FADS1

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Fatty acid desaturase 1 (FADS1) is an enzyme which desaturates fatty acids by introducing double bonds into their structure, and is encoded for by the FADS1 gene.

Dietary fats typically fall into one of two categories, saturated and unsaturated 1. In saturated fats all the bonds between carbon atoms in the fatty acid chain are single, whereas in unsaturated fats some carbon atoms can be linked by double bonds. The science of this is discussed in more detail in the following post as the health impacts of saturated and unsaturated fats is an area of great debate.

Briefly, historical studies proposed that very high levels of saturated fat led to an increase in cholesterol levels, which congealed inside the blood vessels resulting in poor heart health, and so people were encouraged to transition away from saturated fats towards unsaturated fats 2. However, more recent studies have shown that the double bonds in unsaturated fats are susceptible to lipid peroxidation, which can generate harmful free-radicals, which can damage the lining of blood vessels 3.

The exact dietary implications of this conflicting research is unclear, although it is worth noting that the USDA Dietary Guidelines Advisory Committee in 2015 reversed their recommendation that people limit dietary cholesterol intake 4.

As one of the enzymes responsible for converting saturated fats in unsaturated equivalents, FADS1 is clearly of great interest. There is a single SNP associated with poor health outcomes, rs174547 or T61803311C.

T61803311C

Science Grade
B-
Heart Health
rsID Number Major Allele Minor Allele Minor Allele Frequency (%)
rs174547 t c 30

Risk Description

The SNP T61803311C or rs174547 is associated with altered lipid profiles with the ‘C’ allele being associated with reduced LDL cholesterol levels in individuals on a diet low in unsaturated fats 5. This correlated with an earlier study which showed that the largest effects related to this SNP were observed in those with a low unsaturated fat intake 6.

However, it is unclear what, if any, health effects are associated with this SNP as it remains unclear how exactly saturated and unsaturated fats impact health, as such it is not currently possible to provide specific nutrient guidelines.

Lifestyle Considerations:

Behavior Description
Observe lipid intake

It remains unclear how exactly saturated and unsaturated fat intake and the SNP T61803311C or rs174547 interact. As this area of research is under constant our understating is likely to improve rapidly. Therefore, while no current nutrient advice can be provided, it is worthwhile considering your lipid intake, and keeping this polymorphism in mind for later study.

Discuss this information with your doctor before taking any course of action.

Citations:
  1. https://www.ncbi.nlm.nih.gov/books/NBK22497/
  2. https://www.ncbi.nlm.nih.gov/pubmed/3776973
  3. https://www.ncbi.nlm.nih.gov/pubmed/21820297
  4. http://www.health.gov/dietaryguidelines/2015-scientific-report/PDFs/Scientific-Report-of-the-2015-Dietary-Guidelines-Advisory-Committee.pdf
  5. https://www.ncbi.nlm.nih.gov/pubmed/22451038
  6. https://www.ncbi.nlm.nih.gov/pubmed/20364269
  7. Kwong et al. 2019. Genetic profiling of fatty acid desaturase polymorphisms identifies patients who may benefit from high-dose omega-3 fatty acids in cardiac remodeling after acute myocardial infarction—Post-hoc analysis from the OMEGA-REMODEL randomized controlled trial. PLoS ONE, https://doi.org/10.1371/journal.pone.0222061
  8. Omega-3 Fatty Acids: Fact sheet for health professionals.
    National Institutes of Health Office of Dietary Supplements (https://ods.od.nih.gov/factsheets/Omega3FattyAcids-HealthProfessional/)
  9. Mathias RA, et al. 2014. Genetic Variants in the FADS Gene: Implications for Dietary Recommendations for Fatty Acid Intake. Curr Nutr Rep, 3(2): 1390148. https://doi:10.1007/s13668-014-0079-1

A61830500G

Science Grade
B+
Heart Health
rsID Number Major Allele Minor Allele Minor Allele Frequency (%)
rs1535 a g 31

Risk Description

This variant does not affect the composition of FADS1 and FADS2 proteins, but sits in the intron of the FADS2 gene. People with the GG phenotype for this variant have the lowest FADS2 activity, impacting the efficiency of fatty acid desaturation in their body. 7 The biological implications of this variation in generally healthy people remain unclear. However, a recent study 7 looked at the effects of high-dose Omega-3 fatty acid supplementation in patients recovering from a heart attack.

The authors found that a 6-month treatment had different effects on patients depending on their genotype at this variant. Patients with the GG genotype at rs1535 significantly benefited from Omega-3 supplementation, showing improved recovery of cardiac function compared with those carrying the same genotype but receiving placebo instead. In contrast, patients with the more prevalent AA or AG genotypes showed similar heart recovery irrespectively of whether or not they were given Omega-3.

It remains to be tested whether the carriers of the GG genotype (and not just those recovering from a heart attack) generally benefit more from Omega-3 supplementation. It should also be noted that Omega-3 was provided in very high doses to the patients in this study 7 (4 g/day, which is 2.5 times higher than the recommended daily amount. 8

Finally, even this finding came from a post-hoc analysis of a randomized control trial that had other endpoints. The patient cohort was also predominantly male and of the Caucasian race, whereas strong differences in fatty acid metabolism exist between people of African and European descent.  9 Therefore, this result needs to be replicated on a larger and more ethnically and gender-balanced independent cohort. However, since the role of FADS genes and genetic variants within them in polyunsaturated fatty acid metabolism is well-established 9, the preliminary findings implicating these genes in the differential benefits of Omega-3 supplementation 7 deserve some attention.

Discuss this information with your doctor before taking any course of action.

Citations:
  1. https://www.ncbi.nlm.nih.gov/books/NBK22497/
  2. https://www.ncbi.nlm.nih.gov/pubmed/3776973
  3. https://www.ncbi.nlm.nih.gov/pubmed/21820297
  4. http://www.health.gov/dietaryguidelines/2015-scientific-report/PDFs/Scientific-Report-of-the-2015-Dietary-Guidelines-Advisory-Committee.pdf
  5. https://www.ncbi.nlm.nih.gov/pubmed/22451038
  6. https://www.ncbi.nlm.nih.gov/pubmed/20364269
  7. Kwong et al. 2019. Genetic profiling of fatty acid desaturase polymorphisms identifies patients who may benefit from high-dose omega-3 fatty acids in cardiac remodeling after acute myocardial infarction—Post-hoc analysis from the OMEGA-REMODEL randomized controlled trial. PLoS ONE, https://doi.org/10.1371/journal.pone.0222061
  8. Omega-3 Fatty Acids: Fact sheet for health professionals.
    National Institutes of Health Office of Dietary Supplements (https://ods.od.nih.gov/factsheets/Omega3FattyAcids-HealthProfessional/)
  9. Mathias RA, et al. 2014. Genetic Variants in the FADS Gene: Implications for Dietary Recommendations for Fatty Acid Intake. Curr Nutr Rep, 3(2): 1390148. https://doi:10.1007/s13668-014-0079-1
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