Trans-palmitoleic acid (trans-C16:1 n-7), a dairy fat biomarker, and metabolic syndrome components: a study on C57BL/6N mice

Trans-palmitoleic acid (trans-C16:1 n-7, TPA) is commonly found in dairy products. Previous epidemiological work associated TPA with lower risk of metabolic syndrome. To date however, no nutritional study exists to verify such hypothesis, mostly due to the low availability of TPA. Tackling the TPA availability issue, this work aimed at assessing for the first time the nutritional impact of TPA in straight relationship with metabolic syndrome. TPA was chemically synthesized starting from its cis isomer and purified by Flash HPLC. C57BL/6N mice were taken at 5 weeks of age and fed with a high-fat high-sucrose diet for 7 weeks to induce metabolic syndrome, while being TPA-supplemented (4% of total energy). A negative control (i.e., without disorders) and a positive one (supplementation with palmitic acid, C16:0) were also used. Approximately 70 g of 99%-purity TPA were obtained. TPA and its metabolites (e.g., trans-vaccenic acid) were found in the liver, red blood cells, muscle and adipose tissue (visceral and subcutaneous) of mice fed with TPA. Compared with the positive control, TPA supplementation reduced adipose tissue weights and adipocyte size, in both visceral and subcutaneous fat; these parameters did not differ with the negative control. Free fatty acids levels with TPA supplementation also differed with that of positive control but did not with the negative one. Our first results support beneficial effects of TPA, that might act on adipose tissue. Other parameters such as insulin or leptin are to be measured soon, to enable further statements about TPA and metabolic syndrome.