Blackberries and blueberries: one has the trials, the other has the vitamin C

The firmest result on this page belongs to blueberries alone. A meta-analysis of 14 randomized trials in 632 healthy people found that blueberries improved flow-mediated dilation, a measure of how well arteries widen, by 1.11 percent (95% CI 0.50 to 1.72), with doses and forms of blueberry differing from trial to trial. The same trials found no change in blood pressure. In people with cardiometabolic disease, 17 studies of blueberry or cranberry pooled together showed a drop in systolic pressure of 0.81 mmHg that did not reach significance (95% CI from a fall of 2.26 to a rise of 0.63). We found no human trial of blackberries on their own, so every health finding here is about blueberries. On the plate the order flips. Across 8 USDA samples of each, raw blackberries held 15.4 mg of vitamin C per 3.5 oz (100 g) against 8.1 mg for blueberries, whose samples ranged widely, from 4.3 to 11.1 mg. UK tables give blackberries 27 calories, 3.4 g fiber and 5.6 g sugars per 3.5 oz (100 g) and blueberries 40 calories, 1.5 g fiber and 9.1 g sugars, using a fiber method that reads lower than the USDA one.

How much is actually in it

• Raw blackberries averaged about twice the vitamin C of raw blueberries across 8 USDA samples each: 15.4 vs 8.1 mg per 3.5 oz (100 g). — Blackberries, raw and Blueberries, raw; 8 analyzed samples each (n = 16) Evidence E source
  Vitamin C blackberries 15.4 mg (11.3-19.8) vs blueberries 8.059 mg (4.295-11.1); blackberry fiber 5.3 g (3.9-6.1); potassium 167.4 vs 85.64 mg
• Per 100 g, UK data give blackberries 27 calories, 3.4 g fiber and 5.6 g sugars, against 40 calories, 1.5 g fiber and 9.1 g sugars for blueberries. — CoFID codes 14-388 (Blackberries, raw) and 14-325 (Blueberries) (n = -) Evidence E source
  Blackberries 27 calories, AOAC fiber 3.4 g, sugars 5.6 g; blueberries 40 calories, AOAC fiber 1.5 g, sugars 9.1 g

What a real portion looks like

• In the US survey database one cup of raw blackberries or raw blueberries is counted as 150 g. — FNDDS 63201010 (Blackberries, raw) and 63203010 (Blueberries, raw) (n = -) Evidence E source
  1 cup 150 g each; 1 blackberry 5 g; 1 blueberry 2 g

What your body absorbs

• In a crossover trial of 9 adults eating 8.8 oz (250 g) of blueberries, whole fruit produced 108 urinary metabolite signals higher than juice, versus 8 higher after juice. — 9 healthy subjects, single 250 g dose, samples at 2 h (n = 9) Evidence B source
  108 ions higher after whole fruit vs 8 higher after juice; profiles otherwise similar

What cooking and storage change

• By the USDA retention table for Fruits and Fruit Juices, stewing fresh fruit keeps about 70% of vitamin C and 50% of folate. — USDA R6 method 155 FRUITS,FRESH(NOT CITRUS),STEWED (n = -) Evidence E source
  Retained: vitamin C 70%, folate 50%, thiamin 80%, potassium 90%
• In a crossover RCT of 10 volunteers, baking blueberries into products cut anthocyanins by 42% yet improved blood vessel dilation as much as unbaked blueberries. — 10 healthy volunteers, single servings, 6 h follow-up (n = 10) Evidence B source
  Anthocyanins -42%, chlorogenic acid +23% after baking; FMD rise similar to unprocessed drink

What it does to your health

• A meta-analysis of 14 RCTs in 632 healthy people found blueberries improved flow-mediated dilation by 1.11% but did not change blood pressure. — 632 healthy participants in 14 RCTs (n = 632) Evidence A source
  FMD +1.11% (95% CI 0.50 to 1.72); SBP -0.11 mmHg (-2.82 to 2.60); DBP -0.46 mmHg (-2.80 to 1.87)
• In people with cardiometabolic disease, a meta-analysis of 17 articles found blueberry or cranberry did not significantly lower blood pressure (SBP -0.81 mmHg). — Patients with cardiometabolic diseases in 17 RCTs (n = 17 articles) Evidence A source
  SBP -0.81 mmHg (95% CI -2.26 to 0.63); DBP -0.15 mmHg (-1.36 to 1.05)

Safety, limits and interactions

• In a New Zealand hepatitis A outbreak, 56% of cases had eaten raw blueberries versus 14% of controls (odds ratio 7.6). — 39 cases and 71 controls (n = 110) Evidence C source
  OR 7.6 (95% CI 2.6-22.4)
• In healthy volunteers, blueberry juice did not significantly change blood levels of buspirone (ratio 1.39) or flurbiprofen (1.03), unlike grapefruit juice (2.12). — Healthy volunteers in controlled pharmacokinetic studies (n = -) Evidence C source
  Buspirone AUC GMR 1.39 (ns) vs grapefruit 2.12; flurbiprofen GMR 1.03 vs fluconazole 1.71

What people believe that the data does not support

• The EU did not authorize a juice label claim that blueberries have anti-aging properties and maintain urinary tract and vision health. — EU register entry for a wild blueberry juice drink (n = -) Evidence E source
  Status Non-authorized

Who this works differently for

• In a 24-week RCT of 57 cognitively healthy older adults, 20 g a day of freeze-dried blueberry powder did not change brain-injury biomarkers or cognitive tests. — 57 cognitively healthy older adults, 24 weeks (n = 57) Evidence B source
  No difference in serum p-tau181 (p interaction 0.10) or NFL (0.58); diastolic BP reduced (p 0.015)
• In an RCT of 61 breastfed infants given up to 10 g a day of blueberry powder from 5 to 12 months, serum IL-13 fell versus placebo. — Breastfed US infants aged 5 to 12 months; 61 completed (30 blueberry, 31 placebo) (n = 61) Evidence B source
  Symptom trajectories differed (p = 0.05); IL-13 reduced (p = 0.035); IL-10 borderline (p = 0.052)

What is still unknown

• Pooled trials have not shown that blueberries improve thinking in healthy people (executive function SMD 0.21, not significant), so the cognitive effect remains unproven. — Healthy participants in RCTs pooled for cognition (n = 632) Evidence A source
  Executive function SMD 0.21 (95% CI -0.05 to 0.46); mood MD 1.67 (-1.35 to 4.69)

The bottom line

A cup of either berry is counted as 150 g in US survey data, so the per 3.5 oz (100 g) numbers above grow by half for a normal bowl. Processing changes less than you might fear. In a crossover trial of 10 healthy volunteers eating single servings, baking blueberry powder into products cut anthocyanins by 42 percent, and blood vessel dilation still rose over the next 6 hours about as much as after an unbaked blueberry drink. That was one small acute test. When 9 healthy adults ate 8.8 oz (250 g) of blueberries whole or juiced, urine at 2 hours showed 108 metabolite signals higher after the whole fruit and 8 higher after juice, a single time point with no health outcome attached. USDA retention factors, written for stewed fruit as a group in 1975, keep about 70 percent of vitamin C and 50 percent of folate. The brain claims have not held up. Pooled trials in healthy people found no significant effect on executive function (SMD 0.21, 95% CI minus 0.05 to 0.46). In 57 cognitively healthy older adults, 20 g a day of freeze-dried blueberry powder for 24 weeks changed no cognitive test and no brain-injury biomarker, though diastolic pressure did fall (p = 0.015). In 61 breastfed infants given up to 10 g a day of the same kind of powder from 5 to 12 months, the inflammatory marker IL-13 fell versus placebo (p = 0.035). The symptoms in that trial came from parents, and the blueberry group started with more of them. The EU refused a juice drink label saying blueberries are anti-aging and maintain the urinary tract and vision. Who should be careful. In one New Zealand hepatitis A outbreak, 56 percent of 39 cases had eaten raw blueberries against 14 percent of 71 controls, an odds ratio of 7.6 (95% CI 2.6 to 22.4). That is odds from a single outbreak, not a general risk figure. In healthy volunteers, blueberry juice did not significantly change blood levels of buspirone (ratio 1.39) or flurbiprofen (1.03), while grapefruit juice doubled buspirone (2.12), and the abstract does not say how many people took part. We have no card on berry allergy or pregnancy for either berry, the infant trial above measured symptoms and blood markers rather than safety, and that silence is not a clean bill.

Sources

1. bxb-daily-r7-01 · Food composition dataset
   Blackberries, raw | Vitamin C 15.4 mg (range 11.3-19.8, 8 samples) | Fiber, total dietary 5.3 g (range 3.9-6.1, 8 samples) | Potassium 167.4 mg (range 122.0-225.0) | Blueberries, raw | Vitamin C 8.059 mg (range 4.295-11.1, 8 samples) | Potassium 85.64 mg (range 74.2-109.5)
   USDA FoodData Central, Foundation Foods, release 2026-04-30 · checked 2026-10-02
2. bxb-daily-r7-02 · Food composition dataset
   Blackberries, raw | CoFID 14-388 | per 100 g: energy 27 kcal, AOAC fibre 3.4 g, total sugars 5.6 g | Blueberries | CoFID 14-325 | per 100 g: energy 40 kcal, AOAC fibre 1.5 g, total sugars 9.1 g
   CoFID 2021, Public Health England (OGL v3.0) · checked 2026-10-02
3. bxb-daily-r7-03 · Food composition dataset
   Blackberries, raw | FNDDS 63201010 | 1 cup: 150 g | 1 blackberry: 5 g | Blueberries, raw | FNDDS 63203010 | 1 cup: 150 g | 1 berry: 2 g
   USDA FNDDS 2021-2023 (FoodData Central survey foods) · checked 2026-10-02
4. bxb-daily-r7-05 · Randomized crossover trial
   Nine healthy subjects consumed 250 g of fresh blueberries either as the whole fruit or after juicing, and provided blood and urine samples before and 2 h after intake in a cross-over design. ... In urinary samples, whole blueberry treatment resulted in 108 ions that were significantly higher compared with juiced treatment (positive and negative mode combined), whereas only eight were significantly higher after juiced treatment.
   Br J Nutr, 2018 · checked 2026-10-02
5. bxb-daily-r7-04 · Food composition dataset
   FRUITS,FRESH(NOT CITRUS),STEWED | Fruits and Fruit Juices | USDA-RETN-R6:155 | vitamin C 70% | folate 50% | thiamin 80% | potassium 90%
   USDA Table of Nutrient Retention Factors, Release 6 (2007), code 155 · checked 2026-10-02
6. bxb-daily-r7-06 · Randomized crossover trial
   In a randomized, controlled crossover trial, ten healthy volunteers consumed (a) blueberry-containing baked products, (b) an unprocessed blueberry drink containing the same amount of freeze-dried blueberry powder as used in the baked products, and (c) matched control baked products. ... Although processing did not significantly change the total (poly)phenolic amount, the processed products contained significantly less anthocyanins (-42%), more chlorogenic acid (23%) ... FMD increased after 1, 2, and 6 h consumption of the baked products to a similar degree as the unprocessed blueberries
   Mol Nutr Food Res, 2014 · checked 2026-10-02
7. bxb-daily-r7-07 · Meta-analysis of RCTs
   we analyzed 14 randomized controlled trials (RCTs) involving 632 participants. Results indicated that blueberry intervention significantly improved flow-mediated dilation (FMD) by 1.11% (95% CI: 0.50, 1.72; I² = 23%), suggesting a positive impact on vascular health. However, there were no significant changes in systolic blood pressure (SBP) (reduction of 0.11 mmHg; 95% CI: -2.82, 2.60; I² = 0%)
   Nutr Res, 2026 · checked 2026-10-02
8. bxb-daily-r7-08 · Meta-analysis of RCTs
   A total of 17 articles were included, from which two found significant results from blueberry and/or cranberry supplementation in reducing BP. Pooled results revealed statistically non-significant reductions of -0.81 mm Hg for SBP (95% confidence interval [CI]: -2.26, 0.63; I2 = 0%) and -0.15 mm Hg for DBP (95% CI: -1.36, 1.05; I2 = 27%).
   Phytother Res, 2024 · checked 2026-10-02
9. bxb-daily-r7-10 · Case-control
   A case-control study revealed that 56% of 39 cases had consumed raw blueberries, compared with 14% of 71 controls (odds ratio 7.6; 95% confidence intervals 2.6-22.4).
   Epidemiol Infect, 2003 · checked 2026-10-02
10. bxb-daily-r7-11 · Controlled clinical trial
    In clinical studies, GFJ significantly increased area under the plasma concentration-time curve (AUC) for the CYP3A substrate buspirone. The geometric mean ratio (GMR = AUC with GFJ divided by AUC with water) was 2.12. In contrast, the effect of BBJ (GMR = 1.39) was not significant. In the study of flurbiprofen (CYP2C9 substrate), the positive control inhibitor fluconazole significantly increased flurbiprofen AUC (GMR = 1.71), but BBJ had no significant effect (GMR = 1.03).
    Br J Clin Pharmacol, 2013 · checked 2026-10-02
11. bxb-daily-r7-13 · EU claims register
    POL-HC-7636 Name of Food product: Sqeez Wild Blueberry Juice Drink Description of food in terms of food legislation categories: food not covered by specific food legislation Was food on Irish market before 1st July 2007: Yes Exact wording of claim as it appears on product: Blueberries have a wide range of health benefits including anti-ageing properties and the maintenance of urinary tract and vision health Is claim a picture: No Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-7636, snapshot 2026-09-21 · checked 2026-10-02
12. bxb-daily-r7-09 · Randomized controlled trial
    This was a randomized double-blind trial where 57 cognitively healthy subjects were assigned either 20 g/d of freeze-dried blueberry powder or matching placebo for 24 weeks. ... In secondary aims, blueberry intervention reduced diastolic blood pressure (p interaction with time 0.015) but there was no effect on systolic blood pressure, cognitive tests, and other biomarkers.
    Clin Nutr ESPEN, 2026 · checked 2026-10-02
13. bxb-daily-r7-12 · Randomized controlled trial
    In a double-blind, randomized, placebo-controlled trial, infants from the Denver metro area were assigned to receive up to 10 g/day of freeze-dried blueberry powder or an isocaloric placebo from 5 to 12 months of age. ... Of the 76 infants enrolled, 61 completed the study (Blueberry: n = 30; Placebo: n = 31). ... Pro-inflammatory serum IL-13 levels were significantly reduced (p = 0.035)
    Nutrients, 2025 · checked 2026-10-02
14. bxb-daily-r7-14 · Meta-analysis of RCTs
    Cognitive outcomes showed no significant effect executive function (SMD: 0.21; 95% CI: -0.05, 0.46; I² = 42%) or mood (MD: 1.67; 95% CI: -1.35, 4.69; I² = 10%). The findings suggest that blueberries may enhance vascular function, but their impact on cognitive performance remains inconclusive.
    Nutr Res, 2026 · checked 2026-10-02