CIENCIASMEDICASNEWS: A Link Between Omega-6 and Chronic Disease—Does Ancestry Play a Role? [NCCAM Research Results]

jueves, 7 de julio de 2011

A Link Between Omega-6 and Chronic Disease—Does Ancestry Play a Role? [NCCAM Research Results]

A Link Between Omega-6 and Chronic Disease—Does Ancestry Play a Role? [NCCAM Research Results]: "A Link Between Omega-6 and Chronic Disease—Does Ancestry Play a Role?

A population's ancestral background may affect how omega-6 fatty acids are processed and used by the body, according to a 2011 study funded in part by NCCAM. Omega-6 fatty acids—also known as n-6 polyunsaturated fatty acids (PUFAs)—are important for maintaining proper cellular function in the human body and, in particular, play a role in immunity and inflammation. Omega-6 fatty acids, found in foods such as margarine and vegetable oils, differ from omega-3 fatty acids, which are found in fatty fish.

Researchers at Wake Forest University, The Johns Hopkins University, and The University of Chicago studied DNA and blood samples in African Americans and European Americans to see if human ancestry affects how omega-6 fatty acids are metabolized in the body. The researchers showed that a segment of DNA, known as a fatty acid desaturase (FADS) cluster, is responsible for the efficient conversion of dietary medium chain omega-6 fatty acids to long chain omega-6 fatty acids, such as arachidonic acid, which then have the potential to increase inflammation in the body. The researchers found that African Americans may have higher levels of arachidonic acid in their blood due to a genetic variation in the FADS cluster, which is much more prevalent among populations of African descent than European descent. This study builds on previous research that has shown that genetic variations may be associated with an increase of arachidonic acid in the blood, as well as inflammation and other inflammatory disorders.

The researchers concluded that this genetic difference, in addition to a diet that is high in medium chain omega-6 fatty acids, may contribute to the chronic diseases prevalent within the African American population. Further studies are necessary to better understand the genetics that influence omega-6 fatty acid pathways. The results of this study emphasize the importance of tailoring dietary recommendations to a specific population.
Reference

* Mathias RA, Sergeant S, Ruczinski I, et al. The impact of FADS genetic variants on omega-6 polyunsaturated fatty acid metabolism in African Americans. BMC Genetics. 2011;12(1):50.

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BMC Genet. 2011 May 20;12:50.
The impact of FADS genetic variants on ω6 polyunsaturated fatty acid metabolism in African Americans.
Mathias RA, Sergeant S, Ruczinski I, Torgerson DG, Hugenschmidt CE, Kubala M, Vaidya D, Suktitipat B, Ziegler JT, Ivester P, Case D, Yanek LR, Freedman BI, Rudock ME, Barnes KC, Langefeld CD, Becker LC, Bowden DW, Becker DM, Chilton FH.
Source

Division of General Internal Medicine, Department of Medicine, The GeneSTAR Research Program, The Johns Hopkins University, 1830 E, Monument St,, Baltimore, MD 21224, USA. rmathias@jhmi.edu.

Abstract

ABSTRACT:
BACKGROUND:
Arachidonic acid (AA) is a long-chain omega-6 polyunsaturated fatty acid (PUFA) synthesized from the precursor dihomo-gamma-linolenic acid (DGLA) that plays a vital role in immunity and inflammation. Variants in the Fatty Acid Desaturase (FADS) family of genes on chromosome 11q have been shown to play a role in PUFA metabolism in populations of European and Asian ancestry; no work has been done in populations of African ancestry to date.

RESULTS:
In this study, we report that African Americans have significantly higher circulating levels of plasma AA (p = 1.35 × 10-48) and lower DGLA levels (p = 9.80 × 10-11) than European Americans. Tests for association in N = 329 individuals across 80 nucleotide polymorphisms (SNPs) in the Fatty Acid Desaturase (FADS) locus revealed significant association with AA, DGLA and the AA/DGLA ratio, a measure of enzymatic efficiency, in both racial groups (peak signal p = 2.85 × 10-16 in African Americans, 2.68 × 10-23 in European Americans). Ancestry-related differences were observed at an upstream marker previously associated with AA levels (rs174537), wherein, 79-82% of African Americans carry two copies of the G allele compared to only 42-45% of European Americans. Importantly, the allelic effect of the G allele, which is associated with enhanced conversion of DGLA to AA, on enzymatic efficiency was similar in both groups.

CONCLUSIONS:
We conclude that the impact of FADS genetic variants on PUFA metabolism, specifically AA levels, is likely more pronounced in African Americans due to the larger proportion of individuals carrying the genotype associated with increased FADS1 enzymatic conversion of DGLA to AA.