Factors influencing the biological status of polyunsaturated fatty acids (PUFA):
: The role of diet and fatty acid desaturase (FADS) genes

Student thesis: Doctoral Thesis


Polyunsaturated fatty acids (PUFA) are necessary for cell membrane structure and function, have a role in cognition and are important for the inflammatory response. PUFA are also essential during pregnancy for child development. The biological status of PUFA can be influenced by factors such as dietary intake and genetics. This thesis aims to (1) review current evidence relating to fatty acid desaturase (FADS) genotype and its influence on PUFA status and child health outcomes, (2) investigate associations between dietary patterns and maternal PUFA status, (3) examine the influence of maternal and child FADS genotype on cord blood PUFA status, and (4) investigate the effect of fish consumption on PUFA status in women of childbearing age while stratifying by FADS genotype.

A review of the literature within this thesis highlights the influence of FADS genotype on PUFA status during pregnancy and in children, breastmilk PUFA concentrations and child health outcomes.

The association between dietary intake and biological PUFA status of pregnant women in the Seychelles Child Development Study (SCDS), a high fish eating cohort, was investigated through dietary pattern analysis. Higher n-3 PUFA concentrations were associated with a dietary pattern high in fatty fish, fruit and vegetables, highlighting the importance of dietary intake for PUFA status.

In addition to dietary intake, FADS genotype influences PUFA status. Maternal and child FADS genotype were observed to have an impact on cord blood PUFA status in this high fish eating cohort, with the minor allele homozygous genotype in the mothers being associated with lower cord blood DHA and total n-3 concentrations, whereas in the children the heterozygous genotype was associated with lower AA concentrations.

Given the influence of diet and FADS genotype on PUFA status, a randomised control trial was completed in women of childbearing age to investigate the effect of fish consumption on PUFA status while stratifying by FADS genotype. Results from this intervention study indicate higher n-3 PUFA status at post intervention in those consuming two portions of fish per week compared to those consuming no fish or one portion per week. This finding demonstrates the importance of following current international guidelines to consume two portions of fish per week. The increase in n-3 PUFA status was more pronounced in FADS major allele homozygotes, suggesting carriers of the minor allele may need to consume a greater amount of fish to see a similar increase in PUFA status; however further research is needed to determine if this outcome is correct.

Overall, this thesis demonstrates the importance of dietary intake of PUFA from fish during pregnancy, and highlights that genetic variation in FADS also has an influence on PUFA status of cord blood and women of childbearing age. Given the importance of PUFA during pregnancy, future studies investigating PUFA status should consider FADS genotype.
Date of AwardJun 2019
Original languageEnglish
SupervisorEmeir Mc Sorley (Supervisor), Maria Mulhern (Supervisor), Alison Yeates (Supervisor) & Sean J.J. Strain (Supervisor)


  • Polyunsaturated fatty acids
  • Fatty acid desaturase
  • Pregnancy
  • Child development
  • Long-chain polyunsaturated fatty acids
  • Linoleic acid
  • a-linolenic acid
  • Arachidonic acid
  • Eicosapentaenoic acid
  • Docosahexaenoic acid

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