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Keywords:

  • Desaturase;
  • Eating disorder;
  • PUFA ;
  • Triiodothyronine

Abstract

Aim

In starvation, there is down-regulation of metabolism and changes in essential fatty acid (FA) status, which could be related to alterations of desaturase activities. Presently, the relationship between thyroid hormones and desaturase activities has been investigated in adolescents with eating disorders and weight loss.

Methods

Serum triiodothyronine concentrations and proportions of polyunsaturated FA in plasma phospholipids were analysed in blood samples from 227 adolescents with ED. Δ6-desaturase (D6D) activity was calculated as the FA ratio 20:3ω6/18:2ω6 and Δ5-desaturase (D5D) activity as the ratio 20:4ω6/20:3ω6.

Results

Serum triiodothyronine concentrations were related to leanness and ongoing weight loss. The estimated D6D activity was positively correlated with serum triiodothyronine (R2 = 0.232; p < 0.001). D5D activity exhibited a strong inverse correlation with serum triiodothyronine (R2 = 0.410; p < 0.001).

Conclusion

Changes in desaturase activities during starvation cannot be explained by inhibition/disinhibition by essential FA only. It is possible that the effects of starvation on these enzyme activities, and hence on essential FA status, are mediated by triiodothyronine.