Arrowroot: a folate root that reaches you as plain starch

In a 4-week randomized trial in 72 healthy adults, folate from fruit, vegetables and liver was absorbed at about 78 percent of the efficiency of synthetic folic acid (95% CI 48 to 108 percent). In a 30-day trial in 96 men, folate from spinach reached only 30 percent. Neither trial used arrowroot, and the finding matters only for the fresh root. That root has 338 micrograms of folate per 3.5 oz (100 g) in its single USDA record. The white powder sold for thickening sauces has 7 micrograms in the US flour record and only a trace in the UK table, because extracting the starch removes nearly all of the root's folate and protein. The powder is almost pure starch, with 94 g of starch, 0.4 g of protein and 355 calories per 3.5 oz (100 g) in the UK table. The two tables disagree on iron, 2.0 mg per 3.5 oz (100 g) in the UK record and 0.33 mg in the US flour record, a sixfold gap our sources do not explain. Arrowroot is an old home remedy for diarrhea. One uncontrolled pilot in 11 people with irritable bowel syndrome, who took 2 tsp (10 mL) of powder three times a day for a month, reported less diarrhea and pain on questionnaires. In a non-randomized study of 94 tube-fed intensive care patients in India, adding 3.5 oz (100 g) of powder a day to feeds for up to 5 days went with less new diarrhea, 8.8 percent against 26.7 percent (RR 0.33, 95% CI 0.10 to 1.05). That difference did not reach significance, and the comparison was with earlier patients. Both studies are small and neither randomized anyone, so the question is open.

The numbers, per 3.5 oz (100 g)

How much is actually in it

• UK food tables list arrowroot as 94 g starch, 0.4 g protein and 355 calories per 3.5 oz (100 g) with only trace folate, and give 2.0 mg iron where the US flour record gives 0.33 mg. — UK food composition Evidence E source
  Starch 94.0 g, protein 0.4 g, 355 calories, iron 2.00 mg, copper 0.22 mg, folate trace per 3.5 oz (100 g)
• Laboratory analysis of arrowroot starch found 0.72% protein, 0.26% fat and 1.0% crude fiber, in line with earlier samples from four countries. — arrowroot starch samples, laboratory analysis (n = 5) Evidence D source
  Crude protein 0.72%, crude fat 0.26%, crude fiber 1.00% (earlier reports 0.03-1.50%)

What a real portion looks like

• Raw arrowroot root has 65 calories, 4.2 g protein, 13.4 g carbohydrate and 338 ug folate per 3.5 oz (100 g), and a cup of sliced root weighs 4.2 oz (120 g). — US food composition Evidence E source
  Per 100 g: 65 calories, protein 4.24 g, carbohydrate 13.39 g, fiber 1.3 g, folate 338 ug DFE, potassium 454 mg, iron 2.22 mg
• Arrowroot flour is almost pure starch, with 357 calories, 88 g carbohydrate, 0.3 g protein and only 7 ug folate per 3.5 oz (100 g), so extraction removes nearly all the root's folate and protein. — US food composition Evidence E source
  Flour per 3.5 oz (100 g): 357 calories, carbohydrate 88.15 g, protein 0.3 g, fiber 3.4 g, folate 7 ug DFE, potassium 11 mg; 1 cup 128 g

What your body absorbs

• In a 4-week randomized trial in 72 adults, folate from fruit, vegetables and liver was absorbed at about 78% (95% CI 48% to 108%) of the efficiency of synthetic folic acid. — 72 healthy adults randomly divided into a high food folate diet (369 ug/d) or a low-folate diet with folic acid capsules for 4 weeks (n = 72) Evidence B source
  Relative bioavailability 78% (95% CI 48% to 108%) by labeled folate, 85% (52% to 118%) by serum folate
• In a 30-day randomized trial in 96 men, natural folate from spinach and yeast was absorbed at only 30% to 59% of the rate of folic acid. — 96 men randomly assigned to placebo, 200 ug folic acid, or 200 ug natural folate as spinach or yeast for 30 days (n = 96) Evidence B source
  Relative bioavailability 30% (spinach) to 59% (yeast) of folic acid

What cooking and storage change

• No nutrient retention factor exists for arrowroot in the USDA retention table, and the PubMed corpus holds no human study on how cooking or baking changes it. — — (n = 0 records) Evidence E source
  No retention factor, no cooking study

What it does to your health

• The folk use of arrowroot for diarrhea rests on one uncontrolled pilot in 11 people with irritable bowel syndrome who took 2 tsp (10 mL) of powder three times a day for a month and reported less diarrhea and pain. — 11 patients with irritable bowel syndrome with diarrhea, 2 tsp (10 mL) arrowroot powder three times a day for one month then one month off (n = 11) Evidence C source
  Self-reported reduction in diarrhea and abdominal pain, no effect sizes given

Safety, limits and interactions

• In a non-randomized study of 94 tube-fed ICU patients, adding 100 g arrowroot powder a day to feeds for the first 5 days went with less new diarrhea, 8.8% against 26.7%, a difference that was not statistically significant. — 94 critically ill adults on nasogastric feeding in India, up to 5 days (n = 94) Evidence C source
  New-onset diarrhea 8.8% vs 26.7%, RR 0.33 (95% CI 0.10-1.05), p = 0.059

What people believe that the data does not support

• A Korean diet survey named arrowroot the top isoflavone source at 8.3 mg a day, but Korean arrowroot is kudzu root, a different plant from the Maranta starch sold as arrowroot in the West. — Korean National Nutrition Survey 1998 Evidence C source
  Arrowroot 8.3 mg/day of isoflavones, top five foods 88.2% of intake
• Neither the US health claim rules nor the EU claims register mention arrowroot, so no health claim for it has been authorized or even assessed. — — (n = 0 entries) Evidence E source
  0 entries in 21 CFR 101 and 0 of 2,330 claims in the EU register

The bottom line

Use the powder as a thickener and expect starch from it. The folate story belongs to the fresh root, which few shops sell. Who should be careful. We have no data on side effects of arrowroot. The largest daily amount studied, 3.5 oz (100 g) of powder a day for up to 5 days, was given to critically ill adults on tube feeding, a group far from a home kitchen. We found no study on arrowroot and allergy, pregnancy, children or medicines. Some claims about arrowroot come from a mix-up of plants. A Korean diet survey named arrowroot the top source of isoflavones at 8.3 mg a day, but Korean arrowroot is kudzu root, a different plant from the Maranta starch sold under that name in the West. That identification comes from other sources, not from the survey itself. Neither the US health claim rules nor the EU claims register mentions arrowroot, so no health claim for it has been authorized or even assessed. We found no data on how cooking changes the root or the powder.

Sources

1. arw-daily-r7-03 · food composition dataset
   Arrowroot | Starch (g) 94.0 | Protein (g) 0.4 | Energy (kcal) 355 | Iron (mg) 2.00 | Copper (mg) 0.22 | Folate (µg) Tr
   CoFID 2021 (Public Health England, OGL v3.0), code 11-001 Arrowroot · checked 2026-09-29
2. arw-daily-r7-05 · laboratory analysis
   Crude protein content and crude fat contents were 0.72 ± 0.02% and 0.26 ± 0.19%, respectively. ... The crude fiber content (1.00 ± 0.09%) was close to the crude fiber levels reported previously for arrowroot starch (i.e. 0.03–1.50%) from Philipines, Brazil, India, and Venezuela [13,33,46,53].
   Heliyon, 2023 · checked 2026-09-29
3. arw-daily-r7-01 · food composition dataset
   Arrowroot, raw | Energy 65 KCAL per 100 g | Protein 4.24 G | Carbohydrate 13.39 G | Fiber 1.3 G | Folate, DFE 338 UG | Potassium 454 MG | Iron 2.22 MG | 1 cup, sliced 120 g
   USDA SR Legacy 2019, Arrowroot, raw (FDC 168490, NDB 11697) · checked 2026-09-29
4. arw-daily-r7-02 · food composition dataset
   Arrowroot flour | Energy 357 KCAL per 100 g | Carbohydrate 88.15 G | Protein 0.3 G | Fiber 3.4 G | Folate, DFE 7 UG | Potassium 11 MG | 1 cup 128 g
   USDA SR Legacy 2019, Arrowroot flour (FDC 170684, NDB 20003) · checked 2026-09-29
5. arwr-r7-02 · randomized controlled trial
   Bioavailability of food folate relative to that of folic acid was 78% (95% CI: 48%, 108%) according to [(13)C(11)]-labeled folate and 85% (52%, 118%) according to changes in serum folate concentrations.
   Am J Clin Nutr, 2007 · checked 2026-10-02
6. arwr-r7-03 · randomized controlled trial
   Both natural sources of folate were significantly less bioavailable than was folic acid. Overall estimations of folate bioavailability relative to that of folic acid were found to be between 30% (spinach) and 59% (yeast).
   Am J Clin Nutr, 2004 · checked 2026-10-02
7. arwr-r7-07 · USDA Table of Nutrient Retention Factors Release 6, dataset
   USDA Table of Nutrient Retention Factors Release 6 (2007) holds no method for arrowroot. PubMed corpus search for arrowroot with cooking, boiling, baking, frying, processing, storage, fermentation or retention returned only an unrelated Korean isoflavone survey (corpus pubmed:469385, 2026-10-02).
   USDA Table of Nutrient Retention Factors, Release 6 (2007) · checked 2026-10-02
8. arwr-r7-05 · case series
   Arrowroot reduced diarrhoea and had a long-term effect on constipation. It also eased abdominal pain.
   Arq Gastroenterol, 2000 · checked 2026-10-02
9. arw-daily-r7-04 · non-randomized controlled trial
   Patients enrolled during the subsequent 6 months constituted the intervention group and received 100 gm of arrowroot powder (commercially sourced and quality verified) mixed in water and added to their formula feeds for the first 5 days of enteral nutrition. ... Ninety-four patients were included in the analysis. Of these, 34 patients admitted between November 2024 and April 2025 received the intervention, while 60 patients admitted from August to October 2024 and May to June 2025 served as controls. ... The incidence of new-onset diarrhea after starting feeds (26.7 vs 8.8%, control vs intervention) demonstrated a relative risk reduction of 0.67 (relative risk: 0.33, 95% CI: 0.10–1.05; p = 0.059), did not attain statistical significance.
   Indian Journal of Critical Care Medicine, 2026 · checked 2026-09-29
10. arw-daily-r7-06 · nutrition survey
    The top five foods arrowroot, soybean paste, tofu, soybean, and soybean sprout contributed to 88.2% of isoflavone intake, with the corresponding intake from each food being 8.3 mg/day, 4.9 mg/day, 2.6 mg/day, 2.5 mg/day, and 2.0 mg/day, respectively.
    Int J Food Sci Nutr, 2006 · checked 2026-09-29
11. arwr-r7-08 · 21 CFR 101 and EU health claims register, dataset
    claims_search.py arrowroot / Maranta arundinacea: no entry in 21 CFR 101. euclaims_search.py arrowroot / Maranta arundinacea: no entry among 2,330 claims (EU register snapshot 2026-09-21).
    21 CFR 101 and EU Register on nutrition and health claims, snapshot 2026-09-21 · checked 2026-10-02