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Stearic acid
Stearic acid
Stearic acid
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Stearic acid[1]
Skeletal formula of stearic acid
Skeletal formula of stearic acid
Ball-and-stick model of stearic acid
Ball-and-stick model of stearic acid
Stearic acid
Stearic acid
Names
Preferred IUPAC name
Octadecanoic acid
Other names
Identifiers
3D model (JSmol)
608585
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.000.285 Edit this at Wikidata
EC Number
  • 200-313-4
11738
KEGG
RTECS number
  • WI2800000
UNII
  • InChI=1S/C18H36O2/c1-2-3-4-5-6-7-8-9-10-11-12-13-14-15-16-17-18(19)20/h2-17H2,1H3,(H,19,20)
    Key: QIQXTHQIDYTFRH-UHFFFAOYSA-N
  • CCCCCCCCCCCCCCCCCC(=O)O
Properties
C18H36O2
Molar mass 284.484 g·mol−1
Appearance White solid
Odor Pungent, oily
Density 0.9408 g/cm3 (20 °C)[2]
0.847 g/cm3 (70 °C)
Melting point 69.3 °C (156.7 °F; 342.4 K)[2]
Boiling point 361 °C (682 °F; 634 K)
decomposes
232 °C (450 °F; 505 K)
at 15 mmHg[2]
0.0018 g/100 g (0 °C)
0.0029 g/100 g (20 °C)
0.0034 g/100 g (30 °C)
0.0042 g/100 g (45 °C)
0.0050 g/100 g (60 °C)[3]
Solubility Soluble in
[4]
Solubility in dichloromethane 3.58 g/100 g (25 °C)
8.85 g/100 g (30 °C)
18.3 g/100 g (35 °C)[4]
Solubility in hexane 0.5 g/100 g (20 °C)
4.3 g/100 g (30 °C)
19 g/100 g (40 °C)
79.2 g/100 g (50 °C)
303 g/100 g (60 °C)[4]
Solubility in ethanol 1.09 g/100 mL (10 °C)
2.25 g/100 g (20 °C)
5.42 g/100 g (30 °C)
22.7 g/100 g (40 °C)
105 g/100 g (50 °C)
400 g/100 g (60 °C)[3]
Solubility in acetone 4.73 g/100 g[5]
Solubility in chloroform 15.54 g/100 g[5]
Solubility in toluene 13.61 g/100 g[5]
Vapor pressure 0.01 kPa (158 °C)[2]
0.46 kPa (200 °C)
16.9 kPa (300 °C)[6]
−220.8·10−6 cm3/mol
Thermal conductivity 0.173 W/m·K (70 °C)
0.166 W/m·K (100 °C)[7]
1.4299 (80 °C)[2]
Structure
B-form = Monoclinic[8]
B-form = P21/a[8]
B-form = Cs
2h[8]
a = 5.591 Å, b = 7.404 Å, c = 49.38 Å (B-form)[8]
α = 90°, β = 117.37°, γ = 90°
Thermochemistry
501.5 J/mol·K[2][6]
435.6 J/mol·K[2]
−947.7 kJ/mol[2]
−11342.4 kJ/mol[9]
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
1
0
Flash point 205 °C (401 °F; 478 K)
Lethal dose or concentration (LD, LC):
4640 mg/kg (rats, oral)[10]
21.5 mg/kg (rats, intravenous)[4]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Stearic acid (/ˈstɪərɪk/ STEER-ik, /stiˈærɪk/ stee-ARR-ik) is a saturated fatty acid with an 18-carbon chain.[9] The IUPAC name is octadecanoic acid.[9] It is a soft waxy solid with the formula CH3(CH2)16COOH.[9] The triglyceride derived from three molecules of stearic acid is called stearin.[9] Stearic acid is a prevalent fatty acid in nature, found in many animal and vegetable fats, but is usually higher in animal fat than vegetable fat. It has a melting point of 69.4 °C (156.9 °F)  °C and a pKa of 4.50.[11]

Its name comes from the Greek word στέαρ "stéar", which means tallow. The salts and esters of stearic acid are called stearates.[9] As its glycerol ester, stearic acid is one of the most common saturated fatty acids found in nature and in the food supply, following palmitic acid.[12][13] Dietary sources of stearic acid include meat, poultry, fish, eggs, dairy products, and foods prepared with fats; beef tallow, lard, butterfat, cocoa butter, and shea butter are rich fat sources of stearic acid.[9][12]

Production

[edit]

In terms of its biosynthesis, stearic acid is produced from palmitoyl-CoA, with malonyl-CoA a two-carbon building block (after decarboxylation).

Stearic acid is obtained from fats and oils by the saponification of the triglycerides using hot water (about 100 °C). The resulting mixture is then distilled.[14] Commercial stearic acid is often a mixture of stearic and palmitic acids, although purified stearic acid is available. Commercially, oleic acid, as found in palm and soy, can be hydrogenated to give stearic acid.

Uses and occurrence

[edit]

In general, the applications of stearic acid exploit its bifunctional character, with a polar head group that can be attached to metal cations and a nonpolar chain that confers solubility in organic solvents.[9] The combination leads to uses as a surfactant and softening agent. Stearic acid undergoes the typical reactions of saturated carboxylic acids, a notable one being reduction to stearyl alcohol, and esterification with a range of alcohols.[9] This is used in a large range of manufactures, from simple to complex electronic devices.[9]

Food

[edit]

Of the saturated fatty acids consumed in the United States, stearic acid consumption is second (26% of total saturated fatty acid intake) to palmitic acid (56% of total saturated fatty acid intake).[12] Stearic acid is more abundant in animal fat (up to 33% in beef liver[15]: 739 ) than in vegetable fat (typically less than 5%).[12] The important exceptions are the foods cocoa butter (34%) and shea butter, where the stearic acid content (as a triglyceride) is 28–45%.[9][15] Examples of the use of stearic acid in food manufacturing include baked goods, frozen dairy products, gelatins, puddings, hard candy, and nonalcoholic beverages.[9]

Stearic acid (E number E570) is found in some foods.[9][16]

Soaps and cosmetics

[edit]

Stearic acid is mainly used in the production of detergents, soaps, and cosmetics such as shampoos and shaving cream products.[9] Stearate soap, such as sodium stearate, could be made from stearic acid but instead are usually produced by saponification of stearic acid-containing triglycerides. Esters of stearic acid with ethylene glycol (glycol stearate and glycol distearate) are used to produce a pearly effect in shampoos, soaps, and other cosmetic products.[9]

Lubricants, softening and release agents

[edit]

In view of the soft texture of the sodium salt, which is the main component of soap, other salts are also useful for their lubricating properties. Lithium stearate is an important component of grease. The stearate salts of zinc, calcium, cadmium, and lead are used as heat stabilizers for PVC. Stearic acid is used along with castor oil for preparing softeners in textile sizing. They are heated and mixed with caustic potash or caustic soda. Related salts are also commonly used as release agents, e.g. in the production of automobile tires. As an example, it can be used to make castings from a plaster piece mold or waste mold, and to make a mold from a shellacked clay original. In this use, powdered stearic acid is mixed in water and the suspension is brushed onto the surface to be parted after casting. This reacts with the calcium in the plaster to form a thin layer of calcium stearate, which functions as a release agent.[17]

Steric acid can be converted to zinc stearate, which is used as a lubricant for playing cards (fanning powder) to ensure a smooth motion when fanning. Stearic acid is a common lubricant during injection molding and pressing of ceramic powders.[18]

Niche uses

[edit]

Being inexpensive, nontoxic, and fairly inert, stearic acid finds many niche applications.[9][14] Varied examples of stearic acid use in manufacturing include soaps and greases, household soap products, synthetic rubber, cosmetic and pharmaceutical creams and lotions, candles, phonograph records, lubricants, shoe and metal polishes, food packaging, and rubber compounds.[9]

Stearic acid is used as a negative plate additive in the manufacture of lead-acid batteries.[citation needed] It is added at the rate of 0.6 g per kg of the oxide while preparing the paste. It is believed to enhance the hydrophobicity of the negative plate, particularly during dry-charging process. It also reduces the extension of oxidation of the freshly formed lead (negative active material) when the plates are kept for drying in the open atmosphere after the process of tank formation. As a consequence, the charging time of a dry uncharged battery during initial filling and charging (IFC) is comparatively lower, as compared to a battery assembled with plates which do not contain stearic acid additive. Fatty acids are classic components of candle-making. Stearic acid is used along with simple sugar or corn syrup as a hardener in candies.[9]

Metabolism

[edit]

An isotope labeling study in humans[19] concluded that the fraction of dietary stearic acid that oxidatively desaturates to oleic acid is 2.4 times higher than the fraction of palmitic acid analogously converted to palmitoleic acid. Also, stearic acid is less likely to be incorporated into cholesterol esters. In epidemiologic and clinical studies, stearic acid was found to be associated with lowered LDL cholesterol in comparison with other saturated fatty acids.[12]

Examples

[edit]
Salts
Esters

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Stearic acid

View on Grokipedia
from Grokipedia
Stearic acid, systematically named octadecanoic acid, is a long-chain saturated with the molecular formula C₁₈H₃₆O₂ and a molecular weight of 284.48 g/mol. It appears as a white, waxy solid at , with a of 69–70 °C and a of approximately 361 °C at standard pressure; it is practically insoluble in (solubility <0.001 g/100 mL at 20 °C) but readily soluble in , , and . Naturally occurring in many animal and plant lipids, stearic acid constitutes a significant portion of fats such as beef tallow (up to 24%), (around 34%), , , and , where it serves as an molecule and structural component in cell membranes. Commercially, stearic acid is produced primarily through the of animal fats or vegetable oils followed by , or via the of unsaturated C18 fatty acids (like ) derived from sources such as palm, , or oils, yielding a high-purity product often graded by to indicate saturation level. This process ensures a vegetable-derived version suitable for vegan applications, though animal-sourced variants remain common in certain industries. Stearic acid's versatility stems from its emollient, emulsifying, and stabilizing properties, making it a key ingredient in numerous applications: it hardens soaps and candles by forming stearate salts, acts as a and in plastics and rubber , serves as an opacifier and thickener in and pharmaceuticals (e.g., in ointments and tablet coatings), and functions as a (E570) for emulsification in , , and . Unlike other saturated fats, dietary stearic acid is considered neutral or beneficial for levels, as it is rapidly converted to in the body, though excessive intake from processed foods should be moderated.

Properties

Physical properties

Stearic acid has the molecular formula C18H36O2C_{18}H_{36}O_2 and a of 284.48 g/mol. It appears as a white, waxy solid at . The compound exhibits a range of 69.3–69.7 °C and a of 361 °C at 100 mmHg. Its is 0.94 g/cm³ in the solid state and 0.839 g/cm³ in the liquid state at 75 °C. Stearic acid is insoluble in , with a solubility of 0.0003 g/100 mL at 20 °C, but it is soluble in organic solvents such as , , and . The is 1.4299 at 80 °C, and the is 196 °C. Key thermal properties include a of -11,298 kJ/mol (approximately -39.7 kJ/g) and a of the solid phase around 2.1 J/g·K at .
PropertyValue
Molecular formulaC18H36O2C_{18}H_{36}O_2
Molar mass284.48 g/mol
AppearanceWhite waxy solid
Melting point69.3–69.7 °C
Boiling point361 °C (at 100 mmHg)
Density (solid)0.94 g/cm³
Density (liquid, 75 °C)0.839 g/cm³
Solubility in water (20 °C)0.0003 g/100 mL
Refractive index (80 °C)1.4299
Flash point196 °C
Heat of combustion-11,298 kJ/mol (-39.7 kJ/g)
Specific heat capacity (solid)~2.1 J/g·K

Chemical properties

Stearic acid, with the IUPAC name octadecanoic acid, is a straight-chain saturated fatty acid comprising 18 carbon atoms in its carbon backbone. Its molecular formula is C18_{18}H36_{36}O2_2, and the structural formula can be represented as CH3_3(CH2_2)16_{16}COOH, featuring a polar terminal carboxyl group (-COOH) bonded to a nonpolar hydrocarbon chain consisting of 16 methylene (-CH2_2-) units and a terminal methyl group (-CH3_3). This configuration defines it as a saturated fatty acid, lacking any carbon-carbon double bonds, in contrast to its positional isomer oleic acid, which is an 18-carbon monounsaturated fatty acid with a cis double bond between carbons 9 and 10. The primary functional groups in stearic acid are the moiety, responsible for its acidic properties, and the extended alkyl chain, which influences and reactivity. As a typical , it behaves as a weak acid in aqueous environments, partially dissociating to form the stearate anion and a proton, with a pKa value of 4.75 at 25°C. The corresponding KaK_a is 1.78×10−51.78 \times 10^{-5}, calculated as Ka=10−pKaK_a = 10^{-\mathrm{p}K_a}, indicating that at physiological values above 7, stearic acid predominantly exists in its deprotonated form. Stearic acid participates in characteristic reactions of carboxylic acids, including esterification, where it condenses with alcohols under acidic conditions to yield stearate esters; for instance, reaction with produces (tristearin), a common fat used in and . It also readily forms salts through neutralization with bases, such as to generate , a water-soluble widely employed in detergents. Saponification, while typically describing the base-catalyzed of esters to regenerate carboxylic acids and alcohols, applies here to the conversion of stearic acid-containing triglycerides into soaps via alkali treatment. The saturated structure of stearic acid confers notable , particularly resistance to oxidation, as the absence of double bonds prevents facile attack by , unlike unsaturated fatty acids such as that undergo peroxidation more readily. This oxidative stability makes stearic acid suitable for applications requiring long-term durability without degradation.

Sources and production

Natural occurrence

Stearic acid is a common saturated found in various natural , particularly in animal and plant sources where it contributes to the structural integrity of fats. In animal fats, it is abundant, comprising up to 30% of beef tallow and approximately 15% of , reflecting its prevalence in mammalian adipose tissues and rendered fats. These levels highlight stearic acid's role as a major component in animal-derived , often exceeding its concentration in most vegetable oils. Plant sources also contain notable amounts of stearic acid, especially in certain butters and oils. is particularly rich, with stearic acid making up 34–37% of its composition, while contains 20–50%, depending on regional variants and growing conditions. In contrast, holds 4–5% stearic acid, and has smaller quantities around 2–3%. Within these natural triglycerides, stearic acid is typically esterified at the sn-1 or sn-3 positions of the backbone, a stereospecific common in both animal and vegetable fats that influences their physical properties. Microbial sources include certain bacteria, such as species of Mycobacterium, where stearic acid is incorporated into cell wall components like phthiocerol dimycocerosates (PDIMs) and mycolic acids, contributing to envelope stability.

Industrial production

Stearic acid is primarily produced on an industrial scale through the hydrolysis of animal or vegetable fats and oils, followed by purification steps to isolate the desired fatty acid. In this process, triglycerides from sources such as tallow, palm oil, or coconut oil derivatives are hydrolyzed—often via saponification or high-pressure splitting with water at elevated temperatures—to yield a mixture of free fatty acids and glycerol. The fatty acid mixture, which includes stearic acid alongside other saturated and unsaturated fatty acids like palmitic and oleic acid, is then separated from the glycerol phase. A key refinement step involves under conditions, which exploits differences in points to concentrate stearic acid, typically achieving purity levels of 90–99% depending on the grade required for commercial applications. This separates stearic acid ( approximately 361°C at ) from lower- impurities and higher-molecular-weight components, with multiple passes used for higher purity. Raw materials historically favored animal fats like for their high natural stearic content, but production has shifted predominantly to sources such as palm and oils since the 1990s, driven by concerns over (BSE) transmission risks and growing demands for sustainable, ethical alternatives. An alternative or complementary method is the of unsaturated C18 fatty acids, particularly derived from vegetable oils, to produce stearic acid. This catalytic process employs nickel-based catalysts, typically at temperatures around 200°C and pressures of 3 atm, converting double bonds in to yield saturated stearic acid with conversion efficiencies of 80–95%. Byproducts such as may form depending on the feedstock composition, and the reaction is often integrated post-hydrolysis to enhance overall stearic yield from unsaturated-rich sources like palm olein.

Applications

Food applications

Stearic acid serves as an emulsifier and stabilizer in various products, designated as E 570 in the . It is employed to enhance texture and prevent separation in items such as , where it acts as a plasticizing agent, candies for improved consistency, and baked goods to aid dough handling and stability. Usage levels are typically limited to , often around 0.5–2% in these applications to ensure functionality without altering flavor. In chocolate and confectionery, stearic acid contributes significantly to the desired snap and , primarily as a component of , which contains approximately 35% . This saturated helps form the crystalline structure that provides solidity at and a smooth melt in the mouth, and it is also used in cocoa butter equivalents derived from vegetable sources to mimic these properties. Nutritionally, stearic acid is an 18-carbon saturated fatty acid that provides 9 kcal per gram, similar to other dietary fats. Unlike many other saturated fats, it has a neutral effect on total and cholesterol levels, making it a less concerning component in moderation compared to palmitic or lauric acids. Regulatory approvals include (GRAS) status from the U.S. for use in food at levels not exceeding current . The , aligned with dietary guidelines, recommends limiting total intake, including stearic acid, to less than 10% of daily caloric intake to support cardiovascular health. Stearic acid is incorporated into margarines and shortenings through interesterification processes, where it is rearranged with other fats like high-oleic or to create trans-fat-free alternatives with improved spreadability and stability for baking and frying applications. Historically, stearic acid has been used in since the , initially derived from animal in early production, with modern vegan alternatives sourced from to meet plant-based demands.

Personal care and cosmetics

Stearic acid plays a key role in the formulation of soaps and detergents, where it is incorporated at levels of 10–30% to enhance bar hardness and promote stable lather formation through the production of salts. These salts, derived from the of stearic acid with , contribute to the soap's durability and cleansing efficiency by creating a firm structure that resists softening in humid conditions while facilitating effective emulsification of oils and dirt. In cosmetics, stearic acid functions primarily as a thickener and emollient, helping to stabilize emulsions and impart a smooth texture in products such as lotions, creams, and lipsticks, typically at concentrations up to 5%. In lotions and creams, it binds oil and water phases to prevent separation, while providing moisturizing benefits that soften the skin without greasiness. For lipsticks, it enhances opacity and , ensuring even application and longevity on the lips by forming a protective barrier. Its surfactant properties further extend its utility in personal care, where stearic acid reduces to improve foaming and cleansing in shampoos and conditioners. This action allows for better dispersion of active ingredients and removal of residues from and , contributing to a lighter, more manageable feel. Globally, personal care and account for approximately 20–30% of total stearic acid consumption as of 2023 estimates, driven by rising demand for grooming and skincare products. Specific formulations highlight its versatility, such as in where it acts as a binding agent to hold solid components together and maintain product integrity during use. grades of stearic acid, often vegetable-derived, are preferred for sensitive formulations due to their low potential and compatibility with dermatological standards. Sustainability trends in the industry have accelerated since the , with a notable shift toward RSPO-certified palm-derived stearic acid to address environmental concerns related to and . This ensures traceable, responsibly sourced raw materials, aligning with consumer preferences for eco-friendly and regulatory pressures in regions like and .

Industrial and other applications

Stearic acid serves as a versatile additive in various industrial processes due to its lubricating, stabilizing, and emulsifying properties. In , it is commonly employed as a and , particularly in and plastics molding, where it prevents adhesion and facilitates smooth processing. For instance, in plastics production, stearic acid acts as a mold to avoid sticking to metallic molds, thereby maintaining equipment integrity and product quality. In the rubber and plastics industries, stearic acid functions as a softening agent and acid scavenger, enhancing material processability and durability. During production, it improves the dispersion of fillers like , resulting in uniform textures and better wear resistance in the final products. Typical usage levels in rubber range from 1% to 3%, where it reduces between rubber molecules and aids in as an activator. Pharmaceutical manufacturing utilizes stearic acid and its derivatives, such as , as excipients to improve tablet formulation and production efficiency. , derived from stearic acid, serves as a and flow agent at concentrations of 0.5% to 2%, reducing during compression and preventing sticking to equipment, which ensures consistent tablet weight and size. This application enhances powder flowability, with optimal performance observed up to 1–2 wt.% addition before . Niche industrial applications include its use in candle production to increase and opacity, typically added at 5–10% of the weight for improved stability and mold release. In explosives and , stearic acid acts as a binder to enhance formulation cohesion. For textiles, it functions as a agent by forming hydrophobic coatings on fibers, improving fabric resistance to . In environmental applications, stearic acid contributes to the development of biodegradable plastics as a compatibilizer, particularly when grafted onto to improve interfacial in blends like /thermoplastic . This modification enhances tensile strength and reduces , promoting sustainable material properties. Globally, industrial applications represent a major portion of stearic acid consumption, with the plastics segment alone accounting for about 25% of the market in 2024, alongside significant shares in rubber processing and lubricants.

Biological aspects

Metabolism

Stearic acid is biosynthesized in the of eukaryotic cells through the pathway, primarily catalyzed by the multifunctional enzyme complex (FAS). The process begins with the carboxylation of to form by , followed by iterative cycles where is transferred to the (ACP) domain of FAS. Each cycle involves condensation with the growing acyl chain, reduction, dehydration, and further reduction, adding two carbon units per cycle. (C16:0), the primary product of after seven cycles (incorporating seven units to the initial ), is then elongated to stearic acid (C18:0) in the by elongases (ELOVL family), which add one additional two-carbon unit from , resulting in a total of eight additions and 18 carbon atoms overall. The degradation of stearic acid occurs primarily through β-oxidation in the , where it is first activated to stearoyl-CoA in the using ATP and CoA, then transported into mitochondria via the carnitine shuttle system. Inside the mitochondria, β-oxidation proceeds in a series of four enzymatic steps per cycle: dehydrogenation to form trans-Δ²-enoyl-CoA (yielding FADH₂), hydration to L-3-hydroxyacyl-CoA, further dehydrogenation to 3-ketoacyl-CoA (yielding NADH), and thiolysis by CoA to remove a two-carbon unit and regenerate a shortened . For stearic acid (C18:0), this process requires eight cycles, producing nine molecules; each cycle generates one NADH and one FADH₂, which collectively yield 5 ATP equivalents per cycle through (using classical values of 3 ATP per NADH and 2 ATP per FADH₂). The resulting enters the for further oxidation. The complete oxidation of stearic acid can be represented by the balanced equation: C17H35COOH+26 O2→18 CO2+18 H2O+energy\mathrm{C_{17}H_{35}COOH + 26\, O_2 \rightarrow 18\, CO_2 + 18\, H_2O + energy} Regulation of stearic acid metabolism is tightly coordinated with cellular energy status. In the fed state, elevated malonyl-CoA levels, produced by acetyl-CoA carboxylase in response to insulin and high glucose, inhibit carnitine palmitoyltransferase I (CPT1) on the outer mitochondrial membrane, preventing acyl-CoA entry into mitochondria and thus suppressing β-oxidation while favoring synthesis. During fasting or low-energy states, glucagon and AMP-activated protein kinase (AMPK) inhibit acetyl-CoA carboxylase, reducing malonyl-CoA and relieving CPT1 inhibition; this activates the carnitine shuttle (involving carnitine acyltransferase I and II), facilitating fatty acid transport for β-oxidation to meet energy demands. In microbial systems, certain anaerobic bacteria such as species of metabolize stearic acid through fermentation pathways that can yield butyrate as a key product. For instance, ruminal strains, including C. proteoclasticum, utilize saturated fatty acids like stearic acid in , contributing to butyrate production via intermediates in the process. In , stearic acid undergoes desaturation to (C18:1 Δ9) primarily in the chloroplasts and , catalyzed by stearoyl-ACP desaturase (SAD), which introduces a between carbons 9 and 10 of the stearoyl-acyl carrier protein ; this step is essential for maintaining and is a rate-limiting process in unsaturated fatty acid production. In animals, stearic acid is incorporated into phospholipids, particularly at the sn-1 position of glycerophospholipids like and , through acyltransferase enzymes in the , supporting membrane structure and signaling functions.

Health effects

Stearic acid, unlike other saturated fatty acids such as , does not raise (LDL) cholesterol levels and exhibits a neutral effect on total and LDL cholesterol when compared to monounsaturated fats like . Meta-analyses from the and early confirm this neutral cardiovascular profile for stearic acid at dietary intakes below 6% of total energy, distinguishing it from other saturates that may elevate risk. The (AHA) incorporates stearic acid within broader recommendations, advising limits of 5-6% of total daily energy intake to minimize heart disease risk, particularly for individuals with elevated . In terms of digestibility, stearic acid demonstrates an absorption rate of 86-98% in humans when consumed from natural oils and fats, which is lower than that of shorter-chain saturated fatty acids like lauric or . This reduced absorption may contribute to benefits, as evidenced by studies showing decreased visceral accumulation and enhanced fat excretion in models with high stearic acid intake, potentially due to lower net caloric uptake. Safety assessments indicate stearic acid has low , with an oral LD50 greater than 5 g/kg in rats, supporting its classification as non-toxic at typical exposure levels. Regarding carcinogenicity, the International Agency for Research on Cancer (IARC) places stearic acid in Group 3, meaning there is inadequate evidence for its carcinogenicity in humans. In topical applications such as , stearic acid rarely causes and is generally non-sensitizing, making it suitable even for sensitive types, though individuals with allergies to its plant or animal-derived sources may experience mild reactions like redness or itching. Recent studies from the 2020s highlight stearic acid's potential roles in modulating the gut and exerting effects when consumed in moderation; for instance, microbiome-derived stearate has been shown to suppress colorectal tumor growth by inducing and reducing pro-inflammatory Th17 cells in the colon. Additionally, stearic acid extracts demonstrate activity by inhibiting pro-inflammatory secretion in cellular models. As part of overall intake, stearic acid should be limited to less than 6% of total dietary energy per AHA guidelines, with vegan sources from vegetable oils preferred over animal-derived ones to promote environmental .

References

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