Genetic background has an effect on the metabolism of 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 with sunflower oil rich in linoleic acid modifies the concentrations of the metabolites of these fatty acids in the body; however, the changes depended on the study participants FAS1 genotype. The study was conducted with wearers of two FAS1 genotypes.
“Camelina oil increased the plasma concentration of eicosapentaenoic acid produced from alpha-linolenic acid in only one of the genotypes studied,” says researcher and first author Topi Meuronen from the University of Eastern Finland.
Diet and genes have been shown to affect the levels of different fatty acids in the body. The FAS1 gene regulates the metabolism of polyunsaturated fatty acids, and the FAS1 The genotype has previously been associated with impaired glucose and lipid metabolism and the risk of type 2 diabetes.
Linoleic acid and alpha-linolenic acid are essential fatty acids that are not produced by the human body, i.e. they must be obtained from food. Linoleic acid is the most common 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. Among vegetable oils, sunflower oil is particularly rich in linoleic acid. Camelina oil and flaxseed oils, on the other hand, are rich in alpha-linolenic acid.
High intake and high plasma concentration of linoleic acid have been associated, for example, with a lower risk of type 2 diabetes and cardiovascular disease, but the association of alpha-linolenic acid remains unclear. As metabolites of linoleic acid and alpha-linolenic acid, the body produces lipid mediators which are important, but some of which are also pro-inflammatory.
In the new study, the researchers explored whether the rs174550 point mutations in the FAS1 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. Holders of two different FAS1 genotypes were recruited from men participating in the Metabolic Syndrome in Men Study, METSIM. They supplemented their diet with 30-50ml of camelina oil or sunflower oil daily for eight weeks.
Our research design, that is, recruiting subjects based on their genetic background, has proven effective in studying diet-gene interactions.
Maria Lankinen, postdoctoral researcher, University of Eastern Finland
The body can produce eicosapentaenoic acid from alpha-linolenic acid and arachidonic acid from linoleic acid, for example. These long-chain fatty acids and the lipid mediators produced from them are involved in many body functions, such as the inflammatory response and vascular function.
The study showed that the FAS1 Genotype plays a major role in, for example, the efficiency with which essential fatty acids are converted into arachidonic acid and eicosapentaenoic acid. The FAS1 genotype also affected 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, use of linoleic acid-rich sunflower oil did not increase the concentration of arachidonic acid or its derived lipid mediators in carriers of either genotype.
“The changes we observed in plasma eicosapentaenoic acid concentration 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 the oil camelina was used, the changes only occurred in one of the genotypes studied,” says Meuronen.
According to the researchers, the results raise questions about whether it is possible to give increasingly individualized recommendations on the intake of alpha-linolenic acid and linoleic acid. However, further research is needed.
The study was carried out in collaboration with the Karolinska Institutet, and the results have been published in Molecular nutrition and food research.
University of Eastern Finland
Meuronen, T. et al. (2022) The FADS1 rs174550 genotype alters the responses of n-3 and n-6 PUFAs and lipid mediators to a diet high in alpha-linolenic acid and linoleic acid. Molecular nutrition and food research. doi.org/10.1002/mnfr.202200351.
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