Dietary lipids and coronary heart disease: old evidence, new perspective

Distinguishment, identification and aroma compound quantification of Portuguese olive oils based on physicochemical attributes, HS-GC/MS analysis and voltammetric electronic tongue

BACKGROUND

In this paper, various extra-virgin and virgin olive oils samples from different Portuguese markets were studied. For this purpose, a voltammetric electronic tongue (VE-tongue), consisting of two kinds of working electrode within the array, together with physicochemical analysis and headspace gas chromatography coupled with mass spectrometry (HS-GC-MS), were applied. In addition, preliminary considerations of relationships between physicochemical parameters and multisensory system were reported.

RESULTS

The physicochemical parameters exhibit significant differences among the analyzed olive oil samples that define its qualities. Regarding the aroma profile, 14 volatile compounds were characterized using HS-GC-MS; among these, hex-2-enal, hexanal, acetic acid, hex-3-ene-1-ol acetate and hex-3-en-1-ol were semi-quantitatively detected as the main aroma compounds in the analyzed samples. Moreover, pattern recognition methods demonstrate the discrimination power of the proposed VE-tongue system. The results reveal the VE-tongue's ability to classify olive oil samples and to identify unknown samples based of built models. In addition, the correlation between VE-tongue and physicochemical analysis exhibits a remarkable prediction model aimed at anticipating carotenoid content.

CONCLUSION

The preliminary results of this investigation indicate that physicochemical and HS-GC-MS analysis, together with multisensory system coupled with chemometric techniques, presented a satisfactory performance regarding olive oil sample discrimination and identification. © 2017 Society of Chemical Industry.

The pigeon (Columba livia) model of spontaneous atherosclerosis

Multiple animal models have been employed to study human atherosclerosis, the principal cause of mortality in the United States. Each model has individual advantages related to specific pathologies. Initiation, the earliest disease phase, is best modeled by the White Carneau (WC-As) pigeon. Atherosclerosis develops spontaneously in the WC-As without either external manipulation or known risk factors. Furthermore, susceptibility is caused by a single gene defect inherited in an autosomal recessive manner. The Show Racer (SR-Ar) pigeon is resistant to atherosclerosis. Breed differences in the biochemistry and metabolism of celiac foci cells have been described. For example, WC-As have lower oxidative metabolism but higher amounts of chondroitin-6-sulfate and nonesterified fatty acids compared with SR-Ar. Gene expression in aortic smooth muscle cells was compared between breeds using representational difference analysis and microarray analysis. Energy metabolism and cellular phenotype were the chief gene expression differences. Glycolysis and synthetic cell types were related to the WC-As but oxidative metabolism and contractile cell types were related to the SR-Ar. Rosiglitazone, a PPARγ agonist, blocked RNA binding motif (RBMS1) expression in WC-As cells. The drug may act through the c-myc oncogene as RBMS1 is a c-myc target. Proteomic tests of aortic smooth muscle cells supported greater glycosylation in the WC-As and a transforming growth factor β effect in SR-Ar. Unoxidized fatty acids build up in WC-As cells because of their metabolic deficiency, ultimately preventing the contractile phenotype in these cells. The single gene responsible for the disease is likely regulatory in nature.

Study on a novel process for the separation of phospholipids, triacylglycerol and cholesterol from egg yolk

A novel process for effective separation of phospholipids, triacylglycerol and cholesterol from fresh egg yolk has been developed and validated in this study. Ethanol was the only organic solvent used in the whole procedure. Following initial separation of protein and total lipids by ethanol, most of solidified triacylglycerol was removed from total lipids by low temperature treatment of ethanol extracts within 10 h. Then, β-cyclodextrin (β-CD) was used to remove cholesterol from the remaining ethanol extracts and recycling of β-CD was also studied to obtain cholesterol and reusable β-CD powder. The highest cholesterol removal rate of nearly 99 % was obtained at β-CD: cholesterol molar ratio of 5:1, water addition of 15 g/g β-CD and reacting temperature of 50 °C. Ethanol in residual ethanol extracts was removed for obtaining phospholipids by rotary evaporation. The phospholipids produced in this procedure without cholesterol could be safety used as emulsifiers in food or cosmetic industry.

Historical perspectives on the impact of n-3 and n-6 nutrients on health

Current public advice from the Food and Nutrition Board (FNB) about essential fatty acids (EFA) has limited quantitative details about three processes: (1) similar dynamics for n-3 linolenic and n-6 linoleic polyunsaturated fatty acids (PUFA) in maintaining 20- and 22-carbon n-3 and n-6 highly unsaturated fatty acids (HUFA) in tissues; (2) different dynamics for tissue n-3 and n-6 HUFA during formation and action of hormone-like eicosanoids; (3) simultaneous formation of non-esterified fatty acids (NEFA) and low density lipoprotein (LDL) from very low density lipoprotein (VLDL) formed from excess food energy and secreted by the liver. This report reviews evidence that public health may benefit from advice to eat less n-6 nutrients, more n-3 nutrients and fewer calories per meal. Explicit data for linoleic acid fit an Estimated Average Requirement (EAR) near 0.1 percent of daily food energy (en%) meeting needs of half the individuals in a group, a Recommended Dietary Allowance (RDA) near 0.5 en% meeting needs of 97-98 percent of individuals, and a Tolerable Upper Intake Level (UL) near 2 en% having no likely risk of adverse health effects. Quantitative tools help design and monitor explicit interventions that could beneficially replace imprecise advice on "healthy foods" with explicit preventive nutrition.

Effect of Cholesterol Removal Processing Using β -Cyclodextrin on Main Components of Milk

Various concentrations (0%, 0.5%, 1% and 1.5%) of β-CD were mixed with different fat contents (1%, 2.5% and 3%) of raw (unhomogenized) and homogenized milk at two mixing temperatures of 8 and 20°C. The cholesterol residue, fat, protein, lactose, solid nonfat (SNF), density, and ash content of milk were measured for each treatment. The results statistically analysed and showed that the cholesterol content of milk remarkably decreased as the β-CD was increased particularly in homogenized milk at 20°C. However, the reduction rate of cholesterol was decreased when extra β-CD was added due to its intermolecular reactions. The maximum cholesterol reduction was achieved at the level of 1% β-CD. The fat content, SNF, protein, lactose, and density content were decreased with increasing β-CD whereas it did not affect ash content.

Cholesterol extraction from ghee using glass beads functionalized with beta cyclodextrin

Beta-cyclodextrin (β-CD) was covalently immobilized on glass surface. Functionalized glass surface was characterized by X-ray photoelectron spectroscopy (XPS) and elemental analysis. Glass surface functionalized with β-CD was used to remove cholesterol from ghee (clarified butter fat). 78.8 % cholesterol was reduced in 2 h at 25 °C and 170 rpm. Same surface was used repeatedly for 10 cycles and no reduction in cholesterol removal efficiency was observed. Modified glass surface showed almost no degradation in repeated use in cholesterol reduction experiments.

Differentially expressed genes in aortic smooth muscle cells from atherosclerosis-susceptible and atherosclerosis-resistant pigeons

Susceptibility to spontaneous atherosclerosis in the White Carneau (WC-As) pigeon shows autosomal recessive inheritance. Aortic smooth muscle cells (SMC) cultured from susceptible WC-As and resistant Show Racer (SR-Ar) pigeons exhibit developmental and degenerative features corresponding to the respective SMC at atherosclerosis-prone sites in vivo. We used representational difference analysis to identify differentially expressed genes between WC-As and SR-Ar aortic SMC. Total RNA was extracted from cultured primary SMC of each breed, converted to double-stranded cDNA, followed by direct comparison in reciprocal representational difference analysis experiments. Difference products were cloned, sequenced, and identified by BLAST against the chicken genome. Six putative biochemical pathways were distinctly different between breeds with genes involved in energy metabolism and contractility exhibiting the most striking disparity. Genes associated with glycolysis and a synthetic SMC phenotype were expressed in WC-As cells. In contrast, SR-Ar cells expressed genes indicative of oxidative phosphorylation and a contractile SMC phenotype. In WC-As cells, the alternatives of insufficient ATP production limiting contractile function or the lack of functional contractile elements downregulating ATP synthesis cannot be distinguished due to the compressed in vitro versus in vivo developmental time frame. However, the genetic potential for effectively coupling energy production to muscle contraction present in the resistant SR-Ar was lacking in the susceptible WC-As.

Elevated plasma fibrinogen caused by inadequate alpha-linolenic acid intake can be reduced by replacing fat with canola-type rapeseed oil

The effects of canola-type rapeseed oil (RSO) on serum lipids, plasma fibrinogen, lipid oxidation and fatty acids were studied in three groups of subjects, two of which had not been consuming fish in their habitual diets. Forty-two volunteers (35 women, 7 men, 16-62 years) replaced fat with RSO for 6 weeks in a parallel design. The average cholesterol and fibrinogen concentrations were 5.0 mmol/l and 2.6 g/l, respectively. The intake of alpha-linolenic acid (alpha-LLA) was doubled. Efficient competitive inhibition by alpha-LLA was seen as a decrease in long-chain (LC) n-6 PUFA at 3 weeks. Elevated fibrinogen (2.6-3.9 g/l) decreased by 0.95 g/l at 6 weeks. Docosahexaenoic acid (22:6n-3) in plasma phospholipids increased at low fibrinogen levels only. The associations and changes in plasma C18 and LC PUFA followed the competitive and metabolic principles of the body, and especially in the case of n-3 PUFA according to the recycling pathway.

Intrafamilial associations of lipid profiles and the role of nutrition: the Tehran lipid and glucose study

BACKGROUND

The role of gene and environment in the genesis of abnormal lipid profile is still a controversial issue.

OBJECTIVE

To clarify the importance of certain parental risk factors associated with lipid profiles of children and adolescents.

METHODS

We conducted this cross-sectional population-based study in district 13 in the east of metropolitan Tehran. One hundred and thirteen eligible families comprising 455 subjects (including 229 offspring, aged 5-25 years) were enrolled into the study. Anthropometric data were measured using a standard protocol. To measure lipid profiles, venous blood was obtained in the morning after the subjects had fasted for 12-14 h overnight. Dietary intakes were assessed by means of a 2-day dietary recall questionnaire.

RESULTS

The chances of having elevated serum total cholesterol were higher in sons of fathers with high cholesterol intake (OR = 3.1; CI = 1.1-9.2) and mothers with high saturated fatty acid (SFA) intake (3.4; 1.1-10.8). Positive correlations were seen between the energy intake of fathers and serum total cholesterol of their daughters (r = 0.34, p < 0.01); between the SFA intake of fathers and serum triglycerides (TGs) of their sons (0.29, p < 0.01) and between mothers' body mass index and daughters' serum TGs (0.23, p < 0.03). The chances of having low serum high-density lipoprotein cholesterol were lower in sons of mothers with high carbohydrate intake (11.0; 2.8-42.8) and mothers with high serum high-density lipoprotein cholesterol (6.8; 1.7-27.0). There were higher chances of having elevated serum low-density lipoprotein cholesterol in sons with fathers having high SFA intake (4.5; 1.4-14.3), with mothers having high serum TGs (6.1; 1.3-29.0) and with mothers having high cholesterol intake (4.3; 1.2-15.2).

CONCLUSION

The results indicate independent associations between diet contents and the lipid profiles of parents and their offspring as well as between lipid profiles and diet contents among spouses.

A critique of paradoxes in current advice on dietary lipids

Beliefs about credible hypotheses of dietary causes of disease still need well-defined mediators to test for logical proof or disproof. We know that food energy causes transient postprandial oxidative insults that may not be fully reversible. Also, eating vitamin-like 18-carbon polyunsaturated fatty acids (PUFA) in foods maintains the 20- and 22-carbon highly unsaturated fatty acids (HUFA) in tissues. Tissue HUFA form hormone-like mediators that each amplify transient postprandial insults into fatal inflammatory, thrombotic and arrhythmic events in cardiovascular disease, a major preventable cause of death. Similar diet-based amplified events may also occur in other inflammatory proliferative disorders including cancer, dementia, arthritis and asthma. Puzzling paradoxes come from fragmented views of this situation which convey incomplete knowledge in oversimplified messages. Tools now exist to demonstrate successful prevention of two fatal food imbalances with credible dietary preventive interventions, but organizers and financers to help gather the evidence remain unknown. The overall evidence accumulated about diet, disease and death may be nearing a paradigm shift in which prior observed facts remain while beliefs about their accepted interpretation change.

Nutrient intake during peritoneal dialysis at the Prince of Wales Hospital in Hong Kong

BACKGROUND

Individuals undergoing peritoneal dialysis are at increased risk of developing cardiac disease and malnutrition.

STUDY DESIGN

A cross-sectional survey.

SETTINGS AND PARTICIPANTS

249 Chinese continuous ambulatory peritoneal dialysis (CAPD) patients were recruited from the Prince of Wales Hospital in Hong Kong. Another 249 age- and sex-matched controls were recruited from an archive of 1,010 individuals with known food frequency questionnaire (FFQ) data.

OBJECTIVE

To compare the dietary intake pattern of CAPD patients with controls and evaluate its association with background cardiac disease.

OUTCOMES AND MEASUREMENTS

Intake of different nutrients was estimated by using a 7-day FFQ.

RESULTS

Intake of all nutrients was lower in CAPD patients than controls, with resulting lower overall energy intake. Nutrient intake was decreased further in CAPD patients with background cardiac disease, which corresponded to worse nutritional status. Controlling for age, male sex, body weight, diabetes mellitus, dialysis therapy duration, residual renal function, peritoneal dialysis urea clearance, and Charlson Comorbidity Index score, background cardiac disease was associated independently with less intake of energy and most macronutrients and micronutrients. However, the association between background cardiac disease and energy and most nutrient intake was decreased or even lost when additional adjustment was made for C-reactive protein and serum albumin levels.

LIMITATIONS

An FFQ is limited in that nutrient quantitation is not exact and may be underestimated as a result of underreporting by patients. CAPD patients were compared with a control group without cardiovascular disease ascertainment that did not include subjects with diabetes.

CONCLUSIONS

Chinese CAPD patients had significantly lower nutrient intake than age- and sex-matched controls. The association between cardiac disease and lower dietary macronutrient and micronutrient intake in CAPD patients was mediated in part through systemic inflammation, which also was associated with more malnutrition. More attention should be focused on improving the intake pattern of Chinese CAPD patients.

Application of microencapsulated isoflavone into milk

This study was designed to develop a microencapsulated, water-soluble isoflavone for application into milk and to examine the hypocholesterolemic effect of such a milk product in a rat diet. The coating material was medium-chain triglyceride (MCT) and the core material was water-soluble isoflavone. The microencapsulation efficiency was 70.2% when the ratio (w/w) of coating material to core material was 15:1. The isoflavone release from the microcapsules was 8% after 3-day storage at 40 degrees C. In in vitro study, 4.0-9.3% of water-soluble isoflavone in simulated gastric fluid was released in the pH range of 2 to 5 after 60 min incubation; however, in simulated intestinal fluid at pH 8, 87.6% of isoflavone was released from the capsules after 40 min incubation time. In sensory analysis, the scores of bitterness, astringency, and off-taste in the encapsulated isoflavone-added milk were slightly, but not significantly, different from those in uncapsulated, isoflavone-added milk. In blood analysis, total cholesterol was significantly decreased in the isoflavone-added group compared with that in the control after 6-week feeding. Therefore, this study confirmed the acceptability of MCT as a coating material in the microencapsulation of water-soluble isoflavone for application into milk, although a slight adverse effect was found in terms of sensory attributes. In addition, blood total cholesterol was lowered in rats which had been fed a cholesterol-reduced and microencapsulated, isoflavone-added milk for 6 weeks.

Crosslinking of β-cyclodextrin on cholesterol removal from milk

This study was designed to develop crosslinking of beta-cyclodextrin (beta-CD), and determine the optimum conditions of different factors (mixing time, mixing temperature, and mixing speed) on cholesterol reduction from milk. Crosslinked beta-CD was prepared with epichlorohydrin. When milk was treated with different conditions, the cholesterol removal rate was in the range of 79.4 to 83.3% with 1% crosslinked beta-CD addition, which were not significantly different among treatments. After cholesterol removal from milk, the used crosslinked beta-CD was washed for cholesterol dissociation and reused. For recycling study, the cholesterol removal rate in first trial was 81.8%, which was mostly same as that using new crosslinked beta-CD. With five trials repeatedly using the same sample, the mean cholesterol removal rate was 81.2%. The present study indicated that the optimum conditions on cholesterol removal using crosslinked beta-CD were 10 min mixing with 400 rpm speed at 5 degrees C with about 80% cholesterol removal. In addition, crosslinked beta-CD resulted in the effective recycling efficiency almost 100%.

Immobilized β-cyclodextrin as a simple and recyclable method for cholesterol removal in milk

This study was designed to determine the optimum conditions of three different factors (mixing time, mixing temperature, and tube size) in reduction of cholesterol in milk using immobilized beta-CD beads. Immobilized beta-CD glass beads were prepared at different conditions of silanization and beta-CD immobilization reactions. In result, the glass beads (diameter 1 mm) at 20 mM 3-isocyanatopropyltriethoxysilane and 30 mM beta-CD without base showed the highest cholesterol removal rate as 41%. Using above immobilized beta-CD glass beads, the cholesterol removal rate was 40.2% with 6 h of mixing time in 7 mm diameter tube at 10 degrees C. After cholesterol removal from milk, the glass beads were washed for cholesterol dissociation and reused. In recycling study, the cholesterol removal rate was 41%, which was mostly same as that using new glass beads. These results indicated that cholesterol removal rate was about 40% with beta-CD immobilized glass beads, however, the recycling efficiency was almost 100%.

Functional Properties of Cholesterol-Removed Whipping Cream Treated by β-Cyclodextrin

The present study was carried out to examine the changes in functional properties of cholesterol-removed whipping cream by beta-cyclodextrin (beta-CD) treatment. The cholesterol removal rate reached over 90% in cream before whipping in all conditions (different stirring time and speed) applied. The apparent viscosity of beta-CD treated cream after whipping increased with increased stirring time and speed. Comparatively, the overrun percentage reached to 150%, and foam instability was measured as 2.5 ml deformed cream with lower stirring time (10 min) and speed (400 rpm). The thiobarbituric acid value of cholesterol-removed whipping cream increased from 0.08 to 0.14 stored at 4 degrees C during 4 wk; however, no difference was found compared with that of control. Above results indicated that beta-CD treatment process for cholesterol removal did not show a profound adverse effect on functional properties of cream after whipping.

Microencapsulation of water-soluble isoflavone and physico-chemical property in milk

This study was carried out to investigate the addition of water-soluble isoflavone into milk by means of microencapsulation technique. The yield of microencapsulation, sensory attributes, and capsule stability of water-soluble isoflavone microcapsules in milk were measured. Coating materials used was polyglycerol monostearate (PGMS), and core material was water-soluble isoflavone. The encapsulation yield of water-soluble isoflavone with PGMS was 67.2% when the ratio of coating material to core material was 15:1. The rate of water-soluble isoflavone release from capsules was 18, 19, and 25% when stored at 4, 20, and 30 degrees C for 12 days in milk, respectively. In sensory evaluation, beany flavor and color of microencapsuled water-soluble isoflavone added milk were significantly different from uncapsuled water-soluble isoflavone added milk, however, bitterness was not significantly different. In vitro study, micro-capsules of water-soluble isoflavone in simulated gastric fluid with the range of 3 to 6 pHs were released 3.0-15.0%, however, the capsules in simulated intestinal fluid with pH 7 were released 95.7% for 40 min incubation time. In conclusion, this study provided that PGMS as coating materials was suitable for the microencapsulation of water-soluble isoflavone, and the capsule containing milk was almost not affected with sensory attribute.

Influence of fish consumption on the distribution of serum cholesterol in lipoprotein fractions: comparative study among fish-consuming and non-fish-consuming populations

The objective of this study was to investigate serum lipoprotein levels in order to assess cardiovascular disease (CVD) risk factors between fish-consuming populations and non-fish-consuming populations, as it has been speculated that fish intake reduces CVD risk. A representative sample of one thousand subjects (529 men and 471 women) were selected, with ages ranging from 20 to 70 years, from 40 villages belonging to fish-consuming (500) or non-fish-consuming (500) populations. Serum lipoprotein lipids such as total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) were analysed biochemically using standard procedures. The ratios of TC: HDL-C and LDL-C: HDL-C were computed. Mean values of serum LDL-C and the ratios of LDL-C: HDL-C and TC: HDL-C were significantly lower and HDL-C levels were higher in fish-consumers than in non-fish-consumers. The concentrations of HDL-C decreased with increasing age, while the reverse was true for LDL-C and for the LDL-C: HDL-C and TC: HDL-C ratios. There were significant sex differences for certain age groups in both of the population groups. The 5th, 50th and 95th percentile cut-off values for these parameters were lower in fish-consumers than in non-fish-consumers. The prevalence of individuals at risk of CVD because of low HDL-C (<35 mg/dL), high LDL-C (>130 mg/dL) and their atherogenic ratios (LDL-C: HDL-C >3.5 and TC: HDL-C>4.5) was significantly greater in non-fish-consumers. This study highlights that the fish-consuming population had a lower atherogenic risk than the non-fish-consuming population. The intake of fish may have substantial implications for public health and health economy by decreasing the risk of CVD. However, more studies are warranted to better define the mechanisms of cardioprotection by dietary fish and fish oils.

Effect of stable fish oil on arterial thrombogenesis, platelet aggregation, and superoxide dismutase activity

We examined the influence of dietary stable fish oil on aortic thrombosis, platelet aggregation, and superoxide dismutase (SOD) activity in a rat model. Twenty-nine Sprague-Dawley rats were fed regular chow supplemented with stable fish oil preparation (for 1 or 3 weeks), and 37 rats fed regular chow served as controls. The abdominal cavity was opened, and the abdominal aorta isolated. Whatman paper impregnated with 35% FeCl3 was wrapped around the surface of the aorta, and aortic flow was continuously recorded. In control rats, an occlusive platelet-fibrin-rich thrombus was formed in 21 +/- 3 min. Dietary fish oil in a time-dependent fashion delayed time to thrombus formation (24 +/- 2 min in rats fed fish oil for 1 week and 31 +/- 2 min in rats fed fish oil for 3 weeks), inhibited platelet aggregation (21 +/- 5% vs. 45 +/- 6%; p < 0.01) and increased SOD activity (p < 0.01). We conclude that dietary supplementation with stable fish oil delays formation of arterial thrombus, probably by reducing platelet aggregation and oxidative stress-associated arterial injury.

Cholesterol removal from homogenized milk with beta-cyclodextrin

This study was carried out to determine optimum conditions of five different factors (beta-cyclodextrin concentration, mixing temperature, mixing time, centrifugal force, and centrifugation time) in reduction of cholesterol in 3.6% fat, homogenized milk by application of beta-cyclodextrin. beta-Cyclodextrin at 0.5 to 1.5% provided 92.2 to 95.3% removal of cholesterol when mixed at 10 degrees C for 10 min. Among other factors, mixing time (5 to 20 min) did not significantly affect cholesterol removal. Removal was enhanced with increasing centrifugal forces up to 166x g (95.9%) but decreased thereafter. Various centrifugation times (5 to 20 min) did not have significant effects. Based on these results, we suggest that the optimum conditions for the process are addition of 1.5% beta-cyclodextrin, mixing temperature of 10 degrees C, 10-min mixing time, and centrifugation at 166x g for 10 min.

Olive oil- and fish oil-enriched diets modify plasma lipids and susceptibility of LDL to oxidative modification in free-living male patients with peripheral vascular disease: the Spanish Nutrition Study

The present study describes a clinical trial in which Spanish patients suffering from peripheral vascular disease (Fontaine stage II) were given specific lipid supplements. Designed as a longitudinal intervention study, patients were provided with olive oil for 3 months, followed by a 3 month wash-out period, then supplemented with a combination of fish oil and olive oil for the final 3 months. Changes in plasma and lipoprotein fatty acid composition and susceptibility of LDL to in vitro oxidation were examined. Furthermore, lipid-supplement-induced changes in LDL properties were measured as relative electrophoretic mobility and macrophage uptake. In addition, thirteen patients not provided with olive oil and fish oil were included as a control group and twenty healthy age-matched individuals were used as a reference group. A complete clinical study and a nutritional survey concerning food habits and lifestyle were performed every 3 months. Yao indices and claudicometry did not change significantly with dietary intervention although changes in plasma lipid composition suggested an improvement in the condition of the patients. The intake of the fish-oil supplement resulted in significantly increased plasma levels of eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3) in comparison with baseline concentrations, olive-oil and control groups. Fish-oil consumption significantly decreased plasma triacylglycerol levels compared with the olive-oil period, control and reference groups. The susceptibility of LDL to Cu-mediated oxidation was lower in the patients consuming olive oil and the fish-oil supplement than in the control group, and the uptake of LDL by macrophages was significantly lower in the group supplemented with fish oil. In conclusion, consumption of olive oil together with a dietary supplement of fish oil may be useful in the nutritional management of patients suffering from peripheral vascular disease in terms of increasing plasma n-3 long-chain polyunsaturated fatty acids and decreasing susceptibility of LDL to oxidation.

Dietary intake and practices in the Hong Kong Chinese population

OBJECTIVES

To examine dietary intake and practices of the adult Hong Kong Chinese population to provide a basis for future public health recommendations with regard to prevention of certain chronic diseases such as cardiovascular disease, hypertension, and osteoporosis.

PARTICIPANTS

Age and sex stratified random sample of the Hong Kong Chinese population aged 25 to 74 years (500 men, 510 women).

METHOD

A food frequency method over a one week period was used for nutrient quantification, and a separate questionnaire was used for assessment of dietary habits. Information was obtained by interview.

RESULTS

Men had higher intakes of energy and higher nutrient density of vitamin D, monounsaturated fatty acids and cholesterol, but lower nutrient density of protein, many vitamins, calcium, iron, copper, and polyunsaturated fatty acids. There was an age related decrease in energy intake and other nutrients except for vitamin C, sodium, potassium, and percentage of total calorie from carbohydrate, which all increased with age. Approximately 50% of the population had a cholesterol intake of < or = 300 mg; 60% had a fat intake < or = 30% of total energy; and 85% had a percentage of energy from saturated fats < or = 10%; criteria considered desirable for cardiovascular health. Seventy eight per cent of the population had sodium intake values in the range shown to be associated with the age related rise in blood pressure with age. Mean calcium intake was lower than the FAO/WHO recommendations. The awareness of the value of wholemeal bread and polyunsaturated fat spreads was lower in this population compared with that in Australia. There was a marked difference in types of cooking oil compared with Singaporeans, the latter using more coconut/palm/mixed vegetable oils.

CONCLUSION

Although the current intake pattern for cardiovascular health for fat, saturated fatty acid, and cholesterol fall within the recommended range for over 50% of the population, follow up surveys to monitor the pattern would be needed. Decreasing salt consumption, increasing calcium intake, and increasing the awareness of the health value of fibre may all be beneficial in the context of chronic disease prevention.

Effect of the dietary fat type on arterial thrombosis tendency: systematic studies with a rat model

To study the influence of dietary fatty acids on arterial thrombosis tendency 65 groups of male rats were fed diets containing 50% of their digestible energy as fat from 32 different oils and fats. After 8 weeks their arterial thrombosis tendency was assessed by measuring the obstruction time (OT) of a loop-shaped polythene cannula inserted into the abdominal aorta. Using multiple regression analysis log10 OT was modelled as a function of the relative amounts of the various dietary fatty acids and their combinations. The best fit (R2 = 0.79) was obtained for the sums of all monoenoic and (n-6) and (n-3) polyenoic fatty acids, which appeared antithrombotic. The fit for the sum of all saturated fatty acids, which had a prothrombotic effect, was almost as good (R2 = 0.76). The ratio between dietary polyunsaturated and saturated fatty acids (P:S ratio) appeared a strong predictor of arterial thrombosis tendency (R2 = 0.77). Marine oils did not have a more powerful antithrombotic effect than could be expected on the basis of their P:S ratios. Using stepwise regression analysis myristic acid, 14:0, was shown to be the strongest prothrombotic fatty acid whereas linoleic acid, 18:2(n-6), was the strongest antithrombotic fatty acid. Since the number of marine oils was very limited the effects of the 'fish fatty acids' eicosapentaenoic acid, 20:5(n-3) and docosahexaenoic acid, 22:6(n-3), on arterial thrombus formation could not be tested reliably. The same appeared true for gamma-linolenic acid, 18:3(n-6), and stearidonic acid, 18:4(n-3), present in a few vegetable oils only.

Effects of dietary fatty acid composition on plasma cholesterol

It should be clear from the preceding sections that the effects of dietary fatty acids on plasma lipids get more complicated the more we try to simplify them! We have presented one argument as to how different fatty acids may interact to impact human plasma lipids. This is by no means an endorsement that ours is the only argument. Nevertheless, a strong case can be made for 14:0 and 18:2 as being the key players in this scenario. The role of palmitic acid seems to be the most controversial. While clearly certain studies do indeed reveal 16:0 to be hypercholesterolemic relative to 18:1, the data from studies suggesting that it behaves similarly to 18:1 are equally compelling. What is certain is that it is erroneous to assume that 16:0 is the major cholesterol-raising SFA simply because it is the most abundant SFA in the diet. Clearly, 18:0 cannot be considered cholesterol-elevating. One is therefore left with the 12-16C SFA. However, 12:0 and 14:0 are only of concern if diets contain palm-kernel, coconut oil or dairy products as major dietary constituents. Accordingly one is left with 16:0 and its response is highly dependent on the metabolic status as well as the age of the subjects being used. While "elderly" hypercholesterolemic humans clearly benefit from decreased 16:0 (and all SFA) consumption, "younger" normocholesterolemic subjects fail to show such clear-cut effects. Additionally, the concomitant levels of dietary cholesterol and 18:2 also have a major bearing on the cholesterolemic response of 16:0 As far as guidelines for the general public are concerned, clearly for people with TC > 225 and LDL-C > 130 mg/dl and/or those who are overweight (i.e. those percieved to be at high risk), the primary emphasis should clearly be on reducing total fat consumption. Decreasing saturated fat consumption will invariably also lower dietary cholesterol consumption. The latter manouver will generally lower TC and LDL-C. Whether the reduction occurs because of the removal of 14:0, or 16:0 and/or dietary cholesterol is a mute point, since most dietary guidelines advocate curtailing intake of animal and dairy products, which will result in reductions of all the SFA. It remains to be established whether life-long adherence to the above dietary guidelines in those subjects with normal cholesterol levels and an absence of the other conventional risk factors for CHD, will result in a subsequent decrease in CHD risk. In the latest NCEP report 39 million Americans were targeted as those who would benefit from reductions in LDL-C, principally by dietary means. This is indeed a very high number. But that leaves almost 220 million Americans! For them the age old recommendation to consume a moderate fat load, maintain ideal body weight and eat a varied and balanced diet would still appear to be the most powerful advice.