Essential fatty acid status in teenage girls with eating disorders and weight loss.

AIM: To explore the relationship between essential fatty acids (FA) and weight changes in adolescent girls with eating disorders (ED). METHODS: Blood samples were obtained from 220 girls with ED and 39 healthy controls. The girls with ED were 15.3 ± 1.5 years of age and weighed 49.8 ± 8.7 kg (BMI 18.3 ± 2.8 kg/m(2)) after a weight loss of 6.8 ± 6.4 kg. FA were analysed in plasma phospholipids (PPL) and erythrocyte membranes (ERY). RESULTS: The proportions of saturated and monounsaturated FA were increased during weight loss, while linoleic acid (18:2ω6) was decreased. The proportions of eicosapentanoic acid (EPA) (20:5ω3) and docosahexanoic acid (DHA) (22:6ω3) in PPL and ERY did not differ from controls. The activity of stearoyl-CoA-desaturase was increased as evidenced by an increased product/precursor ratio and correlated with the rate of weight loss. The activities of delta-6-desaturase and delta-5-desaturase did not differ from controls. The rate of weight loss was inversely correlated with delta-6-desaturase and directly correlated with delta-5-desaturase. CONCLUSION: The FA profile indicates low-fat intake, fat mobilization from stores and an increased conversion of essential FA at the delta-5-desaturase step during weight loss in adolescent girls with ED. Normal levels of EPA and DHA were maintained.

Desaturation and elongation of Fatty acids and insulin action.

Insulin resistance is characterized by specific changes of the composition of fatty acids in the serum lipids and in the skeletal muscle membranes. Impaired insulin sensitivity is associated with high proportions of palmitic (16:0) acid and low levels of linoleic (18:2 n-6) acid in serum. In addition, there are apparent changes of the fatty acid desaturase activities, suggesting an increased activity of the Delta9 and Delta6 desaturases and a decreased activity of the Delta5 desaturase. The activity of the fatty acid desaturases is regulated by long-chain polyunsaturated fatty acids and insulin and is probably also dependent on the degree of physical activity. A high ratio between arachidonic (20:4 n-6) and dihomo-gamma linolenic (20:3 n-6) acid, as a measure of Delta5 desaturase activity, in the skeletal muscle phospholipids has been related to good insulin sensitivity. Available knowledge seems to indicate that the degree of saturation of the body lipids, and especially the proportion of palmitic acid in the lipid membranes, may be critical for insulin sensitivity. The strong relationships between the Delta5 desaturase activity, a high content of long-chain polyunsaturated fatty acids in the skeletal muscle, and insulin sensitivity may be due to parallel effects of diet and/or physical activity on the fatty acid composition and on insulin sensitivity.

Effects of dietary phenolic compounds on tocopherol, cholesterol, and fatty acids in rats.

The effects of the phenolic compounds butylated hydroxytoluene (BHT), sesamin (S), curcumin (CU), and ferulic acid (FA) on plasma, liver, and lung concentrations of alpha- and gamma-tocopherols (T), on plasma and liver cholesterol, and on the fatty acid composition of liver lipids were studied in male Sprague-Dawley rats. Test compounds were given to rats ad libitum for 4 wk at 4 g/kg diet, in a diet low but adequate in vitamin E (36 mg/kg of gamma-T and 25 mg/kg of alpha-T) and containing 2 g/kg of cholesterol. BHT significantly reduced feed intake (P < 0.05) and body weight and increased feed conversion ratio; S and BHT caused a significant enlargement of the liver (P < 0.001), whereas CU and FA did not affect any of these parameters. The amount of liver lipids was significantly lowered by BHT (P < 0.01) while the other substances reduced liver lipid concentrations but not significantly. Regarding effects on tocopherol levels, (i) feeding of BHT resulted in a significant elevation (P< 0.001) of alpha-T in plasma, liver, and lung, while gamma-T values remained unchanged; (ii) rats provided with the S diet had substantially higher gamma-T levels (P < 0.001) in plasma, liver, and lung, whereas alpha-T levels were not affected; (iii) administration of CU raised the concentration of alpha-T in the lung (P < 0.01) but did not affect the plasma or liver values of any of the tocopherols; and (iv) FA had no effect on the levels of either homolog in the plasma, liver, or lung. The level of an unknown substance in the liver was significantly reduced by dietary BHT (P < 0.001). BHT was the only compound that tended to increase total cholesterol (TC) in plasma, due to an elevation of cholesterol in the very low density lipoprotein + low density lipoprotein (VLDL + LDL) fraction. S and FA tended to lower plasma total and VLDL + LDL cholesterol concentrations, but the effect for CU was statistically significant (P < 0.05). FA increased plasma high density lipoprotein cholesterol while the other compounds reduced it numerically, but not significantly. BHT, CU, and S reduced cholesterol levels in the liver TC (P < 0.001) and percentages of TC in liver lipids (P < 0.05). With regard to the fatty acid composition of liver lipids, S increased the n-6/n-3 and the 18:3/20:5 polyunsaturated fatty acids (PUFA) ratios, and BHT lowered total monounsaturated fatty acids and increased total PUFA (n-6 + n-3). The effects of CU and FA on fatty acids were not highly significant. These results suggest some in vivo interactions between these phenolic compounds and tocopherols that may increase the bioavailability of vitamin E and decrease cholesterol in rats.

Serum alpha tocopherol concentrations and cholesterol ester fatty acid composition in 70-year-old men reflect those 20 years earlier.

OBJECTIVE: It has been suggested that low serum alpha tocopherol concentrations and a low proportion of polyunsaturated fatty acids in the serum cholesterol esters may be associated with a high risk of developing coronary heart disease. DESIGN AND SUBJECTS: In this study the intraindividual reproducibility (biological 'tracking') of these variables was studied in 855 men at the ages of 50 and 70 years. RESULTS: The lipid adjusted tocopherol concentration was positively correlated (r = 0.28, P < 0.0001) between 50 and 70 years of age. Also the proportions of the serum cholesterol ester fatty acids were positively correlated between the same ages with r = 0.31 (P < 0.0001) for palmitic, r = 0.45 (P < 0.0001) for linoleic, and r = 0.58 (P < 0.0001) for arachidonic acid. The body weights of the men at 50 and 70 years of age were strongly correlated (r = 0.78, P < 0.0001). CONCLUSIONS: The tocopherol concentrations and the fatty acid composition are related to vitamin intake and to the dietary fat quality, respectively, and may be useful markers in prospective studies of diseases and of development of diseases. The correlations between the proportions of fatty acids and the body weights, respectively at the ages of 50 and 70 indicate, that changes in diet and body weight in men are probably relatively limited between these years.

Insulin sensitivity is related to the fatty acid composition of serum lipids and skeletal muscle phospholipids in 70-year-old men.

Recent data indicate that peripheral insulin sensitivity may be influenced by dietary fat quality and skeletal muscle phospholipid fatty acid composition. During a health survey of 70-year-old men insulin sensitivity was measured by the euglycaemic hyperinsulinaemic clamp technique and the fatty acid composition of the serum cholesterol esters was determined (n = 215) by gas liquid chromatography. In a subsample the fatty acids of the skeletal muscle phospholipids and triglycerides were determined after fine needle biopsy from m. vastus lateralis (n = 39). The peripheral insulin sensitivity was significantly and negatively correlated to the proportion of palmitic (r = -0.31, p < 0.001), palmitoleic (r = -0.25, p < 0.001) and di-homo-gamma-linolenic (r = -0.33, p < 0.001) acids and positively to the content of linoleic (r = 0.28, p < 0.001) acid in the serum cholesterol esters. There was an even stronger negative relationship to the proportion of palmitic acid in the skeletal muscle phospholipds (r = -0.45, p < 0.004). The fatty acid composition was also significantly related to insulin sensitivity in a stepwise multiple regression analysis in the presence of other clinical variables, which were associated with insulin action in univariate analysis. Thus, more than 51% of the variation of the insulin sensitivity was explained by an equation containing body mass index, serum triglyceride concentration and the content of palmitic acid in the skeletal muscle phospholipids. It is concluded that the fatty acid composition in serum and of the phospholipids of skeletal muscle may influence insulin action in elderly men.

Malondialdehyde concentration in plasma is inversely correlated to the proportion of linoleic acid in serum lipoprotein lipids.

It has been suggested that the susceptibility of low density lipoprotein (LDL) to oxidative stress depends on the balance between its contents of polyunsaturated fatty acids and antioxidants. In a healthy reference population (n = 103), the plasma concentration of malondialdehyde (MDA) (mean 0.86, range 0.50-1.27 mumol/l) was positively correlated to the serum concentrations of LDL cholesterol (r = 0.31, P = 0.001), very low density lipoprotein triglycerides (r = 0.25, P = 0.009) and apolipoprotein B (r = 0.23, P = 0.03), and negatively correlated to lipid corrected alpha tocopherol in serum (r = -0.22, P = 0.02) and lipoprotein(a) (Lp(a)) (r = -0.26, P = 0.01). Plasma MDA was negatively correlated to the content of linoleic acid in the serum lipoprotein phospholipids (r = -0.35, P = 0.0008). In a stepwise regression analysis 12% of the variation in plasma MDA was explained by variations in the content of linoleic acid and 27% after addition of Lp(a) and abdominal sagittal diameter. The significant negative relation between plasma MDA and the amount of linoleic acid in the lipoprotein lipids indicates that other factors, e.g. the availability of anti-oxidants and the lipoprotein metabolism, may be of greater importance for intravascular lipid peroxidation than the proportion of polyunsaturated fatty acids in the lipoprotein lipids.

Tocopherol concentrations in adipose tissue. Relationships of tocopherol concentrations and fatty acid composition in serum in a reference population of Swedish men and women.

The tocopherol concentrations in serum and adipose tissue were studied in relation to the fatty acid composition and clinical characteristics in 110 subjects. The tocopherol concentrations in adipose tissue showed large interindividual variations and were positively correlated to those in serum (r = 0.24-0.31, P < 0.01) but did not increase with age. The ratio between alpha- and gamma-tocopherol in adipose tissue was only about half of that in serum. In serum, but not in adipose tissue, the alpha-tocopherol and linoleic acid concentrations were positively correlated. Serum apolipoprotein B was inversely correlated to lipid-corrected serum alpha-tocopherol (r = -0.22, P = 0.03), indicating decreasing oxidative protection with increasing blood lipids. Measurement of the serum tocopherol concentration in addition to that of the serum lipoprotein concentration may be of value in estimating the risk for coronary heart disease. Whether measurement of the tocopherol concentration in adipose tissue has any advantage over that in serum remains to be determined.

Lower tocopherol serum levels in subjects with abdominal adiposity.

OBJECTIVES: Peroxidation of lipoproteins may be of critical importance in the development of atherosclerosis. Tocopherol is considered to be the most effective lipid-soluble antioxidant. The main aim of this study was to measure the serum tocopherol concentrations in a Swedish reference population and to relate them to family history, lifestyle and serum lipoprotein composition. DESIGN: A health survey of risk factors for coronary heart disease was carried out among the employees of a Swedish company. SUBJECTS: Ninety per cent (906) of the employees participated. RESULTS: Mean alpha, beta and gamma tocopherol levels corrected for lipids were 1.57 (SD 0.24), 0.04 (SD 0.01) and 0.20 (SD 0.07) microgram ml-1, respectively. Alpha tocopherol levels were slightly higher in women than in men, but there was no difference between different ages. Smokers had a lower alpha tocopherol level than non-smokers (1.54 and 1.59 micrograms ml-1; P = 0.03) and persons with low physical activity had a lower level than those with high activity (1.53 and 1.62 micrograms ml-1, respectively; P = 0.0002). Alpha tocopherol concentration was inversely correlated to abdominal sagittal diameter (r = -0.24, P = 0.0001). CONCLUSIONS: The average tocopherol concentrations in this Swedish population were higher than in countries with a high incidence of coronary heart disease but similar to those in countries with a similar, intermediate incidence. The inverse correlation to abdominal adiposity may partly explain why this adiposity is a risk factor for coronary heart disease.