Maple

Maple (Acer spp.): A Comprehensive Reference on Botanical Identity, Traditional Use, Phytochemistry, and Scientific Evidence

1. Identity: Botanical Names, Natural Source, and Common Forms

1.1 Botanical Classification

Maple refers to trees and shrubs of the genus Acer (family Sapindaceae, formerly Aceraceae), a large and diverse genus. The genus Acer includes more than 200 species distributed mainly in the temperate zone of the northern hemisphere. From a dietary supplement and functional-food standpoint, the species of greatest commercial and scientific relevance are:

• Acer saccharum Marshall — the sugar maple, the primary source of commercial maple syrup
• Acer nigrum F. Michx. — the black maple
• Acer rubrum L. — the red maple

Maple syrup is obtained from the sap collected from certain Acer species, such as the sugar maple (Acer saccharum Marshall), the black maple (Acer nigrum F. Michx.), and the red maple (Acer rubrum L.). The trees grow wild in eastern Canada and northeastern United States of America.

1.2 Source and Production

To make maple syrup, sweet watery xylem sap is collected and concentrated. As a result of the pressure build-up caused by the freeze-thaw cycle, this sap pours out of maple tree trunks. Maple tapping often begins late in winter or early in spring and only lasts a few weeks because of the weather. Maple syrup is produced from the sap of this plant through the concentration of sap via thermal evaporation.

Maple syrup is made by boiling the sap collected from certain maple (Acer) species. During this process, phytochemicals naturally present in tree sap are concentrated in maple syrup. In 2017, Quebec produced approximately 92% of all the maple syrup in Canada and is home to more than 13,300 maple syrup producers.

1.3 Commercial Forms and Grades

Since January 1, 2016, Canada introduced a new classification system: it is divided into Grade A or Processing Grade, based on quality parameters, and four different color intensities: Gold, Amber, Dark, and Very Dark. Grades B and C no longer exist. The four varieties of maple syrup are determined based on color and sensory characteristics. The purity and sugar content are virtually the same in all four types.

With the new grading system, the classification of maple syrup depends ultimately on its internal transmittance at 560 nm wavelength through a 10 mm sample. Golden must have 75 per cent or more transmittance, amber must have 50.0 to 74.9 per cent transmittance, dark must have 25.0 to 49.9 per cent transmittance, and very dark is any product having less than 25.0 per cent transmittance.

Produced during the first half of the tapping season, the golden and amber grades are lighter in colour and have a more delicate taste, while the darker grades collected at the end of the harvest are stronger in flavour. From a research perspective, the syrup typically becomes darker in color as the season progresses, and antioxidant activity is proportional to the darkening color of the maple syrup.

Beyond pure syrup, the following forms are commercially available and studied:

• Maple sap / maple water: Due to its high water content (approximately 96–99%), maple sap is known as maple water. Maple sap contains macro- and micronutrients as well as phytonutrients, including sucrose, amino acids, vitamins, minerals, organic acids, phytohormones, and phenolics.
• Maple sugar: Crystallized, dried form produced by continued evaporation of sap.
• Maple syrup extracts (MSX): Concentrated, standardized polyphenol-rich extracts investigated in nutraceutical research.
• Maple bark and leaf extracts: Used in ethnobotanical medicine and subject to laboratory investigation.
• Other products: The Canadian Food Inspection Agency verifies compliance for maple syrup and maple products, including maple sugar, maple candy, maple butter, and maple toffee.

2. Traditional and Historical Use

2.1 Indigenous North American Traditions

The gathering of syrup from maple trees in the woodlands of Canada and the northeastern United States is an ancient practice that had helped sustain Indigenous peoples for thousands of years. Tribes such as the Algonquin, Iroquois, and Ojibwe are credited with pioneering the practice of maple sugaring.

The Algonquians recognized maple sap as a source of energy and nutrition. At the beginning of the spring thaw, they made V-shaped incisions in tree trunks; they then inserted reeds or concave pieces of bark to run the sap into clay buckets or tightly woven birch-bark baskets. The maple sap was concentrated first by leaving it exposed to the low temperatures overnight and disposing of the layer of ice that formed on top. Following that, the sap was transported by sled to large fires where it was boiled in clay pots to produce maple syrup. Often, multiple pots were used in conjunction, with the liquid being transferred between them as it grew more concentrated.

Traditionally, Indigenous people have used maple syrup to cure meats, as a sweetener for bitter medicines, and as an anesthetic. The fresh sap was seen as a tonic that restored energy after the long, harsh winter.

Today we think of maple syrup, but traditionally the end goal was maple sugar. Syrup could spoil, but sugar was easy to store and carry. Maple syrup was also used as a trade item in the form of dried, portable sugar slabs.

The invention of maple syrup is acknowledged as belonging to the Anishinaabe, Haudenosaunee, and Wabanaki peoples of northeastern North America, described simultaneously as food and medicine. Beyond sweeteners and food, maple wood was used to make tools and furniture, and its bark was used as a medicine herb. Among Western Indigenous nations, the Rocky Mountain maple is considered one of the sacred Life Medicines of the Navajo tribe.

Several specific ethnobotanical uses of maple species are recorded in the Native American Ethnobotany database. Douglas maple (Acer glabrum var. douglasii) was used by Plateau tribes as a treatment for diarrhea. The Blackfoot took an infusion of bark in the morning as a cathartic.

2.2 European Colonial Period

After Europeans arrived in the 1600s, they learned from Indigenous people how to turn the sap into sweet and medicinal products. In the early stages of European colonization in northeastern North America, local Indigenous peoples showed the arriving colonists how to tap the trunks of certain types of maples during the spring thaw to harvest the sap. André Thevet, the "Royal Cosmographer of France," wrote about Jacques Cartier drinking maple sap during his Canadian voyages. By 1680, European settlers and fur traders were involved in harvesting maple products. However, rather than making incisions in the bark, the Europeans used the method of drilling tapholes in the trunks with augers.

Prior to the 19th century, processed maple sap was used primarily as a source of concentrated sugar, in both liquid and crystallized-solid form, as cane sugar had to be imported from the West Indies.

2.3 Traditional Medicinal Use in Asian Systems

In traditional medicine, 40 species, 11 subspecies, and one varieta of the genus Acer are known to exhibit a broad spectrum of biological activities. The 2016 review published in the Journal of Ethnopharmacology conducted systematic ethnopharmacological research drawing on libraries and herbaria in both China and the USA, documenting the genus's use in Asian traditional medical systems as well as North American indigenous traditions.

3. Key Constituents and Active Compounds

3.1 Overview of Phytochemical Diversity

To date, 331 compounds have been identified from 34 species of the genus Acer, including flavonoids, tannins, phenylpropanoids, diarylheptanoids, terpenoids, benzoic acid derivatives, and several other types of compounds such as phenylethanoid glycosides and alkaloids.

Maple syrup contains not only abundant amounts of sucrose and glucose, but also various other components such as oligosaccharides, organic acids, amino acids, vitamins, and minerals including manganese and zinc.

3.2 Sugars

The sweetness of maple syrup derives from a high content of sucrose (99% of total sugars). The collection of sugars that give maple syrup its unique flavor profile are very diverse and include sucrose, glucose, fructose, oligosaccharides, quebrachitol, inulin, and others.

3.3 Phenolic Compounds

Recent studies have shown that maple syrup contains various phenolic compounds such as lignans and coumarin, quebecol, and ginnalin. In one systematic isolation effort, 23 naturally derived phenolics belonging to lignan, coumarin, stilbene, and phenolic acid sub-classes were isolated from maple syrup.

3.3.1 Quebecol

Quebecol is a novel process-derived phenolic compound from Canadian maple syrup; its chemical name is 2,3,3-tri-(3-methoxy-4-hydroxyphenyl)-1-propanol. Liquid chromatography mass spectral (LC-MS) analyses revealed that quebecol is not originally present in maple sap. This observation, as well as the lack of a feasible biosynthetic pathway, suggests that quebecol is formed during the processing and/or extraction of maple syrup.

3.3.2 Ginnalins

Multiple gallotannins, named maplexins A–E, were isolated from red maple stems and bark. The related ginnalin compounds (A, B, and C) are gallotannin-class compounds identified in maple species and syrup. The antiproliferative impacts of ginnalins A–C, gallotannin compounds found in maple syrup, on breast (MCF-7) tumorigenic, colon (HCT-116), and non-tumorigenic colon (CCD-18Co) cells were evaluated.

3.3.3 Maplexins

Maplexin compounds were shown in vitro to possess more inhibitory activity than acarbose for inhibition of α-glucosidase activity (IC₅₀ = 8 vs. 160 µM; maplexin E vs. acarbose, respectively).

3.3.4 Acertannin

Acertannin (2,6-di-O-galloyl-1,5-anhydro-d-glucitol) was identified as an active constituent in extracts of A. saccharum leaves. The anti-hyperglycemic effects of A. saccharum leaves were investigated; extracts showed a potent inhibitory effect on α-glucosidase in both in vivo and in vitro experiments.

3.3.5 Additional Phenolics

The sugar maple bark contains unique phenolic glycosides, among which are identified molecules such as gallotannins, lignans, coumarins, and coumarinolignans. Maple syrup contains a wide variety of polyphenols and volatile organic compounds, including vanillin, hydroxybutanone, lignans, propionaldehyde, and numerous organic acids.

Twenty-five compounds, including 3 organic acids, 5 phenolic acids, 8 tannins, 7 flavonoids, and 2 proanthocyanidins, were identified or tentatively identified from A. saccharum preparations, with tannins and flavonoid glucosides as the major active compounds.

3.4 Minerals

The presence of organic acids (malic acid), amino acids, and relevant amounts of minerals such as potassium, calcium, zinc, and manganese make maple syrup unique among sweeteners. According to standardized nutrient data, per 100 g serving, maple syrup contains approximately 73 mg calcium, 21 mg magnesium, 225 mg potassium, 2.3 mg manganese, 0.7 mg zinc, 0.074 mg copper, and 1.27 mg riboflavin.

3.5 Abscisic Acid (ABA)

Maple syrup is particularly rich in abscisic acid. This acid presents a strong defense against diabetes and metabolic syndrome because it promotes the excretion of insulin from pancreatic cells and boosts fat cells' sensitivity to insulin.

3.6 Organic Acids

Malic, succinic, gluconic, acetic, and lactic acids were identified as the main organic acids in maple sap. Malic acid is also notable for conferring the characteristic tartness to maple sap and syrup.

3.7 Quaternary Ammonium Compounds and Amino Acids

Non-targeted metabolomic analysis revealed a series of related compounds that contained quaternary ammonium moieties including choline, hercynine, trigonelline, glycine betaine, and carnitine, which increased in late-season sap.

3.8 Flavor Compounds

Primary flavor-contributing compounds are maple furanone (5-ethyl-3-hydroxy-4-methyl-2(5H)-furanone), strawberry furanone, and maltol.

4. Mechanisms of Action

4.1 Antioxidant Activity

Studies have indicated that phenolic compounds, flavonoids, and anthocyanins are the predominant constituents responsible for the antioxidant activity of Acer species. Cleomiscosin D and scopoletin, isolated from the ethanol extract of the wood of A. saccharum Marshall, showed stronger SOD-like activity than vitamin C. The anthocyanin content was significantly correlated with antioxidant activity in extracts of juvenile leaves from A. saccharum Marshall.

4.2 Anti-Inflammatory Mechanisms

Quebecol has anti-inflammatory properties, as indicated by a significant inhibitory effect on the lipopolysaccharide (LPS)-induced Nuclear Factor Kappa B (NF-κB) activation at 100 mM, a concentration that presented no cytotoxicity. Quebecol prevents the excretion of pro-inflammatory interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) by LPS-catalyzed macrophages at the highest non-cytotoxic concentration.

4.3 Anti-Hyperglycemic Mechanisms

Extracts of A. saccharum leaves have an anti-hyperglycemic effect, which uses a mechanism based on an inhibitory effect toward α-glucosidase. Isolated phenolic glycosides and compounds inhibit α-glucosidase activity in vitro. This mechanism is analogous to that of the antidiabetic drug acarbose but has only been demonstrated in preclinical settings for maple constituents.

4.4 Antimicrobial and Biofilm Mechanisms

Maple syrup, prepared by concentrating the sap from the North American maple tree, is a rich source of natural and process-derived phenolic compounds. A phenolic-rich maple syrup extract (PRMSE) has been reported for its antimicrobial activity. PRMSE exhibited antimicrobial activity as well as strong synergistic interaction with selected antibiotics against Gram-negative clinical strains of Escherichia coli, Proteus mirabilis, and Pseudomonas aeruginosa. At sublethal concentrations, PRMSE and catechol efficiently reduced biofilm formation and increased the susceptibility of bacterial biofilms to antibiotics.

4.5 Neuroprotective Mechanisms

The neuroprotective effects of a chemically standardized phenolic-enriched maple syrup extract (MSX) were investigated using biophysical, in vitro, and in vivo studies. Based on biophysical data, MSX reduced amyloid β1–42 peptide (Aβ1–42) fibrillation in a concentration-dependent manner (50–500 μg/mL) with similar effects as the neuroprotective polyphenol resveratrol at its highest test concentration.

5. Scientific Evidence by Area

5.1 Cardiometabolic Health and Glycemic Response

Human/Clinical Evidence

The strongest human-clinical evidence to date in this area comes from a 2024 randomized controlled trial. In a randomized, double-blind, controlled crossover trial with 42 overweight adults with mild cardiometabolic alterations, participants were instructed to substitute 5% of their total caloric intake from added sugars with either maple syrup or an artificially flavored sucrose syrup for 8 weeks. Replacing refined sugars with maple syrup over 8 weeks decreased the glucose area under the curve when compared with substituting refined sugars with sucrose syrup, as determined during the oral glucose tolerance test, leading to a significant difference between the intervention arms (−50.59 ± 201.92 compared with 29.93 ± 154.90; P < 0.047). Substituting refined sugar with maple syrup also significantly decreased android fat mass (−7.83 ± 175.05 g compared with 67.61 ± 206.71 g; P = 0.02) and systolic blood pressure (−2.72 ± 8.73 mm Hg compared with 0.87 ± 8.99 mm Hg; P = 0.03). No changes in the blood lipid profile were observed.

As an exploratory outcome, substituting refined sugars with maple syrup promoted selective taxonomic changes in the gut microbiota.

Glycemic index comparisons have been reported: according to the United States Department of Agriculture, sugar has a glycemic index of 65, whereas maple syrup has a glycemic index of 54. Compared to dextrose, corn syrup, and brown rice syrup, maple syrup brings about lower glucose and insulin responses, which make it a potentially healthier substitute for refined sugars.

Animal Evidence

A study demonstrated that maple syrup is less detrimental than sucrose on metabolic health and possesses a prebiotic-like activity through novel gut microbiota and liver mechanisms. In OLETF rats fed with maple syrup or sucrose samples, no statistically significant differences were found in insulin levels, but a lowering in plasma glucose and reduction of glucose absorption in the small intestine after oral ingestion of maple syrup compared to sucrose-only administration was observed. The results indicate that maple syrup might partially prevent the absorption of glucose from the small intestine.

Evidence Strength

The human clinical evidence is preliminary but now includes at least one well-designed randomized crossover trial. Results are promising but limited by small sample size, a single trial, and an 8-week duration. Animal and cell-based data are more extensive. Most of the studies performed to support health claims have been done using animal models, making it difficult to extrapolate definitively to human health.

5.2 Hepatoprotective Effects

Animal Evidence

The protective effects of maple syrup ingestion on liver function have been evidenced in rats. In that study, one group of rats was fed a 20% maple syrup diet while a second group was fed a 20% sugar mix syrup diet, each for 11 days. The maple syrup group showed significantly lower values of hepatic function biomarkers compared to the sugar syrup group. The study also found that the expressions of genes for serine/threonine dehydratase and histidine ammonia lyase, which are linked to ammonia formation, were reduced in the liver of the maple syrup group. Additionally, natural sweeteners including maple syrup alleviated hepatic IL-1β levels compared to refined sugars in animal experiments.

Evidence Strength

These findings are based exclusively on animal models. No human clinical trials have specifically investigated maple syrup's hepatoprotective properties. Evidence is considered preliminary.

5.3 Antioxidant and Anti-Inflammatory Properties

In Vitro and Cell-Based Evidence

Maple syrup is rich in phenolic compounds that exhibit antioxidant and anti-inflammatory activity in vitro. Phenolic compounds derived from A. saccharum Marshall sap and syrup exhibited antimutagenic activity by inhibiting mutagenesis induced by chemical agents.

Evidence Strength

Antioxidant and anti-inflammatory effects have been documented in cell culture and biochemical assays. The antioxidant capacity of maple syrup is sometimes claimed to participate in its nutritional value. However, many of these studies are based on maple syrup extracts, and the quantities of maple syrup in normal food applications that would need to be consumed daily by humans to obtain a beneficial effect are still unknown.

5.4 Anti-Diabetic / Anti-Hyperglycemic Properties

In Vitro and Animal Evidence

Several studies have demonstrated the antihyperglycemic potential of Acer species in the management of type 2 diabetes. An in vitro study of a butanol extract from maple syrup demonstrated inhibitory activity toward α-glucosidase. Specifically, for red maple constituents, maplexin compounds were shown in vitro to possess more inhibitory activity than acarbose for inhibition of α-glucosidase activity (IC₅₀ = 8 vs. 160 µM; maplexin E vs. acarbose, respectively).

This is the first report that acertannin from A. saccharum may be used in diabetes care.

Evidence Strength

Anti-diabetic effects related to specific isolated constituents (maplexins, acertannin, abscisic acid) are based primarily on in vitro enzyme-inhibition studies. One human RCT found improvements in glucose AUC during OGTT. These interesting maplexin compounds will need to be further evaluated to determine whether they impart beneficial properties in preventing blood glucose elevations in vivo. Overall, evidence is promising but remains preliminary for clinical application.

5.5 Neuroprotection and Alzheimer's Disease

In Vitro and Model-Organism Evidence

Maple syrup may prevent the misfolding and accumulation of two kinds of proteins, β-amyloid and tau peptide, which have been associated with Alzheimer's disease. Ma et al. investigated the effects of a standardized phenolic-enriched maple syrup extract on β-amyloid aggregation. Based on biophysical results, MSX was shown to decrease amyloid β1−42 peptide fibrillation in a concentration-dependent manner (50–500 μg/mL) with similar efficacy and neuroprotection as resveratrol at its highest test concentration (63.5% at 500 μg/mL vs. 77.3% at 50 μg/mL).

MSX has previously been shown to be non-toxic in animal studies at doses of up to 1000 mg/kg/day for 7 days. Moreover, MSX shows neuroprotective effects in Caenorhabditis elegans and alleviates lipopolysaccharide-induced inflammation and cell stress in murine microglial and human neuronal cells.

Evidence Strength

All neuroprotection evidence is preclinical — conducted in cell cultures, the invertebrate model organism C. elegans, and mouse models. No human clinical trials examining maple syrup or maple extracts for cognitive function or Alzheimer's disease risk have been completed. Evidence is early-stage and exploratory.

5.6 Anticancer Properties

Cell-Based Evidence

CRC (colorectal cancer) cells administered maple syrup showed significantly lower growth rates than cells administered sucrose. In addition, administration of maple syrup to CRC cells caused inhibition of cell invasion, while there was no effect on cell migration.

Ginnalins A–C were twofold more efficacious against tumorigenic than non-tumorigenic cells. At 50 μM concentrations, ginnalin A (84%, HCT-116; 49%, MCF-7) was more efficacious than ginnalins B and C (50%, HCT-116; 30%, MCF-7). Ginnalin stopped cell cycle in the S- and G2/M-phases and reduced D1 protein and cyclin A levels. The study indicated that ginnalin A–C might have potential cancer chemopreventive properties mediated through cell cycle arrest.

Evidence Strength

There are almost no reports or scientific evidence on the effects of the various maple syrup grades on the behavior of cancer cells. Therefore, there is a need to evaluate differences in maple syrup grade on the functions of cancer cells to evaluate the use of maple syrup as a phytomedicine for cancer treatment. All anticancer findings are in vitro only. There are no human trials. Evidence is classified as preliminary and hypothesis-generating only.

5.7 Anti-Glycation Effects

In Vitro Evidence

MSX (500 μg/mL) reduced the formation of advanced glycation end-products (AGEs) by 40% in the bovine serum albumin (BSA)-fructose assay and by 30% in the BSA-methylglyoxal (MGO) assay. MSX also inhibited the formation of crosslinks typically seen in the late stage of glycation. Circular dichroism and differential scanning calorimeter analyses demonstrated that MSX maintained the structure of BSA during glycation.

Evidence Strength

Purely in vitro; no human data. Relevant to potential chronic disease prevention but significance in human physiology is unknown at present.

5.8 Antimicrobial and Biofilm-Reduction Effects

In Vitro Evidence

Maple syrup, prepared by concentrating the sap from the North American maple tree, is a rich source of natural and process-derived phenolic compounds. A phenolic-rich maple syrup extract (PRMSE) was investigated for antimicrobial activity. PRMSE exhibited antimicrobial activity as well as strong synergistic interaction with selected antibiotics against Gram-negative clinical strains of E. coli, Proteus mirabilis, and Pseudomonas aeruginosa.

Evidence Strength

In vitro only. Findings are preliminary and require validation in animal and human studies before clinical relevance can be established.

5.9 Bone Health

Preliminary pharmacological studies have shown that extracts and compounds isolated from the genus Acer exhibit a broad spectrum of biological activities, including promoting osteoblast differentiation. This finding is limited to preclinical data and has not been explored in human clinical trials.

6. Body Systems and Health Areas Associated with Maple

• Metabolic/Endocrine System: Glycemic response, insulin sensitivity, glucose metabolism, metabolic syndrome
• Cardiovascular System: Blood pressure, android fat mass, cardiometabolic risk markers
• Hepatic System: Liver enzyme biomarkers, hepatoprotection
• Gastrointestinal System / Gut Microbiota: Prebiotic-like activity, gut microbiome composition
• Nervous System: β-amyloid aggregation, neuroinflammation, neuroprotection (all preclinical)
• Immune/Inflammatory System: NF-κB inhibition, cytokine modulation, anti-inflammatory activity
• Oncological (Preclinical): Cell cycle arrest, antiproliferative activity
• Musculoskeletal: Osteoblast differentiation (preclinical), mineral contributions (manganese, calcium)
• Antimicrobial: Biofilm reduction, synergy with antibiotics (in vitro only)

7. Dosage Forms and Dosages Reported in Studies

The following dosages are drawn strictly from reported research; they are not recommendations and apply only to the study contexts in which they were used.

• Human crossover RCT (cardiometabolic outcomes): Participants substituted 5% of their total caloric intake from added sugars with maple syrup for 8 weeks.
• Standardized phenolic-enriched maple syrup extract (MSX) — amyloid aggregation: MSX tested in a concentration-dependent manner at 50–500 μg/mL for Aβ1–42 fibrillation inhibition.
• MSX — anti-AGE assay: MSX (500 μg/mL) reduced AGE formation by 40% in the BSA-fructose assay and by 30% in the BSA-methylglyoxal assay.
• MSX — animal safety (toxicity study): MSX has been shown to be non-toxic in animal studies at doses of up to 1000 mg/kg/day for 7 days.
• In vitro ginnalins — cell cycle effects: At 50 μM concentrations, ginnalin A inhibited cancer cell growth at 84% (HCT-116) and 49% (MCF-7).
• Quebecol — anti-inflammatory: Significant inhibitory effect on LPS-induced NF-κB activation was noted at 100 mM, a concentration that presented no cytotoxicity.
• Animal hepatoprotection study: One group of rats was fed a 20% maple syrup diet for 11 days.
• Serving-size context (nutritional): One 60 ml (1/4 cup) serving of maple syrup contains 72% of the daily nutritional requirement of manganese, 27% of riboflavin, 17% of copper, and 6% of calcium and potassium.

Though several studies have reported the pharmacological potential of maple syrup, more studies and clinical data are needed to provide further evidence supporting the pharmacological effectiveness and nutritional benefit of maple syrup in humans.

8. Safety Considerations

8.1 Sugar Content and Metabolic Considerations

As with any sweetener, natural or artificial, overconsumption of maple syrup could lead to obesity problems. However, some studies have shown that controlled consumption of maple syrup, as an alternative sweetener for inclusion in the diet, could have health benefits. Maple syrup is high in sugar (mainly sucrose), and eating it excessively may lead to metabolic, cardiovascular, and dental problems.

8.2 Lead Contamination

Lead residues can be found in maple products, especially when produced with lead-containing equipment. According to Health Canada, the presence of lead in maple syrup at levels of 0.5 parts per million (ppm) or more suggests that avoidable contamination has taken place. A significant portion of the lead is concentrated in the sugar sand suspended in the syrup, even if a large percentage is in dissolved form. Filtration systems such as gravity filtration and press filtration may reduce lead levels in maple syrup. A laboratory analysis would confirm whether the residue level was successfully reduced below 0.5 ppm.

Lead in maple syrup, originating from sap collection or syrup production, storage, or packaging processes, is readily preventable with producer knowledge and use of good manufacturing practices. The ultimate goal is for all equipment and materials containing lead to be phased out of production. This should be done as quickly as possible to ensure that no lead-bearing surfaces come into contact with maple sap or syrup.

8.3 Microbial and Mold Risk

Maple sap must be extensively boiled to produce syrup. This boiling creates a product with a reduced water activity of 0.83–0.86 and acts as an inherent control for foodborne pathogens. The process of making maple syrup and maple candy is considered low risk by the FDA.

8.4 Regulatory Status and Nutrient Addition

Section D.03.002 of the Canadian Food and Drug Regulations prohibits the addition of nutrients or amino acids to maple syrup or maple products sold in Canada. This is relevant to the assessment of supplement-grade standardized extracts, which are regulated differently from whole-food maple syrup.

8.5 Polyphenol Bioavailability Uncertainty

To better understand the potential health benefits of phenolics in maple syrup, there is a crucial need to determine the exact bioavailability and uptake of phenolics in the digestive tract following ingestion of maple syrup. As maple syrup is rich in sugar molecules, esters, and organic acids, these molecules could impact the bioavailability of phenolics in humans.

8.6 Arsenic Contamination

Arsenic contamination of the groundwater is quite common in areas where maple syrup is produced (Maine, Vermont, Canada), and as a result maple syrup can test positive for traces of arsenic. Modern stainless-steel equipment and good manufacturing practices are the standard mitigation approach.

References

• Nour et al. (2023). Nutritional, pharmacological, and sensory properties of maple syrup: A comprehensive review. Food Chemistry: X. PMC10469071.
• Tran et al. (2024). Substituting Refined Sugars With Maple Syrup Decreases Key Cardiometabolic Risk Factors in Individuals With Mild Metabolic Alterations: A Randomized, Double-Blind, Controlled Crossover Trial. PubMed 39163971.
• Yamamoto et al. (2015). Inhibitory effect of maple syrup on the cell growth and invasion of human colorectal cancer cells. Oncology Reports. PMC4358083.
• Zhang et al. (2016). Traditional uses, phytochemistry, and pharmacology of the genus Acer (maple): A review. Journal of Ethnopharmacology. PubMed 27132717.
• Wan et al. (2013). Mining Red Maple (Acer rubrum) Trees for Novel Therapeutics to Manage Diabetes. PMC3715094.
• Maisuria et al. (2015). Polyphenolic Extract from Maple Syrup Potentiates Antibiotic Susceptibility and Reduces Biofilm Formation of Pathogenic Bacteria. Applied and Environmental Microbiology. PMC4421064.
• Li & Seeram (2011). Further Investigation Into Maple Syrup Yields Three New Lignans, a New Phenylpropanoid, and Twenty-Six Other Phytochemicals. PMC3140541.
• Nahar et al. (2015). Chemical Compositional, Biological, and Safety Studies of a Novel Maple Syrup Derived Extract for Nutraceutical Applications. PMC4334281.
• DaSilva et al. (2018). Anti-glycation and anti-oxidative effects of a phenolic-enriched maple syrup extract and its protective effects on normal human colon cells. PMC5818990.
• Ma et al. (2016). Effects of a Standardized Phenolic-Enriched Maple Syrup Extract on β-Amyloid Aggregation, Neuroinflammation in Microglial and Neuronal Cells, and β-Amyloid Induced Neurotoxicity in Caenorhabditis elegans. PMC5819752.
• Soo-Hyun Ong et al. (2011). Anti-hyperglycemic effects of sugar maple Acer saccharum and its constituent acertannin. Food Chemistry.
• Li L. & Seeram N.P. (2011). Quebecol, a novel phenolic compound isolated from Canadian maple syrup. Journal of Functional Foods.
• Zhang et al. (2016). Traditional uses, phytochemistry, and pharmacology of the genus Acer (maple): A review. Journal of Ethnopharmacology.
• Alves Aggio et al. (2023). The metabolic benefits of substituting sucrose for maple syrup are associated with a shift in carbohydrate digestion and gut microbiota composition. American Journal of Physiology–Endocrinology and Metabolism.
• Krishnan et al. (2020). Metabolomics reveals chemical changes in Acer saccharum sap over a maple syrup production season. PMC7444596.
• Canadian Food Inspection Agency (CFIA). Canadian Grade Compendium: Volume 7 – Maple Syrup.
• Canadian Food Inspection Agency. Preventive controls for food: Lead residues in maple products.
• National Museum of the American Indian Magazine. The Indigenous Origins of Maple Syrup.
• Crew et al. (2023). Uncovering the anti-inflammatory mechanisms of phenolic-enriched maple syrup extract in lipopolysaccharide-induced peritonitis in mice. Food & Function. PMC10399132.
• International Maple Syrup Institute. Updated Nutrients and Serving Size for Pure Maple Syrup.