Vegetables: small effects, measured honestly

Almost everything said about vegetables comes from studies that watched what people ate. The trials that actually fed them tell a quieter story. Across 133 randomised trials, vegetables improved blood vessel function by 1.37 percentage points of flow-mediated dilation, and tea did more than twice as much. In eight trials in people who already had metabolic syndrome, adding fruit and vegetables moved diastolic blood pressure a little and left waist, systolic pressure, glucose, HDL and triglycerides where they were. The WHO figure of 400 g a day was picked as an amount most people could reach. Benefit in the observational data kept rising to 800 g. Europe has authorised none of the 20 health claims submitted about vegetables, including the plain one about heart health.

The numbers, per 100 g

What a real portion looks like

• The WHO figure of 400 g of vegetables and fruit a day marks the amount the WHO judged most people could actually reach. Benefit kept growing above it. — adults; intakes for children and adolescents extrapolated from adult values by energy intake because the evidence in children was insufficient Evidence E source
  Risk of all outcomes except cancer kept falling up to 800 g a day, with the steepest fall up to 400 g; 400 g was chosen as a feasible minimum rather than an optimum; recommendation graded strong

What your body absorbs

• Carotenoids from vegetables need fat to be absorbed, and unsaturated fat moves about three times more of them into the blood than saturated fat does. — 27 in vitro studies and 12 randomised controlled trials in humans (n = 39 studies) Evidence A source
  Bioavailability of carotenoids rose with the amount of fat eaten alongside; fats rich in unsaturated fatty acids gave a standardised mean difference of 0.90 (95% CI 0.69-1.11) against 0.27 (95% CI 0.08-0.47) for fats rich in saturated fatty acids; in vitro bioaccessibility rose with fat concentration for every carotenoid except lycopene
• Adding cooked egg to a raw vegetable salad raised how much vitamin E the body took up from the vegetables themselves. — 16 healthy young men, mean age 24 years, mean BMI 24, eating the same salad with 3 g canola oil plus no egg, 75 g cooked egg or 150 g cooked egg (n = 16) Evidence B source
  Alpha-tocopherol area under the curve over 10 hours in triacylglycerol-rich lipoproteins was 981 nmol/L per 10 h with 150 g of egg against 117 without egg; gamma-tocopherol 402 against 72; the 75 g arm did not differ from no egg

What it does to your health

• In trials that actually fed people vegetables, blood vessel function improved by 1.37 percentage points of flow-mediated dilation, and the authors rate their own certainty as moderate to low. — adults in 133 trials: 102 whole-food interventions across 14 food groups and 31 dietary-pattern interventions across 11 patterns (n = 133 trials) Evidence A source
  Vegetables improved fasting brachial artery flow-mediated dilation by 1.37% (95% CI 0.34, 2.40); fruits 0.86% (0.16, 1.55); tea 3.22% (2.01, 4.42), the largest of all; Mediterranean diet 2.32% (1.86, 2.78); weight loss below 10% of body weight changed nothing

What people believe that the data does not support

• Europe refused permission to say that a vegetable-rich diet promotes heart health, and that refusal is about the strength of the dossier rather than proof that vegetables do nothing. — — Evidence E source
  Status Non-authorised; of 20 claims in the register mentioning vegetables, 0 are authorised and 20 are rejected
• The wider claim about fruit and vegetables together and the cardiovascular system was refused as well, so the gap is not about wording alone. — — Evidence E source
  Status Non-authorised

Who this works differently for

• For people who already have metabolic syndrome, adding fruit and vegetables moved diastolic blood pressure and nothing else: waist, systolic pressure, glucose, HDL and triglycerides all stayed where they were. — 396 adults with metabolic syndrome in 8 randomised controlled trials, 205 in intervention arms and 191 in control arms (n = 396) Evidence A source
  Diastolic blood pressure standardised mean difference -0.29 (95% CI -0.57 to -0.02, p = 0.04); no effect on waist circumference, systolic blood pressure, fasting glucose, HDL cholesterol or triglycerides; no difference by intervention period or provision type
• Among people with type 2 diabetes, those eating the most vegetables died less often over follow-up, and the observational design means the link is not proof of cause. — 75 082 adults with type 2 diabetes in 9 prospective cohorts, 7590 deaths (n = 75082) Evidence C source
  Highest vegetable intake against lowest: all-cause mortality hazard ratio 0.85 (95% CI 0.73-0.98, 6 studies) and cardiovascular mortality 0.97 (95% CI 0.94-0.99, 2 studies); highest fruit intake 0.82 (0.75-0.90) and 0.90 (0.84-0.97); an extra 200 g a day of fruit and vegetables went with 26% and 14% lower all-cause mortality

The bottom line

The most useful thing here is not about which vegetable. It is about what sits on the plate next to it. Carotenoids need fat to be absorbed, and unsaturated fat moved about three times more of them into the blood than saturated fat in a pooled analysis of 12 trials. In one crossover trial, 150 g of cooked egg added to a raw vegetable salad raised the vitamin E taken up from that salad several times over, while 75 g did nothing. A fat-free salad is a different meal, not a lighter version of the same one. Cooking matters in the other direction: by the USDA retention table, greens boiled in plenty of water keep about 55 percent of their vitamin C, and about 60 percent when boiled in little water. And the number on any single vegetable is a median, not a property. Raw broccoli in the USDA Foundation dataset ranged from 15 to 182 micrograms of folate per 100 g across eight samples.

Sources

1. veg-dr-06 · WHO guideline
   The threshold of at least 400 g of vegetables and fruits per day was selected because a dose–response relationship was observed in the observational studies: risk for all outcomes except cancer decreased with intakes of vegetables and fruits up to 800 g per day, and the greater the intake, the greater the benefit.
   WHO guideline: Carbohydrate intake for adults and children, 2023 · checked 2026-09-22
2. veg-dr-03 · systematic review and meta-analysis of in vitro studies and randomised controlled trials
   The meta-analysis of RCTs showed that the bioavailability of carotenoids was enhanced when a higher quantity of dietary fats was co-consumed. Moreover, fats rich in unsaturated fatty acids resulted in greater improvement in carotenoid bioavailability (SMD 0.90; 95%CI, 0.69-1.11) as compared with fats rich in saturated fatty acids (SMD 0.27; 95%CI, 0.08-0.47).
   Nutr Rev, 2022 · checked 2026-09-22
3. veg-dr-04 · randomised crossover trial
   The consumption of cooked whole eggs is an effective way to increase the absorption of α-tocopherol and γ-tocopherol from a co-consumed meal that naturally contains vitamin E, such as a raw mixed-vegetable salad, in healthy young men.
   J Nutr, 2016 · checked 2026-09-22
4. veg-dr-01 · systematic review and meta-analysis of randomised controlled trials
   There were 133 studies included: 102 whole food interventions comparing 14 food groups and 31 dietary interventions comparing 11 diet patterns...vegetables (MD: 1.37%; 95% CI: 0.34%, 2.40%)
   Am J Clin Nutr, 2025 · checked 2026-09-22
5. veg-dr-07 · regulatory register entry
   POL-HC-8052 Vegetable-rich diet Diets rich in vegetables promote heart health. Non-authorised
   EU Register on nutrition and health claims, заява POL-HC-8052, знімок 2026-09-21 · checked 2026-09-22
6. veg-dr-08 · regulatory register entry
   POL-HC-7147 Fruits and vegetables Regular consumption of fruit and vegetables support the heart and cardiovascular health. Non-authorised
   EU Register on nutrition and health claims, заява POL-HC-7147, знімок 2026-09-21 · checked 2026-09-22
7. veg-dr-02 · systematic review and meta-analysis of randomised controlled trials
   Fruit and vegetable intake was associated with a reduction in diastolic blood pressure (standardized mean difference: -0.29; 95% confidence interval: -0.57 to -0.02; p = 0.04); however, such intake did not affect waist circumference, systolic blood pressure, fasting glucose, high-density lipoprotein cholesterol, and triglyceride levels in metabolic syndrome patients.
   Int J Food Sci Nutr, 2015 · checked 2026-09-22
8. veg-dr-05 · dose-response meta-analysis of prospective cohort studies
   The highest vegetable intake was also related to reduced all-cause (HR: 0.85; 95% CI: 0.73, 0.98; n = 6) and CVD (HR: 0.97; 95% CI: 0.94, 0.99; n = 2) mortality risk. An additional 200 g/day of fruit and vegetable consumption was associated with a 26% and 14% lower risk of all-cause mortality.
   Nutr Rev, 2025 · checked 2026-09-22