Potato flour: one school trial, a wide label spread and an allergy

The one trial of potato flour in healthy people gave 123 Chinese high-school students steamed bread made partly with potato flour once per school day for eight weeks. Against wheat bread it lowered insulin by 4.35 mIU/L and total cholesterol by 5 mg/dL (0.13 mmol/L), and it also raised systolic blood pressure by 4.6 mmHg and lowered HDL cholesterol by 2.7 mg/dL (0.07 mmol/L). Only four classes were randomized, the groups differed in their share of boys, and the paper gives two different flour ratios, so read those numbers as one uneven test. Potato flour is also a different product from raw potato starch. In 15 young men, 50 g of raw starch produced less than half the five-hour thermogenesis of cooked starch, 46.5 against 115.4 kJ. What a bag contains varies a lot. USDA gives 1,269 mg of potassium per 3.5 oz (100 g) on average, but its eight samples ran from 70.7 to 1,790 mg, and iron from 0 to 86.3 mg, a spread that suggests some products sold under this name are closer to starch. Potato is also an allergen for some young children: of 36 sensitized children aged 4 to 36 months, 17 had a proven allergy, 2 of them with anaphylaxis.

The numbers, per 3.5 oz (100 g)

How much is actually in it

• USDA lists potato flour at 1,269 mg potassium, 5.4 g fiber and 11.97 mg iron per 3.5 oz (100 g), but its eight samples ranged from 70.7 to 1,790 mg potassium and 0 to 86.3 mg iron. — — (n = 8 samples) Evidence E source
  Per 100 g: carbohydrate 79.9 g, potassium 1269 mg (samples 70.7-1790), iron 11.97 mg (0-86.3), fiber 5.4 g (0-6.93), magnesium 73.65 mg

What your body absorbs

• In an RCT of 85 Peruvian children aged 5 to 24 months with acute diarrhea, a home diet based on potato flour and milk gave energy absorption similar to soy formula and shortened diarrhea to 53 hours versus 154. — 85 Peruvian children aged 5-24 months with acute diarrhea, hospitalized (n = 85) Evidence B source
  Median diarrhea duration 53 h (potato-milk diet) vs 154 h (soy formula), p = 0.005; energy absorption similar

What cooking and storage change

• In a crossover trial of 13 volunteers, boiled potatoes that were frozen and thawed produced 186% more colonic fermentation than freshly boiled ones. — 13 healthy volunteers, 375 g potatoes (60 g starch) per test meal (n = 13) Evidence B source
  Breath hydrogen AUC +186% (P < 0.002) frozen-thawed vs fresh; +48% (P < 0.04) when reheated
• According to EFSA, drying peeled potato into flakes, granules or powder cut glycoalkaloid content by 29 to 67%. — — Evidence E source
  Glycoalkaloid reduction 29-67% for drying to flakes, granules or powder; peeling 25-75%
• A 2007 review found Bacillus cereus in 10 to 40% of dehydrated potato products, usually at fewer than 1,000 CFU per gram. — — Evidence C source
  Prevalence 10-40%, usually below 10^3 CFU/g; hazard above 10^4 CFU/g

What it does to your health

• In an 8-week cluster RCT of 123 adolescents, steamed bread made with cooked potato flour lowered insulin by 4.35 mIU/L and total cholesterol by 5 mg/dL (0.13 mmol/L) but raised systolic pressure by 4.6 mmHg versus wheat bread. — 123 Chinese high-school students (four classes randomized), 8 weeks, once per school day (n = 123) Evidence B source
  Net changes: SBP +4.6 mmHg (p = 0.010), insulin -4.35 mIU/L (p < 0.001), TC -0.13 mmol/L (p = 0.032), HDL-C -2.7 mg/dL (-0.07 mmol/L) (p = 0.010)

Safety, limits and interactions

• EFSA set 1 mg of potato glycoalkaloids per kg body weight a day as the lowest dose causing nausea, vomiting and diarrhea, and found no evidence of harm from long-term potato intake. — general population, acute exposure Evidence E source
  LOAEL 1 mg total glycoalkaloids/kg bw per day; health concern at P95 exposure in younger age groups
• A case report describes anaphylaxis in an 8-year-old boy with atopic dermatitis after eating potato starch, which still carried IgE-binding potato proteins. — one 8-year-old boy with atopic dermatitis (n = 1) Evidence D source
  Anaphylaxis requiring epinephrine; potato starch contained IgE-binding proteins

What people believe that the data does not support

• In a crossover trial of 15 young men, 50 g of raw potato starch (54% resistant starch) produced less than half the 5-hour thermogenesis of cooked starch, showing raw starch and cooked potato products behave differently. — 15 healthy normal-weight young men, single meals, crossover (n = 15) Evidence B source
  Thermogenesis 46.5 vs 115.4 kJ/5 h (P = 0.008); lower glucose oxidation, higher fat oxidation

Who this works differently for

• Among 36 sensitized young children, 17 had a confirmed allergy to cooked potato, mostly with eczema, and 80% later became tolerant. — 36 atopic children aged 4-36 months sensitized to potato; 17 with confirmed allergy (n = 36) Evidence C source
  Eczema 16/17, anaphylaxis 2/17; tolerance in 80% at 16-102 months

What is still unknown

• EFSA found that the human data cannot show whether children or people with inflammatory bowel disease are more sensitive to potato glycoalkaloids. — children, people with inflammatory bowel disease Evidence E source
  No data

The bottom line

The oldest trial is from Peru in 1991. In 85 hospitalized children aged 5 to 24 months with acute diarrhea, a diet of potato flour with milk, carrot flour, sugar and oil cut median diarrhea to 53 hours against 154 on soy formula, with similar energy absorption. It was a mixed diet, so the effect cannot be pinned on the flour, and it was given in hospital, so it is not a guide to treating a child with diarrhea at home. Cooling changes potato starch. In 13 volunteers, boiled potatoes that had been frozen and thawed produced 186% more fermentation in the colon than freshly boiled ones. That was whole potato, and nobody has run the test on flour. Potatoes contain glycoalkaloids, natural toxins that cause nausea, vomiting and diarrhea at 1 mg per kg of body weight a day or more, according to EFSA, which found no evidence of harm from eating potatoes over the long term, though it flagged a health concern for the highest-eating 5% of younger age groups. Drying peeled potato into flakes, granules or powder cut glycoalkaloids by 29 to 67%, varying with variety and method. EFSA also says the human data cannot show whether children or people with inflammatory bowel disease are more sensitive. Dehydrated potato products carried Bacillus cereus in 10 to 40% of samples, usually below 1,000 per gram, according to a 2007 review of potato flakes rather than flour. Allergy is the clearest caution. Among 36 young children with eczema-prone skin who were sensitized to potato, 17 had a proven allergy, 16 of them with eczema and 2 with anaphylaxis, and most of them were already allergic to cow milk. An 8-year-old boy with atopic dermatitis needed adrenaline after eating potato starch, a single case showing that refined potato products can still carry the allergen. We have no cards on pregnancy or on interactions with medicines.

Sources

1. ptfl-daily-r3-01 · USDA FoodData Central Foundation Foods, dataset
   Flour, potato (FDC 2261422, Foundation, Vegetables and Vegetable Products): carbohydrate 79.942 g; potassium 1269 mg, samples 70.7-1790 n=8; iron 11.97 mg, samples 0-86.3 n=8; fibre 5.401 g, samples 0-6.93 n=8; magnesium 73.65 mg, samples 2.545-96.6 n=8; per 100 g; CoFID match none
   USDA FoodData Central, Foundation Foods, Flour, potato, FDC 2261422 · checked 2026-09-29
2. ptfl-daily-r3-03 · RCT
   The estimated median durations of diarrhea in the WP group (52 h) and PM group (53 h) were significantly less than in the SF group (154 h, p = 0.005). Energy intakes, energy absorption, and nitrogen retention (% of intake) were generally similar in all dietary groups, although there were minor differences in the absorption of specific macronutrients.
   J Pediatr Gastroenterol Nutr, 1991 · checked 2026-09-29
3. ptfl-daily-r3-05 · RCT
   The extent of colonic carbohydrate fermentation (AUC = area under the breath H2 concentration vs time curve) in experiment B was significantly higher (+186%, P less than 0.002) than in experiment A. The breath hydrogen AUC in experiment C was higher than in experiment A (+48%, P less than 0.04) but lower than in experiment B (-94%, P less than 0.003).
   Dig Dis Sci, 1991 · checked 2026-09-29
4. ptfl-daily-r3-07 · agency risk assessment
   In general, drying of peeled potato and final processing to flakes, granules or powder led to a reduction of the GA content by 29–67%.
   EFSA Journal, 2020 · checked 2026-09-29
5. ptfl-daily-r3-11 · prevalence review
   Dehydrated potato contains Bacillus cereus at a prevalences of 10 to 40% and at numbers usually less than 10(3) CFU g(-1).
   J Food Prot, 2007 · checked 2026-09-29
6. ptfl-daily-r3-02 · RCT
   Compared with the control group, the intervention group had significant net changes in systolic blood pressure (4.6 mmHg, p = 0.010), insulin (-4.35 mIU/L, p < 0.001), total cholesterol (-0.13 mmol/L, p = 0.032), and high-density lipoproteins cholesterol (-0.07 mmol/L, p = 0.010).
   Int J Environ Res Public Health, 2020 · checked 2026-09-29
7. ptfl-daily-r3-06 · agency risk assessment
   In humans, acute toxic effects of potato GAs (α-solanine and α-chaconine) include gastrointestinal symptoms such as nausea, vomiting and diarrhoea. For these effects, the CONTAM Panel identified a lowest-observed-adverse-effect level of 1 mg total potato GAs/kg body weight (bw) per day as a reference point for the risk characterisation following acute exposure. In humans, no evidence of health problems associated with repeated or long-term intake of GAs via potatoes has been identified.
   EFSA Journal, 2020 · checked 2026-09-29
8. ptfl-daily-r3-10 · case report
   At this age, he developed anaphylaxis after consuming potato starch and required administration of intramuscular epinephrine. He tested positive for potato-specific immunoglobulin E, skin prick test, and basophil activation test.
   Asia Pac Allergy, 2021 · checked 2026-09-29
9. ptfl-daily-r3-04 · RCT
   we measured 5-h postprandial thermogenesis and substrate oxidation by indirect calorimetry after ingestion of 50 g pregelatinized (0% RS) and 50 g raw potato starch (54% type II RS) in 15 healthy, normal-weight young males. The subjects consumed each starch (mixed in diluted fruit syrup) twice on separate days and in random order. RS intake was followed by lower thermogenesis (46.5 +/- 13.1 compared with 115.4 +/- 10.4 kJ/5 h; P = 0.008), lower glucose oxidation (P < 0.0005), and greater fat oxidation (P = 0.013) than was pregelatinized starch consumption.
   Am J Clin Nutr, 1995 · checked 2026-09-29
10. ptfl-daily-r3-09 · case-control
    Presenting symptoms in children with proven potato allergy (n = 17) were eczema (16 of 17), gastrointestinal complaints (eight of 17), urticaria and/or angioedema (five of 17), wheezing/rhinitis (three of 17) and anaphylaxis (two of 17). Fifteen children had previously diagnosed cow's milk protein allergy and were egg-sensitized.
    Allergy, 2007 · checked 2026-09-29
11. ptfl-daily-r3-08 · agency risk assessment
    The available human data do not allow to draw conclusions if children or other subgroups of the population, such as individuals with inflammatory bowel diseases, may be more susceptible to adverse effects associated with potato GAs than others.
    EFSA Journal, 2020 · checked 2026-09-29