Vaccenic acid

Vaccenic acid is a naturally occurring trans fatty acid and an omega-7 fatty acid. It is the predominant kind of trans-fatty acid found in human milk, in the fat of ruminants, and in dairy products such as milk, butter, and yogurt. Trans fat in human milk may depend on trans fat content in food.

Its IUPAC name is (11E)-11-octadecenoic acid, and its lipid shorthand name is 18:1 trans-11. The name was derived from the Latin vacca (cow).

Vaccenic acid was discovered in 1928 in animal fats and butter. Mammals convert it into rumenic acid, a conjugated linoleic acid, where it shows anticarcinogenic properties.

Its stereoisomer, cis-vaccenic acid, is found in Sea Buckthorn (Hippophae rhamnoides) oil. Its IUPAC name is (11Z)-11-octadecenoic acid, and its lipid shorthand name is 18:1 cis-11.

Cows milk had highest trans-vaccenic acid content in the first few days of the cows being milked, indicating that it is stockpiled similarly to omega-3 fatty acids.

Health
Two Canadian studies have shown that vaccenic acid could hold benefits over trans fats derived from vegetable shortenings, or a mixture of pork lard and soy fat, by lowering total LDL and triglyceride levels. A study by the US Department of Agriculture showed that vaccenic acid raises both HDL and LDL cholesterol, whereas industrial trans fats only raise LDL with no beneficial effect on HDL.

Obese rats fed a diet enriched with vaccenic acid for 16 weeks had a reduction in total cholesterol, LDL cholesterol and lower triglyceride levels, with an effect comparable to CLA. This effect was not seen in lean rats.

Vaccenic acid accumulates in the orbitofrontal cortex to a higher extent in patients with bipolar disorder and schizophrenia.

Oxidation of omega-7 unsaturated fatty acids on the skin surface, such as palmitoleic acid and vaccenic acid, may be the cause of the phenomenon commonly known as old person smell.

Alkaline phosphatase was inhibited 25% by vaccenic acid in osteoblasts.

A 2023 University of Chicago study found that trans-vaccenic acid enhances anti-tumor immunity by activating CD8+ T cells. This effect is accomplished by deactivating a GPR43 receptor, which activates the CREB pathway instead. The effect was produced with a diet containing 1% w/w TVA.