Quick Summary

Sumac (Rhus coriaria) is a commonly used spice rich in phytochemicals such as flavonoids, tannins, polyphenolic compounds, and organic acids. It has been studied mainly in human randomized controlled trials for potential benefits on cardiovascular disease risk factors, metabolic syndrome markers, inflammation, oxidative stress, and treatment of recurrent aphthous stomatitis. Evidence suggests possible improvements in lipid and glycemic profiles, some reduction in markers of inflammation, and potential benefits in soft tissue healing and oral mucositis. However, variability exists in study populations, duration, and measured outcomes. Safety data are limited but no significant adverse effects have been consistently reported.

What is It?

Sumac is the dried and ground fruit of Rhus coriaria, a shrub widely used as a culinary spice, particularly in Middle Eastern cuisine. It contains a variety of bioactive phytochemicals including flavonoids, tannins, organic acids, and polyphenols, attributed with antioxidant properties.

Traditional Uses

Traditionally, sumac has been used as a spice to flavor foods and in folk medicine for its potential anti-inflammatory and antimicrobial effects. It is also employed topically or as mouthwash preparations for oral conditions such as mouth ulcers and mucositis.

Active Compounds

  • Flavonoids
  • Tannins
  • Polyphenolic compounds
  • Organic acids
  • Other antioxidant phytochemicals

Potential Benefits with Evidence Levels

Cardiometabolic Health (Moderate Evidence)

Supplementation with sumac may improve lipid profiles including reductions in LDL cholesterol, total cholesterol, triglycerides, and increases in HDL cholesterol. It may also support glycemic control by reducing fasting blood glucose, insulin levels, and HOMA-IR. Some evidence suggests reductions in body weight, BMI, and waist circumference among adults with metabolic syndrome or at risk of cardiovascular disease. A randomized controlled trial also indicated a decrease in systolic blood pressure after 6 weeks of supplementation.

  • Key references include meta-analyses of 15–17 RCTs with over 900 to 1,200 participants showing significant improvements in lipid and glycemic parameters but inconsistent effects on inflammatory markers. (PMID: 41329614, PMID: 41372916, PMID: 38352703)
  • Smaller trials showed reductions in blood pressure and metabolic syndrome markers (PMID: 37189189, PMID: 34334274).

Inflammation (Low to Moderate Evidence)

Sumac supplementation may moderately reduce high-sensitivity C-reactive protein (hs-CRP), an inflammatory biomarker. However, evidence for effects on other inflammatory cytokines such as TNF-α and IL-6 is inconsistent. Some studies indicate reductions in oxidative stress markers like malondialdehyde (MDA) and improvements in total antioxidant capacity (TAC).

  • Based on meta-analyses of 7 randomized controlled trials examining inflammatory and oxidative stress markers. (PMID: 41069418, PMID: 38920072)

Oral Health and Wound Healing (Low to Moderate Evidence)

Topical use of sumac in gel or mouthwash form may reduce pain, ulcer size, and healing time in recurrent aphthous stomatitis (mouth ulcers) and radiation-induced oral mucositis. These findings suggest sumac as a potential safe alternative to corticosteroids or standard therapies for these conditions.

  • Supported by meta-analyses and clinical trials demonstrating efficacy and safety of sumac gel and sumac-rose water mouthwash. (PMID: 41408255, PMID: 36947237)

Oncological Potential (Preclinical Evidence)

Preclinical studies in rodents and cell cultures show that sumac extracts may exert oncostatic (anti-cancer) effects against breast cancer models. These effects have been linked to molecular changes promoting apoptosis and inhibiting tumor proliferation. However, no human clinical trials currently support these findings.

  • Evidence derived from animal and in vitro studies only. (PMID: 33375383)

Side Effects

No consistent or significant adverse effects have been reported with oral supplementation or topical use of sumac in clinical trials. Isolated pharmacological activities exist but major toxicity or safety concerns have not been documented.

Drug Interactions

Currently, there is insufficient evidence on drug interactions with sumac. No specific clinically relevant interactions have been reported in human studies or systematic reviews.

Who Should Avoid It

There are no evidence-based contraindications specifically associated with sumac documented in clinical research to date. However, caution is advised during pregnancy and breastfeeding due to insufficient safety data.

Pregnancy and Breastfeeding Caution

Limited clinical evidence is available regarding the safety of sumac consumption or supplementation during pregnancy and lactation. Although some related herbs have been evaluated for lipid-lowering use in pregnancy, sumac-specific safety data are lacking. Pregnant or breastfeeding individuals should consult a healthcare professional before using sumac supplements.

  • Refer to review on lipid-lowering medicinal herbs safety in pregnancy (PMID: 29147122).

Evidence Limitations

  • Most clinical trials are short-term (4–12 weeks) and mainly conducted in Iranian populations, limiting generalizability.
  • Considerable heterogeneity exists in study populations, doses, formulations, and measured outcomes.
  • Several meta-analyses report moderate to high statistical heterogeneity.
  • Few studies report detailed and systematic safety or adverse effects data.
  • Many trials have small sample sizes.
  • Limited data on long-term effects and across diverse demographic groups.
  • Lack of trials addressing drug interactions, contraindications, or use during pregnancy and breastfeeding.
  • Preclinical anticancer findings require cautious interpretation and await human clinical validation.

References

  • PMID: 41329614 – Systematic review and meta-analysis of RCTs demonstrating sumac’s effects on cardiovascular risk factors.
  • PMID: 41069418 – Meta-analysis showing sumac supplementation reduces hs-CRP inflammatory marker.
  • PMID: 41372916 – Comprehensive meta-analysis of sumac effects on cardiovascular risk factors.
  • PMID: 41408255 – Meta-analysis comparing sumac gel to other treatments for recurrent aphthous stomatitis.
  • PMID: 36947237 – Clinical trial of sumac-rose water mouthwash for radiation-induced oral mucositis prevention.
  • PMID: 33375383 – Preclinical animal and in vitro studies on sumac anti-breast cancer activity.
  • PMID: 38352703 – Systematic review and meta-analysis of sumac on cardiometabolic parameters.
  • PMID: 37189189 – RCT showing sumac reduces systolic blood pressure in metabolic syndrome.
  • PMID: 34334274 – Meta-analysis on sumac’s effects on glycemic indices in metabolic syndrome.
  • PMID: 38920072 – Systematic review of sumac effects on inflammation and oxidative stress markers.
  • PMID: 17173106 – Review on safety of traditional Arab herbal medicine relevant to sumac.
  • PMID: 29147122 – Review on lipid-lowering herbs safety in pregnancy; no sumac-specific data.

Last Reviewed

June 2024

Disclaimer: The information provided here is for educational purposes only. It is not intended to diagnose, treat, cure, or prevent any disease. Always consult a qualified healthcare professional before starting any new supplement or herbal product, especially if you are pregnant, breastfeeding, have existing medical conditions, or are taking medications.