Evidence-based·Last reviewed June 1, 2026·How we grade evidence

Blackberry

BotanicalBest with a meal

A genuinely good food — high in fiber, vitamin C, vitamin K, manganese, and anthocyanins. The cardiometabolic evidence for anthocyanin-rich berries as a class is moderate (small BP and biomarker improvements), but there are very few RCTs of blackberry specifically. Use it as food; don't pay supplement prices for blackberry capsules when a cup of fresh or frozen berries gives you the same thing plus the fiber.

Quick decision guide

May help most

Anyone wanting an actually-nutritious whole-food source of fiber, vitamin C, and anthocyanins as part of a varied diet. Excellent fit if you have prediabetes/hypertension and are working on diet quality.

Common dosing range

1 cup (144 g) fresh or frozen blackberries provides 62 kcal, 7.6 g fiber, 30 mg vitamin C (33% DV), 24 μg vitamin K (20% DV), and ~150–250 mg anthocyanins. Eating berries 3–5×/week is realistic and supported by population data.

When to expect effects

Days for fiber/satiety effects; weeks–months for any cardiometabolic biomarker shifts from regular intake.

Watch out for

Whole-food blackberries are very low-risk. Concentrated extracts and 'leaf' herbal preparations are a different category — they carry theoretical tannin-related GI effects and lack clinical evidence.

Evidence snapshot

Fiber and vitamin C/K sourceStrong
Anthocyanins — cardiometabolic biomarkersModerate
Blood pressure (anthocyanin class)Emerging
Blackberry-specific RCTsLow

What is it

Blackberry is a plant-derived ingredient sold as a dietary supplement and used in traditional herbal use. Found on roughly 689 U.S. supplement labels.

Is it worth it for you?

Use this as a quick fit check, not a diagnosis.

Worth considering if…

You want a low-sugar, high-fiber whole fruit you can eat regularly
You're working on cardiometabolic health and adding berries 3–5×/week as part of a varied diet
You like the taste and they fit your budget (fresh in season, frozen year-round)
You're looking for a vitamin C and K boost from a real food rather than a multivitamin
You enjoy them as a substitute for higher-sugar fruits or dessert

Probably skip if…

You're considering an expensive 'blackberry extract' supplement — eat the fruit instead, you get the fiber too
You're hoping blackberry will prevent cancer or treat a chronic disease — direct evidence is thin (and most cancer-chemoprevention work is on black raspberry, a different species)
You're on warfarin and don't currently eat much vitamin K — a sudden large increase in blackberry intake can affect INR (effect is small but real)
You have a known berry allergy or oral-allergy syndrome with related fruits
You're using 'blackberry leaf' tea as a treatment for diarrhoea or other conditions — traditional use, very limited modern evidence

Evidence at a glance

Dietary fiber and vitamin C/K source

Strong Evidence
Effect
Per 1 cup serving: 7.6 g fiber (27% DV), 30 mg vitamin C (33% DV), 24 μg vitamin K (20% DV), 0.9 mg manganese (40% DV)
Best fit
Anyone wanting to increase fiber, vitamin C, vitamin K, and anthocyanin intake from a real food source
Time
Immediate (nutrient delivery); days for satiety and GI regularity benefits

Anthocyanin source for cardiometabolic biomarkers

Good Evidence
Effect
Class-level meta-analysis of anthocyanin foods: ~2.6 mmHg SBP / ~1.6 mmHg DBP reduction; biomarker improvements in endothelial function and lipids
Best fit
Adults with prehypertension or elevated cardiometabolic risk who include berries regularly in a balanced diet
Time
Weeks of regular intake (most trials run 8–12 weeks)

Cancer prevention (often mis-attributed)

Mixed Evidence
Effect
Direct blackberry evidence for cancer prevention: minimal. Black raspberry evidence: promising in preclinical models, limited human data.
Best fit
Anyone interested in a generally healthful diet — colourful berries fit, but don't pay a premium for cancer-prevention claims
Time
Not established

Evidence for 3 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Dietary fiber and vitamin C/K source

Strong Evidence

Blackberries are one of the highest-fiber whole fruits — 7.6 g per cup (144 g), which is ~27% of the daily fiber DV in a single serving. They also provide 30 mg vitamin C (33% DV), 24 μg vitamin K (20% DV), and 0.9 mg manganese (40% DV) per cup. Adding berries 3–5×/week is a realistic way to improve diet quality and is consistently associated with lower cardiovascular and metabolic disease risk in cohort studies.

Effect size
Per 1 cup serving: 7.6 g fiber (27% DV), 30 mg vitamin C (33% DV), 24 μg vitamin K (20% DV), 0.9 mg manganese (40% DV)
Time to effect
Immediate (nutrient delivery); days for satiety and GI regularity benefits
Best fit
Anyone wanting to increase fiber, vitamin C, vitamin K, and anthocyanin intake from a real food source
Less likely
—

Bottom line: Among the best-value whole-fruit choices for fiber, vitamin C, and vitamin K density.

SourceUSDA FoodData Central — Blackberries, raw — USDA

Anthocyanin source for cardiometabolic biomarkers

Supplement benefit
Good Evidence

Blackberries are among the highest-anthocyanin fruits (cyanidin-3-O-glucoside is the dominant compound). The anthocyanin class has moderate-quality meta-analytic support for modest blood pressure reduction (~2.6 mmHg SBP) and improvements in endothelial function, LDL oxidation, and HbA1c across berry/anthocyanin-extract trials. Blackberry-specific RCTs are scarce — most evidence is from blueberry, cherry, and mixed-berry interventions extrapolated to the class.

Effect size
Class-level meta-analysis of anthocyanin foods: ~2.6 mmHg SBP / ~1.6 mmHg DBP reduction; biomarker improvements in endothelial function and lipids
Time to effect
Weeks of regular intake (most trials run 8–12 weeks)
Best fit
Adults with prehypertension or elevated cardiometabolic risk who include berries regularly in a balanced diet
Less likely
People expecting blackberry alone to replace BP medication — the effect is meaningful at a population level but small at an individual level

Bottom line: Eat blackberries as part of a diet rich in colourful fruits and vegetables; don't expect any single berry to be the deciding factor.

Evidence is mixed

Most anthocyanin trials used blueberry, cherry, or extract — not specifically blackberry. Cross-class extrapolation is reasonable given shared anthocyanin chemistry but not certain.

SourceYang et al., 2021 — PubMed — Advances in Nutrition· conflicting
SourceYang et al., 2021 — PubMed — Advances in NutritionKalt et al., 2019 — PMC — Advances in NutritionLinus Pauling Institute — Flavonoids — Oregon State University Linus Pauling Institute

Cancer prevention (often mis-attributed)

Mechanism only
Mixed Evidence

Most cancer-chemoprevention research labelled 'blackberry' is actually on BLACK RASPBERRY (Rubus occidentalis), not blackberry (Rubus fruticosus). Black raspberry powder has shown promising chemopreventive activity in rodent models of oesophageal and colon cancer and in early human biomarker studies. The two fruits look similar but are different species with different anthocyanin profiles — don't assume marketing claims for one apply to the other.

Effect size
Direct blackberry evidence for cancer prevention: minimal. Black raspberry evidence: promising in preclinical models, limited human data.
Time to effect
Not established
Best fit
Anyone interested in a generally healthful diet — colourful berries fit, but don't pay a premium for cancer-prevention claims
Less likely
People seeking a single 'cancer-preventing' food — this is not it

Bottom line: Eat blackberries because they're a good food, not because they prevent cancer.

SourceStoner et al., 2008 — PubMed — Cancer Prevention Research

How it works

Blackberry contains a mixture of plant compounds, and the exact mechanism behind any effects depends on the specific preparation, the part of the plant used, and how it is extracted. Concentrations of active constituents can vary substantially between products. Most botanical effects are studied as a whole-plant or extract effect rather than tied to a single isolated molecule. Without strong human trial data, claims about how Blackberry works should be treated cautiously.

How to take it

1. Typical dose
• 1 cup (144 g) fresh or frozen blackberries 3–5×/week is a realistic and well-supported intake • Daily serving fits easily — top oatmeal, blend into smoothies, eat as a snack • Frozen is nutritionally comparable to fresh; usually cheaper year-round
2. Higher studied dose
Intervention trials often use 1–2 cups/day for 8–12 weeks. There's no upper limit for whole-fruit intake within a balanced diet; concentrated extracts are a separate category and not necessary if you eat the fruit.
3. Timing
Anytime — no special timing requirements. With meals if you want to slow blood-sugar response to other carbs in the meal; as a snack works fine too.
4. With food
Either way.
5. Split dosing
Not applicable for whole fruit.
6. How long to try
Indefinitely as part of a varied diet. Cardiometabolic biomarker shifts in trials typically take 8–12 weeks of regular intake.

What to track

Fiber intake (aim for 25–35 g/day total from all sources)
How they fit your sugar budget if managing prediabetes (~7 g sugar per cup — modest)
INR if you're on warfarin and previously had low vitamin K intake — a daily cup adds meaningful vitamin K
Any oral-allergy symptoms (itching, swelling) if you have related fruit allergies

Bottom line: Add a cup of blackberries 3–5×/week (fresh in season, frozen year-round) for fiber, vitamin C, vitamin K, and anthocyanins. Skip the extract supplements — eat the fruit.

5 commercial forms

Compare the main delivery options and what they’re best suited for.

Fresh blackberries

Best

Peak nutritional and sensory quality in season (typically July–September in temperate climates). Eat within a few days of purchase; rinse just before eating to prevent mold.

Standard whole-fruit form — gold standard for this nutrient.

Frozen blackberries

Excellent year-round

Picked at peak ripeness and flash-frozen; vitamin C, anthocyanin, and fiber content is very close to fresh. Usually cheaper than out-of-season fresh berries. Great for smoothies, baking, oatmeal.

Nutritionally comparable to fresh; sometimes higher anthocyanin retention than off-season fresh imports.

Blackberry juice (unsweetened)

Lower fiber

Concentrates polyphenols and vitamin C but loses most of the fiber. A small glass (~120 mL) is reasonable; large amounts add up quickly in sugar. The whole fruit is better for satiety and glycemic effects.

Higher anthocyanin per mL than whole fruit but much lower fiber.

Freeze-dried blackberry powder

Concentrated, expensive

Whole berries freeze-dried and ground; convenient for smoothies and baking. Often marketed as a supplement at high cost per serving. No measurable advantage over eating the same amount of frozen berries.

Similar to whole fruit on a dry-weight basis; the price premium isn't justified by evidence.

Blackberry leaf (tea / extract)

Traditional only

The leaf has traditional use as a mouth rinse, gargle for sore throats, and tea for diarrhoea — based on its tannin content. Very limited modern clinical evidence. Don't confuse with the fruit.

Tannin-rich; mostly traditional-use evidence base.

Safety

Know the common side effects, key cautions, and who should avoid it.

Common side effects

rarely, GI upset from sudden large increases in fiberharmless red/black staining of teeth and tongue if eaten in large quantityoral-allergy syndrome (itching, mild swelling) in people allergic to related Rosaceae fruits

Serious risks

  • A sudden large increase in blackberry intake (multiple cups daily) can meaningfully increase vitamin K intake and lower INR in people on warfarin. The effect is small per cup but cumulative — keep weekly intake consistent rather than going from zero to several cups overnight if you're on warfarin.

    SourceUSDA FoodData Central — Blackberries, raw — USDA

  • Blackberry leaf preparations (tea, capsules) contain tannins and have been used traditionally for diarrhoea, sore throat, and mouth inflammation. Modern clinical evidence is minimal; high-tannin intake can reduce mineral absorption and rarely causes hepatotoxicity. The fruit and the leaf are separate products.

    SourceLinus Pauling Institute — Flavonoids — Oregon State University Linus Pauling Institute

Who should avoid it

Pregnancy & breastfeeding

Fresh and frozen blackberries are safe in pregnancy and breastfeeding as part of a normal diet — they're an excellent fiber, vitamin C, and folate source. Blackberry-leaf preparations are a different matter and lack safety data in pregnancy — avoid those unless cleared by your obstetrician.

SourceUSDA FoodData Central — Blackberries, raw — USDA

Bottom line: As a food, blackberries are one of the safer, more nutrient-dense fruit choices. Leaf-based herbal preparations are a separate category with much less safety/efficacy data.

Interactions

warfarin (and vitamin K-sensitive anticoagulation)Minor

1 cup blackberries contains ~24 μg vitamin K (20% DV). A consistent intake is fine — a sudden large change can shift INR. Don't go from zero to several cups daily without monitoring.

SourceUSDA FoodData Central — Blackberries, raw — USDA
iron / mineral supplements (high-tannin blackberry leaf preparations)Minor

Tannins in blackberry leaf (and to a much lesser extent the fruit) can reduce iron and other mineral absorption when consumed at the same time. Mostly a concern for concentrated leaf preparations, not the fruit.

SourceLinus Pauling Institute — Flavonoids — Oregon State University Linus Pauling Institute

Food sources

Blackberries, raw — 1 cup (144 g)

Amount
62 kcal · 7.6 g fiber · 4.0 g protein
%DV
—

Vitamin C from 1 cup

Amount
30 mg vitamin C
%DV
33%

Vitamin K from 1 cup

Amount
28.5 μg vitamin K
%DV
24%

Manganese from 1 cup

Amount
0.93 mg manganese
%DV
40%

Fiber from 1 cup

Amount
7.6 g fiber
%DV
27%

Folate from 1 cup

Amount
36 μg folate
%DV
9%

Potassium from 1 cup

Amount
233 mg potassium
%DV
5%

Anthocyanins from 1 cup (typical)

Amount
150–250 mg anthocyanins (mainly cyanidin-3-O-glucoside)
%DV
—

Choosing a product

What to look for on the label — and what to be skeptical of.

Look for…

Fresh: firm, deeply pigmented berries with no green/red drupelets and no mold
Frozen: 'no added sugar' on the label; ingredients should be just 'blackberries'
Organic if you eat them often — blackberries appear on the EWG Dirty Dozen-adjacent lists in some years (pesticide residues)
Local in-season berries from farmer's markets are typically fresher and cheaper than out-of-season imports
Wild blackberries are safe if you can identify them — but avoid roadsides (lead/exhaust) and pesticide-sprayed margins

Be skeptical of…

'Cancer-fighting blackberry extract' — most cancer-chemoprevention work is on BLACK RASPBERRY (a different species)
'Anti-aging' anthocyanin claims — modest biomarker effects, no proven anti-aging endpoint
Expensive freeze-dried blackberry powders sold as supplements — eat the fruit
Blackberry-leaf 'detox' tea claims — limited modern evidence, rare hepatotoxicity reports
'Diabetic-friendly' marketing on jams, fruit spreads, and sweetened products — added sugars erase the fiber-to-sugar ratio

Frequently asked questions

What is Blackberry used for?⌄

Blackberry is used traditionally for various supportive purposes. Human evidence for specific health claims is generally limited, so it is best treated as a complementary option rather than a treatment.

Is Blackberry safe?⌄

Blackberry is generally well tolerated at typical doses, but quality varies between products. People who are pregnant, breastfeeding, taking prescription medications, or managing a medical condition should check with a healthcare provider first.

How long does it take to work?⌄

Effects of botanical supplements often take several weeks of consistent use, if they appear at all. Reassess after 8-12 weeks of regular use.

References by claim

Dietary fiber and vitamin C/K source

USDA FoodData Central — Blackberries, raw — USDA (2024) link

Anthocyanin source for cardiometabolic biomarkers

Kalt et al., 2019 — PMC — Advances in Nutrition (2019) link

Yang et al., 2021 — PubMed — Advances in Nutrition (2021) link

Linus Pauling Institute — Flavonoids — Oregon State University Linus Pauling Institute (2024) link

Cancer prevention (often mis-attributed)

Stoner et al., 2008 — PubMed — Cancer Prevention Research (2008) link

Other references

Blackberry on NIH DSLD — NIH Dietary Supplement Label Database link

Track Blackberry with Pilora

Set up dose reminders, check interactions, and join the community in the Pilora iPhone app.

Coming to App Store
Evidence-based·Last reviewed Jun 1, 2026·Evidence current as of Jun 1, 2026·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.