaker sense of smell went with less liking for pungent foods such as horseradish.

Sources

1. hrs-daily-r5-07 · dataset
   Horseradish, raw, CoFID 13-258: Energy (kcal) 62 · NSP (g) 6.2 · Total sugars (g) 7.3 · Potassium (mg) 580 · Calcium (mg) 120 · Iron (mg) 2.00 · Sodium (mg) 8 · Water (g) 74.7
   CoFID 2021 (Public Health England), code 13-258, OGL v3.0 · checked 2026-09-29
2. hrs-daily-r5-09 · dataset
   Horseradish (FNDDS 75503090, fdc_id 2710083): 1 tablespoon 15 g · Quantity not specified 5 g; Horseradish sauce (FNDDS 81302060, fdc_id 2710174): 1 tablespoon 16 g · Guideline amount on regular sandwich 16 g
   USDA FNDDS, FDC 2710083 and 2710174 · checked 2026-09-29
3. hrs-daily-r5-11 · survey
   Cauliflower, radishes, Kale and horseradish was included in the diet of 7.8-14.9% of the students.
   Vopr Pitan, 2018 · checked 2026-09-29
4. hrs-daily-r5-08 · dataset
   Horseradish, prepared (FDC 173472, SR Legacy, Spices and Herbs): vitamin C 24.9 mg per 100 g = 28% DV; sodium 420 mg = 18% DV; folate 57 µg = 14% DV; CoFID Horseradish, raw 13-258: vitamin C 120 mg, sodium 8 mg
   USDA FoodData Central SR Legacy 2018, FDC 173472 · checked 2026-09-29
5. hrs-daily-r5-01 · randomized crossover trial
   twenty-two young (age 24·9 (SD 4·6) years), normal-weight (BMI 21·8 (SD 2·1) kg/m²) males were randomly assigned to receive a brunch meal with either pepper (1·3 g), ginger (20 g), horseradish (8·3 g), mustard (21 g) or no spices (placebo)... No other spice induced thermogenic effects approaching statistical significance. Subjective measures of appetite (P>0·85), ad libitum EI (P=0·63) and energy balance (P=0·67) also did not differ between the treatments.
   Br J Nutr, 2013 · checked 2026-09-29
6. hrs-daily-r5-02 · randomized crossover trial
   Finally, horseradish decreased heart rate (P=0·048) and increased diastolic blood pressure (P= 0·049) compared with placebo.
   Br J Nutr, 2013 · checked 2026-09-29
7. hrs-daily-r5-13 · RCT
   Here, the treatment showed a clear and significantly flatter course of the cumulative risk of recurrence compared to placebo, with general risk of a rUTI decreased under treatment by a factor of 0.64, i.e. by 36% (OR of Cox regression, 95% CI 0.42–0.97, p = 0.0327) (Fig. 3).
   BMC Complementary Medicine and Therapies, 2026 · checked 2026-09-29
8. hrs-daily-r5-03 · cohort
   259 such patients were tested at the Department of Dermatology, Gentofte Hospital, Denmark, from 1994 to 2003. Only 2 patients (0.8%) had a positive reaction (+) to allyl isothiocyanate and 43 patients (16.6%) had a ?+ reaction.
   Contact Dermatitis, 2004 · checked 2026-09-29
9. hrs-daily-r5-04 · randomized crossover trial
   Both AITC and M/C increased DNA strand breaks 3 h postconsumption (LSmean % DNA in tail±S.E.M.: 3.2±0.7 for control, 8.3±1.7 for AITC, 8.0±1.7 for M/C), and this difference disappeared at 6 h (4.2±0.9 for control, 5.7±1.2 for AITC, 5.5±1.2 for M/C).
   J Nutr Biochem, 2013 · checked 2026-09-29
10. hrs-daily-r5-14 · RCT
    The patients in the treatment group had an average of 3.7 ± 4.5 adverse events during the study, while patients in the placebo group had an average of 3.0 ± 3.2. This difference is not statistically significant (p = 0.651).
    BMC Complementary Medicine and Therapies, 2026 · checked 2026-09-29
11. hrs-daily-r5-05 · register
    POL-HC-6644 Armorica rusticana - common name : Horseradish Traditionally used to enhance the renal elimination of water. Traditionally used to facilitate the elimination functions of the organism. Used to enhance the renal elimination of water. Used to facilitate the elimination functions of the organism. Used for the drainage of the organism. Diuretic effect. Stimulates the elimination function of the organism. Contributes to the functionary of the urinary tract. Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-6644, snapshot 2026-09-21 · checked 2026-09-29
12. hrs-daily-r5-06 · register
    POL-HC-7269 Horseradish root (Armoracia rusticana) ;; Active ingredients of horseradish can support the respiratory system health. Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-7269, snapshot 2026-09-21 · checked 2026-09-29
13. hrs-daily-r5-10 · cross-sectional
    The following nutritional risk pattern was associated with lower olfactory perception: lower interest in food-related activities (eg, enjoying cooking, eating a wide variety of foods); lower preference for foods with predominant sour/bitter taste (eg, citrus fruits) or pungency (eg, horseradish)
    J Am Diet Assoc, 1995 · checked 2026-09-29
14. hrs-daily-r5-12 · register
    horseradish | Armoracia rusticana | allyl isothiocyanate: corpus axis 2 query 0 of all types · retention R6 0 (Spices and Herbs not in table) · 21 CFR 101 0 · interactions 0 · corpus pregnancy slice 0
    Bioma corpus search 2026-09-29 (PubMed snapshot pubmed:469185), USDA R6 2007, 21 CFR 101 · checked 2026-09-29