Improved extraction of saturated fatty acids but not omega-3 fatty acids from sheep red blood cells using a one-step extraction procedure.

Several methods are available to extract total lipid and methylate fatty acids from a range of samples including red blood cells (RBC). Fatty acid analysis of human RBC can be undertaken using a two-step extraction and methylation or a combined one-step extraction and methylation procedure. The lipid composition of sheep RBC differs significantly from that of humans and may affect their extraction. The purpose of the current study was to examine the efficiency of extraction of lipid and detection of fatty acids from sheep RBC using a one-step procedure. Fatty acids were analysed using a one-step extraction and methylation procedure using methanol:toluene and acetyl chloride in comparison with a two-step procedure involving extraction of lipid using chloroform:methanol and separate methylation. Concentrations of saturated fatty acids including C16:0 and C18:0 were significantly higher (42.6 and 33.9 % respectively) following extraction using the one-step procedure compared with the two-step procedure. However, concentrations of some polyunsaturated fatty acids, including C20:5n-3 and C22:6n-3 were not significantly different between either procedure. The improved detection of fatty acids may be related to the ability of different solvents to extract different lipid fractions. The differential extraction of lipids and detection of fatty acids from sheep RBC may have important implications in studies examining the effect of dietary treatment on the possible health benefits of fatty acids.

Oxidized vitamin E and glutathione as markers of clinical status in asthma.

BACKGROUND & AIMS: Antioxidant status is disturbed in asthma. Measurement of both oxidized and reduced forms of antioxidants provides important information regarding the oxidant/antioxidant balance. The aim of this study was to investigate the clinical relevance of key antioxidants (alpha-tocopherol and glutathione) in asthma, by measuring the oxidized and reduced forms, in the airways (induced sputum) and systemically (peripheral blood). METHODS: This cross-sectional study examines stable asthmatics (n=44) and healthy controls (n=31) recruited through John Hunter Hospital, NSW, Australia. We collected peripheral blood and induced sputum during hypertonic saline challenge. Alpha-tocopherol and alpha-tocopherol quinone were measured by HPLC. Total glutathione and glutathione disulfide were determined by a colorimetric assay. RESULTS: Plasma alpha-tocopherol was low in asthma versus controls. Subjects with asthma had higher levels of whole blood alpha-tocopherol quinone and %alpha-tocopherol quinone than controls and %alpha-tocopherol quinone correlated with asthma control (p=0.009). Sputum supernatant levels of total, reduced and oxidized glutathione were elevated in asthma versus controls. Oxidized glutathione in sputum supernatant negatively correlated with FEV(1)/FVC% (p=0.029). CONCLUSIONS: In asthma, both systemic and airway antioxidant defences are disturbed. Oxidized forms of alpha-tocopherol and glutathione are associated with clinical asthma outcomes, and should be further investigated as a tool for monitoring asthma.

Macadamia nut consumption modulates favourably risk factors for coronary artery disease in hypercholesterolemic subjects.

Macadamia nuts are rich source of monounsaturated fats (oleic and palmitoleic acids) and contain polyphenol compounds, therefore, their consumption can be expected to impart health benefits to humans. This study was conducted to examine the effects of consuming macadamia nuts in hypercholesterolemic male individuals on plasma biomarkers of oxidative stress, coagulation and inflammation. Seventeen hypercholesterolemic male subjects were given macadamia nuts (40-90 g/day), equivalent to 15% energy intake, for a period of 4 weeks. As expected, monounsaturated fatty acids (16:1n-7, 18:1n-9 and 20:1n-9) were elevated in the plasma lipids of all volunteers following intervention with macadamia nuts. Plasma markers of inflammation (leukotriene, LTB(4)) and oxidative stress (8-isoprostane) were significantly lower (1,353 +/- 225 vs. 1,030 +/- 129 pg/mL and 876 +/- 97 vs. 679 +/- 116 pg/mL, respectively) within 4 weeks following macadamia nut intervention. There was a non-significant (23.6%) reduction in the plasma TXB(2)/PGI(2) ratio following macadamia nut consumption. This study demonstrates, for the first time, that short-term macadamia nut consumption modifies favourably the biomarkers of oxidative stress, thrombosis and inflammation, the risk factors for coronary artery disease, despite an increase in dietary fat intake. These data, combined with our previous results on cholesterol-lowering effects of macadamia nuts, suggest that regular consumption of macadamia nuts may play a role in the prevention of coronary artery disease.

Long-chain n-3 polyunsaturated fatty acid incorporation into human atrium following fish oil supplementation.

Recent studies have demonstrated that long-chain n-3 PUFA (LCn-3PUFA) are beneficial in reducing the risk of cardiac arrhythmias. This study was conducted to determine the extent of incorporation of LCn-3PUFA into human atrium following supplementation with a fish oil concentrate high in LCn-3PUFA. Volunteers preparing for coronary bypass surgery were randomized either to the treatment group (n = 8), receiving 6 g/d of fish oil concentrate (4.4 g of LCn-3PUFA), or the placebo group (n = 9), receiving 6 g/d of olive oil for a minimum period of 6 wk. Blood samples were collected prior to commencement of treatment, and preoperatively before bypass surgery. Atrial biopsies were obtained during surgery. The plasma and atrium samples were analyzed by GC following trans-methylation to determine FA profile. Post-supplementation, the treatment group had significantly higher plasma levels of 20:5n-3, 22:5n-3, and 22:6n-3 than the placebo group. Analysis of the atrium total lipids revealed a significant increase in the proportion of 20:5n-3 following fish oil supplementation. There was no significant difference in the concentration of 22:5n-3 and 22:6n-3 in the atrium total lipids; however, an upward trend was observed in subjects receiving fish oil supplementation. In the phospholipid fraction of the atrium, both 20:5n-3 and 22:6n-3 increased, whereas 20:4n-6 levels decreased. This study demonstrates for the first time that short-term supplementation with fish oil concentrate results in significant incorporation of LCn-3PUFA with a concomitant depletion of the eicosanoid substrate (20:4n-6) in the human atrium.

Airway and circulating levels of carotenoids in asthma and healthy controls.

BACKGROUND: Elevated oxidative stress and impaired antioxidant defences are increasingly recognised features of asthma. Carotenoids are potent dietary antioxidants that may protect against asthma by reducing oxidative damage. OBJECTIVES: This study aimed firstly, to characterise circulating and airway levels of carotenoids in asthma compared to healthy controls, in relation to dietary intake. Secondly, the study aimed to test whether airway lycopene defences can be improved using oral supplements. METHODS: Induced sputum and peripheral blood samples were collected from subjects with asthma (n = 15) and healthy controls (n = 16). Dietary carotenoid intakes were estimated using the 24-hour recall method and analysed using a modified version of the Foodworks 210 Nutrient Calculation Software. Another group of healthy controls (n = 9) were supplemented with 20 mg/day lycopene for 4 weeks. Carotenoids (beta-carotene, lycopene, alpha-carotene, beta-cryptoxanthin, lutein/zeaxanthin) were measured by HPLC. RESULTS: Despite similar dietary intake, whole blood levels of total carotenoids, lycopene, lutein, beta-cryptoxanthin, alpha-carotene and beta-carotene were significantly lower in asthma than controls. However, there were no differences in plasma or sputum carotenoid levels. Induced sputum carotenoid levels were significantly lower than plasma and whole blood levels, but correlated strongly with plasma levels (r = 0.798, p < 0.001). Although there were no overall increases in either plasma or sputum lycopene levels following supplementation, changes in airway lycopene levels correlated with changes in plasma levels (r = 0.908, p < 0.002). CONCLUSIONS: Whole blood, but not plasma or sputum, carotenoid levels are deficient in asthma. Plasma carotenoid levels reflect airway carotenoid levels and when plasma levels are improved using oral supplements this is reflected in the airways.

Antioxidant-restricted diet reduces plasma nonesterified fatty acids in trained athletes.

Nonesterified FA (NEFA) are a major fuel source for humans at rest and during moderate exercise. The effect of dietary antioxidant restriction on plasma NEFA levels and exercise performance in trained athletes was examined. Seventeen athletes followed a 2-wk restricted-antioxidant (R-AO) diet, which resulted in a threefold reduction in antioxidant intake (ascorbic acid, 139 to 49 mg; beta-carotene, 5093 to 1142 microg) and a significant (P = 0.001) reduction in the plasma NEFA. The amount and types of fat consumed were not different between the R-AO and habitual diets. Exercise time to exhaustion was not affected by the R-AO diet, but rating of perceived exertion (RPE) was significantly (P = 0.03) elevated. The increase in RPE may have occurred as a result of the R-AO diet and subsequent reduction in plasma NEFA; however, further research is required to confirm this conclusion.

Macadamia nut consumption lowers plasma total and LDL cholesterol levels in hypercholesterolemic men.

This study was conducted to assess the cholesterol-lowering potential of macadamia nuts. Seventeen hypercholesterolemic men (mean age 54 y) were given macadamia nuts (40-90 g/d), equivalent to 15% energy intake, for 4 wk. Plasma total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides and homocysteine concentrations and the fatty acid composition of plasma lipids were determined before and after treatment. Plasma MUFA 16:1(n-7), 18:1(n-7) and 20:1(n-9) were elevated after intervention with macadamia nuts. Plasma (n-6) and (n-3) PUFA concentrations were unaffected by macadamia nut consumption. Plasma total cholesterol and LDL cholesterol concentrations decreased by 3.0 and 5.3%, respectively, and HDL cholesterol levels increased by 7.9% in hypercholesterolemic men after macadamia nut consumption. Plasma triglyceride and homocysteine concentrations were not affected by treatment. Macadamia nut consumption was associated with a significant increase in the relative intake of MUFA and a reduced relative intake of saturated fatty acids and PUFA. This study demonstrates that macadamia nut consumption as part of a healthy diet favorably modifies the plasma lipid profile in hypercholesterolemic men despite their diet being high in fat.