The FADS cluster comprising three genes (FADS1, FADS2, and FADS3) is essentially a single large expanse of high linkage disequilibrium (LD) in populations of European ancestry which explains the numerous single nucleotide polymorphisms (SNPs) in the literature that have been shown to have exceedingly strong effects on PUFA metabolism.
FADS2 encodes for a protein called D6D which is involved in plant-derived omega-6 conversion effectiveness.
The FADS2 gene controls the first and rate-limiting step in the pathway to convert LA into gamma-linoleic acid (GLA). FADS2 is also required for the endogenous synthesis of DHA from EPA and ALA.
There are 3 types of PUFAs: omega-3, omega-6, and omega-9. PUFAs play an important role in reproductive health. Omega-3 and omega-6 fatty acids are essential and need to be obtained from the diet.
Omega-3 consists primarily of:
• Eicosapentaenoic acid (EPA)
• Docosahexaenoic acid (DHA)
• Alpha-linolenic acid (ALA) - that can be converted into EPA and DHA
Omega-6 consists primarily of:
• Linoleic acid (LA)
• Gamma-linolenic acid (GLA) - that can be converted into arachidonic acid (AA)
Omega-3 synthesis is as follows and in this order:
1. The FADS2 gene converts alpha-linolenic acid (ALA) into stearidonic acid (SDA). Your FADS2 gene is inefficient.
2. The FADS1 gene converts SDA into eicosapentaenoic acid (EPA)
3. The FADS2 gene converts EPA into docosahexaenoic acid (DHA). Your FADS2 gene is inefficient.
Omega-6 synthesis is as follows and in this order:
1. The FADS2 converts linoleic acid (LA) into gamma-linolenic acid (GLA). Your FADS2 gene is inefficient.
2. The FADS1 converts GLA into arachidonic acid (AA)
The GG genotype is associated with slow FADS2 activity. This leads to less formation of GLA and DHA levels. The result has shown 29% poorer conversion of ALA to EPA and up to 56% less EPA with a given level of ALA.
• Increase dietary DHA.
• Increase dietary GLA.
• Increase choline intake.
• Reduce dietary intake of the precursor's ALA and LA.
Vegetarians need to obtain DHA in the form of supplementing with preformed DHA such as algal oil. Meat and seafood eaters have less need for increased FADS1 and FADS2 enzymes to get proper nutrition because their omega-3 and the omega-6 fatty acid conversion process is simpler and requires fewer steps. In short, it enables more effective conversion of omega fatty acids from plant-based fats to its functional forms like EPA and DHA.