Genetic background has an effect on the metabolism of the essential polyunsaturated fatty acids alpha-linolenic acid and linoleic acid, according to a recent study from the University of Eastern Finland.
Supplementing the diet with camelina oil rich in alpha-linolenic acid, or sunflower oil rich in linoleic acid changed the concentrations of the metabolites of these fatty acids in the body; however, the changes depended on the study participants FADS1 genotype. The research was carried out among carriers of two different FADS1 genotypes.
“Camelina oil increased the plasma concentration of eicosapentaenoic acid produced from alpha-linolenic acid in only one of the genotypes studied,” said researcher and first author Topi Meuronen of the University of Eastern Finland.
Both diet and genes appear to have an effect on the concentrations of various fatty acids in the body. The FADS1 gene regulates the metabolism of polyunsaturated fatty acids, and the FADS1 genotype has previously been associated with disorders of glucose and fat metabolism and with the risk of type 2 diabetes.
Linoleic acid and alpha-linolenic acid are essential fatty acids that are not produced by the human body, ie they must be obtained from food. Linoleic acid is the most abundant dietary fatty acid in the omega-6 family. Alpha-linolenic acid, on the other hand, belongs to the family of omega-3 fatty acids. Varying concentrations of both are found in vegetable oils, seeds and nuts. Of vegetable oils, sunflower oil is particularly rich in linoleic acid. Camelina oil and linseed oil, on the other hand, are rich in alpha-linolenic acid.
A high intake and plasma concentration of linoleic acid has been associated with, for example, a lower risk of type 2 diabetes and cardiovascular disease, but the association with alpha-linolenic acid remains unclear. As metabolites of linoleic acid and alpha-linolenic acid, the body produces lipid mediators that are important, but some of which are also pro-inflammatory.
In the new study, the researchers examined whether rs174550 point mutations in the FADS1 gene modify the effect of alpha-linolenic acid and linoleic acid on the composition of fatty acids in plasma and the concentrations of lipid mediators derived from polyunsaturated fatty acids. Carriers of two different FADS1 genotypes were recruited from men enrolled in the Metabolic Syndrome in Men study, METSIM. They supplemented their diet with 30-50 ml of camelina oil or sunflower oil daily for eight weeks.
Our research design, i.e. recruiting subjects based on their genetic background, has proven to be effective in investigating the interactions between diet and genes.”
Maria Lankinen, Postdoctoral Researcher, University of Eastern Finland
For example, the body can produce eicosapentaenoic acid from alpha-linolenic acid and arachidonic acid from linoleic acid. These long-chain fatty acids and the lipid mediators produced from them are involved in many functions in the body, such as the inflammatory response and vascular function.
The investigation showed that the FADS1 for example, genotype plays a large role in how efficiently essential fatty acids are converted to arachidonic acid and eicosapentaenoic acid. The FADS1 genotype also influenced the concentrations of metabolites derived from it.
The use of camelina oil rich in alpha-linolenic acid increased the concentration of eicosapentaenoic acid and lipid mediators derived from it in only one of the genotypes studied. In contrast, the use of sunflower oil rich in linoleic acid did not increase the concentration of arachidonic acid or its derivative lipid mediators in carriers of either genotype.
“The changes we observed in the plasma concentration of eicosapentaenoic acid were at the same level as in our previous study, where people ate fatty fish containing eicosapentaenoic acid. However, an interesting observation is that when camelina oil was used, the changes only occurred in one of the genotypes studied,” says Meuronen.
According to the researchers, the results give cause to consider whether it is possible to provide increasingly individualized guidelines for the intake of alpha-linolenic acid and linoleic acid. However, further research is needed.
The research was carried out in collaboration with the Karolinska Institutet and the findings have been published in Molecular nutrition and nutrition research.
Meurons, T., et al. (2022) The FADS1 rs174550 genotype modifies the n-3 and n-6 PUFA and lipid mediator responses to diets high in alpha-linolenic acid and high in linoleic acid. Molecular nutrition and nutrition research. doi.org/10.1002/mnfr.202200351.