Bee Pollen as Functional Food: Insights into Its Composition and Therapeutic Properties

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TL;DR

Bee pollen is a nutrient-dense hive product containing proteins, carbohydrates, lipids, vitamins, minerals, and phenolic compounds that exhibits antioxidant, antidiabetic, hepatoprotective, nephroprotective, and anti-inflammatory properties. Its therapeutic effects are mediated through multiple molecular pathways including Nrf2/HO-1, NF-κB, and MAPK signaling, with individual phenolic compounds such as quercetin, kaempferol, and caffeic acid demonstrating specific mechanisms of action. Despite significant compositional variability depending on botanical and geographical origin, bee pollen shows promise as a functional food and potential ingredient for pharmaceutical and nutraceutical applications.

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**Background:** Bee pollen is a hive product composed of flower pollen grains, nectar, and bee salivary secretions, collected by worker bees and processed within the hive through lactic fermentation to become bee bread. It has gained prominence as a functional food due to its rich composition of macronutrients (proteins 10–40%, carbohydrates 13–55%, lipids 1–13 g/100 g) and micronutrients including vitamins, minerals, and phenolic compounds. The German Federal Ministry of Health has formally acknowledged bee pollen as a drug. This narrative review aimed to provide a comprehensive summary of bee pollen's composition, particularly phenolic compounds, and its biological and therapeutic properties along with the involved molecular pathways.

**Methods:** The authors conducted a literature search using Science Direct, Google Scholar, Web of Science, PubMed, and Scopus databases with keywords including 'bee pollen', 'chemical composition of bee pollen', 'therapeutic effect of bee pollen', and 'protective effect of bee pollen'. Collected articles were summarized and used in this review.

**Key Results:** The review reports that bee pollen contains 20–30% water in fresh form, with maximum allowed water content varying by country (4% in Brazil, 6% in Poland and Switzerland, 8% in Argentina, 10% in Bulgaria). Total amino acid content ranges from 108.1 to 287.7 mg/g, with proline being the most abundant in dried pollen and glutamic acid in fresh pollen. Dietary fiber ranges from 0.3 to 20 g/100 g dry weight. Potassium is the principal mineral (400–2000 mg/100 g), with 15 g of bee pollen covering up to 25% of the recommended daily intake. Trace elements including iron, zinc, copper, and manganese cover up to 37%, 79%, 36%, and 85% of respective RDIs. The phenolic profile includes phenolic acids (chlorogenic, gallic, cinnamic, ferulic acid) and flavonoids (quercetin, kaempferol, rutin, apigenin, chrysin, luteolin, naringenin, pinocembrin). In vitro antioxidant studies showed DPPH IC50 values ranging from 0.39 ± 0.13 mg/mL (Moroccan fresh bee pollen aqueous extract) to 1.28 ± 0.03 mg/mL (Chinese ethanol extract) and 1.72 mg/mL (Chinese methanol extract). The review details therapeutic mechanisms for individual phenolic compounds: caffeic acid (6 mg/kg/day for 45 days) improved alcohol-induced oxidative stress by increasing non-enzymic antioxidants; rutin (50 and 100 mg/kg/day for 20 days) enhanced antioxidant enzymes and downregulated COX, p38-MAPK, i-NOS, and NF-κB; quercetin decreased TNFα, IL-1β, and IL-6 expression; luteolin upregulated Nrf-2 pathway and increased HO-1 expression; pinocembrin decreased oxidative stress, apoptotic, and inflammatory markers. For antidiabetic effects, cinnamic acid (50 mg/kg/day for 5 weeks) stimulated insulin and adiponectin secretion; kaempferol (50 mg/kg/day) reduced hepatic glucose production and increased hexokinase activity; apigenin enhanced GLUT4 translocation via AMPK pathway. Hepatoprotective studies showed naringenin (50 mg/kg/day) boosted enzymatic and non-enzymatic antioxidant activities and reduced NO, TNF-α, and IL-6 levels. Ferulic acid protected against CCL4-induced liver damage via upregulation of p-JNK, p-p38 MAPK, and Bcl-2 pathways. Nephroprotective effects included protocatechuic acid increasing SOD, CAT, GSH, and GPX activities while decreasing RNOS, LPO, NO, TNF-α, and IL-1β. Pinocembrin mitigated gentamicin-induced renal toxicity via Nrf2/HO-1 and NQO1 pathways. Anti-inflammatory mechanisms included caffeic acid, ferulic acid, and cinnamic acid inhibiting TNF and downregulating NF-κB; ellagic acid inhibiting NO, TNF-α, IL-6, COX-2, and PGE2; galangin inhibiting iNOS, COX-2, IL-1β, and TNF-α expression.

**Clinical Implications:** Bee pollen demonstrates broad therapeutic potential against oxidative stress-related diseases including diabetes, liver and kidney disorders, and inflammatory conditions through multiple molecular pathways. The review identifies lactic acid bacteria in fresh bee pollen (Lactobacillus species, Lactococcus lactis, Pediococcus species) as potential novel probiotics. However, significant compositional variability due to botanical and geographical origins limits standardized clinical application. The authors recommend expanding standardization to include phenolic composition and nutritional value, conducting more bioavailability studies, performing clinical trials to investigate health benefits in humans, and developing bee pollen-enriched food products and dietary supplements for the food and pharmaceutical industries.