Cinnamic acid

Cinnamic acid is a naturally occurring phenolic acid derived primarily from the amino acid phenylalanine via the shikimate and phenylpropanoid biosynthetic pathways. It acts as a precursor to numerous bioactive plant compounds, including flavonoids, lignins, and coumarins, and exhibits preliminary antioxidant activity by scavenging reactive oxygen species.

Origin & History

Cinnamic acid is an unsaturated aromatic carboxylic acid derived from cinnamon bark and other plant sources like shea butter. It is produced in plants via the shikimate and phenylpropanoid pathways through the action of phenylalanine ammonia-lyase on phenylalanine.

Historical & Cultural Context

The search results do not contain information on the historical or traditional use of cinnamic acid in medicine. Its presence in cinnamon suggests historical use in culinary contexts.

Health Benefits

• Potential antioxidant properties (Preliminary evidence)
• May support plant biosynthetic pathways (Preliminary evidence)
• Presence in food compounds suggests potential health benefits (Preliminary evidence)
• Possible role in shikimate and phenylpropanoid pathways (Preliminary evidence)
• Suggested use in cinnamon derivatives (Preliminary evidence)

How It Works

Cinnamic acid is biosynthesized from L-phenylalanine by the enzyme phenylalanine ammonia-lyase (PAL), positioning it as the entry point of the phenylpropanoid pathway. It is subsequently converted into p-coumaric acid by cinnamate-4-hydroxylase (CYP73A), a cytochrome P450 enzyme, which feeds downstream synthesis of flavonoids, stilbenes, and lignins. Its antioxidant activity is attributed to the hydroxyl-substituted aromatic ring structure, which can donate hydrogen atoms to neutralize free radicals and chelate transition metal ions.

Scientific Research

The research dossier lacks specific human clinical trials or meta-analyses evaluating the health benefits of cinnamic acid. No PMIDs are available to reference.

Clinical Summary

Research on cinnamic acid in humans remains extremely limited, with most evidence derived from in vitro cell studies and rodent models. Animal studies have suggested potential anti-inflammatory and glucose-regulating effects, with one murine study observing reduced fasting blood glucose at doses of approximately 20–40 mg/kg body weight. No large-scale randomized controlled trials in humans have been completed specifically isolating cinnamic acid as an intervention. The current body of evidence is preliminary and insufficient to establish clinical efficacy or therapeutic dosing guidelines for human supplementation.

Nutritional Profile

Cinnamic acid (C9H8O2, molecular weight 148.16 g/mol) is a naturally occurring aromatic carboxylic acid and phenylpropanoid compound, not a macronutrient or direct dietary supplement in isolated form. It contains no protein, fat, fiber, or caloric macronutrient value in typical exposure quantities. As a bioactive phytochemical, it is found in cinnamon bark at approximately 1–5 mg/g dry weight, in balsam of Peru, shea butter, and various fruits and vegetables at trace concentrations (typically 0.1–10 mg/kg fresh weight). It exists in two geometric isomers: trans-cinnamic acid (more common, biologically active form) and cis-cinnamic acid. Bioactive compound class: hydroxycinnamic acid precursor and phenylpropanoid backbone. It is a direct precursor to numerous bioactive derivatives including p-coumaric acid, caffeic acid, ferulic acid, and chlorogenic acid via the shikimate/phenylpropanoid pathway. Estimated dietary intake from natural food sources is approximately 0.5–50 mg/day depending on diet richness in spices and plant foods. Bioavailability: absorbed in the small intestine via passive diffusion; rapidly metabolized via beta-oxidation to benzoic acid and subsequently excreted as hippuric acid in urine. Plasma half-life is short (estimated 1–3 hours). No established RDA or DRI exists. Vitamins and minerals: none inherent to this compound itself.

Preparation & Dosage

The research provided does not specify clinically studied dosage ranges for cinnamic acid. Consult a healthcare provider before starting any new supplement.

Synergy & Pairings

Cinnamon extract, shea butter, phenylalanine, benzene, ethanol

Safety & Interactions

Cinnamic acid is generally recognized as safe (GRAS) by the FDA when consumed in food-level amounts used as a flavoring agent, and it is well tolerated in typical dietary exposures. High-dose supplemental intake has not been rigorously studied in humans, and dermal application of cinnamate esters has been associated with contact dermatitis in sensitive individuals. Cinnamic acid may theoretically interact with cytochrome P450 enzymes, potentially altering metabolism of co-administered drugs, though clinical drug interaction data are absent. Pregnant and breastfeeding women should avoid supplemental doses beyond normal dietary intake due to insufficient safety data.