Bee Pollen: Clinical Trials and Patent Applications

Bee pollen is a natural cocktail of floral nectar, flower pollen, enzymes, and salivary secretions produced by honeybees. Bee pollen is one of the bee products most enriched in proteins, polysaccharides, polyphenols, lipids, minerals, and vitamins. It has a significant health and medicinal impact and provides protection against many diseases, including diabetes, cancer, infectious, and cardiovascular. Bee pollen is commonly promoted as a cost-effective functional food. In particular, bee pollen has been applied in clinical trials for allergies and prostate illnesses, with a few investigations on cancer and skin problems. However, it is involved in several patents and health recipes to combat chronic health problems. This review aimed to highlight the clinical trials and patents involving bee pollen for different cases and to present the role of bee pollen as a supplementary food and a potential product in cosmetic applications.

. Clinical trials involving bee pollen.
A double-blind, placebo-controlled clinical trial was conducted in 47 patients with benign prostatic hyperplasia (BPH) to investigate the efficacy and safety of the 12-week intake of food supplemented with honeybee-collected pollen lump extract (HPLE). The participants were randomly assigned to three study groups: placebo or group P (0 mg HPLE per day), lower dose or group L (160 mg HPLE per day), and high dose or group H (320 mg HPLE per day). The maximum flow rate was significantly higher in group H (P0.05), but not in groups L or P. While the residual urine volume increased significantly in groups L and P (P0.05 each), it decreased in group H. There were no HPLE-related health risks or clinically significant laboratory abnormalities found [24].
Cernitin pollen extract was also administered to 79 patients suffering from BPH. The patients' ages ranged from 62 to 89 years (mean, 68 years), and Cernitin pollen extract was taken three times a day at a dose of 126 mg (2 tablets, 63 mg each), for more than 12 weeks. Symptom scores decreased significantly, and this positive trend continued throughout the treatment period. The maximum and average flow rates of urine increased from 9.3 mL/s to 11 mL/s and 5.1 mL/s to 6 mL/s, respectively. The volume of residual urine decreased significantly, from 54.2 mL to less than 30 mL. The prostatic volume remained unchanged. However, after more than a year of treatment, 28 patients had a mean decrease in prostatic volume of 26.5 cm 3 , with no negative reactions observed. The overall clinical efficacy was 85% [25].

Cancer Diseases
The anticancer impact of bee pollen administration is explained by the observed underlying mechanism, such as the stimulation of apoptosis, the inhibition of cell proliferation in multiple cell lines, and the reduction of tumor growth [26][27][28]. Lotus (Nelumbo nucifera) bee pollen can induce apoptosis and inhibit the proliferation of human prostate cancer PC-3 cells (Figure 1) [29].
The utilization of bee pollen and honey in 46 patients >18 years old, with breast cancer and receiving antihormonal treatment, was reported in a clinical study. The patients were advised to consume a tablespoonful of pollen and honey mixture for a consecutive 14 days. In breast cancer patients receiving antihormonal therapy, honey and bee pollen ameliorated the expected menopausal symptoms [30]. The impact of non-estrogenic pollen extract PCC-100 on 300 women between 50 and 65 years old, who suffered from vasomotor symptoms during adjuvant hormonal treatment for breast cancer, was estimated in a double-blind study. PCC-100, has been indicated to treat vasomotor symptoms in postmenopausal women receiving adjuvant hormone therapy, as well as menopausal women who have never developed breast cancer [31].

Allergic Diseases
Grass pollen immunotherapy is effective in patients with summer hay fever, attributed to its ability in preventing the late reactions brought about by allergens [32]. Forty-four patients with severe summer hay fever participated in a randomized, double-blind, placebocontrolled, parallel-group study. The patients received injections of a depot grass pollen vaccine in a rapid up-dosing cluster, for four weeks, followed by monthly injections for two years ( Figure 1). Grass pollen immunotherapy improved the quality of life in those with seasonal allergic rhinitis and decreased the symptoms of seasonal asthma and hyperresponsiveness in the lungs [33,34]. In a double-blind clinical trial, subcutaneous grass pollen immunotherapy using Phleum pretense was administrated to 18 patients. Compared to the placebo group, the treated group showed significantly reduced symptom and medication scores after one year of immunotherapy. Allergen-specific IgG antibodies induced by immunotherapy can disrupt the formation of allergen IgE complexes that bind to antigen-presenting cells [35]. In an in vivo study, bee pollen phenolic extract (BPPE) (200 mg/kg) from Eucalyptus, Cecropia, Eupatorium, and Mimosa together was tested on ovalbumin-sensitized mice. The extract reduced the anti-allergic activity of the cells via the reduction of IgE and IgG1 and inhibited cell migration to the pulmonary cavity [36].

Skin Diseases
Bee pollen has at least 200 active compounds, allowing it to be used in cosmetics. Because of its ability to strengthen and seal capillaries, as well as its sebo-balancing action, it could be employed in the formulation of cosmetics such as creams, shampoos, and conditioners ( Figure 1). Furthermore, it prevents fungal development, and, hence, bee pollen is widely used in anti-dandruff shampoos [37]. The bee pollen from acorn trees (Quercus acutissima) has a high content of phenolic acids, contributing to the recognized antimelanogenesis and antioxidant activity. The underlying mechanism of action is thought to be via the inhibition of tyrosinase activity, a key enzyme in melanin synthesis [38]. Similarly, in an in vitro study that compared the impact of free (FPE) and bound (BPE) phenolic extracts of rape bee pollen on melanogenesis, FPE showed a stronger ability in protecting cells from abnormal melanogenesis compared to BPE. This action was attributed to the suppression of cyclic adenosine monophosphate cAMP, downregulation of microphthalmiaassociated transcription factor (MITF), and blockage of antioxidant and anti-tyrosinase TYR pathways [18].
The impact of Dactylis glomerata pollen on cutaneous symptoms in individuals with atopic dermatitis was assessed in a placebo-controlled, single-center, randomized, parallelgroup trial with 18 participants aged 18 to 65 years; there was a change in SCO Ring Atopic Dermatitis (SCORAD) between day 1/baseline and day 3, but the study did not mention the impact of pollen as having a positive or negative effect on cutaneous symptoms [39].

Prostatitis Diseases
Prostatitis, or inflammation of the prostate, is a common condition that can be caused by bacterial or non-bacterial pathogenic causes [40]. In an in vivo study, pollen was found to have the ability to suppress various inflammatory pathways, including nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), prostaglandin E2 (PGE2), and malondialdehyde (MDA) [40]. Brassica campestris pollen could help rats with prostate hyperplasia by affecting the expression of miRNAs including rno-miR184, which rose as the prostate improved [41]. In addition, four weeks of administration of bee pollen or date palm suspension (100 mg/kg) improved male reproductive parameters such as testis weight, testosterone, luteinizing hormone (LH) and follicle stimulating hormone (FSH), as well as spermatogenesis, motility, and viability, in STZ-induced diabetic Wistar male rats [42].
As stated in Table 1 and Figure 2, sixteen patents were filed between 1994 and 2021 on the use of bee pollen to improve prostate function, in the form of tablets, capsules, suspensions, powders, drops, and solutions. The composition includes bee pollen coupled with other natural sources (e.g., plants and bee products). The formulations can be used to treat several disorders associated with prostatic hyperplasia by reducing the prostate volume and alleviating lower urinary tract symptoms. The formulation is used for reducing the effects of prostate inflammation on male sexual function and enhancing male sexual function [43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58].

Diabetes Disease β
Bee pollen contains phenols and flavonoids, which inhibit carbohydrate-hydrolyzing enzymes such as amylase and glucosidase, as well as carbohydrate absorption in the small intestine, and decrease blood glucose levels significantly ( Figure 2). Furthermore, postprandial blood glucose levels were lower after bee pollen intake [59]. In mice with diabetes mellitus, oral administration of pectic bee pollen polysaccharide from Rosa rugosa Thunb (Rosaceae) (RBPP-P) improved diabetic symptoms and protected the pancreas (Type 1). RBPP-P increased insulin secretion and functions through the stimulation of key transcription factors MafA and Pdx1 in cells. RBPP-P also increased β-cell proliferation, and upregulated the phosphorylation levels of p38, ERK, and AKT [60]. The phenolic compounds from bee pollen Camellia sinensis L. extract, including 3-O-[2 ,6 -di-O-(trans-p-coumaroyl)-β-D-glucopyranosyl]kaempferol, 3-O-[6 -O-(trans-p-coumaroyl)-β-Dglucopyranosyl]kaempferol, and gallic acid (GA), had a hypoglycemic effect for patients with type 2 diabetes. Through interactions with glucose transporters, the three phenolic compounds decrease glucose absorption and transport. In addition, molecular docking showed that phenolic compounds have the ability to form hydrogen bonds with D -glucose and amino acids [61].
As shown in Table 2, patents reveal that bee pollen has a positive influence on sugar regulation. The combination of bee pollen and propolis had a considerable impact on diabetes patients' blood glucose levels, with no side effects [62]. Bee pollen, Philippine flemingia root, Radix Astragali, and Radix Puerariae were incorporated into a pharmaceutical formulation to help reduce blood sugar levels [63]. A bee pollen and propolis formulation was tested on 28 hyperglycemic individuals. For 12 and 23 patients, the blood sugar level was lower after one week and two weeks, respectively [62]. In addition to other ingredients, bee pollen lipopenicillinase cold tea, rehmannia rhizome, and selenium could help to cure diabetes by protecting beta cells in the pancreas from oxidative damage, promoting sugar metabolism, and lowering blood sugar and glucose levels in urine [64].  [62]

Immunity-Related Disorders
The active compounds in bee pollen are vital for boosting the number and activity of humoral immune cells and phagocytes, increasing the number of red blood cells, acceler-ating antibody formation, and delaying the elimination of antibodies ( Figure 2) [72]. Bee pollen polysaccharide CCP-1 and CPP-2 isolated from bee pollen Crataegus pinnatifida Bge improved the phagocytic rates and phagocytic indexes of macrophages. Moreover, CCP-2 stimulated splenocyte proliferation and NK cells [73]. Four hundred birds were fed with bee pollen at concentrations of 0, 0.5, 1, and 1.5% for five replicates in a fully randomized model. Immunoglobulin M (IgM) titers increased linearly with bee pollen dietary intake for 21 days, and similarly, thymus weight increased linearly with bee pollen dietary intake for 42 days, indicating that up to 1.5 percent bee pollen could be added to broiler feed until the age of 21 days to improve bird immunity [4,74].
According to the patents published, bee pollen in combination with other materials has a positive impact on immunity, as shown in Table 3. Corn pollen polysaccharide promotes immune organ growth in the spleen, bone, lymph nodes, and thymus gland, and moreover boosts immunocyte activity and improves the body's ability to fight bacteria and viruses [75]. Oral liquid administration of wolfberry bee pollen is easily absorbed by the human body and has anti-fatigue and immune-boosting effects [76]. More than 20 amino acids and polyphenols, including flavone compounds, sterols, and polysaccharides, are found in Fructus lycii bee pollen, which are beneficial for immunological function and additionally have anti-aging and anticancer effects [77] (Table 3).

Chronic Diseases
Polyphenols found in bee pollen have antioxidant and antiproliferative properties, as well as the ability to regulate cell proliferation and cause apoptosis (Figure 2) [28]. The steroid fraction of bee pollen derived from Brassica campestris chloroform extract induced apoptosis in prostate cancer PC-3 cells, resulting in cytotoxicity [109]. It has been reported that bee pollen has a synergistic effect with the chemotherapy drug cisplatin, which is used to treat breast cancer, and that it might be used as a supplement during treatment [28]. Melissa pollen displayed a substantial impact on the treatment of breast diseases when administered once a day, as demonstrated in Table 4 [110]. The capsule/tablet also included wall-broken bee pollen and Ganoderma lucidum spore powder, which acts as an anti-tumor agent [111].
Heart and coronary artery diseases are examples of cardiovascular diseases. Atherosclerosis is an inflammatory and reactive process in the arteries, associated with high serum cholesterol, oxidative stress, blood clotting, and a disrupted renin-angiotensin-aldosterone system equilibrium. For 16 weeks, 54 ApoE-knockout female mice were fed diets rich in bee pollen ethanolic extract (dosage 0.1 g/kg body mass). The levels of total cholesterol (TC), asymmetric di-methylarginine (ADMA), oxidized low-density lipoprotein (ox-LDL), angiotensin-converting enzyme (ACE), and angiotensin-converting factor (ACEF) decreased significantly [4,112].
As shown in Table 4, bee pollen stimulates microcirculation and leads to lipid reduction. In patients with cardiovascular and cerebrovascular disease, a bee pollen formulation had a curative effect. Salviae miltiorrhizae, bee pollen, and kudzuvine root were used in a mixture that improved cardiovascular disease symptoms [113].   Ampelopsis grossdentata/ND One kind of anti-aging health wine and its preparation method/107034106 A/CN Tumor inhibition, improves gastrointestinal functions, protect liver, and anti-aging impact. [121] ND: Not detected.

Microbial Diseases
Because bee pollen comprises flavonoids and phenolic acids, its ethanol extracts are beneficial against Gram-positive and Gram-negative bacteria such as Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeurgionsa, as well as fungi such as Candida albicans [122,123]. The usage of bee pollen and propolis inhibits the growth and reproduction of bacteria and microbes, as shown in Table 5 and Figure 2 [124]. Wallbroken bee pollen honey wine is a stronger antibacterial agent that can be used to limit the growth and reproduction of dangerous bacteria such as Helicobacter pylori [125]. Bee pollen contains antibacterial and antioxidant components such as flavones and polysaccharides, and the flavone component can also suppress COX-2 activity in gingival tissues, making it an excellent anti-inflammatory agent [126]. Furthermore, bee pollen is utilized in toothpaste because of its ability to suppress germs and also reduce inflammation in the mouth, teeth, and gums, thus preventing and treating oral inflammation, and increasing oral immunity [127]. Mi, Y. China Parts of raw materials by weight: 5-15 g rose bee pollen, 5-15 g rape bee pollen, 5-15 g buckwheat bee pollen, 5-15 g corn bee pollen, 5-15 g lotus bee pollen, 5-15 g hundred flower bee pollen, 60-80 g honey, and 500-600 g Fenjiu honey wine/ND Wall-broken bee pollen honey wine and preparation method thereof/CN 111454811 A/CN Enhancing metabolism, inhibition of Helicobacter pylori growth. [125]

Applications in Food Industry
Bee pollen is used in food processing due to its nutritive, chemical, physical, and techno-functional properties ( Figure 2). It has higher oil absorption capacity than water absorption capacity, low protein but high carbohydrate solubility, better emulsifying properties, and foam depressing activity [13]. Black pudding with bee pollen is a natural antioxidant source to prevent lipid oxidation [130]. Moreover, its addition to pineapple juice at 400 MPa increased the overall bioactive compounds such as phenolic and carotenoids within 15 min [131]. Due to its content of proteins, including essential amino acids, enzymes, coenzymes, large numbers of vitamins, and trace elements [132], bee pollen was used as a food supplement for older horses and prevented the reduction in hematological parameters seen in control horses; it increased the homeostasis of several lipid parameters, and improved the homeostasis of urea and plasma proteins [133]. Table 6 illustrates how its stability can make it attractive for daily consumption, and it is highly recommended for diabetes patients [134].

Cosmetic Applications
Rose bee pollen has a substantial impact on acne therapy when taken as tablets, oral liquid, capsules, electuary, recreational food, or a beverage. It contains proteins, minerals, vitamins, vital amino acids, and fatty acids such as linoleic and linolenic acids [147]. Melissa bee pollen acts on skin cell trophism, wrinkle reduction, as well as freckle therapy [148]. Ganoderma bee pollen extract maintains skin moisture and smoothness, improves skin tension, and maintains skin youth (Table 7 and Figure 2) [149].   Filtrate of the fermented product of two-splitting yeast, bee pollen, silk protein, elastin, protease, eggshell membrane ext., egg white ext., propolis ext., xanthan gum, milk protein, astaxanthin, hydrolyzed silk, orange oil, pearl ext. herbal ext., and deionized water/ND Freeze-dried essence facial mask and manufacturing process thereof/CN 111773113 A/CN Suitable for any skin type, and used for whitening, dark spots, anti-aging, moisturizing, hydrating, sterilizing, and astringent effects. [163] Mi, Y. China 5-15 g rape bee pollen, 5-15 g buckwheat bee pollen, 5-15 g corn bee pollen, 5-15 g rose bee pollen, 5-15 g lotus bee pollen, 5-15 g lily bee pollen, 60-80 g honey, and 500-600 g Fenjiu wine/ND Wall-broken bee pollen honey wine and preparation method thereof/CN 111454811 A/CN Moistened and beautified skin tissue. [125] ND: Not detected.

Concluding Remarks and Future Perspectives
Pollen from bees has been used since prehistoric times due to its remarkable medical potential. Bee pollen has gained considerable interest because of its proven nutritional value, particularly in the fields of functional and health-beneficial manufacturing. Many ailments, including diabetes, cancer, cardiovascular diseases, prostatitis, and microbial and immune diseases, have been treated with bee pollen. The use of bee pollen in bread, fried, stewed, and canned foods, pastries, and beverages increases the nutritional value of the product, as well as its antioxidant and sterilizing properties. Scientists should apply the results from patent reports in clinical trials.
However, there are limitations in the use of bee pollen-based products due to their complexity and variability, which highlight the need for standardization before safe therapeutic usage.