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Long-chain omega fatty acids levels

Long-chain polyunsaturated fatty acids or LC-PUFAs are fatty acids that typically comprise 20 or more carbon and two or more double bonds that are divided into two groups: omega-3 and omega-6 depending on where the first double bond is placed in the molecule.

We can obtain polyunsaturated fatty acids from the diet as “essential fatty acids” that are precursors of the LC-PUFAs and contain 18 carbons.  We can find these in plant-derived foods as alpha-linolenic acid or ALA (18:3 n-3) and linoleic acid or LA (18:2 n-6) and our body must process both following two biosynthetic pathways to obtain LC-PUFAs omega-3 and omega-6 respectively.

On the other hand, we can obtain LC-PUFAs directly from seafood-derived products, especially cold-water fish, that are rich in long-chain omega-3 PUFAs as eicosapentaenoic acid or EPA (20:5 n-3) and docosahexaenoic acid or DHA (22:6 n-3). Processed omega-6 PUFAs are also present in animal products such as eggs and poultry.

LC-PUFAs serve to constitute other substances that have important roles in blood pressure and inflammatory responses, among other processes.

The key substrates LA and ALA are transformed by the same conversion enzymes, thus both biosynthetic pathways compete to produce long-chain omega-3 (EPA and DHA) and long-chain omega-6 (AA or arachidonic acid).

The modern western diet has dramatically changed in terms of the nutritional content of fats following the recommendations of replacing foods rich in saturated fatty acids with those rich in polyunsaturated fatty acids with the aim of reducing total serum cholesterol and LDL lipoproteins and, therefore, the risk of cardiovascular diseases. However, the modern diet is richer in fatty acids from soybean, corn, and canola oils, as well as in margarine and shortening that are rich in omega-6 and poor in omega-3. The increase in omega-6 consumption, in turn, translates into a greater inhibition of the production of omega-3 synthesized by our body that, if not compensated with the intake of omega-3, can have an impact on our health since it has been shown that long-chain omega-3 fatty acids have crucial roles in:

- Maintenance plasma membrane function. DHA is the most abundant fatty acid in complex lipids constituting approximately 50% of the weight of neurons membranes. Thus, it is important for neurotransmission, neurogenesis, and signal transduction affecting brain development and function.

- Energy production through the beta-oxidation process.

- Act as precursors of other metabolites that are present in practically of cells and organs of the body and participate in a wide variety of processes such as inflammation. These substances can have opposite effects, for example, AA derivates act as local hormones leading to acute and chronic inflammation while EPA, DPA, and DHA derived metabolites have anti-inflammatory properties.

World Health Organization recommends daily personal consumption of 0.5-1.0 g of EPA + DHA.

Recent studies have found polymorphisms in the FADS (fatty acid desaturase) gene cluster, which is strongly associated with our body capacity to convert the essential fatty acids LA and ALA into LC-PUFAs that can explain, in part, the inter-individual differences in blood and tissue PUFAs levels. It is suggested that these genetic variants may have an adaptative role in human populations that have moved to more vegetarian diets with a low intake of LC-PUFAs.

Gene or region studied

  • FADS1
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