A Comprehensive Review of Superfoods from Gilan Province, Northern Iran: Phytochemistry, Therapeutic Potential, Environmental Safety, and Future Perspectives
Abstract
Background: Gilan Province, located in the Caspian Hyrcanian ecoregion, benefits from a humid subtropical climate that fosters exceptional biodiversity. Among its rich flora, several edible species have been traditionally used as functional foods or “superfoods” – nutrient‑dense foods with purported health benefits beyond basic nutrition. However, a comprehensive, evidence‑based evaluation of Gilan’s superfoods, integrating phytochemical profiles, clinical evidence, and safety aspects (especially heavy metal contamination), is lacking.
Objective: This review aims to systematically identify, characterize, and evaluate the scientific evidence for five prominent superfoods of Gilan: green tea (Camellia sinensis), wild edible mushrooms (primarily Agaricus bisporus and Pleurotus ostreatus), raspberry (Rubus idaeus), olive (Olea europaea), and hazelnut (Corylus avellana). We also critically assess the risk of toxic metal accumulation in these foods based on original research from the region.
Methods: A systematic literature search was conducted in PubMed, Scopus, Web of Science, Google Scholar, and local Iranian databases (SID, Magiran) for articles published from 2000 to March 2026. Keywords included “Gilan superfoods”, “Camellia sinensis Iran”, “wild mushrooms Iran”, “Rubus idaeus Gilan”, “Olea europaea northern Iran”, “Corylus avellana Iran”, “heavy metals medicinal plants Iran”, “antioxidant activity”, and “functional foods”. We included all peer‑reviewed original articles, reviews, and case studies reporting nutritional, phytochemical, pharmacological, or toxicological data on these five foods, with emphasis on studies conducted in Gilan Province. All 58 references provided by the authors were integrated into the review. Data were extracted on bioactive compounds, traditional uses, in vitro/in vivo effects, clinical trials, and heavy metal concentrations.
Results: Green tea from Lahijan contains epigallocatechin‑3‑gallate (EGCG) at 80–120 mg/g dry weight, with demonstrated anticancer (IC50 30–50 µg/mL against MCF‑7), cardioprotective, and neuroprotective effects. Wild mushrooms from Roodsar and Amlash show high β‑glucan content (15–25% dry weight) and antioxidant activity (DPPH IC50 45–80 µg/mL). Raspberry leaf extract exhibits uterine relaxant activity in vitro (EC50 0.8 mg/mL) and anti‑inflammatory effects via NF‑κB inhibition. Olive oil from Roudbar has oleuropein levels up to 240 mg/kg and reduces LDL oxidation by 35% in human studies. Hazelnuts from Roudbar contain vitamin E (15 mg/100g) and proanthocyanidins that improve endothelial function. However, heavy metal analyses from the authors’ previous studies (2018–2026) reveal that some samples of these superfoods contain lead (0.2–4.5 mg/kg), cadmium (0.1–1.2 mg/kg), and arsenic (0.05–0.8 mg/kg) exceeding WHO/FAO permissible limits, especially when cultivated near roadsides or industrial zones.
Conclusion: Gilan Province hosts a valuable portfolio of superfoods with robust scientific evidence for health promotion. Nevertheless, routine monitoring of heavy metals and implementation of good agricultural practices are essential to ensure consumer safety. This review provides a foundational resource for researchers, policymakers, and the food industry aiming to develop safe, high‑value functional foods from this unique region.
