Home Ingredients Sloe Berry (Prunus spinosa)

Sloe Berry (Prunus spinosa)

Prunus spinosa L.
Evidence Level
Preliminary
3 Clinical Trials
5 Documented Benefits
1/5 Evidence Score

Sloe berries are the small, dark blue fruits of blackthorn (Prunus spinosa), a thorny wild shrub of Europe and western Asia. They taste sharply astringent from their tannins and are mostly cooked into jam, pressed for juice, dried for tea or steeped in alcohol to flavor sloe gin and similar liqueurs. The fruit is rich in polyphenols: phenolic acids, quercetin glycosides such as rutin, proanthocyanidins and anthocyanins, mainly cyanidin and peonidin glycosides. No controlled human study of sloe fruit was found; the antioxidant, immune cell and stomach lining findings all come from test tubes, donated human cells or rats. The kernel inside each stone contains small amounts of amygdalin, a compound that can release cyanide when kernels are crushed, so stones should be left whole and never eaten. Blackthorn flowers and leaves are different materials from the fruit.

Studied Dose No human dose has been tested. Rat studies used a single 100 or 200 mg/kg dose of fruit extract, or 400 to 800 mg/kg of freeze-dried fruit daily for 4 weeks; these do not convert into a human serving. Sloes are eaten as food (jam, juice, tea, liqueur).
Active Compound Fruit polyphenols: phenolic acids (caffeoylquinic acids such as neochlorogenic acid), flavonols (rutin and other quercetin glycosides), proanthocyanidins and anthocyanins (mainly cyanidin and peonidin glycosides, such as cyanidin-3-rutinoside). The stone kernel contains the cyanogenic glycosides amygdalin and prunasin.

Benefits

A source of polyphenols and anthocyanins

Laboratory analyses of the fruit identify dozens of phenolic compounds: caffeoylquinic acids, quercetin glycosides such as rutin, proanthocyanidins and anthocyanins, chiefly cyanidin-3-rutinoside, peonidin-3-rutinoside and cyanidin-3-glucoside. Levels vary widely with growing site and processing. This describes what the fruit contains, not a measured effect in people.

Supported by Trial 1

Antioxidant activity in lab and rat studies

Fresh sloe juice scavenged free radicals in test tubes and protected cultured human cells from hydrogen peroxide. In rats on a high-fat diet, 4 weeks of freeze-dried fruit lowered liver and brain oxidation markers but did not change blood glucose, cholesterol or liver enzymes; the higher dose did lower total liver fat. No study has measured oxidative stress in people who ate sloes.

Supported by Trial 2

Immune cell signals in laboratory tests

Polyphenol-rich fruit extracts added to human white blood cells in the lab lowered reactive oxygen species, TNF-alpha and elastase release and raised the anti-inflammatory signal IL-10, with only slight effects on IL-6 and IL-8. A separate cell study linked fruit extract to the Nrf2 antioxidant pathway. These are cell findings, not effects shown after eating the fruit.

Supported by Trial 1

Stomach lining in an animal injury model

In rats given the painkiller indomethacin, a single dose of sloe fruit extract (100 or 200 mg/kg) taken just before reduced the damaged stomach area by about 81 to 84% and lowered tissue inflammation markers at 6 hours. The reduction in white cell infiltration was not statistically significant. This has not been tested in people.

Supported by Trial 3

Starch-digesting enzymes and probiotic growth in test tubes

Sloe fruit extracts slowed the starch-digesting enzymes alpha-amylase and alpha-glucosidase in test tubes and, at 0.3 to 5 mg/mL, boosted the growth of several probiotic microbes, especially the yeast Saccharomyces boulardii. Whether eating sloes does either in the human gut is unknown.

Supported by Trial 1, Trial 2

Mechanism of action

1

Polyphenols as antioxidants and Nrf2 activators (cell studies)

Sloe polyphenols scavenge free radicals in chemical tests, and in human monocyte cells a fruit extract modulated Nrf2, a switch for the cell's own antioxidant defenses, and cut reactive oxygen species after an inflammatory challenge. How much of these compounds reaches human tissues after eating sloes has not been measured.

2

Lower inflammatory signaling in white blood cells (lab finding)

In donated human neutrophils and mononuclear cells, fruit extracts reduced TNF-alpha and elastase release and raised IL-10; tests with pure compounds pointed to the polyphenols as the main contributors. These are test-tube results at set concentrations.

3

Cyanogenic glycosides in the stone

The kernel inside the stone holds small amounts of amygdalin and prunasin, reported in earlier work but not measured in the studies cited here. In related plum seeds, these compounds release toxic hydrogen cyanide when seed cells are broken, which is why crushing or chewing the stones is the step to avoid. The fruit flesh is the part used as food.

Clinical trials

1
Sloe Fruit Extracts in Human Immune Cells (laboratory study)
PubMed

Laboratory (ex vivo) study of polyphenol-enriched extracts of fresh sloe fruit, profiled by UHPLC-MS and tested on immune cells isolated from human blood. (Magiera et al. 2022, Molecules)

Human neutrophils and peripheral blood mononuclear cells in culture; no one ate the fruit.

The extracts strongly reduced the release of reactive oxygen species, TNF-alpha and neutrophil elastase, raised IL-10, and only slightly reduced IL-8 and IL-6 in stimulated cells. Tests with pure compounds pointed to the polyphenols. Cell safety was confirmed across a wide concentration range. These findings have not been tested in people.

2
Freeze-Dried Sloe Fruit and Oxidation Markers in Rats (animal study)
PubMed

Animal study with in vitro work: wild Italian sloe fruit given by gavage at 400 or 800 mg/kg body weight for 4 weeks to rats fed a high-fat diet and given streptozotocin. (Pozzo et al. 2019, Foods)

Male Wistar rats; 8 per treated group, with untreated high-fat diet and normal-diet control groups.

The fruit lowered malondialdehyde in liver and brain in a dose-dependent way and lowered liver protein carbonyls at 800 mg/kg; glutathione did not change. It did not improve body or liver weight, blood glucose, insulin, liver enzymes, cholesterol or triglycerides, but 800 mg/kg significantly lowered total liver fat compared with the untreated high-fat group. Animal data only.

3
Sloe Fruit Extract and Painkiller-Induced Stomach Injury in Rats (animal study)
PubMed

Animal study comparing a single oral dose of sloe fruit ethanol extract (100 or 200 mg/kg) with the drug lansoprazole, each given 5 minutes before oral indomethacin; stomachs examined after 6 hours. (Cetin et al. 2024, Iran J Basic Med Sci)

60 male Wistar rats, randomly divided into 5 groups of 12.

The damaged area was about 81% (low dose) and 84% (high dose) smaller than with indomethacin alone, versus about 100% with lansoprazole; TNF-alpha, IL-6, IL-1beta, IL-8 and NF-kB were lower than in the indomethacin group. The drop in neutrophil infiltration with the extract was not statistically significant. Single-dose animal data only.

Side effects and drug interactions

Common Potential side effects

No human trial of sloe fruit was found, so side effects and safe amounts have not been studied in people.
Do not crush, chew or eat the stones. Sloe kernels contain small amounts of amygdalin and prunasin, and in related plum seeds these release hydrogen cyanide when seed cells are broken. Remove stones when making jam or juice, and leave them whole when steeping fruit.
Liqueurs made from crushed apricot or cherry kernels kept measurable cyanogenic glycosides; levels in homemade sloe gin made with whole fruit have not been reported in the cited studies.
Wild sloes picked near roads or in towns carried more metals and combustion pollutants in one Romanian survey, so pick away from traffic.
Sloe gin and other liqueurs contain alcohol; the cautions for any alcoholic drink apply, including during pregnancy.

Important Drug interactions

No interactions with sloe fruit have been studied in people.
Blood-thinning medicines (such as warfarin): blackthorn flower extracts inhibited thrombin in test tubes. This has not been shown for the fruit or in people, but check with your doctor before using concentrated blackthorn flower products.
Sloe gin and other liqueurs contain alcohol, which interacts with many medicines; follow the alcohol warnings on your medicine labels.

Explore Other Ingredients

Immune Support
Probiotics (Multi-strain Blends)
Multi-strain probiotic blends combine live microbes, usually from Lactobacillus and Bifido…
Metabolic Health
Inulin
Inulin is a soluble prebiotic fiber found naturally in chicory root, agave, and many veget…
Muscle & Recovery
L-Glutamine
L-glutamine is the most abundant amino acid in the body, and cells of the intestinal linin…

Frequently asked questions about Sloe Berry (Prunus spinosa)

Has sloe berry been tested in human studies?

No controlled human trial of sloe fruit has been published. The antioxidant, immune cell and stomach lining findings come from test tubes, donated human cells and rats, and a 2025 review points to the scarcity of animal and clinical studies. Sloes are a traditional food, but their effects in people are unmeasured.

Why should sloe stones be left whole?

The kernel inside each stone contains small amounts of amygdalin and prunasin, and in related plum seeds these compounds release hydrogen cyanide when the seed is crushed or chewed. Pit the fruit for jam or juice, steep whole fruit for liqueurs, and never eat or grind the stones.

Are blackthorn flowers and leaves the same as sloe berries?

No. Flowers and leaves are separate materials with their own chemistry; flower extracts are rich in flavonols and A-type proanthocyanidins, and a USDA database also lists amygdalin in the flower. Lab findings on flower extracts, such as thrombin inhibition, do not carry over to the fruit.

Does steeping sloes in alcohol keep their anthocyanins?

Only partly. In a study of sloe tinctures, anthocyanins peaked early and then declined over weeks of steeping, while total polyphenols were highest at 84 days with whole unprocessed fruit. A sweetened liqueur is still an alcoholic drink, not a health product.

What is Sloe Berry?

Sloe berries are the small, dark blue fruits of blackthorn (Prunus spinosa), a thorny wild shrub of Europe and western Asia. They taste sharply astringent from their tannins and are mostly cooked into jam, pressed for juice, dried for tea or steeped in alcohol to flavor sloe gin and similar liqueurs.

What is Sloe Berry used for?

NutraSmarts does not list Sloe Berry under a health category. What the research covers: Laboratory analyses of the fruit identify dozens of phenolic compounds: caffeoylquinic acids, quercetin glycosides such as rutin, proanthocyanidins and anthocyanins, chiefly cyanidin-3-rutinoside, peonidin-3-rutinoside and cyanidin-3-glucos…

What is the recommended dosage of Sloe Berry?

No human dose has been tested. Rat studies used a single 100 or 200 mg/kg dose of fruit extract, or 400 to 800 mg/kg of freeze-dried fruit daily for 4 weeks; these do not convert into a human serving. Sloes are eaten as food (jam, juice, tea, liqueur). Always follow the product label and check with a healthcare provider for personal advice.

Is Sloe Berry safe, and does it have side effects?

Side effects and cautions reported for Sloe Berry include: No human trial of sloe fruit was found, so side effects and safe amounts have not been studied in people. Do not crush, chew or eat the stones. It may also interact with some medications. Sloe Berry is not right for everyone, so check with a healthcare provider first if you are pregnant or breastfeeding, have a medical condition, or take prescription medication.

Does Sloe Berry interact with any medications?

Possible interactions include: No interactions with sloe fruit have been studied in people. Blood-thinning medicines (such as warfarin): blackthorn flower extracts inhibited thrombin in test tubes. If you take prescription medication, check with a pharmacist or doctor before using it.

How strong is the scientific evidence for Sloe Berry?

NutraSmarts rates the evidence for Sloe Berry as Preliminary (1 out of 5). It is backed by 3 study summaries and 16 cited references summarized on this page. A higher rating reflects more, larger, and better-designed human studies.

References(16 citations)

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

  1. Fraternale D, Giamperi L, Bucchini A, Sestili P, Paolillo M, Ricci D. Prunus spinosa fresh fruit juice: antioxidant activity in cell-free and cellular systems. Nat Prod Commun. 2009;4(12):1665-70..PubMedUsed to support: Laboratory study of fresh juice from wild sloes (central Italy): good activity in DPPH and 5-lipoxygenase tests, an ORAC value of 36.0 micromol Trolox equivalents per g of fruit, and protection of cultured human promonocytes (U937 cells) exposed to hydrogen peroxide. Names cyanidin-3-rutinoside, peonidin-3-rutinoside and cyanidin-3-glucoside as the main juice anthocyanins. No human or animal testing.
  2. Magiera A, Czerwińska ME, Owczarek A, Marchelak A, Granica S, Olszewska MA. Polyphenol-Enriched Extracts of Prunus spinosa Fruits: Anti-Inflammatory and Antioxidant Effects in Human Immune Cells Ex Vivo in Relation to Phytochemical Profile. Molecules. 2022;27(5):1691. doi: 10.3390/molecules27051691.PubMedUsed to support: Identified 57 phenolic compounds in fresh sloe fruit extracts; enriched fractions reached up to 91.3 mg/g phenolic acids (caffeoyl-, coumaroyl- and feruloylquinic acids), 41.1 mg/g flavonoids (mostly quercetin glycosides), 44.5 mg/g proanthocyanidins and 9.2 mg/g anthocyanins (cyanidin and peonidin glycosides). Applied to human neutrophils and blood mononuclear cells in the lab, the extracts lowered reactive oxygen species, TNF-alpha and elastase release and raised IL-10, with only slight effects on IL-8 and IL-6. Cell work only; no one ate the fruit.
  3. Pozzo L, Russo R, Frassinetti S, Vizzarri F, Árvay J, Vornoli A, Casamassima D, Palazzo M, Croce CMD, Longo V. Wild Italian Prunus spinosa L. Fruit Exerts In Vitro Antimicrobial Activity and Protects Against In Vitro and In Vivo Oxidative Stress. Foods. 2019;9(1):5. doi: 10.3390/foods9010005.PubMedUsed to support: Wild Italian sloe fruit extract (rutin the main phenolic) showed antibacterial and antioxidant activity in lab tests. In rats given a high-fat diet and streptozotocin, freeze-dried fruit at 400 or 800 mg/kg by gavage for 4 weeks (8 rats per group) lowered liver and brain oxidative damage markers (malondialdehyde; liver protein carbonyls only at 800 mg/kg), but per the full text it did not change blood glucose, insulin, liver enzymes, cholesterol or liver weight; 800 mg/kg did lower total liver fat. Animal study only.
  4. Cetin N, Menevse E, Ceylan C, Celik ZE, Akdam N, Rama ST, Buyukyildirim T, Pasayeva L, Tugay O, Gumus M. Histopathological and biochemical evaluation of the protective efficacy of Prunus spinosa L. extract in a rat model of indomethacin-induced gastric ulcer. Iran J Basic Med Sci. 2024;27(11):1464-1474. doi: 10.22038/ijbms.2024.78382.16941.PubMedUsed to support: Rat study (60 rats, 12 per group): a single oral dose of sloe fruit ethanol extract (100 or 200 mg/kg) given 5 minutes before the painkiller indomethacin reduced the damaged stomach area by about 81 to 84% versus indomethacin alone at 6 hours (the drug lansoprazole, about 100%) and lowered tissue TNF-alpha, IL-6, IL-1beta, IL-8 and NF-kB. Per the full text, the reduction in neutrophil infiltration with the extract was not statistically significant. Animal study only.
  5. Marčetić M, Samardžić S, Ilić T, Božić DD, Vidović B. Phenolic Composition, Antioxidant, Anti-Enzymatic, Antimicrobial and Prebiotic Properties of Prunus spinosa L. Fruits. Foods. 2022;11(20):3289. doi: 10.3390/foods11203289.PubMedUsed to support: Laboratory analysis of Serbian sloe fruit extracts: 27 phenolics identified, caffeoylquinic acid the most abundant. In test tubes the extracts inhibited alpha-amylase, alpha-glucosidase, acetylcholinesterase and tyrosinase (IC50 0.43 to 2.16 mg/mL) and, at 0.3 to 5 mg/mL, stimulated the growth of several probiotic microbes, especially the yeast Saccharomyces boulardii. No human or animal testing.
  6. Negrean OR, Farcas AC, Pop OL, Socaci SA. Blackthorn-A Valuable Source of Phenolic Antioxidants with Potential Health Benefits. Molecules. 2023;28(8):3456. doi: 10.3390/molecules28083456.PubMedUsed to support: Review of sloe fruit composition: flavonoids, anthocyanins, phenolic acids, vitamins, minerals and organic acids. The full text notes the small fruits taste astringent because of their tannins and are usually made into jams, drinks and supplements or preserved for herbal teas. Health effects discussed are from laboratory and animal work.
  7. Tamayo-Vives C, Úbeda M, Morales P, García-Herrera P, Sánchez-Mata MC. Crataegus monogyna Jacq., Sorbus aria (L.) Crantz and Prunus spinosa L.: From Edible Fruits to Functional Ingredients: A Review. Foods. 2025;14(13):2299. doi: 10.3390/foods14132299.PubMedUsed to support: Narrative review of hawthorn, whitebeam and sloe fruits: rich in phenolic compounds, flavonoids and anthocyanins with antioxidant and anti-inflammatory activity in laboratory work, but the authors state that the scarcity of in vivo and clinical studies limits how far these findings translate, and call for research on efficacy and safety in people.
  8. Marchelak A, Owczarek A, Matczak M, Pawlak A, Kolodziejczyk-Czepas J, Nowak P, Olszewska MA. Bioactivity Potential of Prunus spinosa L. Flower Extracts: Phytochemical Profiling, Cellular Safety, Pro-inflammatory Enzymes Inhibition and Protective Effects Against Oxidative Stress In Vitro. Front Pharmacol. 2017;8:680. doi: 10.3389/fphar.2017.00680.PubMedUsed to support: Laboratory study of blackthorn flower extracts, a different material from the fruit: 57 constituents, mostly flavonoids, A-type proanthocyanidins and phenolic acids. The extracts protected human plasma components from peroxynitrite damage in test tubes and did not harm human blood mononuclear cells. Describes the flowers as a traditional Central and Eastern European remedy. No human intake studied.
  9. Marchelak A, Kolodziejczyk-Czepas J, Ponczek MB, Liudvytska O, Markowicz-Piasecka M, Bielska B, Miłowska K, Olszewska MA. Flavonol and A-type procyanidin-rich extracts of Prunus spinosa L. flower exhibit anticoagulant activity through direct thrombin inhibition, but do not affect platelet aggregation in vitro. Front Pharmacol. 2023;14:1307373. doi: 10.3389/fphar.2023.1307373.PubMedUsed to support: Test-tube study of blackthorn flower extracts at 1 to 50 micrograms/mL: slightly prolonged prothrombin and thrombin times and inhibited thrombin activity (by 91.2% and 74.8% in two assays at 50 micrograms/mL), with no effect on platelet aggregation. Not tested in people or with the fruit; basis for the theoretical caution about blood-thinning medicines.
  10. Kristl J, Golenač LP, Sem V. Dynamics of cyanogenic glycosides in apple and plum fruits, products, and byproducts: A concise review. J Food Sci. 2024;89(11):6839-6862. doi: 10.1111/1750-3841.17377.PubMedUsed to support: Review on apples and cultivated plums (Prunus domestica, a relative of sloe): their seeds are rich in cyanogenic glycosides, which release toxic hydrogen cyanide when plant cells are broken. For distillates made with plum stones it recommends monitoring cyanide during storage because it can rise over time. Sloe itself was not studied.
  11. Senica M, Stampar F, Veberic R, Mikulic-Petkovsek M. Transition of phenolics and cyanogenic glycosides from apricot and cherry fruit kernels into liqueur. Food Chem. 2016;203:483-490. doi: 10.1016/j.foodchem.2016.02.110.PubMedUsed to support: Liqueurs made by steeping crushed apricot or cherry kernels in alcohol still contained considerable cyanogenic glycosides (38.79 and 16.08 micrograms per mL), though less than the kernels themselves. Sloe stones were not tested; cited to show that compounds in crushed stone-fruit kernels pass into alcoholic drinks.
  12. Piras A, Porcedda S, Smeriglio A, Trombetta D, Piras F, Sogos V, Rosa A. Chemical Composition and Bioactivity of Extracts Obtained from Prunus spinosa Seeds by Supercritical CO(2) Extraction. Molecules. 2025;30(8):1757. doi: 10.3390/molecules30081757.PubMedUsed to support: Laboratory extraction of sloe seeds: extracts contained oleic and linoleic acids, polyphenols and benzaldehyde. The full text notes, citing earlier work, that sloe seeds contain the cyanogenic glycosides amygdalin and prunasin in small amounts that require careful processing for safety, and explains benzaldehyde as a breakdown product of such glycosides. No human testing.
  13. Wilk M, Seruga P, Nowicka P. Effect of Processing Parameters on the Content of Bioactive Compounds of Prunus spinosa L. Fruit Tinctures. Foods. 2025;14(18):3200. doi: 10.3390/foods14183200.PubMedUsed to support: Food science study of sloe fruit tinctures (40 to 80% ethanol, 28 to 84 days of steeping): total polyphenols peaked at day 84 with whole unprocessed fruit and sugar added at the start; neochlorogenic acid dominated; anthocyanins peaked early and then declined as steeping went on. The study did not measure cyanogenic glycosides. No human testing.
  14. Colomba M, Benedetti S, Fraternale D, Guidarelli A, Coppari S, Freschi V, Crinelli R, Kass GEN, Gorassini A, Verardo G, Roselli C, Meli MA, Di Giacomo B, Albertini MC. Nrf2-Mediated Pathway Activated by Prunus spinosa L. (Rosaceae) Fruit Extract: Bioinformatics Analyses and Experimental Validation. Nutrients. 2023;15(9):2132. doi: 10.3390/nu15092132.PubMedUsed to support: Computer predictions plus a cell study in human U937 monocytes: sloe fruit ethanol extract modulated Nrf2, a cell switch for antioxidant defenses, and strongly reduced reactive oxygen species after a bacterial endotoxin (LPS) challenge; no effects were seen on p53 or mitochondrial membrane potential. Cell work only.
  15. Băbălău-Fuss V, Dordai L, Roman M, Bianca S, Stroe TC, Timar AV, Becze A. Biochemical Profiling and Ecotoxicological Assessment of Prunus spinosa L. Fruits from the Cluj Region: Phytochemical Composition, Contaminant Load, and Antioxidant Potential. Foods. 2026;15(17):3135. doi: 10.3390/foods15173135.PubMedUsed to support: Analysis of wild sloes from five Romanian sites over three harvests: total polyphenols ranged from 124 to 1172 mg GAE/kg dry weight, and urban and roadside samples had higher metals and polycyclic aromatic hydrocarbons than rural and forest-edge samples. The authors caution that the differences cannot be attributed only to pollution.
  16. US Department of Agriculture, Agricultural Research Service. Dr. Duke's Phytochemical and Ethnobotanical Databases: Prunus spinosa. USDA ARS. 2026;Database entry citing Duke 1992; accessed 2026..SourceUsed to support: Not PubMed-indexed (USDA database, read online). Lists amygdalin, a cyanogenic glycoside, in the seed and in the flower of Prunus spinosa, and pectin and beta-sitosterol in the fruit; no amounts are given.