Stearic acid is a long-chain (18:0) dietary saturated fatty acid. It occurs naturally in animal and vegetable fats. For example, in soya beans where its content is typically between 2% and 5% of total fatty acids. It is produced by hydrolysis of oil

It appears as a white powder insoluble in water, easily soluble in hot ethanol, slightly soluble in benzene and carbon disulphide. Tasteless.

What it is used for and where

Food

Recent investigations specifically comparing stearic acid with other fatty acids in human studies have confirmed that stearic acid is not hypercholesterolaemic. Stearic acid has been shown not to increase low-density lipoprotein cholesterol compared to oleic acid, which is known to be neutral in its effects on cholesterol concentrations. In contrast, palmitic acid, another long-chain saturated fatty acid, markedly increases cholesterol concentrations. For this reason, fats rich in stearic acid could be used instead of those high in palmitic acid in cholesterolaemic diets (1).

Medical

Stearic acid has been shown to possess anti-inflammatory potential. In this study, it was evaluated whether stearic acid has protective effects against cholestasis-related liver damage and indeed its hepatoprotective role was found to be associated with anti-inflammatory potential (2).

Stearic acid can protect cortical neurons from oxidative stress by increasing internal antioxidant enzymes (3).

Chemical synthesis and characterisation of a lipophilic ester conjugate, propofol stearate, and evaluation of its antitumour efficacy on human breast cancer cell lines MDA-MB-361, MCF-7 and MDA-MB-231. Exogenous stearic acid applied as an ester derivative inhibits the growth of human breast cancer cells and shows a beneficial role in the treatment of breast cancer in vitro (4).

Skin disorders are often treated with creams containing various active substances that also contain emulsifiers, surfactant ingredients used to stabilise the emulsion. Emulsifiers are potential irritants and in the present study, the influence of stearic acid did not show any differences with regard to blood flow in the skin. Furthermore, stearic acid as emulsifier unexpectedly reduced transepidermal water loss (TEWL). These results point to the possibility of absorption of stearic acid as emulsifier  into the lipid bilayer, which increases TEWL in normal skin and decreases TEWL in damaged skin (6).

Used to prepare suppositories, ointments, etc.

Cosmetics

Stearic acid is incorporated into skin care products as a non-ionic emulsifier, solubiliser, and lubricant. Emulsifiers have the property of reducing interfacial tension and also directly influence the stability, sensory properties and surface tension of sunscreens by modulating their filmometric performance.

Pharmaceuticals

Coating agent for tablets.

Other uses

Raw material for lubricants, plasticisers, PVC stabiliser, vulcanising agent for natural rubber, synthetic rubber (except butyl rubber) and latex.

For more information:

Stearic acid studies

Typical commercial product characteristics Stearic Acid

Appearance	White powder
Boiling Point	361°C
Melting Point	67-72°C
Flash Point	>230 °F
Density	0.84
Vapor Pressure	1 mm Hg  173.7°C
Refraction Index	1.4299
Water Solubility	0.1-1 g/100 mL/ 23ºC
PSA	37.30000
LogP	6.33250
Saponification value	195-211 mg KOH /g
Acid value	195-211g mg KOH /g
Iodine	≤0.6
Water content	≤0.1
C16	4 ~ 59%
C18	37 ~ 96%
Shelf life	2 years
Chemical risk

• Molecular Formula   C₁₈H₃₆O₂
• Linear Formula    CH₃(CH₂)₁₆COOH
• Molecular Weight    284,4772
• Exact Mass    284.27200
• CAS    57-11-4
• UNII    4ELV7Z65AP
• EC Number   266-928-5    200-313-4
• DSSTox Substance ID  DTXSID8021642
• IUPAC  octadecanoic acid
• InChl=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)
• InChl Key      QIQXTHQIDYTFRH-UHFFFAOYSA-N
• SMILES   CCCCCCCCCCCCCCCCCC(=O)O
• MDL number  MFCD00002752
• PubChem Substance ID    24899616
• ChEBI  28842
• RTECS  WI2800000
• Beilstein    608585
• NCI    C68426
• ICSC    0568
• NSC      25956
• NSC     261168
• FEMA     3035
• JECFA    116
• RXCUI    1310551
• NACRES NA.25

Synonyms

• Octadecanoic acid
• Cetylacetic acid
• 1-Heptadecanecarboxylic acid
• Pearl stearic
• n-Octadecanoic acid
• Stearophanic acid

References______________________________________________________________

(1) Grundy SM. Influence of stearic acid on cholesterol metabolism relative to other long-chain fatty acids. Am J Clin Nutr. 1994 Dec;60(6 Suppl):986S-990S. doi: 10.1093/ajcn/60.6.986S.

(2) Pan PH, Lin SY, Ou YC, Chen WY, Chuang YH, Yen YJ, Liao SL, Raung SL, Chen CJ. Stearic acid attenuates cholestasis-induced liver injury. Biochem Biophys Res Commun. 2010 Jan 15;391(3):1537-42. doi: 10.1016/j.bbrc.2009.12.119. 

(3) Wang ZJ, Liang CL, Li GM, Yu CY, Yin M. Stearic acid protects primary cultured cortical neurons against oxidative stress. Acta Pharmacol Sin. 2007 Mar;28(3):315-26. doi: 10.1111/j.1745-7254.2007.00512.x. 

(4) Khan AA, Alanazi AM, Jabeen M, Chauhan A, Abdelhameed AS. Design, synthesis and in vitro anticancer evaluation of a stearic acid-based ester conjugate. Anticancer Res. 2013 Jun;33(6):2517-24. 

(6) Bárány E, Lindberg M, Lodén M. Unexpected skin barrier influence from nonionic emulsifiers. Int J Pharm. 2000 Feb 15;195(1-2):189-95. doi: 10.1016/s0378-5173(99)00388-9.