Sweet Science: The Polyphenol Profile
of New Zealand Honey
and its Health Implications

Introduction

New Zealand is known for its clean natural environment, and the quality and taste of the food which we produce. This extends to New Zealand honey, which is directly affected by the environment surrounding the hives. Honey is a rich source of polyphenols, which act as free radical and reactive oxygen species (ROS) scavengers reducing inflammation and interfering with signalling pathways of oxidative stress and/or inflammatory pathways at a molecular level. An opportunity exists to increase the commercial potential of both non-mānuka and mānuka honeys through increased awareness of their properties and biological and physiological activities, which will allow innovative uses of New Zealand honeys that meet global market and consumer demands.

The Codex Alimentarius Standard 12 (FAO, 1981) defines honey as "… the natural sweet substance produced by honey bees from the nectar of plants or from secretions of living parts of plants or excretions of plant sucking insects on the living parts of plants, which the bees collect, transform by combining with specific substances of their own, deposit, dehydrate, store and leave in the honey comb to ripen and mature." Each type of honey reflects the intricate interplay between the bees, the flowering plants they visit, and the environmental factors of their respective habitats.

A complex and natural product, honey is recognised globally for its diverse nutritional and medicinal properties. Used for centuries as a medicinal remedy, honey can be regarded as one of the first known functional foods (Marić et al., 2021), with the first evidence of its use in the Mesolithic era (9000 BC – 4000 BC). It was used as a topical treatment for wound care by the Egyptians (3200 BC – 31 BC), and as a remedy for gout, pain, fever and healing in ancient Greece (1200 BC – 146 BC) (Barreiros, Cepeda, Franco, Nebot & Vazquez, 2024; Nolan, Harrison & Cox, 2019). The popularity of honey has increased due to evidence of its antioxidant, antimicrobial, anticancer and antidiabetic effects, and is an ingredient in many food products (Alvarez-Suarez, Tulipani, Romandini, Bertoli, & Battino, 2010).

Ranked second globally by value, New Zealand honey exports contribute substantially to New Zealand's economy. In 2023, New Zealand exported 10,340 tonnes of honey with a value of $401M, 11% lower than 2022 (MPI, 2024). The greatest proportion of honey exports was mānuka honey (75%), while other honey exports generated only 8% (Apiculture NZ, 2023). Monofloral mānuka ($48.40/kg), multifloral mānuka ($25.92/kg), and non-mānuka honey ($21.40/kg), are the predominant exported honey varieties, primarily to the United States, China, the United Kingdom, and Australia, and growing markets in Japan and South Korea.

New Zealand generates the highest export revenue from the lowest export volume due to the health properties associated with mānuka honey. The demand for mānuka honey led to an increased focus by beekeepers on mānuka honey production (George, Gannabathula, Kantono & Hamid, 2024), and the devaluation of non-mānuka honeys. Between 2000 and 2020 honey production increased substantially, with the number of hives more than tripling in the late 2000s. This unchecked hive expansion and honey production resulted in an oversupply of mānuka honey, and combined with deadened export prices, global trading challenges and inflationary pressure on consumers, many businesses have been unable to sell their honey, resulting in significant financial losses, and hive numbers contracting (Apiculture NZ, 2023).

Honey Composition

The composition of honey is a complex blend of approximately 180–200 different organic and inorganic compounds (Nolan et al., 2019; Barreiros et al., 2024). These compounds contribute to a honey's taste, texture, pH, osmolality, and potential health benefits. The physical and chemical properties of honey is directly affected by its botanical origin, geographical location, soil composition, climatic conditions, and processing, production and storage time (Mărgăoan et al. 2021).

The chemical composition of honey is determined primarily by its botanical origin and is generally classified according to its source. Honey obtained predominantly from the nectar of flowers is called blossom honey, while honeydew honey is created when bees collect honeydew secretions of insects of the Rhynchota genus (Terzo et al., 2020). Multifloral honey has several non-predominant botanical sources and mono-floral honey is produced when bees forage on one type of plant.

Honey is mostly carbohydrates (75–80%), mainly fructose (38.2%), and glucose (31.3%), and small amounts of maltose and other more complex disaccharides and trisaccharides (Barreiros et al., 2024; Terzo et al. 2020). Organic acids such as gluconic acid and citric acid contribute to honey's acidic nature, as well as distinctive taste and antimicrobial properties (Rahman, Sultana, Ali, Rahman, Chowdhury, & Islam, 2024). Honey contains proteins (~0.5%), which are mostly enzymes (e.g. invertase, glucose oxidase, catalase), and essential and non-essential amino acids, of which proline is the most abundant. The water-soluble vitamins ascorbic acid (C), thiamine (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyroxidine (B6), and vitamins E (tocopherol) and K are found in honey (Terzo et al. 2020), as well as minerals. Phenolic compounds represent a significant portion of honey's chemical composition and are one of the most studied constituents of honey due to their known biological activities, and to identify honey varieties (Lawag, Lim, Joshi, Hammer & Locher, 2022).

Phenolic compounds are found extensively across the plant kingdom as a class of natural bioactive phytochemicals derived from the secondary metabolism of plants (Fraga, Croft, Kennedy, & Tomás-Barberán, 2019; Cianciosi et al., 2019). Bees transfer the phenolic compounds present in the pollen, resins and/or oils from plants, incorporating these metabolites during honey production (Lawag et al., 2022). Chemically, the term 'phenolic' or 'polyphenol' is defined as a substance that possesses an aromatic ring bearing one or more hydroxyl substituents, including functional derivatives such as esters and glycosides. Polyphenols represent a wide variety of compounds, divided into several classes and sub-classes as a function of the number of phenol rings they contain, and elements that bind these rings to one another (Manach, Scalbert, Morand, Rémésy, & Jiménez, 2004). Of all the major groups of polyphenols, only phenolic acids and flavonoids are found in honey (Hossen, Ali, Jahurul, Abdel-Daim, Gan & Khalil, 2017).

Phenolic acids can be distinguished in two classes: derivatives of benzoic acid and cinnamic acid, the latter being more common. Hydroxycinnamic acids consist of p-coumaric, caffeic, ferulic and sinapic acids, typically found in bound forms (Manach et al., 2004). Common phenolic antioxidants in honey are gallic acid, caffeic acid and chlorogenic acid (formed when caffeic and quinic acid combine) (Gośliński, Nowak, & Kłębukowska, 2020; Cheung, Meenu, Yu & Xu, 2019). Flavonoids are one of the most studied polyphenols due to their presence in a wide variety of foods (Fraga et al., 2019). Flavonoids share a common structure of two aromatic rings bound together by three carbon atoms to form an oxygenated heterocycle. Flavonoids can be divided into six subclasses based on the heterocycle: flavan-3-ols, flavonols (catechins and proanthocyanins), flavones, isoflavones, flavanones, and anthocyanidins (Fraga et al., 2019; Manach et al., 2004).

Mānuka Honey

Mānuka honey has attracted significant attention due to its high antimicrobial activity against a variety of microorganisms and bacterial pathogens (Leong et al., 2011; Nolan et al., 2019), and has biomedical applications in wound healing (Lin, Daniels, Middleditch, Stephens & Loomes, 2020). The antibacterial actions associated with mānuka honey are attributed to its physiochemical properties (pH and osmotic activity), the presence of high levels flavonoids and phenolic acids, and methylglyoxal (MGO) (Adams et al., 2008; Schmidt, Eichelberger & Rohm, 2021).

Methylglyoxal is formed in mānuka honey by the non-enzymatic dehydration from dihydroxyacetone (DHA) that is present in the nectar of the mānuka flowers (Adams, Manley-Harris & Molan, 2009; Schmidt et al., 2021). Concentrations of MGO in mānuka honey vary depending on geographic location, climate, environmental conditions, harvesting year (Schmidt et al., 2021), and genetic differences in wild varieties of L. scoparium (Stephens et al., 2010). MGO content of up to 1022 mg/kg (Green, Lawag, Locher & Hammer, 2022) have been reported but is typically lower in commercial honey (100–550 mg/kg) (Gośliński et al., 2020). Methylglyoxal increases over time due to the spontaneous conversion of DHA to MGO during storage (Lin et al., 2020) and increases 5-hydroxymethylfurfural (HMF) (Stephens et al., 2010).

The high commercial value of mānuka honey compared to other varieties has made mānuka honey vulnerable to adulteration and fraud (Green et al., 2022; Hegazi, Elghani & Farag, 2022). The most frequent method of honey adulteration is the addition of sugar syrups and/or cheaper honeys added to mānuka honey (Siddiqui, Musharraf, Choudhary & Rahman, 2017), which is difficult to detect due to the similarities in carbohydrate composition of the honeys (Cheng, Zhang, Abdulla & Sun, 2024). Another adulteration practice is the prolonged storage of mānuka honey before selling to increase the MGO content (Cheng et al., 2024). The native kānuka tree (Kunzea ericoides) is superficially similar to mānuka, shares the same geographical location and flowering season, and the pollen grains are practically indistinguishable in a honey medium (Lin et al., 2020; Stephens et al., 2010). This reduces the likelihood of mānuka and kānuka honey being harvested from a single species, and therefore the mono-florality of the honey (Stephens et al., 2010).

The New Zealand Ministry for Primary Industries (MPI) developed a regulatory definition for mono- and multifloral mānuka honeys, and the unique mānuka factor (UMF) scale was developed as an industry standard to detect and authenticate mono-floral mānuka honey (Stephens et al., 2010; Lin et al., 2020). While 2′methoxyacetophenone (2′-MAP), 2-methoxybenzoicacid (2MB), 4-hydroxyphenyllacticacid (4-HPA), 3-phenyllacticacid (3-PA), and DNA from mānuka pollen are key criteria, methyl syringate and leptosin are also characteristic substances (Oelschlaegel et al., 2012).

Most of the research related to mānuka honey has focussed on MGO and compounds associated with anti-bacterial effects and wound healing. Limited research has explored the polyphenol composition of mānuka honey, and the data obtained for this review has been drawn from international studies where mānuka has been used as a comparator to other honeys.

Mānuka honey has significantly higher polyphenolic content than other nectar honeys and a high antioxidant capacity (Schmidt et al., 2021; Gośliński, Nowak, & Kłębukowska, 2020; Alvarez-Suarez et al., 2016). In a study by Cheung et al. (2019), the total phenolic content of mānuka honey was 235.50 ± 16.01 µg/g, while Rata honey (105.60 ± 11.58 µg/g) and Kamahi honey (139.10 ± 11.18 µg/g) had lower phenolic content. The phenolic compounds present in mānuka honey include phenolic acids (gallic acid, protocatechuic acid, 4-hydroxybenzoic acid, vanillic acid, caffeic acid, syringic acid, p-coumaric acid, trans-ferulic acid, ellagic acid, and trans-cinnamic acid), and flavanols (rutin, myricetin, fisetin, quercetin, luteolin, apigenin, kaempferol, and isorhamnetin) (Cianciosi et al., 2020; Gośliński et al., 2020).

In a study comparing Australian jelly bush honey and mānuka honey, the mānuka honey samples had a total flavonoid content of 3.06 mg/100g, while the reported total flavonoid content of the jelly bush honey was 2.22 mg/100g (Yao, Datta, Tomás-Barberán, Ferreres, Martos, & Singanusong, 2003). Quercetin (13.8%), isorhamnetin (12.9%), an unknown flavonoid (12.7%), chrysin (12.6%) and luteolin (12.6%) were the predominant flavonoids detected in the mānuka honey. George et al. (2025) have reported a total flavonoid content of 192 mg RUE/kg in mānuka honey, with pinocembrin present in the highest concentration (5.53 µg/mL). Pinobanksin (1.854 µg/mL), chrysin (0.868 µg/mL), kaempferol (0.150 µg/mL), and quercetin (0.098) were also reported.

The concentration of phenolic acids reported by Yao et al. (2003) in the mānuka honey samples was 14.0 mg/100g. Gallic acid represented approximately 50% (~7.05 mg/100g) of the phenolic acids detected in mānuka honey, while an unknown phenolic acid, ellagic acid and caffeic acid were present in smaller proportions (11.9%, 10.8% and 10.4% respectively). George et al. (2025) reported a total phenolic content of 726 mg GAE/kg in mānuka honey, with hydroxybenzoic acid (3.386 µg/mL), quinic acid (0.725 µg/mL) and caffeic acid (0.553 µg/mL) being present in the highest proportion.

It is worth noting that the number of mānuka honey samples in these studies were small (n = 1 to 2) and do not represent a true indication of the range of phenolics present in mānuka honey, nor the true concentrations. Analytical extraction techniques will affect the outcomes of polyphenol research considerably, and future work needs to take this into consideration. The maturity of the honey may also affect polyphenol concentrations. A study by Stephens et al. (2009) found a greater proportion of phenyllactic acid in freshly harvested mānuka than matured honeys.

Mānuka honey contains high concentrations of leptosperin. While not technically a phenolic compound, leptosperin has been shown to be hydrolysed in vivo to yield methyl syringate, which is a phenolic compound (Ishisaka et al., 2017). Methyl Syringate-glucuronide and sulfates were identified metabolites in both plasma and urine after the ingestion of 15g of mānuka honey in human subjects (Ishisaka et al., 2017). Methyl syringate has been shown to activate transient receptor potential cation channel, subfamily A, member 1 (TRPA1), and significantly suppressed food intake and delayed gastric emptying in a murine model (Kim, Son, Song, Jung, Kim & Rhyu, 2013). TRPA1 is found in enteroendocrine cells in the GI tract of humans, mice, and rats, where it plays an important role in delayed gastric emptying, secretion of gut hormones, and reduction of food intake (Kim et al., 2013). Methyl syringate provides honey with its ability to scavenge potent superoxide free radicals and exert its antibacterial activity (Maric et al. 2021), however further research on the pharmacokinetics, pharmacodynamics, and bioactivity derived from ingested leptosperin and methyl syringate is required to identify other biological functions.

Kānuka Honey

Mānuka and kānuka honeys share a common phenolic profile. Kānuka (Kunzea ericoides) belongs to the same Myrtaceae family as mānuka and are visually similar. Kānuka honey does not contain MGO, however phenyllactic acid, methyl syringate, and a methoxylated benzoic acid, a structural isomer of syringic acid, are evident in both mānuka and kānuka (Stephens et al., 2010; Spiteri et al., 2017; Beitlich, Koelling-Speer, Oelschlaegel, & Speer, 2004). While MGO appears to be a significant component of mānuka honey, Ph04 (4-methoxyphenyllactic acid) is a primary compound in kānuka honey (Stephens et al., 2010). The total phenolic content of kānuka honeys has been reported to be 424–1575 mg/kg (Stephens et al., 2010), and 558 mg/kg (George et al., 2025), and the total flavonoid content 186 mg RUE/kg (George et al., 2025).

Kānuka honey has been reported to be effective against the growth of S. aureus (George et al., 2025), and exhibit antibacterial (Allen, Molan, & Reid, 1991), and anti-inflammatory effects (Leong, Herst & Harper, 2012). Research suggests that the antibacterial and antioxidant activity of the phenolics in mānuka and kānuka honey are reliant on both the variety and concentrations of their phenolic compounds (Stephens et al., 2010; Nolan et al., 2019).

Rewarewa & Other New Zealand Native Honeys

Rewarewa (Knightia excelsa) is a tree common to coastal, lowland and lower montane shrublands found on the North Island, and the Marlborough Sounds in the South Island (Zucchetts, Tangohau, McCallion, Hardy & McCormick, 2022). Bees can access rewa (the flower) nectar without touching pollen, and rewarewa honey is therefore unable to be identified by pollen analysis. Rewarewa honey has not been extensively researched, and very little is known about the chemical properties of this native honey variety.

What limited research there is has identified high levels of quinic acid in rewarewa honey (George et al., 2024; George et al., 2025). Quinic acid, an organic acid present in several medicinal plants, has been shown to exert antibacterial, antiviral, and antidiabetic effects (Benali et al., 2024). Rewarewa honey also contains hydroxybenzoic acid, caffeic acid, p-Coumaric acid, rutin, luteolin, kaempferol, pinobanksin, chrysin and pinocembrin (George et al., 2024; George et al., 2025), and a total phenolic content higher than Kānuka honey (652 ± 1.06 mg GAE/kg vs. 588 ± 7.13 mg GAE/kg).

Rewarewa has been shown to reduce both inflammatory leukocyte infiltration and AA-induced oedema in vitro, indicating rewarewa honey can affect multiple inflammatory targets (Leong, Herst & Harper, 2011), and displays inhibition of S. typhirium bacteria, and significant inhibitory effects of P. aeruginosa (George et al., 2025). However, further work exploring these effects has not been reported.

There are several other New Zealand honey varieties. Rāta honey is derived from the dark scarlet stamens of the New Zealand rāta, which flowers between November and January (Rashidinejad, 2024). The bark of the rāta has been used traditionally for its antimicrobial properties, while the nectar has been used to treat sore throats (Rashidinejad, 2024). Rāta honey may therefore exert bioactivity and offer health effects, however no information regarding the chemical properties of rāta honey could be found in peer-reviewed literature.

Kāmahi (Weinmannia sylvicola and W. racemosa) is a common tree found throughout New Zealand. Little is known about the chemical properties of Kāmahi honey. It has a mean mineral content of 1930 mg/kg, of which potassium is present in the highest concentration (1770 mg/kg) (Grainger et al., 2021). A recent study by George et al. (2025) reported a total phenolic content of 398 GAE/kg, and total flavonoid content 101 RUE/kg in kāmahi honey. Kāmahi honey significantly inhibited S. typhimurium bacterial growth, and P. aeruginosa, where it showed greater inhibition than either mānuka or kānuka (George et al., 2025). Nor-sesquiterpenoids called kamahines have been identified in kāmahi honey (Broom, Wilkins, Lu & Ede, 1994), and the chemical origins of the kamahines are unexplained, however Broom et al. (1994) speculated that they are formed in the oxidative processes occurring in the honey, rather than from floral extractives.

Mineral & Elemental Content of New Zealand Honey

The mineral elements within honey play key roles in numerous biological activities and can be considered another positive nutritional feature of honey. The concentrations of minerals and heavy metals of nectar honey are influenced by floral source (botanical origin), soil, water and air composition and environmental changes influenced by human activity (Grainger, Klaus, Hewitt & French, 2021). The elemental content of honey is 0.04–0.2% (0.02–1.03g/100g) depending on honey type, and dark coloured honeys have higher mineral content than lighter honey varieties (Vanhanen, Emmertz, & Savage, 2011). Twenty-seven different mineral elements have been measured in honey, with potassium (K), magnesium (Mg), calcium (Ca) and phosphorous (P) the most abundant (Vanhanen et al., 2011; Grainger et al., 2021; Barreiros et al., 2024). Potassium accounts for almost 80% of the total mineral content of honey due to its fast secretion by nectar sources (Mărgăoan et al., 2021).

Research has explored the potential of 'elemental signatures' to discriminate and categorise honey from separate countries and predict the origin of a particular honey sample (Aceto, 2016; Grainger, Klaus, Hewitt, Gan & French, 2024), as well as classify mono-floral honeys by their mineral composition (de Alda-Garcilope et al., 2012). In a study by Grainger et al. (2024), Potassium (K) was the most abundant element found in all 352 honey samples analysed (New Zealand samples n = 245), accounting for 87% of the elemental composition. Sodium (Na) (4.49%), Calcium (Ca) (4.34%) and Magnesium (Mg) (2.24%) were the next most abundant. Significant differences in the concentrations of Boron (B), Na, Manganese (Mn), Copper (Cu), Rubidium (Rb), Cesium (Cs), Thallium (Tl), Ca and K were observed between New Zealand and international honeys — enabling discrimination with high accuracy.

Mineral analysis at a floral species level by Vanhanen et al. (2011) explored the mineral content of 10 mono-floral New Zealand honeys. The overall mean mineral content was highest in honeydew honey (4060 mg/kg), twice the content of kāmahi honey which had the second highest (1930 mg/kg). Rewarewa (1540 mg/kg) and Mānuka (1470 mg/kg) were third and fourth respectively. The mineral content of New Zealand honeys is similar to international honey varieties, with only small differences in minor elements (Grainger et al., 2024).

The heavy metal composition of New Zealand honeys is generally low (Grainger et al., 2021; Vanhanen et al., 2011), although have been detected in some New Zealand honey samples. Concentrations of Pb in New Zealand honey are considerably lower (10–40 µg kg⁻¹) than concentrations reported in honey samples from Egypt (9300 µg kg⁻¹), India (920 µg kg⁻¹), and Italy (620 µg kg⁻¹). The concentrations of toxic elements in New Zealand honey are very low, and the consumption of 25g of honey per day does not represent a risk to the health of consumers. These low levels of toxic elements in New Zealand honey can be considered a commercial advantage for New Zealand honeys.

Bioavailability of Honey Polyphenols

Honey contains different bioactive and antioxidant compounds depending on the botanical source and variety. While the phenolics and minerals within honey have therapeutic properties, their ability to exert antioxidant and therapeutic effects in the human body are contingent on the absorption, metabolism and transformation of these compounds through the digestive tract. The bioavailability, bioaccessibility, and the bioactivity of the specific compounds within honey are impacted by the oral, gastric and intestinal phases of the digestive process (Seraglio et al., 2021; Alcoléa et al., 2024).

Bioavailability is the fraction of nutrients that are released from the food matrix, absorbed by the enterocytes and transported into systemic circulation to reach various cells in the human body. For a bioactive to exert a health benefit, it must first be bioavailable. Bioavailability includes several processes — liberation from the food matrix, absorption, distribution, metabolism and elimination (LADME) (Rein, Renouf, Cruz‐Hernandez, Actis‐Goretta, Thakkar, & da Silva-Pinto, 2013). Bioavailability is not solely dependent on the food matrix. Inter-individual differences in genetics, diet, and gut microbiota composition and activity means the rate of absorption of bioactive compounds varies considerably between individuals (Rein et al., 2013), and results in individual responses to dietary interventions (Hajam, 2024). Furthermore, absorption is affected by both the chemical structure and isomeric configuration of bioactive food compounds.

The chemical structure of polyphenols will affect their bioavailability, antioxidant activity, and their interactions with cell receptors and enzymes (Scalbert Morand, Manach, & Rémésy, 2002; Fraga et al., 2019). Polyphenols with lower molecular weight (such as caffeic acid) are readily absorbed in the gut barrier, and only a small portion of flavonoids are absorbed in the small intestine where glycosides must be hydrolysed by intestinal phase II enzymes before entering systemic circulation (Cardoso, Amorim, Silvério, & Rodrigues, 2021; Fraga et al., 2019). It is estimated that approximately 90–95% of total polyphenol intake remains unabsorbed, and metabolites with physiological significance are produced by colonic bacteria enzymatically (Makarewicz, Drożdż, Tarko, & Duda-Chodak, 2021).

The polyphenols and sugars in honey synergistically interact in the colon, creating an environment that proliferates beneficial bacteria, and inhibits pathogens in the gut (Hajam, 2024). Honey has been shown to act as a substrate for Bifidobacteria and Lactobacilli in the colon, and the non-digestible sugars in honey reach the colon where they serve as a nutritional source for these beneficial bacteria. The polyphenols in honey also exert antioxidant and anti-inflammatory effects which positively affect the gut environment. A bidirectional relationship exists between the gut microbiome and polyphenols. The presence of polyphenols and their metabolites in the colon directly impact the health of the colon by modulating the microbiome composition (Fraga et al., 2019).

The gut microbiota plays an essential role in digestion, immune function, metabolism and cognitive health (Hajam, 2024), and microbiota deviations have been linked to many diseases (de Vos, Tilg, Van Hul & Cani, 2022). Emerging evidence indicates that a balanced gut microbiota can improve digestion, enhance nutrient absorption and strengthen the immune system, while dysbiosis of the gut microbiome have been linked to metabolic disorders such as diabetes and obesity (Terzo et al., 2020).

An in vivo study exploring the changes in phenolic content and antioxidant activity in mānuka honey after gastrointestinal digestion showed a significant decrease in the quantity of phenolic compounds (3.59% to 1.52%), and flavonoids (15%–19%) in the bioaccessible fraction compared to undigested honey (Cianciosi et al., 2020). In vitro simulated digestion of mānuka honey has also shown that MGO concentration decreases due to reactions with digestive enzymes. A placebo-controlled human intervention trial assessed the effect of honey consumption (1.5g/kg) on plasma antioxidant status (Schramm et al., 2003). Honey ingestion increased both plasma-total phenolic content and plasma antioxidant capacity, indicating the polyphenols from honey are bioavailable, and have the potential to augment oxidative defence in the human body.

Traditionally polyphenols were thought to exert only direct antioxidant effects, however other mechanisms related to intra-and intercellular signalling pathways, modulation of inflammation mediators and regulating nuclear transcription factors have been identified. Flavonoids are stored in plants as glycoside and non-glycosylated conjugates, which undergo changes in the human body, and the metabolites that exert effects may differ from their original form and function (Fraga et al., 2019; Manach et al., 2004; Scalbert et al., 2002).

Potential Health Effects

Naturally occurring polyphenols exhibit a wide range of biological effects including antibacterial, anti-inflammatory, hepatoprotective, antithrombotic, antiviral, vasodilatory, cytotoxic, antidiabetic, cardioprotective and neuroprotective actions (Akanda, Mehjabin, & Parvez, 2024; Scepankova, Saraiva, & Estevinho, 2017; Pasupuleti, Sammugam, Ramesh, & Gan, 2017; Farooqui & Farooqui, 2011; Johnston, McBride, Dahiya, Owusu-Apenten, & Nigam, 2018). Many of these ailments are underpinned by high levels of oxidative stress.

Dietary polyphenols act as free radical and reactive oxygen species (ROS) scavengers reducing the harmful effects of oxidative stress by reducing inflammation and interfering with signalling pathways of oxidative stress and/or inflammatory pathways at a molecular level. Phenolic compounds scavenge nitric oxide (NO) and inhibits NO synthase and therefore nitric oxide synthase (iNOS) activities. These actions can impede the expression of pro-inflammatory cytokines tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and interferon-α (Xu, Tang, Zhang, Wang & Feng, 2021). The nuclear factor erythroid 2–related factor 2 (Nrf2) pathway is a key regulator of cellular antioxidant responses and plays a crucial role in countering oxidative stress by regulating the expression of antioxidant enzymes (Hadidi, Liñán-Atero, Tarahi, Christodoulou, & Aghababaei, 2024). Under stress conditions, Nrf2 is released from Keap1 and activates its target genes, providing cellular protection. Polyphenols can activate Nrf2, which regulates the expression of antioxidant enzymes and protects against oxidative stress (Hadidi et al., 2024). Honey polyphenols may also act as agonists of NF-kB receptors and toll-like 4 receptors which are involved in the initiation of inflammation and oxidative stress (Wilczyńska & Żak, 2024).

Oxidative stress is a fundamental underlying cause of diabetes, and elevated levels of oxidative stress plays a role in the retinopathy, neuropathy and diabetic wounds in type 2 diabetic patients (Ebrahimi et al., 2025). Gallic acid, present in most honeys, has been reported to possess antihyperglycaemic potential due to its antioxidant and anti-inflammatory properties (Xu et al., 2021), and its ability to increase insulin sensitivity and plasma insulin secretion. Other honey polyphenols such as quercetin, resveratrol, p-coumaric acid, luteolin, kaempferol and apigenin are the most effective polyphenols against arthropathies such as gout, osteoarthritis and rheumatoid arthritis due to their ability to regulate the inflammatory pathways these conditions (Aziz, Kim, & Cho, 2018; Chang, He, Zhu, Gao, Wei, Ma, & Yan, 2015; Pragasam, Murunikara, Sabina, & Rasool, 2012).

The antioxidant capacity/activity has been shown to be correlated with the total phenolic content and concentration of the honeys, where higher phenolic content produces an elevated anti-inflammatory effect (Tomblin, Ferguson, Han, Murray & Schlothauer, 2014). The levels of individual polyphenols in honey are too low to have individual antioxidant significance, but the total antioxidant capacity of honey is associated with synergistic antioxidant effects, and combined activities and interactions of the other compounds in honey (Scepankova et al., 2017). Furthermore, honey contains both aqueous and lipophilic antioxidants, which means they can act at different cellular levels (Scepankova et al., 2017) — an advantage of honey over other antioxidants such as Vitamin C and E. If honey were used as a sweetener rather than refined sugar, the quantity of antioxidants consumed would be considerable.

Conclusion

Honey has been used nutritionally and medicinally for centuries by most ancient cultures. The unique flora of New Zealand, and its geographic location provides New Zealand honey with distinct flavour, pH, and phenolic compounds. An opportunity exists to increase the commercial potential of both non-mānuka and mānuka honeys through increased awareness of their properties and biological and physiological activities, which will allow innovative uses of New Zealand honeys that meet global market and consumer demands.

Furthermore, exploring the therapeutic effects of honey ingestion, including mānuka, in human randomised control trials, the pharmacokinetics in the gut microbiome and the biological upstream or downstream cascades will enhance our insight, understanding and application of this natural superfood. Increased evidence of the health effects of New Zealand honey consumption will improve the commercial outcomes for New Zealand's apiary industry, export outcomes, and our reputation as world leaders in honey production and research.

It is important to note that in New Zealand, native plants hold a unique status that extends beyond their botanical characteristics and are considered "Taonga" (treasures) by Māori. Given their cultural significance, initiatives and research involving their use must be approached with the highest respect and sensitivity of Māori customs and beliefs. Furthermore, the sustainable and holistic approach of Mātauranga Māori is required, and a collaborative approach to facilitate the exchange of traditional knowledge and practices and ensure the safe, ethical and sustainable use of these Taonga is essential.