Delta 9 desaturase index

metabolic

$$\frac{C18:1(\omega -9)}{C18:0+C18:1(\omega -9)}\text{\hspace{1em}(1, 2, 3)}$$

$$\frac{C16:1(\omega -7)+C18:1(\omega -9)}{C16:0+C18:0+C16:1(\omega -7)+C18:1(\omega -9)}\text{\hspace{1em}(3, 4)}$$

Note

There are different versions of this index calculation. The first version calculates only the conversion from $\mathrm{C}\text{18:0}$ to $\mathrm{C}\text{18:1}$, while the second calculates the total conversion of $\mathrm{C}\text{16:0}$ and $\mathrm{C}\text{18:0}$.

Abbreviations

• $\Delta 9$-DI

Description

Represents the estimated activity of the delta 9 desaturase enzyme (also known as stearoyl-CoA desaturase) in tissues, calculated using the product/substrate ratio approach. This enzyme catalyzes the introduction of a double bond at the delta-9 position of saturated fatty acids, primarily converting palmitic acid ($\mathrm{C}\text{16:0}$) and stearic acid ($\mathrm{C}\text{18:0}$) into their corresponding monounsaturated fatty acids, palmitoleic acid ($\mathrm{C}\text{16:1}(\omega \text{-}7)$) and oleic acid ($\mathrm{C}\text{18:1}(\omega \text{-}9)$).

This is a metabolic indicator used to evaluate the endogenous synthesis of monounsaturated fatty acids from saturated precursors. It is widely used in animal nutrition and meat/egg quality research to discriminate metabolic changes caused by dietary factors, genetics, age, or rearing systems. Like the elongase and thioesterase indices, it serves as a practical and cost-effective surrogate for measuring true desaturase enzyme activity in the laboratory.

References

1. Vessby et al., 2002
2. Zhang et al., 2007
3. Dal Bosco et al., 2022
4. Kralik et al., 2025