A monounsaturated fatty acid-rich pecan-enriched diet favorably alters the serum lipid profile of healthy men and women

Frequent consumption of nuts is associated with decreased risk of cardiovascular disease. We investigated the effect of pecans rich in monounsaturated fat as an alternative to the Step 1 diet in modifying serum lipids and lipoproteins in men and women with normal to moderately high serum cholesterol. In a single-blind, randomized, controlled, crossover feeding study, we assigned 23 subjects (mean age: 38 y; 9 women, 14 men) to follow two diets, each for 4 wk: a Step I diet and a pecan-enriched diet (accomplished by proportionately reducing all food items in a Step I diet by one fifth for a 20% isoenergetic replacement with pecans). The percentage of energy from fat in the two diets was 28.3 and 39.6%, respectively. Both diets improved the lipid profile; however, the pecan-enriched diet decreased both serum total and LDL cholesterol by 0.32 mmol/L (6.7 and 10.4%, respectively) and triglyceride by 0.14 mmol/L (11.1%) beyond the Step I diet, while increasing HDL cholesterol by 0.06 mmol/L (2.5 mg/dL). Serum apolipoprotein B and lipoprotein(a) decreased by 11.6 and 11.1%, respectively, and apolipoprotein A1 increased by 2.2% when subjects consumed the pecan compared with the Step I diet. These differences were all significant (P < 0.05). A 20% isoenergetic replacement of a Step I diet with pecans favorably altered the serum lipid profile beyond the Step I diet, without increasing body weight. Nuts such as pecans that are rich in monounsaturated fat may therefore be recommended as part of prescribed cholesterol-lowering diet of patients or habitual diet of healthy individuals.     

Betaine supplementation lowers plasma homocysteine in healthy men and women

Elevated levels of plasma total homocysteine are associated with a higher risk of cardiovascular disease. Betaine and 5-methyltetrahydrofolate can remethylate homocysteine into methionine via independent reactions. We determined the effect of daily betaine supplementation, compared with both folic acid and placebo, on plasma concentrations of total homocysteine after an overnight fast and after methionine loading in men and women with mildly elevated homocysteine. Groups of twelve subjects ingested 6 g betaine, 800 micro g folic acid with 6 g placebo or 6 g placebo each day for 6 wk. A methionine-loading test (i.e., ingestion of 100 mg L-methionine/kg body mass) was performed before and after 6 wk of supplementation. Fasting plasma homocysteine decreased by 1.8 micro mol/L (95% confidence interval [CI]: -3.6, 0.0, P < 0.05) in the betaine group and by 2.7 micro mol/L (95% CI: -4.5, -0.9, P < 0.05) in the folic acid group. These changes are relative to the change in the placebo group, in which fasting plasma homocysteine rose by 0.5 micro mol/L. Furthermore, betaine suppressed the total area under the plasma homocysteine-time curve after methionine loading by 221 micro mol. 24 h/L (95% CI: -425, -16, P < 0.05) compared with placebo, whereas folic acid had no effect. In conclusion, betaine appears to be highly effective in preventing a rise in plasma homocysteine concentration after methionine intake in subjects with mildly elevated homocysteine. It is not known whether this potential of betaine to "stabilize" circulating homocysteine concentrations lowers the risk of cardiovascular disease.     

Tocotrienol rich fraction supplementation improved lipid profile and oxidative status in healthy older adults: A randomized controlled study

Background

Vitamin E supplements containing tocotrienols are now being recommended for optimum health but its effects are scarcely known. The objective was to determine the effects of Tocotrienol Rich Fraction (TRF) supplementation on lipid profile and oxidative status in healthy older individuals at a dose of 160 mg/day for 6 months.

Methods

Sixty-two subjects were recruited from two age groups: 35-49 years (n = 31) and above 50 years (n = 31), and randomly assigned to receive either TRF or placebo capsules for six months. Blood samples were obtained at 0, 3^rd and 6^th months.

Results

HDL-cholesterol in the TRF-supplemented group was elevated after 6 months (p < 0.01). Protein carbonyl contents were markedly decreased (p < 0.001), whereas AGE levels were lowered in the > 50 year-old group (p < 0.05). Plasma levels of total vitamin E particularly tocopherols were significantly increased in the TRF-supplemented group after 3 months (p < 0.01). Plasma total tocotrienols were only increased in the > 50 year-old group after receiving 6 months of TRF supplementation. Changes in enzyme activities were only observed in the > 50 year-old group. SOD activity was decreased after 3 (p < 0.05) and 6 (p < 0.05) months of TRF supplementation whereas CAT activity was decreased after 3 (p < 0.01) and 6 (p < 0.05) months in the placebo group. GPx activity was increased at 6 months for both treatment and placebo groups (p < 0.05).

Conclusion

The observed improvement of plasma cholesterol, AGE and antioxidant vitamin levels as well as the reduced protein damage may indicate a restoration of redox balance after TRF supplementation, particularly in individuals over 50 years of age.     

Leucine supplementation combined with resistance exercise improves the plasma lipid profile of dexamethasone-treated rats

The impact of leucine supplementation and resistance exercise (RE) on plasma lipid profile was evaluated in adult rats treated with dexamethasone, an experimental model of dyslipidemia. Total cholesterol did not differ among groups. Furthermore, leucine supplementation did not promote improvement in the plasma total cholesterol and LDL-c of the animals. However, plasma TG and VLDL-c were significantly decreased and HDL-c increased after 7 days of leucine supplementation combined with RE. In conclusion, leucine supplementation combined with RE, but not isolated, improved the plasma lipid profile of dexamethasone-induced dyslipidemic rats.     

Fish oil affects blood pressure and the plasma lipid profile in healthy Danish infants

Animal and epidemiologic studies indicate that early nutrition has lasting effects on metabolism and cardiovascular disease risk. In adults, (n-3) long-chain PUFA (LCPUFA) from fish oils improve blood pressure, the lipid profile, and possibly cardiovascular disease mortality. This randomized trial is the first to investigate the effects of fish oil on blood pressure and the lipid profile in infancy. Healthy term 9-mo old infants (n = 83) were randomly assigned to 5 mL fish oil daily or no fish oil for 3 mo and to 2 different milk types. Before and after the intervention, blood pressure was measured with an oscillometric device, and blood was sampled for analysis of erythrocyte fatty acid composition and the plasma lipid profile. This paper examines the effects of the fish oil supplement, with adjustment for the effects of the milk intervention when relevant. The fish oil intervention increased erythrocyte (n-3) LCPUFA content (P < 0.001). At 12 mo, infants administered fish oil had a lower systolic blood pressure [adjusted mean difference (95% CI)] 6.3 mm Hg (0.9, 11.7) (P = 0.02), a 0.51 mmol/L (0.07, 0.95) higher plasma total cholesterol (P = 0.02), and a 0.52 mmol/L (0.02,1.01) higher LDL cholesterol (P = 0.04) than infants not administered fish oil. Plasma triacylglycerol was inversely associated with the erythrocyte content of eicosapentaenoic acid (r = 0.34, P < 0.01), a biomarker of fish oil dose. The observed effects of fish oil are in accordance with findings in adults. The long-term health implications warrant further investigation.     

A healthy body, a healthy mind: long-term impact of diet on mood and cognitive function

Certain dietary risk factors for physical ill health are also risk factors for depression and cognitive impairment. Although cholesterol lowering has been suggested to increase vulnerability to depression, there is better support for an alternative hypothesis that intake of n-3 long-chain polyunsaturated fatty acids can affect mood (and aggression). Possible mechanisms for such effects include modification of neuronal cell membrane fluidity and consequent impact on neurotransmitter function. Stronger evidence exists concerning a role for diet in influencing cognitive impairment and cognitive decline in older age, in particular through its impact on vascular disease. For example, cognitive impairment is associated with atherosclerosis, type 2 diabetes and hypertension, and findings from a broad range of studies show significant relationships between cognitive function and intakes of various nutrients, including long-chain polyunsaturated fatty acids, antioxidant vitamins, and folate and vitamin B12. Further support is provided by data on nutrient status and cognitive function. Almost all this evidence, however, comes from epidemiological and correlational studies. Given the problem of separating cause and effect from such evidence, and the fact that cognitive impairment and cognitive decline (and depression) are very likely to be significant factors contributing to the consumption of a poor diet, greater emphasis should now be placed on conducting intervention studies. An efficient approach to this problem could be to include assessments of mood and cognitive function as outcome measures in studies designed primarily to investigate the impact of dietary interventions on markers of physical health.     

Inhibition of tumour necrosis factor-alpha and interleukin 6 production by mononuclear cells following dietary fish-oil supplementation in healthy men and response to antioxidant co-supplementation

Increased dietary consumption of the n-3 polyunsaturated fatty acids (PUFA) eicosapentaenoic acid (20 : 5n-3; EPA) and docosahexaenoic acid (22 : 6n-6; DHA) is associated with their incorporation into circulating phospholipid and increased production of lipid peroxide metabolites. The relationship between peripheral blood mononuclear cell (PBMC) function, n-3 PUFA intake and antioxidant co-supplementation is poorly defined. We therefore investigated tumour necrosis factor (TNF)-alpha and interleukin (IL) 6 production by PBMC and phospholipid fatty acid composition in plasma and erythrocytes of healthy male subjects (n 16) receiving supplemental intakes of 0.3, 1.0 and 2.0 g EPA+DHA/d, as consecutive 4-week courses. All subjects were randomised in a double-blind manner to receive a concurrent antioxidant supplement (200 microg Se, 3 mg Mn, 30 mg D-alpha-tocopheryl succinate, 90 mg ascorbic acid, 450 microg vitamin A (beta-carotene and retinol)) or placebo. There was a positive dose-dependent relationship between dietary n-3 PUFA intake and EPA and DHA incorporation into plasma phosphatidylcholine and erythrocyte phosphatidylethanolamine, with a tendency towards a plateau at higher levels of intake. Production of TNF-alpha and IL-6 by PBMC decreased with increasing n-3 PUFA intake but tended towards a 'U-shaped' dose response. Both responses appeared to be augmented by antioxidant co-supplementation at intermediate supplementary n-3 PUFA intakes. Thus, increased dietary n-3 PUFA consumption resulted in defined but contrasting patterns of modulation of phospholipid fatty acid composition and PBMC function, which were further influenced by antioxidant intake.     

A monounsaturated fatty acid-rich diet reduces macrophage uptake of plasma oxidised low-density lipoprotein in healthy young men

During atherogenesis, a pathological accumulation of lipids occurs within aortic intimal macrophages through uptake of plasma oxidised LDL (oxLDL). The aim of the present study was to determine whether macrophage uptake of plasma oxLDL and LDL susceptibility to oxidation may be determined by quantity and quality of dietary fat. Twenty healthy young men were subjected to three dietary periods, each lasting 4 weeks. The first was an SFA-enriched diet (38 % fat, 20 % SFA), which was followed by a carbohydrate (CHO)-rich diet (30 % fat, < 10 % SFA, 55 % CHO) or a MUFA olive oil-rich diet (38 % fat, 22 % MUFA) following a randomised cross-over design. After each diet period, LDL particles were oxidised with Cu ions to determine LDL susceptibility to oxidation and subsequently incubated with the U937-macrophage cell line to determine the percentage of uptake of plasma oxLDL. The shift from the MUFA diet to the SFA- or CHO-rich diets reduced the resistance of LDL particles to oxidation, decreasing lag time (P = 0.038) and increasing the propagation rate (P = 0.001). Furthermore, the MUFA-rich diet demonstrated reduced macrophage uptake of plasma oxLDL (P = 0.031) as compared with the SFA-rich diet. Finally, macrophage uptake of plasma oxLDL was correlated (r 0.45; P = 0.040) with total amount of conjugated dienes after LDL oxidation. Our data suggest that a MUFA-rich diet may have favourable effects on cardiovascular risk since it prevents the oxidative modifications of LDL and reduces macrophage uptake of plasma oxLDL.     

Effects of arachidonate-enriched triacylglycerol supplementation on serum fatty acids and platelet aggregation in healthy male subjects with a fish diet

The changes in fatty acid composition of serum and in platelet aggregation induced by supplementation of arachidonate-enriched TAG were investigated in twenty-four healthy Japanese men in a double-blind, placebo-controlled study. The arachidonate-enriched TAG ingested was an edible oil, extracted and purified from a biomass of submerged fermented Mortierella alpina. Mean daily intake of fish and shellfish by subjects was 87.2 (se5.3) g/d, while dietary intakes of arachidonic acid (ARA) by the ARA group and placebo group were 175 (se12) and 179 (se13) mg/d, respectively. In the ARA group, after 2-week supplementation of 838 mg ARA/d, ARA concentration in serum phospholipids was increased from 9.6 (se0.4) to 13.7 (se0.4) g/100 g total fatty acids, and was significantly different from that in the placebo group (P < 0.001). This level was maintained for 4 weeks but returned to baseline level after a 4-week washout period. Linoleic acid concentration in serum phospholipids decreased from 19.2 (se0.8) to 16.3 (se0.6) g/100 g total fatty acids in the ARA group. Similarly, ARA content of serum TAG increased after ARA supplementation. Neither the EPA nor DHA content of serum phospholipids or TAG was altered by ARA supplementation. The platelet aggregation induced in platelet-rich plasma by adding adenosine diphosphate, collagen and ARA, physical characteristics of subjects, and biochemical parameters were unchanged throughout the test period. These findings suggest that ARA concentration in serum phospholipids and TAG can be safely increased by supplementation of arachidonate-enriched TAG oil.     

Supplementation of a diet low in carotenoids with tomato or carrot juice does not affect lipid peroxidation in plasma and feces of healthy men

Antioxidant properties of carotenoids are thought to be at least partly responsible for the protective effects of fruits and vegetables rich in carotenoids against colon cancer. There are large amounts of in vitro data supporting this hypothesis. But there is little known about the antioxidant effects of carotenoid-rich food in vivo particularly in the gastrointestinal tract. In a randomized, crossover trial, healthy men (n = 22) who were consuming a low-carotenoid diet drank 330 mL/d tomato juice or carrot juice for 2 wk. Antioxidant capacity was assessed by the "lag time" of ex vivo LDL oxidation induced by copper and lipid peroxidation as determined by measurements of malondialdehyde (MDA) in plasma and feces using HPLC with fluorescence detection. Although consumption of both carotenoid-rich juices for 2 wk increased the carotenoid level in plasma and feces (P < 0.001), the antioxidant capacity of LDL tended to be increased by only approximately 4.5% (P = 0.08), and lipid peroxidation in the men's plasma and feces was not affected. Thus, processes other than lipid peroxidation could be responsible for the preventive effects of tomatoes and carrots against colon cancer.     

Bifidobacteria supplementation: Effects on plasma lipid profiles in dyslipidemic children

ObjectivePreclinical investigations support the use of probiotics in the treatment of hypercholesterolemia, but clinical evidence is often contrasting. The aim of this study was to evaluate the effects of a probiotic formulation containing three Bifidobacterium strains on lipid profiles in children affected by primary dyslipidemia.MethodsThirty-eight children with dyslipidemia, ages 10.8 ± 2.1 y, were enrolled in a randomized, double-blind, placebo-controlled cross-over study. After a 4-wk diet run-in period, the children received probiotics (B. animalis subspecies lactis MB 2409, B. bifidum MB 109B, and B. longum subspecies longum BL04) or placebo for 3 mo. After 1 mo, wash-out treatments were switched. A strict dietary evaluation concerning satured fatty acids and cholesterol content, STEP I diet accordingly, was performed by a dietitian who examined the weekly dietary diary at each visit.ResultsBaseline lipid profile was (mean ± SD): total cholesterol (TC) 222.8 ± 23.2 mg/dL, high-density lipoprotein cholesterol (HDL-C) 55.8 ± 12.2 mg/dL, triglycerides (TG) 99.0 ± 61.7 mg/dL, and low-density lipoprotein cholesterol (LDL-C) 147.2 ± 21.9 mg/dL. After 3 mo of probiotic treatment, the lipid profile was: TC 211.9 ± 27.3 mg/dL, HDL-C 60.7 ± 14.2 mg/dL, TG 79.5 ± 34.5 mg/dL, and LDL-C 135.3 ± 24.2 mg/dL. Compared with placebo, probiotics reduced TC by 3.4% (P = 0.02) and LDL-C by 3.8% (P = 0.001). No significant dietary change occurred through the study and no relevant adverse effects were observed.ConclusionsTreatment with a Bifidobacterium probiotic formulation was well tolerated and useful in combination with to diet therapy. Children with dyslipidemia benefited from this approach, although the results need to be confirmed by larger controlled studies.     

Effect of 6 dietary fatty acids on the postprandial lipid profile, plasma fatty acids, lipoprotein lipase, and cholesterol ester transfer activities in healthy young men

BACKGROUND: There is increasing evidence that postprandial triacylglycerol-rich lipoproteins may be related to atherogenic risk. OBJECTIVE: The objective was to investigate the effect of individual fatty acid intakes on postprandial plasma lipoprotein triacylglycerol and cholesterol concentrations, plasma fatty acids, and preheparin lipoprotein lipase and cholesterol ester transfer protein (CETP) activities. DESIGN: Six test fats high (approximately 43% by wt) in stearic acid, palmitic acid, palmitic + myristic acid, oleic acid, elaidic acid (trans 18:1), and linoleic acid were produced by interesterification. After having fasted for 12 h, 16 healthy young men were served the individual test fats incorporated into meals (1 g fat/kg body wt) in random order on different days separated by washout periods. Blood samples were drawn before and 2, 4, 6, and 8 h after the meals. RESULTS: Different responses to the test-fat meals were observed for plasma lipoprotein triacylglycerol and cholesterol concentrations, plasma fatty acid concentrations, and lipoprotein lipase and CETP activities (diet x time interaction: 0.001 < P < 0.05). Intake of the long-chain saturated fatty acids stearic and palmitic acids resulted in a relatively lower lipemic response than did intake of the unsaturated fatty acids, probably because the saturated fatty acids were absorbed less and at a lower rate; therefore, the lipemic response took longer to return to postabsorptive values. CONCLUSIONS: Fatty acid chain length and degree of saturation appear to affect the extent and duration of lipemia and affect hepatic output indirectly. These effects may not be mediated via effects on lipoprotein lipase and CETP activities.     

Comparison of the effects of fish and fish-oil capsules on the n 3 fatty acid content of blood cells and plasma phospholipids

BACKGROUND: n-3 Fatty acids (FAs) have been shown to be beneficial for cardiovascular health. Whether n-3 FAs from oily fish consumed weekly or from fish-oil capsules taken daily are equally bioavailable is not clear. OBJECTIVE: The purpose of this study was to compare the rate and extent of enrichment of blood cell membranes [ie, red blood cells (RBCs)] and plasma phospholipids with n-3 FAs from these 2 sources. DESIGN: Healthy premenopausal female volunteers were randomly assigned to consume a daily average of 485 mg eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids either from 2 servings of oily fish (ie, salmon and albacore tuna) per week or from 1-2 capsules/d. RESULTS: After 16 wk, EPA+DHA in RBCs in the fish group (n = 11) increased from 4.0 +/- 0.6% of total FAs to 6.2 +/- 1.4%, whereas it rose from 4.3 +/- 1.0% to 6.2 +/- 1.4% in the capsule group (P < 0.0001 for both; NS for group effect). Similar results were observed in plasma phospholipids. EPA+DHA stabilized in the latter after 4 wk but continued to rise through week 16 in RBCs. EPA in RBCs increased significantly (P = 0.01) more rapidly in the fish group than in the capsule group during the first 4 wk, but rates did not differ significantly between groups thereafter. Total FA variances were less in RBCs than in plasma phospholipids (P = 0.04). CONCLUSION: These findings suggest that the consumption of equal amounts of EPA and DHA from oily fish on a weekly basis or from fish-oil capsules on a daily basis is equally effective at enriching blood lipids with n-3 FAs.     

Low dose betaine supplementation leads to immediate and long term lowering of plasma homocysteine in healthy men and women

High plasma homocysteine is a risk for cardiovascular disease and can be lowered through supplementation with 6 g/d of betaine. However, dietary intake of betaine is approximately 0.5-2 g/d. Therefore, we investigated whether betaine supplementation in the range of dietary intake lowers plasma homocysteine concentrations in healthy adults. Four groups of 19 healthy subjects ingested three doses of betaine or placebo daily for 6 wk. A methionine loading test was performed during run in, on d 1 of betaine supplementation, and after 2 and 6 wk of betaine supplementation. Fasting plasma homocysteine after 6-wk daily intakes of 1.5, 3 and 6 g of betaine was 12% (P < 0.01), 15% (P < 0.002) and 20% (P < 0.0001) less than in the placebo group, respectively. Furthermore, the increase in plasma homocysteine after methionine loading on the 1st d of betaine supplementation was 16% (P < 0.06), 23% (P < 0.008) and 35% (P < 0.0002) less than in the placebo group, respectively, and after 6 wk of supplementation was 23% (P < 0.02), 30% (P < 0.003) and 40% (P < 0.0002) less, respectively. Thus, doses of betaine in the range of dietary intake reduce fasting and postmethionine loading plasma homocysteine concentrations. A betaine-rich diet might therefore lower cardiovascular disease risk.     

Effects of acute chromium supplementation on postprandial metabolism in healthy young men

BACKGROUND: Chromium (Cr) potentiates the action of insulin in the cell and improves glucose tolerance after long-term supplementation. OBJECTIVE: We hypothesized that Cr may also have acute effects and might be beneficial in lowering the glycemic index of a meal. METHODS: We studied the effects of short-term Cr supplementation using a randomized crossover design. Thirteen apparently healthy, non-smoking young men of normal body mass index performed three trials each separated by one week. Test meals, providing 75 g of available carbohydrates, consisted of white bread with added Cr (400 or 800 microg as Cr picolinate) or placebo. RESULTS: After addition of 400 and 800 microg Cr incremental area under the curve (AUC) for capillary glucose was 23% (p = 0.053) and 20% (p = 0.054), respectively, lower than after the white bread meal. These differences reached significance if the subjects were divided into responders (n = 10) and non-responders (n = 3). For the responders AUC after 400 and 800 microg Cr was reduced by 36% and 30%, respectively (Placebo 175 +/- 22, Cr400 111 +/- 14 (p < 0.01), Cr800 122 +/- 15 mmol. min/L (p < 0.01)). Glycemia was unchanged after addition of Cr in the non-responders. Responders and non-responders differed significantly in their nutrient intake and eating pattern, and total serum iron concentration tended to be lower in the responder group (p = 0.07). CONCLUSIONS: Acute chromium supplementation showed an effect on postprandial glucose metabolism in most but not all subjects. The response to Cr may be influenced by dietary patterns.     

A high-fructose diet impairs basal and stress-mediated lipid metabolism in healthy male subjects

The effects of a 7 d high-fructose diet (HFrD) or control diet on lipid metabolism were studied in a group of six healthy lean males. Plasma NEFA and beta-hydroxybutyrate concentrations, net lipid oxidation (indirect calorimetry) and exogenous lipid oxidation (13CO2 production) were monitored in basal conditions, after lipid loading (olive oil labelled with [13C]triolein) and during a standardised mental stress. Lactate clearance and the metabolic effects of an exogenous lactate infusion were also monitored. The HFrD lowered plasma concentrations of NEFA and beta-hydroxybutyrate as well as lipid oxidation in both basal and after lipid-loading conditions. In addition, the HFrD blunted the increase in plasma NEFA and exogenous lipid oxidation during mental stress. The HFrD also increased basal lactate concentrations by 31.8 %, and lactate production by 53.8 %, while lactate clearance remained unchanged. Lactate infusion lowered plasma NEFA with the control diet, and net lipid oxidation with both the HFrD and control diet. These results indicate that a 7 d HFrD markedly inhibits lipolysis and lipid oxidation. The HFrD also increases lactate production, and the ensuing increased lactate utilisation may contribute to suppress lipid oxidation.