Short- and medium-chain fatty acids (SCFAs and MCFAs)

This assay determines the concentrations of short-chain (SCFA) (2-5 carbons) and medium-chain (MCFA) (6-12 carbons) fatty acids, along with crucial ketone bodies. SCFAs and MCFAs are vital in maintaining gut health and contribute significantly to overall human well-being. SCFAs, derived from fiber fermentation, support colon health, immune function, and metabolic regulation. MCFAs, absorbed directly for quick energy, also aid in antimicrobial defense and metabolic efficiency.

About SCFAs

Gut bacteria produce short-chain fatty acids (SCFAs) during fiber fermentation. The most common SCFAs are acetate, propionate, and butyrate. They play a crucial role in human health by serving as an energy source for colon cells, maintaining the integrity of the gut barrier, and modulating inflammation and immune responses. SCFAs are linked to protective effects against diseases such as colorectal cancer, IBD, obesity, and type 2 diabetes, and they may also influence mood regulation and neurodegenerative conditions by reducing inflammation and oxidative stress.

About MCFAs

Medium-chain fatty acids (MCFAs) differ from SCFAs in their chain length (6-12 carbons) and are typically found in foods like coconut oil, palm kernel oil, and dairy products. Unlike long-chain fatty acids, MCFAs are absorbed directly from the small intestine and transported to the liver, rapidly metabolizing them for energy production. This process does not require bile salts, making MCFAs easier to digest. While the evidence is still in its early stages, there is growing interest in using MCFAs as a dietary intervention to support brain health and manage neurological conditions.

Concentration determination of SCFAs and MCFAs

The method utilizes high-resolution mass spectrometry (HRMS) using Orbitrap technology, coupled with ultra-high-performance liquid chromatography (UHPLC) to determine the concentrations of seven SCFAs (Acetic acid, Propionic acid, Isobutyric acid, Butyric acid, 2-methylbutyric acid, Isovaleric acid and Valeric acid), three MCFAs (Hexanoic acid, Octanoic acid, and Lauric acid), and three ketone bodies (3-hydroxybutyric acid, Acetoacetic acid, and 2-hydroxy butyric acid) in negative ionization.

Before analysis, the samples are derivatized with a derivatization agent that targets carboxylic acids for improved detection sensitivity and selectivity. The fatty acids are quantified using calibration curves and deuterated internal standards.

Simultaneously, lipid features are relatively quantified at high resolution (70,000 FWHM) in negative ionization.

Platform strengths

Incorporating deuterated standards and calibration curves allows for accurate concentration determination of SCFAs and MCFAs. The simultaneous relative quantification of lipid features of unknown identity allows for relative comparisons between samples. Collection of MS/MS data provides high confidence in lipid identification.

Example data

Serum: In a set of 120 samples, the concentrations of seven SCFAs, three MCFAs, and three ketone bodies were reported (no missing values).