Lotus root: a starchy vegetable with one small human trial

The best human evidence on lotus root is one 30-day randomized pilot in 25 Chinese adults over 60, and it had no placebo arm. The 12 people in the lotus root group took 0.88 oz (25 g) of juice powder a day, equal to 11 oz (300 g) of fresh root. Their plasma vitamin C rose by 56.5 percent and uric acid fell by 41.7 percent, counted only as change within the group. The comparison group got cucumber powder, and its numbers moved further: vitamin C up 67.1 percent, uric acid down 45.1 percent. In the test tube lotus root had far higher antioxidant capacity than cucumber. In the older adults who ate them, the authors found the two not remarkably different. On the plate, cooked lotus root is a starchy vegetable. US survey data give 87 calories, 3 g of fiber and 352 mg of potassium per 3.5 oz (100 g), and 33 mg of vitamin C in a 125 g cup.

The numbers, per 3.5 oz (100 g)

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

How much is actually in it

• A cup of cooked lotus root (125 g) carries about 33 mg of vitamin C. — US survey food code, per 125 g cup Evidence E source
  26.5 mg/100 g, 33.1 mg per cup, 2.6 mg per 10 g slice
• Cooked lotus root gives 87 calories, 3 g fiber and 352 mg potassium per 3.5 oz (100 g). — US survey food code, per 3.5 oz (100 g) Evidence E source
  87 calories, fiber 3 g, potassium 352 mg per 3.5 oz (100 g); cup 109 calories, 3.8 g fiber, 440 mg K
• In the diets of 1,393 Chinese adults, lotus root and taro were the richest vegetable sources of flavonoids after fruits. — 1,393 Chinese adults, 2008-2010 (n = 1393) Evidence C source
  Lotus root ranked among top vegetable flavonoid sources

What a real portion looks like

• US survey portions for cooked lotus root are 10 g per slice and 125 g per cup, with 63 g used when the amount is not stated. — US survey portion weights Evidence E source
  Slice 10 g, cup 125 g, unspecified 63 g
• In a 30-day randomized pilot in adults over 60, the lotus root arm drank 0.88 oz (25 g) of juice powder a day, equal to 11 oz (300 g) of fresh lotus root. — 16 men and 9 women over 60, Tianjin, China, 30 days (n = 25) Evidence B source
  Dose 300 g fresh lotus root equivalent a day

What your body absorbs

• No human study has measured how well starch or minerals from lotus root are digested or absorbed, and published work on its digestibility is laboratory only. — PubMed corpus snapshot Evidence E source
  —

What cooking and storage change

• By USDA factors for root vegetables boiled in water to cover and drained, about 65% of vitamin C and folate and 90% of potassium stay in the food. — USDA root vegetable group, boiled and drained Evidence E source
  Vitamin C 65%, folate 65%, potassium 90%, copper 95% retained

What it does to your health

• After 30 days on lotus root powder, plasma vitamin C in 12 older adults rose by 56.5% and uric acid fell by 41.7%, counted as change within the group. — 12 adults over 60 in the lotus root arm, 30 days (n = 12) Evidence B source
  Plasma vitamin C +56.5%, total phenolics +14.9%, uric acid -41.7%, FRAP unchanged
• Lotus root starch served as the placebo in a 5-week trial of 69 obese adults, and the placebo group showed no significant change in weight or blood markers. — 69 obese adults aged 25-35, Kunming, China, 5 weeks, 10 g a day (n = 69) Evidence B source
  No significant change in the lotus root starch placebo group

Safety, limits and interactions

• A woman without teeth needed two emergency operations within a year for bowel blockage from swallowing lotus root unchewed. — one 58-year-old edentulous woman, Japan (n = 1) Evidence D source
  Two laparotomies for food-bolus ileus, no recurrence after dentures
• In 346 lotus root samples from eight main growing areas of China, arsenic was found in every sample and 2.89% exceeded national limits. For high-exposure eaters in two provinces the modeled cancer risk from arsenic passed the US EPA threshold. — 346 lotus root samples from eight producing areas, China; risk modeled for adults (n = 346 samples) Evidence C source
  Arsenic detected 100%, 2.89% above national limit; Fujian exceedance nickel 15%, arsenic 5%, lead 5%; 90th-percentile carcinogenic risk of As 1.05e-4 (Hubei) and 1.24e-4 (Fujian) vs threshold 1e-4; proposed intake limits 10 g/day (Hubei) and 9 g/day (Fujian) vs Chinese average about 14 g/day

What people believe that the data does not support

• Lotus root had far higher antioxidant capacity than cucumber in the test tube, yet over 30 days the two gave older adults no clearly different antioxidant benefit. — 25 healthy adults over 60, 30 days (n = 25) Evidence B source
  No remarkable difference between vegetables in vivo despite in vitro gap
• Neither the US 21 CFR health claims nor the EU claims register holds any claim for lotus root. — US and EU claim registers Evidence E source
  —

Who this works differently for

• In 70 adults with liver failure, a 200 calories late-evening snack of lotus-root starch for 14 days raised fasting carbohydrate oxidation and lowered fat oxidation. — 70 hospitalized adults with acute-on-chronic liver failure due to hepatitis B, China, 14 days (n = 70) Evidence B source
  Fasting RQ higher vs control (P = 0.02), CHO oxidation higher (P = 0.001), fat oxidation lower (P = 0.02)

The bottom line

Nobody has measured in people how well the starch or minerals in lotus root are absorbed, and the published digestibility work is laboratory only. Boiling costs something. USDA factors for root vegetables boiled and drained keep about 65 percent of vitamin C and folate and 90 percent of potassium, though that is a group factor from 1975 and was never measured on lotus root itself. Two trials used lotus root starch as a tool rather than a treatment. In a 5-week trial of 69 obese Chinese adults aged 25 to 35, 10 g a day of it was the placebo, and the placebo group showed no significant change in weight, body fat or blood markers. In 70 hospitalized adults with liver failure caused by hepatitis B, a 200 calories late-evening snack of lotus root starch for 14 days raised fasting carbohydrate oxidation and lowered fat oxidation against standard care. That trial was unblinded and measured metabolism only. Neither the US nor the EU register holds any health claim for lotus root. The one clinical safety record we have is a single case from Japan. A 58-year-old woman with no teeth needed two emergency operations within a year because lotus root she swallowed unchewed blocked her bowel, and it did not happen again once she had dentures. If chewing is hard for you or someone you cook for, that case is worth remembering. The other signal comes from the soil. In 346 lotus root samples from eight main growing areas of China, arsenic turned up in every sample and 2.89 percent exceeded national limits. For the heaviest eaters in Hubei and Fujian, a model put the cancer risk from arsenic above the US EPA threshold, a figure modeled for those regions, never measured in people and not transferable to lotus root grown elsewhere. We carded nothing on allergy, pregnancy or medicines. That is a gap in our reading, and it says nothing about whether the root is safe for everyone.

Sources

1. lotr-r3-01 · dataset
   Lotus root, cooked [fdc_id 2709936] | Vitamin C, total ascorbic acid 26.5 MG per 100 g | 1 cup 125 g 33.1 MG | 1 slice 10 g 2.6 MG
   USDA FNDDS 2021-2023, food code 75218501 (Lotus root, cooked), fdc_id 2709936 · checked 2026-09-29
2. lotr-r3-02 · dataset
   Lotus root, cooked [fdc_id 2709936] | Energy 87 KCAL per 100 g | Fiber, total dietary 3 G per 100 g | Potassium, K 352 MG per 100 g
   USDA FNDDS 2021-2023, food code 75218501 (Lotus root, cooked), fdc_id 2709936 · checked 2026-09-29
3. lotr-r3-11 · cross-sectional
   The richest sources of flavonoids and stilbenes were the fruit group including apple, plum, pear, and peach, followed by the vegetable group containing lotus root and taro.
   J Acad Nutr Diet, 2013 · checked 2026-09-29
4. lotr-r3-03 · dataset
   Lotus root, cooked [75218501] | 1 cup 125 g | 1 slice 10 g | Quantity not specified 63 g
   USDA FNDDS 2021-2023, food code 75218501 (Lotus root, cooked) · checked 2026-09-29
5. lotr-r3-05 · RCT (pilot)
   During the intervention period, the subjects received daily 25g of lotus root powder or 12.5g of cucumber powder, which was equivalent to 300g of fresh lotus root or cucumber, respectively.
   J Nutr Health Aging, 2015 · checked 2026-09-29
6. lotr-r3-13 · corpus absence
   corpus_search ("lotus root") AND (absorption OR bioavailability OR bioaccessib* OR digestib* OR uptake): 0 records
   PubMed corpus snapshot pubmed:469185, 2026-09 · checked 2026-09-29
7. lotr-r3-04 · dataset
   USDA-RETN-R6:3455 VEG,ROOTS,ETC,BLD,DRAIND,WTR COVER | vitamin_c_mg 65% | folate_total_ug 65% | potassium_mg 90% | copper_mg 95%
   USDA Table of Nutrient Retention Factors, Release 6 (2007), Retn_Code 3455 VEG,ROOTS,ETC,BLD,DRAIND,WTR COVER · checked 2026-09-29
8. lotr-r3-06 · RCT (pilot)
   As shown in Table 4, the content of plasma VC in the lotus root and cucumber groups was significantly increased by 56.5% and 67.1% and total phenolics by 14.9% and 18.9%, respectively after the intervention. Meanwhile, the content of uric acid was significantly decreased in the two groups by 41.7% and 45.1%, respectively.
   J Nutr Health Aging, 2015 · checked 2026-09-29
9. lotr-r3-09 · RCT
   Body mass index (BMI), fat mass, percentage body fat (PBF), triglyceride (TG), glycated hemoglobin A1c (HbA1c), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were significantly reduced in KF consumers ( Table 1 ) (p <0.05 or p <0.01). There were no significant differences in the control group ( Table 1 ).
   Front Cell Infect Microbiol, 2022 · checked 2026-09-29
10. lotr-r3-10 · case report
    An emergency laparotomy was performed and a diagnosis of ileus caused by ingestion of lotus root was established.
    Nihon Shokakibyo Gakkai Zasshi, 2015 · checked 2026-09-29
11. lotr-ws10-14 · cross-sectional contamination survey with risk modeling
    Results showed arsenic (As) was the most prevalent contaminant, with a 100 % detection rate and 2.89 % of samples exceeding national food safety limits.
    J Hazard Mater, 2025;497:139499 · checked 2026-09-29
12. lotr-r3-07 · RCT (pilot)
    These results suggest that lotus root and cucumber are not remarkably different in improving antioxidant function in aged subjects, though they are significantly different in antioxidant capacity in vitro.
    J Nutr Health Aging, 2015 · checked 2026-09-29
13. lotr-r3-12 · registry absence
    claims_search lotus root in 21 CFR 101: nothing; euclaims_search lotus root in the EU register (2330 claims, 262 authorised, 2067 non-authorised, 1 revoked): nothing
    21 CFR 101 and EU Register on nutrition and health claims, snapshot 2026-09-21 · checked 2026-09-29
14. lotr-r3-08 · RCT
    Fasting RQ was significantly higher in the LES supplemented verses the control group after 2 weeks (P=0.02). CHO oxidation was significantly higher (P=0.001) and fat oxidation (P=0.02) was lower in the LES-supplemented group when compared with controls after 2 weeks.
    Eur J Clin Nutr, 2013 · checked 2026-09-29