Potato and tomato: trials for one, cohorts for the other

According to a meta-analysis of 21 intervention trials in adults, tomato products lowered LDL cholesterol by 8.5 mg/dL (0.22 mmol/L) and improved flow-mediated dilation, a measure of blood vessel function, by 2.53%. The abstract does not say every trial was randomized, the products ranged from whole tomato to lycopene, and both outcomes are markers. In 11 randomized trials in adults with overweight or obesity, tomato interventions, extracts among them, trimmed waist circumference by 0.45 in (95% CI -0.89 to -0.02; metric: 1.15 cm, -2.27 to -0.04) with no consistent change in body weight. Potatoes have no trial like that here. Their evidence comes from cohorts, and it splits by cooking method. In three US cohorts of 205107 people, every 3 weekly servings of French fries went with a 20% higher rate of type 2 diabetes (HR 1.20, 1.12 to 1.28). Baked, boiled or mashed potatoes showed no association (HR 1.01, 0.98 to 1.05). These are associations from food questionnaires, open to confounding by overall diet quality. We found no study that compared potatoes with tomatoes directly.

How much is actually in it

• USDA Foundation Foods measured potassium of 427 to 516 mg and vitamin C of 14.2 to 29.6 mg per 3.5 oz (100 g) across 8 samples of raw red potatoes, and russet potatoes averaged only 10.9 mg vitamin C. — 8 samples per potato type, raw without skin (n = 8) Evidence E source
  Red potato K 472 mg (427-516), vitamin C 21.3 mg (14.2-29.6), russet vitamin C 10.9 mg (7.44-19.8)
• USDA Foundation Foods found 1827 to 4345 ug lycopene and 12.3 to 25.9 mg vitamin C per 3.5 oz (100 g) across 8 roma tomatoes, while canned crushed tomatoes averaged 9.1 mg vitamin C. — 8 samples of raw roma tomatoes, 8 of canned crushed tomatoes (n = 8) Evidence E source
  Lycopene 2863 ug (1827-4345), vitamin C 17.75 mg raw vs 9.1 mg canned crushed

What a real portion looks like

• According to the NIH Office of Dietary Supplements, potatoes are among the top sources of potassium for US adults and children. — US adults and children Evidence E source
  Top dietary source ranking
• In FNDDS a medium baked potato weighs 10 oz (285 g) and a large one 400 g, while a whole raw tomato weighs 4.4 oz (125 g) and a cup of tomato 180 g. — US dietary survey portion database Evidence E source
  Portion weights in grams

What your body absorbs

• In 28 iron-deficient Peruvian women, iron-biofortified potatoes delivered 0.35 mg absorbed iron per 460 g meal against 0.24 mg from a regular variety, although fractional absorption was lower (12.1% vs 16.6%). — 28 young women with low iron stores, Peruvian highlands, 10 meals of each potato (n = 28) Evidence B source
  Total iron absorbed 0.35 vs 0.24 mg per 460 g meal, fractional absorption 12.1% vs 16.6%
• In 37 women eating 18 oz (500 g) of potato, zinc-biofortified potatoes gave 0.49 mg absorbed zinc against 0.40 mg from regular potatoes, with fractional absorption of 20.8% vs 25.5%. — 37 women aged 18-45, Peruvian highlands, 500 g boiled potato (n = 37) Evidence B source
  Total zinc absorbed 0.49 vs 0.40 mg/500 g, fractional 20.8% vs 25.5%
• In 11 volunteers, 26 oz (750 g) of unheated tomato juice with added olive oil raised all plasma lycopene isomers, while the same juice without oil did not. — 11 healthy volunteers, single intake of 750 g tomato juice per 70 kg with or without 10% refined olive oil (n = 11) Evidence B source
  All lycopene isomers rose significantly with oil, peak at 24 h
• In 33 men before prostatectomy, daily tomato soup, sauce or vegetable juice raised plasma lycopene by 66%, 71% and 59%, and prostate lycopene was 3.5 and 3.6 fold higher after soup and sauce. — 33 men scheduled for prostatectomy, 25-35 mg lycopene per day from tomato products vs lycopene-restricted diet (n = 33) Evidence B source
  Plasma lycopene +66% soup, +71% sauce, +59% juice, control -24%

What cooking and storage change

• In three US cohorts every 3 weekly servings of French fries went with a 20% higher type 2 diabetes rate, while baked, boiled or mashed potatoes showed no association. — 205107 US nurses and health professionals free of diabetes, CVD and cancer, followed 1984-2021 (n = 205107) Evidence C source
  HR 1.20 (1.12 to 1.28) per 3 servings/week French fries, HR 1.01 (0.98 to 1.05) baked/boiled/mashed
• Across seven cohorts total potato intake was not linked to cardiovascular disease, but 1 or more weekly servings of fried potatoes went with a 10% higher risk of hypertension. — 110063 adults in seven prospective cohorts for CVD and 67146 in five for hypertension (n = 110063) Evidence C source
  CVD HR 0.96 (0.89-1.04) for 5+ servings/week, hypertension +10% (95% CI 4% to 17%) for fried potatoes
• USDA retention factors predict potatoes boiled in their skin keep 75% of vitamin C, 80% of thiamin and 90% of potassium, while boiled or baked tomatoes keep 95% of vitamin C but only 70% of folate. — USDA group factors for vegetables Evidence E source
  Potato boiled in skin: vitamin C 75%, thiamin 80%, K 90%; tomatoes boiled/baked: vitamin C 95%, folate 70%

What it does to your health

• According to a meta-analysis of 21 intervention trials, tomato products lowered LDL cholesterol by 8.5 mg/dL (0.22 mmol/L) and improved flow-mediated dilation by 2.53% in adults. — adults over 18 in 21 intervention trials of tomato products or lycopene (n = 21 trials) Evidence B source
  LDL-C -8.5 mg/dL (-0.22 mmol/L), IL-6 SMD -0.25, FMD +2.53%
• Observational data from 103 studies link fried potato intake with a 16% higher diabetes risk, while total potato intake was not associated with hypertension, diabetes or cardiovascular disease. — 51 articles (103 observational studies) (n = 103 studies) Evidence C source
  Fried potatoes and diabetes RR 1.16 (1.04, 1.30), total potatoes and CVD RR 0.97 (0.91, 1.03)
• Prospective studies link higher total tomato intake with 11% lower cancer mortality, pooled across a dose-response meta-analysis of 119 studies. — adults in 121 prospective studies, follow-up 2-32 years (n = 119 studies) Evidence C source
  Cancer mortality RR 0.89 (0.85-0.93), I2 65.7%
• In the EPIC cohort of 341519 adults, the highest quartile of potato intake went with a 51% higher risk of ulcerative colitis over a median 13.4 years. — 341519 adults in EPIC, median follow-up 13.4 years, 379 UC cases (n = 341519) Evidence C source
  AHR 1.51 (95% CI 1.05-2.17), fourth vs first quartile

Safety, limits and interactions

• Adding 500 mg calcium carbonate to a tomato paste meal cut lycopene bioavailability by 83% in 10 healthy adults. — 10 healthy adults, test meal with 19 mg lycopene from tomato paste, 7 h postprandial (n = 10) Evidence B source
  Lycopene bioavailability -83% with calcium
• EFSA set 1 mg of potato glycoalkaloids per kg body weight a day as the lowest level causing acute gut symptoms and found a health concern for young age groups at high exposure, while tomato glycoalkaloid risk could not be characterized. — EU consumers, all age groups Evidence E source
  LOAEL 1 mg total potato glycoalkaloids/kg bw per day (acute)

What people believe that the data does not support

• The EU register holds no authorized claim for potato and refused the claim that a potato extract reduces body weight in overweight people. — EU labeling Evidence E source
  0 authorized, 4 non-authorized potato claims
• The EU register holds no authorized claim for tomato and refused the claim that tomato extract with lycopene helps maintain prostate health. — EU labeling Evidence E source
  0 authorized, 16 non-authorized tomato claims
• The EU also refused the claim that lycopene from tomato extract protects cells and DNA as an antioxidant. — EU labeling Evidence E source
  Non-authorized claim

Who this works differently for

• According to a meta-analysis of 11 RCTs in people with overweight or obesity, tomato-based interventions cut waist circumference by 0.45 in (1.15 cm) with no consistent effect on body weight or BMI. — adults with mean BMI 25 or more, 11 RCTs of tomatoes, tomato products or extracts (n = 11 RCTs) Evidence A source
  Waist MD -0.45 in (95% CI -0.89 to -0.02; metric: -1.153 cm, -2.27 to -0.04)

What is still unknown

• A scoping review found only 12 original studies on how industrial processing changes tomato nutrients, with inconsistent results and no simple answer on processed versus fresh. — 12 original research papers on industrial tomato processing (n = 12 studies) Evidence D source
  Direction depends on compound and process

The bottom line

Seven other cohorts, 110063 adults, found no link between total potato intake and cardiovascular disease, while 1 or more weekly servings of fried potatoes went with a 10% higher risk of hypertension (95% CI 4% to 17%). A pooled analysis of 103 observational studies linked fried potatoes to a 16% higher diabetes risk (RR 1.16, 1.04 to 1.30). The EPIC cohort of 341519 adults found the top quarter of potato eaters had a 51% higher risk of ulcerative colitis (95% CI 1.05 to 2.17), based on 379 cases and one of many foods compared. For tomatoes, a dose-response meta-analysis of prospective studies linked higher intake with 11% lower cancer mortality (RR 0.89, 0.85 to 0.93), with substantial heterogeneity between studies. Raw red potatoes held 427 to 516 mg potassium and 14.2 to 29.6 mg vitamin C per 3.5 oz (100 g) across 8 US samples, and russets averaged 10.9 mg vitamin C. The NIH Office of Dietary Supplements lists potatoes among the top potassium sources for US adults and children. A medium baked potato weighs 10 oz (285 g) in the US survey database and a whole raw tomato 125 g. Roma tomatoes carried 1827 to 4345 mcg lycopene per 3.5 oz (100 g). Canned crushed tomatoes averaged 9.1 mg vitamin C against 17.75 mg in raw roma, measured on different samples. USDA factors from 1975 predict that potatoes boiled in their skin keep 75% of vitamin C and 90% of potassium, and that boiled or baked tomatoes keep 95% of vitamin C and 70% of folate. On industrial tomato processing, a scoping review found only 12 laboratory studies with inconsistent results, so fresh against processed has no simple answer yet. Oil in the meal mattered in one small trial. In 11 volunteers, 26 oz (750 g) of unheated tomato juice with olive oil raised every plasma lycopene isomer and the same juice without oil did not, with no size given. In 33 men awaiting prostate surgery, daily tomato soup, sauce or vegetable juice raised plasma lycopene by 66%, 71% and 59%. Biofortified potato clones bred for the question delivered more total iron and zinc than a regular variety to women in the Peruvian highlands. Women with low iron stores absorbed 0.35 against 0.24 mg iron per 460 g meal (28 women), and 37 women absorbed 0.49 against 0.40 mg zinc per 500 g. The share absorbed was lower from the biofortified potatoes in both trials. The EU refused a potato extract claim on body weight, a tomato extract claim on prostate health, and a claim that lycopene from tomato extract protects cells and DNA. A refusal means the evidence fell short at assessment. Who should be careful. EFSA set 1 mg of potato glycoalkaloids per kg body weight a day as the lowest level seen to cause acute nausea, vomiting and diarrhea, and found a health concern for younger age groups at the highest exposures. For tomato glycoalkaloids it could not characterize the risk, for lack of occurrence data. If you take calcium supplements, one trial in 10 healthy adults found 500 mg calcium carbonate with a tomato paste meal cut lycopene bioavailability by 83%. We have no card on allergy, pregnancy or medicines for either food.

Sources

1. pvt-r3-16 · composition dataset
   Potatoes, red, without skin, raw | Potassium, K 472.0 MG range 427.0-516.0 n=8 | Vitamin C 21.29 MG range 14.2-29.6 n=8 || Potatoes, russet, without skin, raw | Vitamin C 10.9 MG range 7.44-19.8 n=8
   USDA FoodData Central, Foundation Foods, release 2026-04-30 · checked 2026-09-28
2. pvt-r3-17 · composition dataset
   Tomato, roma | Lycopene 2863.0 UG range 1827.0-4345.0 n=8 | Vitamin C 17.75 MG range 12.3-25.9 n=8 || Tomatoes, crushed, canned | Vitamin C 9.1 MG range 3.2-15.0 n=8
   USDA FoodData Central, Foundation Foods, release 2026-04-30 · checked 2026-09-28
3. pvt-r3-15 · agency fact sheet
   Milk, coffee, tea, other nonalcoholic beverages, and potatoes are the top sources of potassium in the diets of U.S. adults [14]. Among children in the United States, milk, fruit juice, potatoes, and fruit are the top sources [15].
   NIH ODS, Potassium Fact Sheet for Health Professionals · checked 2026-09-28
4. pvt-r3-19 · portion dataset
   Potato, baked, NFS | 1 small 230 g | 1 medium 285 g | 1 large 400 g | 1 cup 130 g || Tomatoes, raw | 1 whole 125 g | 1 cup 180 g | 1 slice 20 g | 1 cherry 17 g
   USDA FNDDS, fdc_id 2709383 and 2709719 · checked 2026-09-28
5. pvt-r3-08 · RCT crossover
   Geometric mean (95% CI) fractional iron absorption from the iron-biofortified clone and the nonbiofortified variety were 12.1% (10.3%-14.2%) and 16.6% (14.0%-19.6%), respectively (P < 0.001). Total iron absorption from the iron-biofortified clone and the nonbiofortified variety were 0.35 mg (0.30-0.41 mg) and 0.24 mg (0.20-0.28 mg) per 460 g meal, respectively (P < 0.001).
   J Nutr, 2023 · checked 2026-09-28
6. pvt-r3-09 · RCT crossover
   in which 37 women consumed 500-g biofortified or regular potatoes twice a day...Mean fractional zinc absorption (FZA) from the biofortified potatoes was lower than from the regular potatoes, 20.8% (SD: 5.4%) and 25.5% (SD: 7.0%), respectively (P < 0.01). However, total zinc absorbed was significantly higher (0.49; SD: 0.13 and 0.40; SD: 0.11 mg/500 g, P < 0.01, respectively).
   J Nutr, 2023 · checked 2026-09-28
7. pvt-r3-11 · RCT crossover
   eleven healthy volunteers were assigned to receive a single ingestion of 750g of tomato juice (TJ) containing 10% of refined olive oil/70kg body weight (BW) and 750g of TJ without oil/70kg BW on two different days. All lycopene isomers increased significantly in subjects consuming TJ with oil, reaching the maximum concentration at 24h.
   Food Chem, 2015 · checked 2026-09-28
8. pvt-r3-12 · RCT
   Tomato soup, sauce and juice consumption significantly increased plasma lycopene concentration from 0·68 (sem 0·1) to 1·13 (sem 0·09) μmol/l (66 %), 0·48 (sem 0·09) to 0·82 (sem 0·12) μmol/l (71 %) and 0·49 (sem 0·12) to 0·78 (sem 0·1) μmol/l (59 %), respectively
   Br J Nutr, 2015 · checked 2026-09-28
9. pvt-r3-03 · cohort
   For every increment of three servings weekly of total potato, the rate for T2D increased by 5% (hazard ratio 1.05, 95% confidence interval (CI) 1.02 to 1.08) and for every increment of three servings weekly of French fries the rate increased by 20% (1.20, 1.12 to 1.28). Intake of combined baked, boiled, or mashed potatoes was not significantly associated with T2D risk (pooled hazard ratio 1.01, 95% CI 0.98 to 1.05).
   BMJ, 2025 · checked 2026-09-28
10. pvt-r3-04 · cohort meta-analysis
    total potato intake was not associated with the risk of either CVD or HTN: multivariable adjusted HR (95% CI) comparing 5+ servings/week to no potato intake: 0.96 (0.89-1.04) for CVD and 1.04 (0.99-1.08) for HTN...while fried potato consumption was not associated with CVD risk, there was a 10% higher risk of HTN (95% CI: 4% to 17%) comparing 1+ servings/week to no fried potato intake.
    Nutrients, 2025 · checked 2026-09-28
11. pvt-r3-18 · retention dataset
    USDA-RETN-R6:3307 POTATOES,BOILED IN SKIN | vitamin_c_mg 75% | thiamin_mg 80% | potassium_mg 90% | folate_total_ug 90% || USDA-RETN-R6:3751 TOMATOES,BOILED/BAKED | folate_total_ug 70% | vitamin_c_mg 95% | thiamin_mg 95%
    USDA Table of Nutrient Retention Factors, Release 6 (2007) · checked 2026-09-28
12. pvt-r3-01 · meta-analysis
    Out of 1189 publications identified, 21 fulfilled inclusion criteria and were meta-analysed. Overall, interventions supplementing tomato were associated with significant reductions in LDL-cholesterol (-0.22 mmol/L; p = 0.006), IL-6 (standardised mean difference -0.25; p = 0.03), and improvements in FMD (2.53%; p = 0.01)
    Atherosclerosis, 2017 · checked 2026-09-28
13. pvt-r3-05 · meta-analysis of observational studies
    Fifty-one articles (103 studies) were identified in the current meta-analysis...fried potato intake was not associated with overweight/obesity (1.24; 95% CI: 0.90, 1.70) or GDM (1.03; 95% CI: 0.97, 1.09) but was significantly associated with increased diabetes risk (1.16; 95% CI: 1.04, 1.30)
    Nutr Rev, 2025 · checked 2026-09-28
14. pvt-r3-06 · cohort meta-analysis
    In total, 121 prospective studies were included in the systematic review and 119 in the meta-analysis...Regarding cancer mortality, negative relationships were found with total tomato intake (Pooled RR: 0.89, 95% CI: 0.85-0.93, I2 = 65.7%, p < 0.001)
    Front Nutr, 2025 · checked 2026-09-28
15. pvt-r3-07 · cohort
    In total, 341,519 individuals were followed prospectively. Among them, 149 developed CD and 379 developed UC after a median follow-up of 13.4 years...A higher risk of UC was observed with high intakes of potatoes (fourth vs first quartile aHR 1.51; 95% CI: 1.05-2.17).
    Am J Gastroenterol, 2026 · checked 2026-09-28
16. pvt-r3-10 · RCT crossover
    in a randomised, two-way cross-over study, ten healthy adults consumed either a test meal that provided 19-mg (all-E)-LYC from tomato paste or the same meal plus 500-mg calcium carbonate as a supplement...LYC bioavailability was diminished by 83 % following the addition of Ca in the test meal.
    Br J Nutr, 2016 · checked 2026-09-28
17. pvt-r3-14 · 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...The MOEs for the younger age groups indicate a health concern for the food consumption surveys with the highest mean exposure, as well as for the P95 exposure in all surveys...For tomato and aubergine GAs, the risk to human health could not be characterised due to the lack of occurrence data and the limited toxicity data.
    EFSA CONTAM Panel, Risk assessment of glycoalkaloids in feed and food, EFSA Journal 2020, doi 10.2903/j.efsa.2020.6222, PMID 32788943 · checked 2026-09-28
18. pvt-r3-20 · regulatory decision
    POL-HC-8425 Slendesta® Potato Extract Slendesta® contributes to the reduction of body weight in overweight individuals -/- Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-8425, snapshot 2026-09-21 · checked 2026-09-28
19. pvt-r3-21 · regulatory decision
    POL-HC-8037 Tomato extract containing lycopene Helps to maintain normal prostate health. Helps to maintain a healthy prostate. Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-8037, snapshot 2026-09-21 · checked 2026-09-28
20. pvt-r3-22 · regulatory decision
    POL-HC-7531 Lycopene (from Tomato extract) lycopene is an antioxidant and helps to protect the body’s cells/helps to maintain intact body cells. Lycopene or a diet rich in lycopene helps to maintain intact cell DNA/contributes to healthy ageing by maintaining intact cell DNA/ Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-7531, snapshot 2026-09-21 · checked 2026-09-28
21. pvt-r3-02 · meta-analysis of RCTs
    Forty-seven studies met the inclusion criteria: 11 clinical trials (RCTs), 5 epidemiological studies, and 31 preclinical studies. In the RCTs, tomato-based interventions produced a small but significant reduction in waist circumference (MD: -1.153 cm, 95% CI: -2.27 to -0.04, p = 0.0432), with no consistent effects on body weight or BMI.
    Food Funct, 2026 · checked 2026-09-28
22. pvt-r3-13 · scoping review
    Twelve original research papers were found to study the effects of different industrial processing methods on the nutrients and/or bioactive compounds in tomato products. The data suggested that different processing methods had different effects on different compounds in tomatoes. However, currently available data are still limited, and the existing data are often inconsistent.
    Adv Nutr, 2022 · checked 2026-09-28