Associations of n-6 and n-3 polyunsaturated fatty acids and tocopherols with proxies of membrane stability and subcutaneous fat sites in male elite swimmers

Nutr Res. 2009 Sep;29(9):623-30. doi: 10.1016/j.nutres.2009.08.005.


We hypothesize that membrane stability of elite swimmers adapted to chronic intense training is dependent on polyunsaturated fatty acids (PUFAs) and tocopherols in blood pools and that the composition of PUFA in plasma nonesterified fatty acids (NEFAs) might be associated with specific subcutaneous fat sites. Our aims were to investigate in male elite swimmers the associations of n-6 and n-3 PUFA and alpha- and gamma-tocopherols with proxies of membrane stability (phase angle and erythrocyte osmotic fragility) and of PUFA in plasma NEFA with specific skinfolds. Brazilian male elite swimmers (n = 20) under regular training for an average of 4.1 h/d and 6.1 d/wk took part in the study. Blood samples were obtained once after 18-hour rest and an overnight fast. Fatty acids were determined in plasma NEFA and erythrocytes by gas chromatolography and tocopherols were determined in plasma and erythrocytes by high-performance liquid chromatography. The status of PUFA was assessed as mean melting point, PUFA index [(Sigman-6 + Sigman-3) / (Sigman-7 + Sigman-9)] and docosahexaenoic acid indices (22:5n-6/22:4n-6 and 22:6n-3/22:5n-6 ratios) calculated from erythrocyte fatty acids. Phase angle was associated with an index of docosahexaenoic acid inadequacy (22:5n-6/22:4n-6; r = -0.53, P = .019) and with 22:5n-3 in erythrocytes (r = 0.51, P = .024), and erythrocyte osmotic fragility was associated with plasma alpha-tocopherol (r = -0.51, P = .05), which is a biomarker of vitamin E status. Plasma NEFAs 18:3n-3 and 20:4n-6 were positively associated with skinfolds of the trunk and arms (r = 0.49-0.59, P = .011-.043). The data presented indicate that n-3 PUFA and vitamin E states possibly improve membrane stability in elite swimmers and that the extent of specific anatomic sites of subcutaneous adipose tissue in the upper body might contribute to the composition of NEFA in the resting state.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Athletes
  • Cross-Sectional Studies
  • Electric Impedance
  • Erythrocyte Membrane / metabolism*
  • Exercise / physiology*
  • Fatty Acids / blood*
  • Fatty Acids, Nonesterified / blood
  • Fatty Acids, Nonesterified / chemistry
  • Fatty Acids, Omega-6 / blood
  • Humans
  • Male
  • Osmosis
  • Physical Exertion / physiology*
  • Skinfold Thickness
  • Subcutaneous Fat* / metabolism
  • Swimming / physiology*
  • Vitamin E / blood*
  • Young Adult
  • alpha-Tocopherol / blood
  • gamma-Tocopherol / blood


  • Fatty Acids
  • Fatty Acids, Nonesterified
  • Fatty Acids, Omega-6
  • Vitamin E
  • gamma-Tocopherol
  • alpha-Tocopherol