The influence of dietary fatty acids and antioxidant micronutrients on plasma, red blood cell and platelet fatty acids in healthy men and women

Neville, Marita (2012) The influence of dietary fatty acids and antioxidant micronutrients on plasma, red blood cell and platelet fatty acids in healthy men and women. Doctoral thesis, London Metropolitan University.


Cardiovascular disease rates (CVD) are high in the UK, particularly in men. National surveys report a dietary imbalance of fats and antioxidant micronutrients, which may adversely influence blood fatty acid profile and risk for CVD. We investigated relationships between saturated and unsaturated dietary fat, and antioxidant (retinol, alpha-tocopherol, beta-carotene, iron, zinc, selenium, magnesium and copper) intakes, and blood glucose, lipoproteins and cell membrane fatty acids in a homogenous group of educated, healthy Caucasian men and women. Volunteers (20 to 50 years, men 52, women 52) were recruited from staff and students of London Metropolitan University. Following correction for under-reporting 40 women and 31 men were included in the dietary analysis. Dietary intake, body composition, blood pressure, fasting blood glucose and lipids, and fatty acid composition of plasma and blood cell membranes (red blood cells, and platelets) were analysed. The men consumed more saturated fat (11.0 vs 9.8 %energy intake, p<0.05), and exhibited elevated glucose (5.41 vs 4.81 mmolll, p<0.001), systolic blood pressure (126.4 vs 112.0 mm/Hg, p<0.001), triglycerides (1.22 vs 0.98 mmolll, p<0.05), LDLcholesterol (2.90 vs 2.55 mmolll, p<0.05), LDL:HDL (2.09 vs 1.44, p<0.001) and lower HDL-cholesterol (1.47 vs 1.87 mmolll, p< 0.001) levels compared to the women, despite higher total body and trunk fat in the women (26.5 vs 15.6 %, and 23.3 vs 16.8 %, p<0.001 for both). In addition, the men consumed more zinc (11.7 vs 8.8 mg/d, p<0.001), and selenium (84 vs 54 jJg/d, p<0.01), while women consumed more beta-carotene (2.9 vs 2.3 mg/d, p<0.05), and vitamin C (138 vs 108 mg/d, p<0.05). In addition, gender comparisons of micronutrient densities demonstrated higher copper, magnesium, iron and vitamin E densities in the women's' diets, indicating more balanced nutritional intakes. Despite these findings no differences were found in plasma micronutrient levels (copper, iron, magnesium, retinol and alpha-tocopherol) between the men and women. Furthermore, despite similar total n-3 intakes, women displayed higher proportions of DHA in plasma (PC: 2.8 vs 3.2 area%, p<0.01), RBCs (PE: 7.8 vs 6.8 area%, p<0.01), and in platelets (PC: 1.19 vs 1.0S area%, p<O.OS; PE: 3.62 vs 3.21 area%, p<O.OS), and a greater DHA: DPAn-3 (PC: 1.91 vs 1.67 area%, <O.OS; PE: 1.1S vs 0.98 area%, p<O.OS) compared to the men, suggesting enhanced bioconversion rates in this age group of women. In addition, proportionally, lower total n-6 levels and n-6:n-3 fatty acids were found in the platelets of women (PC: 23.9 vs 2S.0 area%, p<0.01; 10.0 vs 11.7, p<0.05) providing further evidence for greater cardioprotection in these women of Child-bearing age. Further analysis suggested that in the women DHA levels appeared to be unrelated to dietary intake, while in contrast in the men, there appeared to be a greater reliance on pre-formed dietary intake, and LDI cholesterol was more responsive to the lowering effect of dietary n-6 fat (Beta -0.382, R2 0.214, p<0.01). In contrast, many associations were found between dietary antioxidants, in particular zinc, and plasma and RBC EPA and DHA levels especially in the women. The data of this study indicate gender-related differences in fat and micronutrient intakes, and associations with lipoproteins and blood fatty acids. Further research should investigate whether requirements for dietary LC-PUFAs particularly DHA differ for men and women.

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