Effects of cis-9,trans-11 CLA in rats at intake levels reported for breast-fed infants.

CLA intake in exclusively breast-fed infants is close to levels found to have physiological effects in animals. However, in the majority of studies mixtures of CLA isomers have been used and the independent effects of the major CLA isomer in human milk, cis-9,trans-11 CLA, at the intake level in exclusively breast-fed infants have hardly been studied. We therefore studied the effects of cis-9,trans-11 CLA on plasma lipids and glucose, immune function, and bone metabolism in growing rats. Thirty male Sprague-Dawley rats (n = 10/group) were fed either 20 mg/kg/d cis-9,trans-11 CLA and 20 mg/kg/d sunflower oil (CLA20), 40 mg/kg/d cis-9,trans-11 CLA (CLA40), or 40 mg/kg/d sunflower oil (placebo) for 8 wk. No significant differences between groups were found in plasma lipids, glucose, insulin, C-reactive protein, or lipid peroxidation. Liver fat content was lowest in the CLA20 group. In vitro interleukin 2 (IL-2) production increased, and tumor necrosis factor alpha, IL-1beta, prostaglandin E2, and leukotriene B4 production decreased in the CLA20 group. No differences between groups were detected in IL-4, IL-6, or interferon gamma production, plasma osteocalcin, insulin-like growth factor, or urinary deoxypyridinoline crosslinks. Plasma tartrate-resistant acid phosphatase 5b activity was significantly increased in the CLA40 group. The results indicate anti-inflammatory effects and enhanced T-cell function for the CLA20 group. No adverse effects were seen in the CLA20 group, whereas indications of increased bone resorption rate were observed in the CLA40 group.

High linoleic acid, low vegetable, and high oleic acid, high vegetable diets affect platelet activation similarly in healthy women and men.

Upregulation of protein kinase C (PKC), an important enzyme in platelet activation, could be one step toward platelet hyperactivity. PKC activation can be modulated by dietary components in vitro, but few data are available concerning the in vivo effects. In this strictly controlled human dietary intervention, the influence of dietary unsaturated fatty acids and vegetable compounds on platelet activation was investigated. A high linoleic acid diet (10% of energy) with small amounts of vegetables (no berries or apples) was consumed by 9 women and 4 men (24.1 +/- 3.9 y), and was compared with a high oleic acid diet (12% of energy) with considerable amounts of vegetables, berries and apples consumed by 8 women and 4 men (24.2 +/- 5.5 y). Subjects were healthy Finnish volunteers. Compliance with the experimental protocol was good, as indicated by changes in plasma fatty acids and concentrations of vitamin C, beta-carotene and alpha-tocopherol. No differences between groups were seen in indices of platelet activation, including platelet aggregation, total PKC activity and distribution of PKC isoenzymes alpha, beta(II) and delta. The results indicate that in apparently healthy and fairly young subjects with adequate vitamin intakes, diets differing markedly in their amounts of linoleic and oleic acids, and vegetables, berries and apples do not differ in platelet activation.

Similar responses in hemostatic factors after consumption of wholemeal rye bread and low-fiber wheat bread.

OBJECTIVE: Both epidemiological and experimental evidence suggests a protective effect of dietary fiber against disease, such as cancer and cardiovascular disease. The effects of fiber on lipoproteins are modest, indicating that other mechanisms may be involved. As the hemostatic effects of different types of fiber are poorly known, we compared the effects of wholemeal rye bread and low-fiber wheat bread on factors related to coagulation, fibrinolysis and platelet function. DESIGN: Subjects consumed rye and wheat bread as part of their habitual diet in a cross-over manner for 4 weeks, with a 4 week washout period between the diet periods. SUBJECTS: Forty healthy subjects (18 men, 22 women), aged 43+/-2 y. RESULTS: Mean daily intake of fiber during the rye bread period was 31 g for men and 26 g for women, while the respective figures for the wheat bread period were 15 g and 12 g. However, no significant differences between the two periods were seen in factor VII coagulant activity (FVIIc), fibrinogen, prothrombin fragments 1+2 (F1+2), tissue plasminogen activator (tPA) plasminogen activator inhibitor 1 (PAI-1) or 2,3,-dinor-thromboxane B2. Fibrin degradation products, D-dimers, were slightly lower after the wheat period (P=0.046). CONCLUSIONS: The results indicate that wheat and rye bread do not differ in their effects on coagulation, fibrinolysis or platelet function. SPONSORSHIP: Fazer Bakeries Ltd, Lahti Finland; Vaasan & Vaasan Ltd, Helsinki, Finland.

Similar effects of diets high in oleic or linoleic acids on coagulation and fibrinolytic factors in healthy humans.

BACKGROUND AND AIM: Monounsaturated fatty acids (MUFA) have been shown to be beneficial. Their haemostatic effects, however, are poorly known. We compared the effects of oleic acid (OA) and linoleic acid (LA) on variables related with coagulation and fibrinolysis in healthy subjects. METHODS AND RESULTS: Thirty-eight healthy volunteers (20 women, 18 men; mean age 27) consumed a saturated fat baseline diet for four weeks and were then switched to either a high LA diet (11.5 en%) or a high OA diet (18.0 en%) for another four weeks when nearly all food was provided for the whole day. A control group of 13 subjects consumed their habitual diet throughout the study. No differences between the OA and LA diets were found in the plasma levels of fibrinogen, plasminogen activator inhibitor, antithrombin III, von Willebrand factor antigen or D-dimers. Factor FVII coagulant activity was significantly lower after the OA diet. CONCLUSIONS: The results indicate largely similar effects for OA and LA on factors related with coagulation and fibrinolysis in humans. The effects of dietary fatty acid composition on FVII coagulant activity should be further studied.

A high linoleic acid diet increases oxidative stress in vivo and affects nitric oxide metabolism in humans.

Evidence from in vitro studies shows that increased intake of polyunsaturated fatty acids leads to increased oxidative stress, which may be associated with endothelial damage. We measured the urinary levels of 8-iso-PGF2alpha and nitric oxide metabolites as well as plasma sICAM-1 levels from healthy subjects after strictly controlled diets rich in either linoleic acid (LA, C18:2 n-6) or oleic acid (OA, C18:1 n-9). Thirty-eight volunteers (20 women and 18 men, mean age 27 years) consumed a baseline diet rich in saturated fatty acids (SFA) for 4 weeks and were then switched to either a high LA diet (11.5 en%) or a high OA diet (18.0 en%) also for 4 weeks. During the LA and OA diets, nearly all food was provided for the whole day. A control group of 13 subjects consumed their habitual diet throughout the study. Urinary excretion of 8-iso-PGF2alpha was significantly increased after the LA diet (170 vs 241 ng/mmol creatinine, P=0.04), whereas the urinary concentration of nitric oxide metabolites decreased (4.2 vs 2.6 mg/mmol creatinine, P=0.03). No significant changes were seen in the OA group. Significant differences between the LA and control group were found for both 8-oxo-PGF2alpha (P=0.03) and NO (P=0.02), whereas the OA and LA groups did not differ with respect to any parameter. Also plasma sICAM-1 remained unchanged in both groups throughout the study. In conclusion, the high-LA diet increased oxidative stress and affected endothelial function in a way which may in the long-term predispose to endothelial dysfunction.

Replacement of dietary saturated by unsaturated fatty acids: effects of platelet protein kinase C activity, urinary content of 2,3-dinor-TXB2 and in vitro platelet aggregation in healthy man.

The present study was conducted to compare the effects of oleic (OA) and linoleic acids (LA) on platelet function in healthy subjects. After a 4-week period on a diet rich in saturated fatty acids (SAFA), 38 volunteers (20 female, 18 male) had a high OA (18.0 en%) diet or a high LA diet (11.5 en%) for four weeks in a controlled manner. A control group of 13 subjects consumed their habitual diet throughout the study. Replacing the SAFA diet by the OA or LA diet did not affect the membrane-associated activity of platelet protein kinase C (PKC). However, both diets tended to increase the cytosolic activity to a comparable extent. Both the OA and the LA diets increased urinary excretion of 2.3-dinor-TXB2, as compared to the SAFA diet, whereas the urinary excretion of beta-thromboglobulin remained unchanged. As compared to the initial SAFA diet, platelet aggregation to collagen increased after both diets, while ADP induced aggregation showed no diet-induced changes. The results indicate increased platelet activity after both oil diets with no differences between the OA and LA diet and confirm in vitro findings that cis-unsaturated fatty acids have a distinct effect on cytosolic PKC, in particular.

Lack of effect on blood pressure by low fat diets with different fatty acid compositions.

We compared the effects on blood pressure (BP) of three isocaloric diets with reduced total fat and saturated fatty acid (SAFA) contents but with different proportions of monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA). Diet LF (low fat) provided 20 en% fat (7.9% SAFA, 7.8% MUFA, 3.0% PUFA); diet HP (high PUFA) 26 en% fat (7.5% SAFA, 8.2% MUFA, 8.1% PUFA), and diet HM (high MUFA) 26 en% fat (7.3% SAFA, 14.1% MUFA, 3.2% PUFA). The diets were consumed for 8 weeks (intervention) preceded by 2 weeks and followed by 8 weeks on a habitual diet (baseline/ switchback) with 33-34 en% fat (13-14% SAFA, 12% MUFA, 6% PUFA). Forty-five free-living couples were randomly allocated into the three diet groups, and 43 men and 44 women completed the study. BP was measured weekly with an automatic device. Compliance to diet was monitored by repeated food records, serum fatty acid compositions, and weekly visits to a nutritionist. Both systolic BP (SBP) and diastolic BP (DBP) remained unchanged throughout the study in all three groups. The weight-adjusted mean (s.e.m.) BP values showed changes in SBP of +1.7 (1.8), -0.4 (1.7), and +1.9 (1.9) mm Hg on the LF, HP, and HM diets, respectively (difference NS), and DBP of +0.1 (1.0), +0.6 (1.0), and -0.3 (1.0) mm Hg, respectively (difference NS) between the last 2 weeks of the baseline and intervention periods. The expected fatty acid intakes were achieved, and there were no between-group differences in change of body weight, intake of dietary fibre and potassium, and 24-h sodium excretion. A reduction in total fat and SAFA intake and changes in the proportions of dietary MUFA and PUFA did not affect the BP levels of this normotensive population with an adequate intake of PUFA at baseline.

Similar effects of diets rich in stearic acid or trans-fatty acids on platelet function and endothelial prostacyclin production in humans.

The effects of stearic acid (C18:0) and trans-fatty acids (trans-FAs) on measures of platelet function and prostacyclin (PGI2) production are poorly understood in humans. In this controlled dietary study, platelet function and endothelial PGI2 production were studied in healthy humans after they consumed diets rich in C18:0 or trans-FAs. For 5 weeks, 80 subjects consumed a baseline diet high in saturated FAs and were then switched to a diet containing 9.3% of energy as stearic acid or a diet containing 8.7 energy% as trans-FAs from hydrogenated vegetable oils for another 5 weeks. All diets contained 32.2 to 33.9 energy% fat, 14.6 to 15.8 energy% saturated plus trans-FAs, 12.2 to 12.5 energy% cis-monounsaturated, and 2.9 to 3.5 energy% polyunsaturated FAs. No significant differences between the C18:0 and trans-FA diets were found in the urinary excretion of 2,3-dinor-thromboxane B2 or 2,3-dinor-6-keto-prostaglandin F1alpha. In vitro production of thromboxane B2 by platelets as well as urinary excretion of beta-thromboglobulin were also similar after both diets. Collagen-induced in vitro aggregation was significantly enhanced after the C18:0 diet compared with the trans-FA diet (P=.02), whereas no differences between the diets were found with ADP. The results indicate similar effects of C18:0 and trans-FA diets on platelet activation and endothelial PGI2 production.

Effects of reduced-fat diets with different fatty acid compositions on serum lipoprotein lipids and apolipoproteins.

OBJECTIVE: To compare the effects on serum lipoproteins of three isocaloric diets with reduced total fat and saturated fatty acid (SFA) contents but with different proportions of monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA). DESIGN: A low-fat diet (LF) provided 20 en% fat, 7.9% SFA, 7.8% MUFA, 3.0% PUFA; a high-PUFA diet (HP) 26 en% fat, 7.5% SFA, 8.2% MUFA, 8.1% PUFA; and a high-MUFA diet (HM) 26 en% fat, 7.3% SFA, 14.1% MUFA, 3.2% PUFA. Diets were consumed for 8 weeks in a parallel design, after 2 weeks on a habitual diet with 33-34 en% fat, 13-14% SFA, 12% MUFA, 6% PUFA, and followed by an 8-week period on habitual diet. Compliance to diet was monitored by repeated food records and weekly visits to a nutritionist. SUBJECTS: 45 free-living, middle-aged couples who were randomly allocated into the three diet groups; 43 men and 44 women completed the study. RESULTS: During the diet periods, a small but significant reduction in body weight of 0.4-1.0 kg was observed in all groups. Similar and significant reductions of mean weight-adjusted serum total cholesterol (4-8%), low-density lipoprotein (LDL) cholesterol (7-11%), and high-density lipoprotein (HDL) cholesterol (8-11%) were observed during the diets. HDL2-cholesterol and apoprotein (apo) A-I levels were reduced whereas HDL3-cholesterol and apoA-II increased. ApoB was significantly decreased during the HM diet only. Serum triglycerides increased significantly during diets LF (25%, P < 0.01) and HP (19%, P < 0.05) but not during diet HM (5%, NS). CONCLUSIONS: Reduction in the intake of total fat and saturated fatty acids reduced serum LDL-cholesterol and HDL2-cholesterol concentrations irrespective of the relative proportions of MUFA and PUFA in the diets. The results suggest that there might be some advantage in increasing the proportion of MUFA in low-fat diets, since the HM diet rich in MUFA reduced apoB and slightly attenuated the increase in serum triglycerides that is commonly associated with dietary fat reduction.

Plasma and lipoprotein lipid peroxidation in humans on sunflower and rapeseed oil diets.

The effects of natural mixed diets on lipid peroxidation were investigated in humans. In the first study, 59 subjects were fed a rapeseed oil-based diet rich in monounsaturated fatty acids (MUFA) and a sunflower oil-based diet rich in polyunsaturated fatty acids (PUFA) in a cross-over manner for three and a half weeks. The lipid peroxidation products in plasma were determined by measuring conjugated dienes and malondialdehyde (MDA). In a second study, plasma thiobarbituric acid reactive substances (TBARS), lipid hydroperoxides, and the susceptibility of very low density lipoprotein+low-density lipoprotein (LDL) to in vitro oxidation were measured from subjects fed similar MUFA and PUFA diets for six weeks diets. No significant differences in plasma MDA or conjugated diene concentrations were found after the rapeseed oil diet or the sunflower oil diet in Study 1. In the second study, a small but significant decrease (P < 0.05) in both lipid hydroperoxides and TBARS was observed in the LDL fraction after the sunflower oil diet. The in vitro oxidation gave opposite results, showing increased oxidation after the sunflower oil diet. Despite a high intake of alpha-tocopherol during the oil periods, no increase in plasma alpha-tocopherol was noticed in either study. The results suggest that moderate changes in the fatty acid composition in the Western-type diet may be adequate to affect lipoprotein susceptibility to oxidation in vitro, but there is considerable disparity with some indices of in vivo lipid peroxidation.