Burdock root: a fibrous vegetable with two small trials behind it

The best evidence on burdock root is two small randomized trials from Iran, and neither used the cooked vegetable. In 60 women with polycystic ovary syndrome, 460 mg a day of burdock root powder for 12 weeks lowered CRP and malondialdehyde against placebo (p < 0.001), in a single-center double-blind trial of a capsule dose far below culinary amounts. In 36 adults aged 50 to 70 with knee osteoarthritis, three cups a day of burdock root tea, each brewed from 2 g of root, for 42 days lowered IL-6 (P = 0.002) and hs-CRP (P = 0.003) compared with hot water. That trial was unblinded, and its abstract gives neither the size of the change nor any pain or function outcome. Both trials moved blood markers. As food, the raw root gives 72 calories, 3.3 g of fiber, 308 mg of potassium and 0.24 mg of vitamin B6 per 3.5 oz (100 g), from a single USDA record with no second national number to check it against.

The numbers, per 3.5 oz (100 g)

How much is actually in it

• Raw burdock root gives 72 calories, 3.3 g of fiber, 308 mg of potassium and 0.24 mg of vitamin B6 per 3.5 oz (100 g). — USDA SR Legacy record for raw burdock root (n = 1 record) Evidence E source
  Energy 72 calories, carbohydrate 17.34 g, fiber 3.3 g, potassium 308 mg, magnesium 38 mg, vitamin B6 0.24 mg per 3.5 oz (100 g)

What cooking and storage change

• In the USDA records, boiled and drained burdock root lists 1.8 g of fiber per 3.5 oz (100 g) against 3.3 g raw, while energy rises from 72 to 88 calories as water drops. — USDA SR Legacy records for raw and for boiled, drained burdock root without salt (n = 2 records) Evidence E source
  Fiber 3.3 g raw vs 1.8 g boiled, energy 72 vs 88 calories, water 80.09 g vs 75.64 g per 3.5 oz (100 g)
• By the USDA table for root vegetables boiled in little water and drained, about 70% of vitamin C and folate and 95% of vitamin B6 and magnesium remain. — USDA retention factors for the vegetable group, method roots boiled, drained, little water Evidence E source
  Retained: vitamin C 70%, folate 70%, thiamin 85%, potassium 90%, magnesium 95%, vitamin B6 95%

What it does to your health

• In an RCT of 36 adults with knee osteoarthritis, three cups a day of burdock root tea for 42 days lowered IL-6 and hs-CRP compared with plain hot water. — 36 patients aged 50 to 70 with knee osteoarthritis in Tabriz, all on acetaminophen and glucosamine (n = 36) Evidence B source
  IL-6 (P = 0.002), hs-CRP (P = 0.003) and malondialdehyde (P < 0.001) decreased, sizes not given in the abstract

Safety, limits and interactions

• The same 12 week PCOS trial of 460 mg a day of burdock root powder reported no side effects and no dropouts among its 60 participants. — 60 women with polycystic ovary syndrome, 12 weeks (n = 60) Evidence B source
  No side effects reported, no dropouts

What people believe that the data does not support

• One published case links a six-herb tea sold for liver cleansing, burdock root among them, to cholestatic liver injury in a 36-year-old woman. — One 36-year-old woman (n = 1) Evidence D source
  Clinically significant acute cholestatic liver injury, causal ingredient not identified

Who this works differently for

• In a double-blind RCT of 60 women with polycystic ovary syndrome, 460 mg a day of burdock root powder for 12 weeks lowered CRP and malondialdehyde against placebo. — 60 women with polycystic ovary syndrome in Arak, Iran, 30 per arm, 12 weeks (n = 60) Evidence B source
  Malondialdehyde and CRP decreased (p < 0.001) vs placebo, right and left ovary volume reduced (p = 0.02, p = 0.01)

The bottom line

Boiling changes the numbers on paper. The USDA record for boiled, drained root lists 1.8 g of fiber per 3.5 oz (100 g) against 3.3 g raw, while energy rises from 72 to 88 calories as water drops. These are two separate records, so the fiber gap may reflect different samples as much as the pot. USDA factors for root vegetables boiled in little water keep about 70 percent of vitamin C and folate and 95 percent of vitamin B6 and magnesium, group figures from 1975 that were never measured on burdock itself. Burdock root turns up in teas sold for liver cleansing. The one published case we have points the other way. A 36-year-old woman developed cholestatic liver injury after a six-herb tea of that kind that included burdock, and with six ingredients and no rechallenge the case cannot pin the injury on burdock. It does undercut the cleansing claim. On safety, the PCOS trial reported no side effects and no dropouts among its 60 women over 12 weeks, a group too small and too short to catch rare harms. Everyone in the osteoarthritis trial was also taking acetaminophen and glucosamine. We found no study of burdock root in pregnancy, while breastfeeding or with other medicines, and no study of how the body absorbs anything from it.

Sources

1. brdk-r6-01 · USDA FoodData Central SR Legacy, dataset
   Burdock root, raw (FDC 169974, NDB 11104): energy 72 kcal; carbohydrate 17.34 g; fiber 3.3 g; sugars 2.9 g; potassium 308 mg; magnesium 38 mg; vitamin B6 0.24 mg per 100 g; portion 1 cup (1 inch pieces) = 118 g
   USDA FoodData Central, SR Legacy 2019, FDC 169974 · checked 2026-09-29
2. brdk-r6-02 · USDA FoodData Central SR Legacy, dataset
   Burdock root, raw (FDC 169974): fiber 3.3 g; energy 72 kcal; water 80.09 g per 100 g. Burdock root, cooked, boiled, drained, without salt (FDC 170384): fiber 1.8 g; energy 88 kcal; water 75.64 g per 100 g
   USDA FoodData Central, SR Legacy 2019, FDC 169974 and 170384 · checked 2026-09-29
3. brdk-r6-03 · USDA retention factors, dataset
   VEG,ROOTS,ETC,BLD,DRAIND,LITTLE WTR (Retn_Code 3454): vitamin_c_mg 70%; folate_total_ug 70%; thiamin_mg 85%; potassium_mg 90%; magnesium_mg 95%; vitamin_b6_mg 95%
   USDA Table of Nutrient Retention Factors, Release 6 (2007), code 3454 · checked 2026-09-29
4. brdk-r6-04 · RCT
   The intervention group received daily three cups of Burdock root tea (each cup containing 2 g/150 mL boiled water) half-hour after the meal...The results showed that burdock root tea significantly decreased the levels of serum IL-6 (P = 0.002), hs-CRP (P = 0.003) and malondialdehyde (P < 0.001), while the levels of serum TAC (P < 0.001) and activities of SOD (P = 0.009) were significantly increased.
   Int J Rheum Dis, 2016 · checked 2026-09-29
5. brdk-r6-06 · RCT
   All 60 participants completed the study without any dropouts, and importantly, no side effects were reported throughout the trial.
   JBRA Assist Reprod, 2026 · checked 2026-09-29
6. brdk-r6-07 · case report
   We describe the case of a 36-year-old female who developed a clinically significant acute liver injury with a cholestatic pattern due to an over-the-counter herbal liver detox tea. This is the first case reported of a hepatotoxic effect from any of these compounds or ingredients in the detox tea: burdock root, stinging nettle leaf, cleavers herb, dandelion root, lemon peel, and lemon myrtle leaf (Backhousia citriodora).
   Case Rep Gastroenterol, 2022 · checked 2026-09-29
7. brdk-r6-05 · RCT
   Furthermore, values of oxidative and inflammation markers such as malondialdehyde and C-reactive protein decreased significantly (p<0.001) in the Arctium lappa L. compared to the placebo group.
   JBRA Assist Reprod, 2026 · checked 2026-09-29