Blueberries and huckleberries: one artery finding, and no human data on huckleberries

By a meta-analysis of 14 randomized trials in 632 healthy people, eating blueberries raised flow-mediated dilation, a measure of how well an artery widens, by 1.11 percentage points (95% CI 0.50 to 1.72). Systolic blood pressure did not change significantly, 0.11 mmHg lower (95% CI minus 2.82 to plus 2.60), and neither did executive function. Doses and forms differed between those trials, and several of the single trials below used freeze-dried blueberry powder at 20 to 26 g a day, not fresh fruit. For huckleberries we found no human study at all. What exists is one USDA record from Alaska Native data, listing raw huckleberries at 37 calories and 2.8 mg vitamin C per 3.5 oz (100 g), against 57 calories and about 8 mg for raw blueberries.

How much is actually in it

• Across 8 USDA samples, raw blueberries held 4.3 to 11.1 mg vitamin C and 74 to 110 mg potassium per 3.5 oz (100 g), with no sucrose at all. — USDA FoodData Central Foundation Foods, Blueberries raw, 8 samples, per 3.5 oz (100 g) (n = 8 samples) Evidence E source
  Vitamin C mean 8.059 mg (4.295-11.1); potassium 85.64 mg (74.2-109.5); fructose 4.939 g; glucose 4.417 g; sucrose 0 g
• USDA lists raw huckleberries at 37 calories and 2.8 mg vitamin C per 3.5 oz (100 g), against 57 calories and about 8 mg vitamin C for raw blueberries. — USDA SR Legacy FDC 169808 Huckleberries, raw (Alaska Native) and Foundation FDC 2346411 Blueberries, raw, per 3.5 oz (100 g) Evidence E source
  Huckleberries: 37 calories, carbs 8.7 g, water 90.7 g, vitamin C 2.8 mg, iron 0.3 mg; blueberries: 57.4 calories, carbs 14.6 g, water 84.2 g, vitamin C 8.1 mg, iron 0.34 mg
• UK tables list blueberries at 40 calories, 1.5 g fiber, 9.1 g sugars and 6 mg vitamin C per 3.5 oz (100 g). — CoFID 2021 entry 14-325 Blueberries, per 3.5 oz (100 g) Evidence E source
  Energy 40 calories, AOAC fiber 1.5 g, total sugars 9.1 g, vitamin C 6 mg, carotene 14 ug

What a real portion looks like

• In the US dietary survey database a cup of raw blueberries weighs 5.3 oz (150 g), a single berry about 2 g, and an unspecified portion 2.6 oz (75 g). — USDA FNDDS food code 63203010 Blueberries, raw Evidence E source
  1 cup = 150 g; 1 berry = 2 g; quantity not specified = 75 g

What your body absorbs

• In a crossover RCT of 18 adults, polyphenols from 150 g of raw blueberries and from a protein bar made with the same berries were absorbed to a similar extent. — 18 adults (age 42, BMI 24.8), 150 g Elliott or Olympia blueberries, a protein bar with 1 serving of Elliott blueberries, or control beverage (n = 18) Evidence B source
  Similar serum AUC across berry treatments; urinary recovery higher after Elliott berries than Olympia and bar (21% and 29%); timing of peaks differed

What cooking and storage change

• By the USDA retention table for fresh fruit, baking keeps 80% of vitamin C and 60% of folate, while minerals stay at 90 to 100%. — USDA Table of Nutrient Retention Factors Release 6, group Fruits and Fruit Juices, code 151 (fresh, not citrus, baked) Evidence E source
  Vitamin C 80%, thiamin 80%, folate 60%, potassium 90%, iron 100%

What it does to your health

• Across 17 trials in people with cardiometabolic disease, blueberry or cranberry supplements lowered systolic blood pressure by a non-significant 0.81 mm Hg. — Patients with cardiometabolic diseases in 17 randomized clinical trials of blueberry or cranberry, searched to August 2023 (n = 17 trials) Evidence A source
  SBP -0.81 mm Hg (95% CI -2.26 to 0.63); DBP -0.15 mm Hg (-1.36 to 1.05)
• A meta-analysis of 21 studies found blueberries improved blood pressure and blood lipids in metabolic syndrome, but not waist, BMI, HbA1c or glucose. — Human studies of blueberry supplementation for at least 2 weeks, 2007-2021; 25 in review, 21 pooled (n = 21 studies) Evidence B source
  Significant improvement in SBP, DBP, TG, total cholesterol, LDL, HDL, insulin; no effect on waist, BMI, HbA1c, glucose, HOMA-IR; sizes not in abstract
• In a double-blind RCT of 45 adults with metabolic syndrome, the equivalent of 1 cup of blueberries with a high-fat meal cut 3-hour insulin to 23.4 versus 52.9 pmol/L on placebo. — 45 participants with metabolic syndrome, age 63.4, BMI 31.4, 26 g freeze-dried blueberries (1 cup fresh) or placebo with a 969 calories drink (n = 45) Evidence B source
  3 h glucose 77 vs 92 mg/dL (4.3 vs 5.1 mmol/L); 3 h insulin 23.4 vs 52.9 pmol/L; 1 h glucose peak higher (148 vs 124 mg/dL (8.2 vs 6.9 mmol/L)); no effect on FMD or BP
• In a 12-week double-blind RCT of 43 postmenopausal women with raised blood pressure, 22 g a day of freeze-dried blueberries improved endothelial function but not blood pressure. — 43 postmenopausal women aged 45-65 with elevated BP or stage 1 hypertension (32 for endothelial function), 22 g/d freeze-dried highbush blueberry powder vs placebo (n = 43) Evidence B source
  FMD/SRAUC 96% higher vs baseline in blueberry group; no major differences in BP, arterial stiffness or blood biomarkers

Safety, limits and interactions

• In a double-blind RCT of 61 breastfed infants given up to 10 g a day of freeze-dried blueberry from 5 to 12 months, allergy symptoms resolved more often than on placebo. — 76 enrolled, 61 completed breastfed infants in Denver, up to 10 g/day freeze-dried blueberry powder or isocaloric placebo from 5 to 12 months (n = 61) Evidence B source
  Different symptom trajectories (p = 0.05); serum IL-13 lower (p = 0.035)
• In healthy volunteers, blueberry juice did not significantly raise blood levels of buspirone or flurbiprofen, unlike grapefruit juice, which doubled buspirone exposure. — Healthy volunteers given oral buspirone (CYP3A) or flurbiprofen (CYP2C9) with water, blueberry juice, grapefruit juice or fluconazole Evidence C source
  Buspirone AUC ratio 1.39 with blueberry juice (ns) vs 2.12 with grapefruit juice; flurbiprofen 1.03 (ns) vs 1.71 with fluconazole

What people believe that the data does not support

• The EU register lists the claim that blueberry supports proper night vision as non-authorized, and no claim for any Vaccinium berry is authorized. — EU Register on nutrition and health claims, snapshot 2026-09-21 Evidence E source
  0 authorized claims for Vaccinium or blueberry; night vision claim POL-HC-8226 non-authorized

What is still unknown

• In a meta-analysis of 14 RCTs with 632 healthy people, blueberries raised flow-mediated dilation by 1.11 percentage points but left blood pressure and executive function unchanged. — 632 healthy participants in 14 randomized controlled trials of blueberry consumption (n = 632) Evidence A source
  FMD +1.11% (95% CI 0.50 to 1.72); SBP -0.11 mmHg (-2.82 to 2.60); executive function SMD 0.21 (-0.05 to 0.46)
• In a 24-week double-blind RCT of 57 adults aged about 73, 20 g a day of freeze-dried blueberries did not change blood markers of brain aging or cognitive test scores. — 57 cognitively healthy older adults (mean age 73.5 and 73.3), 20 g/d freeze-dried blueberry powder vs placebo for 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); no effect on cognitive tests
• Laboratory analysis of two Pacific Northwest huckleberry species found 15 anthocyanins in each, with Vaccinium ovatum richer in anthocyanins and antioxidants than V. membranaceum. — Berries of Vaccinium membranaceum and Vaccinium ovatum native to Pacific Northwestern North America Evidence D source
  Same 15 anthocyanins in different proportions; V. ovatum higher total anthocyanin, total phenolics, ORAC and FRAP

The bottom line

On blood pressure the pooled trials disagree, and they studied different people. Across 17 trials in people with cardiometabolic disease, blueberry or cranberry lowered systolic pressure by 0.81 mmHg (95% CI minus 2.26 to plus 0.63), which did not reach significance. A 2022 meta-analysis of 21 studies in metabolic syndrome reported significant improvements in blood pressure, triglycerides, LDL and HDL, with no effect on waist, BMI, HbA1c or glucose. Its abstract gives no sizes. In 43 women after menopause with raised blood pressure, 22 g a day of freeze-dried blueberry powder for 12 weeks raised a measure of artery function by 96% from baseline, while blood pressure did not change. Only 32 of the women had artery function measured. In 45 adults with metabolic syndrome, 0.92 oz (26 g) of freeze-dried blueberries, about 1 cup fresh, taken with a 969 calories high-fat drink cut 3-hour insulin to 23.4 pmol/L against 52.9 on placebo. Glucose first peaked higher in the blueberry group, 8.2 against 124 mg/dL (6.9 mmol/L) at 1 hour. In 57 adults aged about 73, 20 g a day of the powder for 24 weeks did not change blood markers of brain aging or cognitive test scores, and diastolic pressure fell. A cup of raw blueberries weighs 5.3 oz (150 g) in the US survey database, and a single berry about 2 g. Across 8 USDA samples, raw blueberries held 4.3 to 11.1 mg vitamin C per 3.5 oz (100 g), and none of their sugar was sucrose. UK tables put them at 40 calories and 1.5 g fiber per 3.5 oz (100 g), lower than the 57 calories USDA lists, a gap that may come from different energy methods and varieties. In 18 adults, polyphenols from 150 g of raw blueberries and from a protein bar made with the same berries reached similar total blood levels, with peaks at different times. By the USDA retention factor for baked fresh fruit, 80% of vitamin C and 60% of folate stay, and that table has no values for anthocyanins. Laboratory analysis of two Pacific Northwest huckleberry species found the same 15 anthocyanins in each, in different proportions, with Vaccinium ovatum richer in anthocyanins and antioxidant capacity than V. membranaceum. That is chemistry in berries, with no people involved. The night vision claim for blueberry was put to the EU and is listed as non-authorized. No claim for any Vaccinium berry is authorized there. Who should be careful. In healthy volunteers, blueberry juice did not significantly raise blood levels of buspirone or flurbiprofen, while grapefruit juice doubled buspirone exposure. Only those two drugs were tested, and the study was not randomized. In a trial of 61 breastfed infants given up to 10 g a day of freeze-dried blueberry from 5 to 12 months, allergy symptoms resolved more often than on placebo, at p = 0.05. Parents reported the symptoms, and the blueberry group started with more of them. We found no source on blueberry allergy or on pregnancy.

Sources

1. bbhk-daily-r3-11 · reference dataset
   Blueberries, raw | Vitamin C, total ascorbic acid 8.059 MG | range 4.295-11.1 | samples 8 | Potassium, K 85.64 MG | range 74.2-109.5 | samples 8 | Fructose 4.939 G | range 3.92-6.9 | Glucose 4.417 G | range 3.38-6.39 | Sucrose 0.0 G | samples 8
   USDA FoodData Central, Foundation Foods, release 2026-04-30 · checked 2026-09-29
2. bbhk-daily-r3-12 · reference dataset
   169808 Huckleberries, raw (Alaska Native) | energy 37 kcal | carbs 8.7 g | water 90.7 g | vitamin C 2.8 mg | iron 0.3 mg || 2346411 Blueberries, raw | energy 57.385 kcal | carbs 14.572 g | water 84.19 g | vitamin C 8.059 mg | iron 0.34 mg
   USDA FoodData Central, SR Legacy FDC 169808 and Foundation FDC 2346411 · checked 2026-09-29
3. bbhk-daily-r3-13 · reference dataset
   14-325 Blueberries | Energy (kcal) 40 | AOAC fibre (g) 1.5 | Total sugars (g) 9.1 | Vitamin C (mg) 6 | Carotene (ug) 14
   CoFID 2021, Public Health England, OGL v3.0, code 14-325 · checked 2026-09-29
4. bbhk-daily-r3-14 · reference dataset
   63203010 Blueberries, raw | 1 berry 2 g | 1 cup 150 g | Quantity not specified 75 g
   USDA FNDDS, food code 63203010 Blueberries, raw · checked 2026-09-29
5. bbhk-daily-r3-06 · RCT
   Serum AUC was similar across berry-derived treatments, whereas differences in maximum concentration (Cmax) and time at maximum concentration (Tmax) were observed
   Am J Clin Nutr, 2025 · checked 2026-09-29
6. bbhk-daily-r3-15 · reference dataset
   USDA-RETN-R6:151 | FRUITS,FRESH(NOT CITRUS),BAKED | vitamin_c_mg 80% | thiamin_mg 80% | folate_total_ug 60% | potassium_mg 90% | iron_mg 100%
   USDA Table of Nutrient Retention Factors, Release 6 (2007), code 151 · checked 2026-09-29
7. bbhk-daily-r3-02 · meta-analysis
   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 2026-09-29
8. bbhk-daily-r3-03 · meta-analysis
   The results of the meta-analysis demonstrated that BB had no significant effect on waist circumference, body mass index (BMI), glycated hemoglobin (HbA1C), glucose level and homeostatic model assessment for insulin resistance (HOMA-IR); however, studies showed a significant improvement in systolic and diastolic blood pressure, triglycerides, total cholesterol, low-density lipoproteins (LDL), high-density lipoproteins (HDL) and insulin levels.
   Food Funct, 2022 · checked 2026-09-29
9. bbhk-daily-r3-05 · RCT
   After a transient higher peak glucose concentration at 1 h after blueberry intake ([8.2 mmol/L, 95%CI: 7.7, 8.8] vs placebo [6.9 mmol/L, 95%CI: 6.4, 7.4]; p = 0.001), blueberries significantly attenuated 3 h glucose ([4.3 mmol/L, 95%CI: 3.8, 4.8] vs placebo [5.1 mmol/L, 95%CI: 4.6, 5.6]; p = 0.03) and insulin concentrations (blueberry: [23.4 pmol/L, 95%CI: 15.4, 31.3] vs placebo [52.9 pmol/L, 95%CI: 41.0, 64.8]; p = 0.0001).
   Clin Nutr, 2022 · checked 2026-09-29
10. bbhk-daily-r3-07 · RCT
    Absolute FMD/SRAUC was 96% higher following blueberry consumption compared to baseline (p < 0.05) but unchanged in the placebo group (p > 0.05) ... No major differences were found for blood pressure, arterial stiffness, blood biomarkers, or endothelial cell protein expression following blueberry consumption.
    Food Funct, 2023 · checked 2026-09-29
11. bbhk-daily-r3-08 · RCT
    While more infants in the blueberry group had allergy-related symptoms at baseline, they had significantly different longitudinal symptom trajectories than the placebo (p = 0.05), showing a greater resolution rate of symptoms by study end.
    Nutrients, 2025 · checked 2026-09-29
12. bbhk-daily-r3-09 · controlled clinical trial
    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 2026-09-29
13. bbhk-daily-r3-16 · regulatory decision
    POL-HC-8226 blueberry extracts blueberry can support maintainig of proper night vision Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-8226, snapshot 2026-09-21 · checked 2026-09-29
14. bbhk-daily-r3-01 · meta-analysis
    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%) or diastolic blood pressure (DBP) (reduction of 0.46 mmHg; 95% CI: -2.80, 1.87; I² = 0%). Cognitive outcomes showed no significant effect executive function (SMD: 0.21; 95% CI: -0.05, 0.46; I² = 42%)
    Nutr Res, 2026 · checked 2026-09-29
15. bbhk-daily-r3-04 · RCT
    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. CONCLUSION: A 24-week intervention with freeze-dried blueberries had no effect on serum p-tau181 and serum NFL in older adults.
    Clin Nutr ESPEN, 2026 · checked 2026-09-29
16. bbhk-daily-r3-10 · food composition study
    Vaccinium ovatum had greater total anthocyanin (ACY), total phenolics (TP), oxygen radical absorbing capacity (ORAC), and ferric reducing antioxidant potential (FRAP) than did V. membranaceum. ... Each species contained 15 anthocyanins (galactoside, glucoside, and arabinoside of delphinidin, cyanidin, petunidin, peonidin, and malvidin) but in different proportions.
    J Agric Food Chem, 2004 · checked 2026-09-29