Genes may influence plasma lipid profiles in an ethnic-specific manner

By Joshua Gauci
SPARK

A new study has found evidence that genetic variations between different ethnic groups may influence fat metabolism.

These findings, published in Molecular Genetics and Metabolism, may help researchers to better understand differences in fat metabolism that could have a role in altering an individual’s risk for diseases such as heart disease.

The study was led by researchers from the University of Guelph in collaboration with colleagues at the University of Toronto. The DNA samples used in this study were collected from young Asian and Caucasian adults recruited in the Toronto Nutrigenomics and Health Study. The samples were examined to see if there was a relationship between a gene that modifies fat metabolism called fatty acid desaturase 1 (FADS1) and blood levels of polyunsaturated fatty acids.

david_mutch_final-photo by bruce sargent

Prof. David Mutch, and research student Kaitlin Roke are pictured with a DNA model, the focus of their study on fat metabolism and heart disease. Photo By: Bruce Sargent, SPARK

“Now we have found that genetics can affect differences in lipid metabolism between ethnicities,” says Prof. David Mutch, a nutrigenomics professor at the University of Guelph involved in the study. “This begs the question: does the genetic control of lipid metabolism underlie some of the ethnic-specific risks in cardiovascular disease?”

The researchers found that a common genetic variation in the FADS1 gene significantly altered the activity of the corresponding fat modifying enzyme that it produces, delta-5-desaturase (D5D). The “T” version of FADS1 made a more active form of D5D and was the most common form in Caucasians. The “C” version was less active and the most common form in Asian participants.

D5D can act on both omega-6 and omega-3 essential polyunsaturated fats from our diets. When D5D acts on omega-6 fats, from sources such as vegetable oils, it forms arachidonic acid (AA). The increased D5D activity in individuals with the T form of FADS1 means that they are better at converting omega-6 fats into AA.

This may have a relation to heart disease, because one of AA’s roles within the body is in the formation of eicosanoid compounds. High levels of eicosanoids promote inflammation reactions that may increase heart disease risk.

Mutch calls these results significant. “Typically, the impact of any one genetic variation on disease risk is small,” he says. “Anything that increases variability in risk factors above one per cent is huge, because heart disease risk is multi-factorial and is influenced by hundreds of genes, in addition to lifestyle and diet.”

Western diets tend to contain a greater amount of omega-6 fats than omega-3 fats. Eicosanoids can also be formed after D5D acts on omega-3 fats, however eicosanoids produced from omega-3 fats are believed to be much less inflammatory.

This research was completed with support from the Advanced Food and Materials Network, the Ontario Ministry of Agriculture, Food and Rural Affairs, the Canada Foundation for Innovation and the Public Health Agency of Canada.

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