IngredientsLac resin, also known as shellac, is a natural resin secreted by the lac insect (Kerria lacca) found in South and Southeast Asia. The producing organism sits within a well-characterized taxonomic framework: shellac is the resinous excretion of the insect Laccifer (Tachardia) lacca Kerr, order Homoptera, belonging to the family Coccidae. The commercially cultured species is Kerria lacca, which is also known by such synonyms as Laccifer lacca Kerr, Tachardia lacca, and Carteria lacca.
The English terms for the substance and its various processed grades have accumulated over centuries. Species designations include Kerria lacca (Kerr), synonymous with Laccifer lacca as commonly cited in classical and Ayurvedic texts. In English the substance is variously called lac, lac resin, shellac (in its refined form), sticklac, and seedlac. Regional commercial terms distinguish sticklac (raw resin on twigs), seedlac (washed, with dye removed), and shellac (the purified resin). In the food-additive regulatory context, the term "lac-resin" may be substituted for the term "shellac."
In Ayurvedic and South Asian classical traditions, the material is known as Laksha or Lakh. The name "lac" is said to derive from lakh, the Sanskrit word for one hundred thousand — a reference to the very large number of insects involved in producing appreciable amounts of the product.
Shellac is scraped from the bark of the trees where the female lac bug, Kerria lacca (order Hemiptera, family Kerriidae, also known as Laccifer lacca), secretes it to form a tunnel-like tube as it traverses the branches of the tree. The insects suck the sap of the tree and excrete "sticklac" almost constantly.
The lac insect feeds on the sap of trees such as palasha (Butea monosperma), ber (Zizyphus mauritiana), babul (Acacia arabica), khadira (Acacia catechu), and peepal (Ficus religiosa). The least-coloured shellac is produced when the insects feed on the kusum tree (Schleichera). India contributes 50–60% of global lac production.
The number of lac bugs required to produce 1 kilogram of shellac has variously been estimated between 50,000 and 300,000. Shellac is the only commercially used natural resin of animal origin and is quite different from all other natural resins.
After harvest, the raw material passes through a defined sequence of processing steps. The harvester cuts twigs coated with lac into small pieces called sticklac. The crude material is ground and soaked in water to remove debris and insect bodies. The remaining material is soaked in sodium carbonate, which removes laccaic acid, a complex mixture of at least four structurally related pigments. Broken branches sold as sticklac are chopped and, after grinding and washing with water to eliminate wood and red pigments (lac dye), seed lac is obtained. Purification of seed lac gives the more homogeneous product known as shellac.
The refined material is a mixture of resin (70–80%), wax (6–7%), and colourant molecules (4–8%), obtained by refining sticklac. It is processed and sold as dry flakes and dissolved in alcohol to make liquid shellac, which is used as a brush-on colorant, food glaze, and wood finish.
In Ayurvedic medicine, a distinct purification protocol applies: lac used in Ayurvedic and Unani medicine is a pure form of lac collected from the plants with no other ingredients mixed with it. To remove impurities and dust particles, it undergoes natural purification processes, including washing with hot water, heating, and filtering. It is also processed with herbs, herbal juices, and mixed with herbal powder or extract before using it therapeutically.
Laksha, scientifically known as Laccifer lacca, is a significant substance in traditional medicine systems such as Ayurveda and Unani. It is cited in ancient texts like the Rigveda and Atharvaveda, where it has been recognized for its various therapeutic properties. References in these ancient texts highlight its application for wound healing and fractures. Specifically, the Atharvaveda mentions using lac extracts on open wounds to facilitate quick healing and tissue regeneration, while the Rigveda refers to its use in treating bone fractures.
In traditional Indian systems — Ayurveda, Unani, and Siddha — Laksha is valued as a bone-healing, wound-healing, and styptic agent and is an important ingredient in classical formulations such as Lakshadi Guggulu. Applications spanned bone fractures, heavy bleeding (including menstrual flow and internal bleeding), skin issues such as herpes, and cough and hiccups. Ayurvedic formulations combined Laksha with milk or ghee to support bone strength and wound healing.
Classical sources describe a variety of specific preparations and their indications:
One compound formula for fracture management recorded in Ayurvedic literature, Rasonadi Kalka, comprises five key ingredients: Rasona (garlic), Madhu (honey), Laksha (lacca), Gau Ghrita (clarified butter), and Sarkara (sugar). The recommended dosage of this preparation is 5 grams, taken twice daily, preferably with one glass of cow's milk.
In Ayurvedic descriptive terms, Laksha is characterized as astringent in taste and cool in potency (virya), and is thought to balance both Kapha and Pitta doshas.
Shellac is an age-old material of animal origin, whose quality and quantity depend largely on the host–insect interaction. Lac scales are main cash crops and are cultured in Burma, India, and Thailand. Beyond medicine, lac resin has seen extensive application in food, pharmaceutical, and cosmetic industries, often as a glaze, coating, or binding agent. Historical records from India and Southeast Asia document a dual role: therapeutic ingredient and commercial commodity processed for dye, wax, and lacquer — trade routes distributing it across South Asia, the Middle East, and eventually Europe.
Shellac is a resin purified from the secretion of the insect Laccifer lacca and consists of polyhydroxy polycarboxylic esters, acids, and alkanes. Shellac is a physically refined form of lac resin, a natural biopolymer of animal origin. In its basic form, it is a polyester macromolecule composed of inter- and intra-esters of polyhydroxy aliphatic and sesquiterpene acids.
The major component of shellac is a resin that on being subjected to mild hydrolysis yields a complex mixture of aliphatic and alicyclic hydroxy acids and their polyesters. The composition of the resultant hydrolysate depends on the source of shellac and the time of collection. The major component of the aliphatic fraction is aleuritic acid, while the major component of the alicyclic fraction is shellolic acid. It also contains isomers of shellolic acid along with small amounts of kerrolic acid and butolic acid.
Shellac chiefly contains esters of aleuritic, jalaric, shellolic, and butolic acid. A detailed structural analysis by natural product chemistry has gone further: seven sesquiterpenes — including four α-cedrene types (Shellolic acid A–C, Laccishellolic acid), two R-curcumene types (Shellolic acid D–E), and Shellolic acid F — were isolated from shellac, of which six were previously unknown.
The colouring matter is due to the presence of laccaic acid, which is water-soluble. Laccaic acid-A is the major component, while the rest are present in relatively smaller quantities. Laccifer lacca (Kerr) produces a mixture of polyhydroxy anthraquinones (laccaic acid) known as lac dye. These laccaic acids are structurally classified as anthraquinone derivatives and represent the primary bioactive pigment fraction of lac.
The other main constituents of lac materials are shellac wax as well as dye, which equally hold their position to contribute to the food industry, especially postharvesting. Shellac possesses good emulsification properties due to the high percentage of C28 to C32 fatty alcohols that characterize its wax component.
The resin appears to be composed of a network of hydroxy fatty acid esters and sesquiterpene acid esters with a molecular weight of about 1,000. Shellac has a high structural organization due to its characteristics of forming supramolecular and self-assembled colloidal structures. Modern studies treat lac as a complex natural resin composed mainly of polyesters of hydroxy fatty acids and terpenic acids, plus an anthraquinone-type dye fraction.
The most thoroughly characterized mechanism of action for shellac at the material level is its pH-dependent solubility. Because shellac only dissolves in aqueous solutions with pH > 7.00, it is a favorable natural raw material for colon-targeted drug delivery and is often used as an enteric coating or pharmaceutical carrier. Shellac possesses good resistance to gastric juice; the major disadvantage of this polymer is its low solubility in intestinal fluid. This dual property — gastric acid resistance combined with alkaline-environment dissolution — underpins its use in enteric and sustained-release formulations.
Shellac is also useful in enteric coating, sugar coating applications, and colon-delivery applications due to its high dissolution pH. For enteric coating, shellac must accompany some additives that boost drug release. It has been used in several industries for ages due to its exceptional properties such as film-forming, adhering, bonding, thermoplasticity, water-resistance, and easy solubility in spirit and aqueous alkali solvents.
Laccaic acid, the major constituent of the food colouring agent lac dye, possesses antioxidant and anti-inflammatory properties. The antioxidant activities of laccaic acids and their aluminum lake were evaluated using the DPPH assay. The assay revealed that laccaic acids demonstrated a higher antioxidative activity (EC50 = 0.38 mg/mL) compared to the aluminum lake (EC50 = 1.63 mg/mL) and butylated hydroxytoluene (EC50 = 0.57 mg/mL), but lower than ascorbic acid (EC50 = 0.14 mg/mL) and gallic acid (EC50 = 0.05 mg/mL).
Western blotting experiments showed that laccaic acid increased phosphorylation of IRS1/2/AKT/GSK3β, which is suppressed under insulin-resistant conditions in the liver. Furthermore, it also attenuated the inflammatory ERK/NFκB signalling, thereby reducing the expression of inflammatory cytokines TNFα, IL-1β, and IL-6. The anti-inflammatory efficacy of laccaic acid was reported by Kuramoto et al. (1996), whereby natural colorants containing laccaic acid inhibited the production of allergen-specific immunoglobulin E by rat spleen lymphocytes at low concentrations ranging from 1 to 10 µM. Furthermore, these compounds also exhibited potential immunomodulatory properties, showing inhibition of IgG and IgM even at a low concentration of 1 mM. These findings imply that lac dye may possess the ability to regulate immunoglobulin production, which can be attributed to the presence of laccaic acids.
Literature suggests that laccaic acids have a structural resemblance with the anticancer drug Adriamycin (ADR); hence, they may possess potential anticancer activity. Laccaic acid A demonstrated significant anticancer activity with an IC50 value of less than 100 nM, comparable to that of Adriamycin. Further investigations into the apoptotic activity of laccaic acid A were conducted using flow cytometry, revealing that laccaic acid A is a non-necrotic and apoptotic inducer. Laccaic acid enhanced insulin signaling pathways, reduced inflammatory signals, and affected gluconeogenesis-related genes. Notably, laccaic acid influenced the epigenetic landscape by preventing histone methylation changes associated with insulin resistance and upregulating the H3K27 methylating enzyme EZH2.
Laksha possesses qualities described in Ayurvedic tradition as Rakta Stambhaka (hemostasis), Vranaropaka (wound healing), and Bhagnasandhana (bone healing). From a modern phytochemical perspective, the astringent resin constituents may support hemostasis, while the anti-inflammatory laccaic acid fractions could modulate the inflammatory phase of fracture repair, though these connections remain largely inferential in the absence of controlled clinical trials isolating lac resin's contribution.
Evidence strength: Strong (applied materials science level; well-established in pharmaceutical technology).
Shellac is widely used as a protective coating or confectionary glaze in the food industry and in the pharmaceutical industry as an enteric coating for the masking of odor or taste. As an enteric coating material for tablets and capsules, shellac protects the drug from the damaging gastric acid environment and ensures its release in the intestine. Shellac-based nanoparticles have been developed for targeted drug delivery, and these nanoparticles can improve the solubility and bioavailability of insoluble drugs.
Shellac is the only pharmaceutically used resin of animal origin and has been widely used in the development of various delivery systems owing to its pH responsiveness, biocompatibility, and degradability. Multiscale shellac-based delivery systems from the macroscale to nanoscale include matrix tablets, films, enteric coatings, hydrogels, microcapsules, microparticles, nanoparticles, and nanofibers.
Because of the comparatively high dissolution pH of shellac, further additives are required if it is used as an enteric coating material. However, this dissolution behaviour may be of interest for sustained-release or colon-targeting applications. In one study, different subcoats containing calcium chloride, citric acid, or Eudragit® E, respectively, were applied to immediate-release theophylline pellets subsequently coated with shellac. Drug release from the resulting pellet formulations was measured. The mechanism of interaction between the modifying subcoat ingredients and the shellac coating was investigated using FT-IR spectroscopy. All formulations with modifying subcoats prolonged drug release.
This body of pharmaceutical evidence is robust and reproducible but relates to shellac's role as an excipient rather than as a therapeutic agent per se.
Evidence strength: Weak — traditional use is well-documented; modern clinical evidence is limited to case reports and historically framed reviews with no controlled clinical trials isolating lac resin specifically.
Laksha (lac) is a reddish-brown resin secreted by the female lac insect (Laccifer lacca) and is used in Ayurveda for bone fracture healing and to strengthen bones. In traditional Indian systems — Ayurveda, Unani, and Siddha — Laksha is valued as a bone-healing, wound-healing, and styptic agent and is an important ingredient in classical formulations such as Lakshadi Guggulu.
One published case report from a PMC-indexed journal describes the use of Ayurvedic medicines including Lakshadi Guggul in an 18-month tibial non-union case: Lakshadi Guggul contains Laksha and is described as having anti-inflammatory (Shothahara) and fracture-healing (Bhagna Sandhanakara) qualities. Additionally, it has been described as effective in treating bone fractures. However, this is a single case report in which Laksha-containing formulas were used as part of a complex multi-ingredient regimen alongside Panchakarma procedures, making it impossible to attribute any outcomes to lac resin alone.
Research suggests that Rasonadi Kalka — a formula incorporating Laksha — may effectively promote early bone healing. However, clinical trials are necessary to confirm its therapeutic efficacy for fracture patients. This characterization accurately reflects the current state of the evidence: supportive traditional data and preliminary observational findings exist, but no randomized controlled trials (RCTs) isolating Laksha's contribution to fracture healing have been published in indexed peer-reviewed literature as of the most recent searches.
Evidence strength: Preliminary — in vitro studies only; no human clinical data.
In vitro DPPH and hydrogen peroxide scavenging assays have been performed on lac dye extracts. Antioxidant activity was performed by DPPH, reducing power, and hydrogen peroxide scavenging activity. Ethyl acetate and methanol extracts were found to have the most potent antioxidant activity, with more than 50% inhibition at a concentration of 16 µg/mL across all three methods. A 25.00 g/mL lac dye concentration showed 68% DPPH scavenging capacity, implying antioxidant properties of lac dye, whereas the capacity was about 1/5th that of ascorbic acid.
These results are drawn entirely from in vitro models. No human clinical trials on the antioxidant effects of lac resin or its constituents have been identified in the indexed literature.
Evidence strength: Preliminary — in vitro cell-line studies only; no animal models or human data published for this application.
This study was designed to explore the in vitro anticancer activity of three fractions of lac dye — chloroform (C), methanol (M), and water (W) fractions. The SRB (Sulforhodamine B) assay method was employed to evaluate the inhibitory action of all three fractions. Only the methanolic fraction showed promising inhibitory action with GI50 <10, which runs in parallel with Adriamycin inhibition (GI50 <10). The final structures of the isolated active constituents — laccaic acid D and laccaic acid B — were confirmed by 13C and 2D NMR data. Only the methanol fraction showed promising anticancer activity against in vitro MDA-MB-231 and SiHa cell lines compared to the standard Adriamycin.
A more recent study similarly found that laccaic acid A demonstrated significant anticancer activity with an IC50 value of less than 100 nM, comparable to that of Adriamycin. Further investigations revealed that laccaic acid A is a non-necrotic and apoptotic inducer. The isolated laccaic acids were also assessed for antioxidant, anti-inflammatory, and anti-angiogenesis properties. The results were described as promising, indicating that laccaic acids could offer a multifaceted approach to cancer treatment.
With structural similarities to Adriamycin, laccaic acid has shown anticancer properties, warranting in-depth investigation and evaluation for its efficacy in cancer treatment. The prospect of investigating lac dye for its antiangiogenic effects adds a new dimension, suggesting the possibility of a multimodal anticancer approach. This area of research holds promise for uncovering novel mechanisms and therapeutic strategies for cancer treatment. All results, however, are from cell-line models. Translation to human use would require preclinical animal testing and then clinical trials — neither of which has been reported in the indexed literature at this stage.
Evidence strength: Preliminary — single animal study (murine model); no human data.
Laccaic acid was evaluated for effects on high-fat diet-induced insulin resistance in C57BL/6J mice. Insulin resistance was developed in mice by feeding a high-fat diet for 12 weeks. A 6-week treatment with laccaic acid showed significant improvement in morphometric, biochemical parameters, and liver function. Concomitantly, laccaic acid increased AMPK/AKT-mediated phosphorylation of FOXO1, preventing its nuclear translocation and transcriptional activation of gluconeogenic genes (G6PC and PCK1). Interestingly, treatment with laccaic acid also prevented high-fat diet-induced alterations of histone methylation at a global level. Chromatin-immunoprecipitation data showed that high-fat diet-induced loss of the inactivation mark H3K27me3 at the FOXO1 promoter was regained upon laccaic acid treatment.
This represents a single mouse study with mechanistically interesting findings that have not been replicated or translated to human subjects.
Evidence strength: Preliminary — in vitro studies only.
In vitro evaluations by Srivastava et al. investigated the antimicrobial activity of lac extracts. The synthesized laccaic acid-based nanostructured polymer incorporated into electrospun nanofibrous scaffolds was observed to endow the nanofibers with antimicrobial characteristics. Documented antioxidant, antimicrobial, and anti-inflammatory characteristics position lac dye as a valuable resource for drug development, holding the potential to address diverse health challenges. These in vitro findings are not yet supported by human clinical trials.
Evidence strength: Very preliminary — a single referenced study.
A research study conducted on the healing effect of Laksha powder mixed with honey concluded it as an effective treatment for tartar without any oral medications. No further information on study design, sample size, or population was available from source text to evaluate this claim's strength. Patch testing data (see Safety section) has established shellac as a potential contact allergen in dental products, including mouthguards.
As a pharmaceutical excipient, shellac is applied as a coating in quantities determined by formulation design rather than therapeutic dose. In acute oral toxicity studies, shellac was administered to albino rats with a single gavage dose of 5 g/kg body weight. No toxicologically relevant effects were seen in oral subchronic studies in rats at doses amounting to 1,600 mg/kg body weight per day, the highest dose tested.
For the regulatory ADI in humans: the EFSA has established an acceptable daily intake (ADI) of 4 mg/kg body weight per day for wax-free shellac. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) has not established a specific ADI, as no safety concerns were identified at the levels used in food.
In the Ayurvedic tradition, the only specific reported dosage identified in reviewed sources is for the multi-ingredient Rasonadi Kalka formula: the recommended dosage of Rasonadi Kalka is 5 grams, taken twice daily, preferably with one glass of cow's milk. No standardized, dose-escalation, or pharmacokinetic dosing data for isolated lac resin as a standalone oral therapeutic agent in humans were identified in the indexed literature reviewed.
Regarding absorption: in a 4-week study in rats, the absorption of what is called "shellac monomer" — an ester derived from jalaric acid and aleuritic acid — was analysed in plasma, showing that the absorption of this component was very low. Information on absorption, distribution, metabolism, and excretion (ADME) was not available to the Scientific Committee on Food (SCF) or JECFA at the time of their evaluations.
A refined lac product called shellac has been granted GRAS approval by the USFDA and EU with the E number E904 for use as a food additive. The European Food Safety Authority (EFSA) and the U.S. Food and Drug Administration (FDA) have evaluated shellac's safety. According to their assessments, E904 is generally recognized as safe (GRAS) when used within specific limits. As a natural-origin material, shellac is biocompatible and is listed as GRAS by the FDA.
Shellac (E 904) is considered to be of low acute toxicity. In acute oral toxicity testing, shellac was administered to albino rats with a single gavage dose of 5 g/kg body weight. No deaths were recorded during the observation period of 14 days. Shellac (E 904) is considered to be of low acute toxicity. No toxicologically relevant effects were seen in the oral subchronic studies in rats at doses amounting to 1,600 mg/kg body weight per day, the highest dose tested.
There are no significant toxicological effects reported at typical exposure levels, and no known drug interactions, as shellac is an inert substance that is not systemically absorbed.
The most current regulatory safety assessment is the EFSA Panel's 2024 re-evaluation. For several age groups, the ADI was exceeded at the 95th percentile in the non-brand-loyal exposure assessment scenario and maximum level exposure assessment scenario. Considering the low exceedance and the fact that both the exposure estimation and the toxicological evaluation of shellac were conservative, the panel concluded that the calculated exceedance of the ADI does not indicate a safety concern.
The panel concluded that the calculated exceedance of the ADI does not indicate a safety concern. The Panel recommended to the European Commission separating specifications for E 904 depending on the manufacturing process (chemical bleaching and physical decolouring), because they result in different impurities; revising the definition of the food additive; deleting information on wax-containing shellac from EU specifications; revising the acid value for wax-free shellac produced by chemical bleaching; lowering the maximum limit for lead; and considering introducing limits for other toxic elements potentially present in shellac.
Skin sensitization to shellac is rare. Nonetheless, clinically documented cases exist across multiple publication series. In the 1990s and the first decade of the 21st century, several cases of contact dermatitis associated with shellac use in lipsticks, eyeliners, and mascaras were described. From 2009 to 2012, shellac was included in the North American Contact Dermatitis Group (NACDG) baseline series, with a relatively high prevalence of positive tests — 1.6–1.7% of all patients tested; however, it was removed from the NACDG baseline series because more than 50% of positive tests were of unknown relevance.
More recently, several clinical reports described new sources of shellac exposure, such as tattoo ink, a mouth guard, ecological hairspray, and cases related to occupational exposure in food handlers due to the use of shellac as a coating agent for fruits and sweets. Shellac 20% alcohol is included in the British Society for Cutaneous Allergy/European Society of Contact Dermatitis extended facial series based on frequency of reactions exceeding the 0.3% threshold.
Allergic contact dermatitis commonly presents as erythema and swelling, but may progress to the development of blisters in severe reactions. Shellac contact allergy can be diagnosed through examination, history-taking, and skin patch testing. A positive reaction may be seen over the site of application during the 48-hour or 96-hour reading. The reaction rate with patch testing varies between 2–10%. Given that the product is tested in 20% alcohol, some of the reactions may be irritant in nature.
Despite shellac being a natural substance, its extraction entails the collection of lac resin from lac beetles, raising ethical concerns due to the unavoidable harm to insects during the harvesting process. Consequently, many vegans opt to steer clear of products containing shellac because of its insect-derived origin.
The toxicological studies on shellac include acute and short-term oral toxicity tests, mutagenicity, and reproductive toxicity evaluation. In view of the limited toxicological studies available on the safety aspects of shellac, the U.S. FDA and European Union (EU) had permitted the use of shellac as a food additive. Critical data gaps persist: information on absorption, distribution, metabolism, and excretion (ADME) was not available to the SCF or JECFA at the time of their evaluations.
Lac resin occupies a distinctive position in the natural products landscape: it has a robust, millennia-long record of traditional medicinal use in South and Southeast Asian pharmacopoeial traditions; a well-characterized role as a pharmaceutical excipient backed by decades of formulation science; and an emerging — but still highly preliminary — body of in vitro and animal research exploring the bioactive potential of its constituent laccaic acids.
The clearest distinction to maintain is between:
A review of Laccifer lacca noted that there are some areas not much explored, including the chemical characteristics of the lac, active ingredients, principal compound quantification, and parameters for quality assurance. This accurately reflects the significant knowledge gaps that remain in transitioning lac resin from traditional pharmacopeia to evidence-based clinical application.
Health conditions that Lac resin may help support.
Body systems that Lac resin may help support.
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