Changes in plasma lipids and other cardiovascular risk factors during 3 energy-restricted diets differing in total fat and fatty acid composition

BACKGROUND: The well-established relation between changes in dietary fatty acids and plasma lipids has been determined in energy-balance states. Whether this relation is altered in states of energy restriction and active weight loss is not clear. OBJECTIVE: The objective of this 12-wk study was to compare the time course of lipid changes and other cardiovascular risk factors in 3 energy-restricted diets (all 6500 kJ) with different total fat and fatty acid compositions. DESIGN: Sixty-two subjects with a body mass index (in kg/m(2)) >24 were stratified into 1 of 3 parallel dietary intervention groups: 1) a very-low-fat (VLF) diet (10% of energy from fat; 3% from saturated fat), 2) a high-saturated-fat (HSF) diet (32% of energy from fat; 17% from saturated fat), and 3) a high-unsaturated-fat (HUF) diet (32% of energy from fat; 6% from saturated fat). RESULTS: After 12 wk, LDL cholesterol decreased by 0. 66 +/- 0.11 (mean +/- SEM) and 0.68 +/- 0.12 mmol/L ( approximately 20%) with the VLF and HUF diets, respectively, compared with a decrease of only 0.24 +/- 0.11 mmol/L (7%) with the HSF diet (P < 0.02 between groups). Diet affected the time course of changes in HDL cholesterol with both high-fat diets, resulting in smaller reductions in HDL cholesterol at weeks 1 (P = 0.0004) and 4 (P = 0.02); however, these differences were no longer apparent by 12 wk. Overall weight loss was 8.6 +/- 0.4 kg (9.7%) and waist circumference decreased by 7.3 +/- 5 cm (8%) for the combined groups, with no significant differences between diets. CONCLUSIONS: Significantly greater decreases in LDL cholesterol during active weight loss are achieved with diets low in saturated fatty acids. Changes in HDL cholesterol between diets appear dependent on both the fat content of the diet and the duration of energy restriction.     

Palmitic and stearic acids similarly affect plasma lipoprotein metabolism in cynomolgus monkeys fed diets with adequate levels of linoleic acid

This study was designed to evaluate whether the exchange of specific saturated fatty acids [SFA; palmitic acid (16:0) for stearic acid (18:0)] would differentially affect plasma lipids and lipoproteins, when diets contained the currently recommended levels of total SFA, monounsaturated fatty acids and polyunsaturated fatty acids (PUFA). Ten male cynomolgus monkeys were fed one of two purified diets (using a cross-over design) enriched either in 16:0 (palmitic acid diet) or 18:0 (stearic acid diet). Both diets provided 30% of energy as fat (SFA/monounsaturated fatty acid/PUFA: 1/1/1). The palmitic acid and stearic acid diets were based on palm oil or cocoa butter (59% and 50% of the total fat, respectively). By adding different amounts of sunflower, safflower and olive oils, an effective exchange of 16:0 for 18:0 of approximately 5% of energy was achieved with all other fatty acids being held constant. Monkeys were rotated through two 10-wk feeding periods, during which time plasma lipids and in vivo lipoprotein metabolism (following the simultaneous injection of (131)I-LDL and (125)I- HDL were evaluated). Plasma triacyglycerol (0.40 +/- 0.03 vs. 0.37 +/- 0.03 mmol/L), plasma total cholesterol (3.59 +/- 0.18 vs. 3.39 +/- 0.23 mmol/L), HDL cholesterol (1.60 +/- 0.16 vs 1.53 +/- 0.16 mmol/L) and non-HDL cholesterol (2.02 +/- 0.26 vs. 1.86 +/- 0.23 mmol/L) concentrations did not differ when monkeys consumed the palmitic acid and stearic acid diets, respectively. Plasma lipoprotein compositional analyses revealed a higher cholesteryl ester content in the VLDL fraction isolated after consumption of the stearic acid diet (P < 0.10), as well as a larger VLDL particle diameter (16.3 +/- 1.7 nm vs. 13.8 +/- 3.6 nm; P < 0.05). Kinetic analyses revealed no significant differences in LDL or HDL transport parameters. These data suggest that when incorporated into diets following current guidelines, containing adequate PUFA, an exchange of 16:0 for 18:0, representing approximately 11 g/(d.10.46 mJ) [ approximately 11 g/(d.2500 kcal)] does not affect the plasma lipid profile and has minor effects on lipoprotein composition. Whether a similar effect would occur in humans under comparable dietary conditions remains to be established.     

Comparison of Effects of Long-Term Low-Fat vs High-Fat Diets on Blood Lipid Levels in Overweight or Obese Patients: A Systematic Review and Meta-Analysis

Dietary fat plays an important role in the primary prevention of cardiovascular disease, but long-term (≥12 months) effects of different percentages of fat in the diet on blood lipid levels remain to be established. Our systematic review and meta-analysis focused on randomized controlled trials assessing the long-term effects of low-fat diets compared with diets with high amounts of fat on blood lipid levels. Relevant randomized controlled trials were identified searching MEDLINE, EMBASE, and the Cochrane Trial Register until March 2013. Thirty-two studies were included in the meta-analysis. Decreases in total cholesterol (weighted mean difference –4.55 mg/dL [–0.12 mmol/L], 95% CI –8.03 to –1.07; P=0.01) and low-density lipoprotein (LDL) cholesterol (weighted mean difference –3.11 mg/dL [–0.08 mmol/L], 95% CI –4.51 to –1.71; P<0.0001) were significantly more pronounced following low-fat diets, whereas rise in high-density lipoprotein (HDL) cholesterol (weighted mean difference 2.35 mg/dL [0.06 mmol/L], 95% CI 1.29 to 3.42; P<0.0001) and reduction in triglyceride levels (weighted mean difference –8.38 mg/dL [–0.095 mmol/L], 95% CI –13.50 to –3.25; P=0.001) were more distinct in the high-fat diet groups. Including only hypocaloric diets, the effects of low-fat vs high-fat diets on total cholesterol and LDL cholesterol levels were abolished. Meta-regression revealed that lower total cholesterol level was associated with lower intakes of saturated fat and higher intakes of polyunsaturated fat, and increases in HDL cholesterol levels were related to higher amounts of total fat largely derived from monounsaturated fat (of either plant or animal origin) in high-fat diets (composition of which was ～17% of total energy content in the form of monounsaturated fatty acids, ～8% of total energy content in the form of polyunsaturated fatty acids), whereas increases in triglyceride levels were associated with higher intakes of carbohydrates. In addition, lower LDL cholesterol level was marginally associated with lower saturated fat intake. The results of our meta-analysis do not allow for an unequivocal recommendation of either low-fat or high-fat diets in the primary prevention of cardiovascular disease.     

Replacing cows' with sheep's dairy fat lowers plasma cholesterol concentration in participants consuming dairy fat-rich diets

OBJECTIVE: To determine the effects on plasma cholesterol concentration of replacing cows' dairy fat with sheep's dairy fat. DESIGN: Randomised crossover dietary intervention. SETTING: General community, Dunedin, New Zealand. SUBJECTS: Volunteer sample of 41 healthy adults with initial plasma cholesterol concentration between 4.8 and 7.8 mmol/l. INTERVENTIONS: Participants were asked to follow a self-selected low-fat background diet throughout the study to which, during each of the 2, 3-week dairy diets, they were asked to add sheep's or cows' dairy products. MAIN OUTCOME MEASURES: Energy and nutrient intakes, plasma triacylglycerol fatty acids, and plasma cholesterol. RESULTS: Energy and nutrient intakes on the sheep-dairy and cow-dairy diets were very similar, with total, saturated, monounsaturated and polyunsaturated fat contributing 34, 18-19, 9, and 3% of total energy intake, respectively. Participants consumed approximately 50 g/day of dairy fat on each diet. Replacing cows' with sheep's dairy fat led to a 0.33 (0.11-0.56, 95% CI) mmol/l decrease (6%) in plasma total cholesterol concentration, from 5.53 (0.90, s.d.) to 5.20 (0.90) mmol/l. Plasma low-density lipoprotein (LDL) cholesterol was 0.18 (0.02-0.33) mmol/l lower on the sheep-dairy diet as was the concentration of plasma high-density lipoprotein (HDL) cholesterol, 0.11 (0.02-0.20) mmol/l. The LDL to HDL cholesterol ratio at the end of the sheep-dairy diet, 2.91 (1.10), was not significantly different (P>0.05) from the cow-dairy diet, 2.73 (0.83). CONCLUSIONS: Within the context of a diet high in dairy fat (50 g/day), replacing cows' milk fat with sheep's milk fat leads to a small reduction in plasma cholesterol concentration, but no change in the ratio of LDL to HDL cholesterol.     

Effects of diet on blood lipid levels: western-type diet and 'prudent' diet compared

A small cross-over study among ten free-living volunteers was carried out to determine the changes in plasma cholesterol levels [total, high density lipoproteins (HDL) and subfractions) during two dietary regimens. One diet, designated as 'western' was characterized by high saturated fat (46% energy from fat, 24% from saturated fat), low fibre and no fish; the other designated 'prudent' permitted ad lib consumption of fish, chicken, high-fibre bread and cereals, vegetables and fruit but a minimum of dairy and meat products (21% energy from fat, 6% saturated). Between the ends of the 'western' and 'prudent' periods total cholesterol levels fell in all subjects, on average by 0.93 mmol/1. HDL cholesterol and its subfractions also tended to decrease, but not consistently in all subjects. Correlations between individual changes in fat intake and changes in plasma total cholesterol suggested a positive relationship (a large change in dietary fat associated with a large change in plasma total cholesterol). Changes in HDL cholesterol appeared to be negatively related to changes in fat and positively to changes in carbohydrate intakes. Changes in dietary energy levels showed no association with changes in lipid levels. On the basis of the present results, further studies are desirable to determine optimal dietary changes to achieve low plasma total cholesterol levels and conservation of HDL-cholesterol levels.     

Influence of type and amount of dietary lipid on plasma lipid concentrations in endurance athletes

Changes in plasma total cholesterol, triglyceride, and lipoprotein concentrations were assessed in three male endurance cyclists who consumed isoenergetic diets for 28-day periods in which carbohydrate, polyunsaturated fat, or saturated fat contributed about 50% of the daily energy intake. Dietary cholesterol was similar among the diets. Maximal aerobic capacity was maintained at 62 ml O2/(kg X min). Body weights were held within 3% of admission levels. The polyunsaturated fat diet significantly (p less than 0.05) reduced mean fasting plasma total cholesterol in comparison to the saturated fat and carbohydrate diets (160 versus 254 and 243 mg/dl, respectively). Similarly, the polyunsaturated fat diet depressed (p less than 0.05) mean plasma triglycerides relative to the saturated fat and carbohydrate diets (37 versus 62 and 79 mg/dl, respectively). No significant dietary effects were seen on high-density lipoprotein cholesterol. The observed changes in plasma total cholesterol were not significantly different than the values predicted by the Keys' equation, delta CHL = 1.35(2 delta S-delta P) + 1.5 delta Z. We conclude that under controlled conditions in which physical activity is constant l) dietary lipid differences influence fasting serum lipid and lipoprotein concentrations among men with high energy expenditures, and 2) the Keys' equation gives useful predictions of changes in plasma total cholesterol among vigorous men consuming different types and amounts of dietary lipid.     

Longitudinal study of dietary intakes and plasma lipids in healthy elderly men and women.

Dietary intakes and blood lipid concentrations were assessed in elderly men (n = 65) and women (n = 92) from 1980 through 1989. Mean age in 1980 was 70 y (range 60-84 y). Health and socioeconomic status was above that found in the general US elderly population. Cross-sectional and longitudinal changes in variables were determined by using least-squares linear regression. No significant cross-sectional differences in energy (kJ/kg), protein (g/kg), total fat, and carbohydrate intake with age was noted. Significant longitudinal decreases in total fat, saturated and polyunsaturated fatty acids, and cholesterol intakes were noted in both men and women. Significant decreases in total, HDL, and LDL plasma cholesterol concentrations were noted over time in both men and women. Ratios of both total and LDL cholesterol to HDL cholesterol increased over time. The decrease in total fat and cholesterol intakes were significantly correlated with the decrease in total plasma cholesterol.     

Dietary and other determinants of lipoprotein levels within a population of 315 Dutch males aged 28 and 29

The objective of this study was to estimate the strength of the association between diet and serum lipids and lipoproteins within a free-living population. Three hundred and fifteen Dutch males aged 28 and 29 were located via the Army registry. Their diets were assessed through a dietary history questionnaire plus oral cross-check, and blood was sampled twice at a 1-week interval. Height, weight, skinfolds, and waist and hip circumference were measured to estimate amount and location of body fat. Physical activity, social status and smoking were estimated through questionnaires. The range of cholesterol values predicted from differences in dietary fatty acid and cholesterol intake as summarized by the Keys equation score was 5.11 to 6.29 mmol/l, while the actual levels ranged from 3.30 to 9.28 mmol/l. Multiple regression analysis showed a weak but significant association of the Keys score with total cholesterol (slope 0.83, P less than 0.05), LDL cholesterol (slope 0.71, P less than 0.05), and the HDL/total cholesterol ratio (slope -0.04, P less than 0.01). The percentage of energy from alcohol was strongly and independently associated with both total and HDL cholesterol (slopes 0.04 and 0.02, P less than 0.001). Body fat parameters were strongly associated with all serum lipids and lipoproteins. We conclude that the contribution of dietary differences to differences in serum lipids and lipoproteins within this population is real but small.     

Changes in plasma lipoproteins during low-fat, high-carbohydrate diets: effects of energy intake

BACKGROUND: Low-fat diets can increase plasma triacylglycerol and reduce HDL cholesterol. Changes in energy intake and body weight can influence the lipoprotein response. OBJECTIVE: We sought to prospectively examine the effects of euenergetic and ad libitum dietary fat restriction on plasma lipoproteins in healthy postmenopausal women. DESIGN: Participants first received a controlled euenergetic diet in which dietary fat was reduced stepwise from 35% to 25% to 15% over 4 mo. Thereafter, participants followed an ad libitum 15%-fat diet for 8 mo; 54 women completed the intervention. RESULTS: During the controlled euenergetic diet, plasma triacylglycerol increased from 1.70 +/- 0.10 to 2.30 +/- 0.16 mmol/L, total cholesterol decreased from 5.87 +/- 0.13 to 5.53 +/- 0. 13 mmol/L, LDL cholesterol decreased from 3.41 +/- 0.10 to 2.87 +/- 0.10 mmol/L, HDL cholesterol decreased from 1.76 +/- 0.08 to 1.50 +/- 0.08 mmol/L, and apolipoprotein (apo) A-I decreased from 5.11 +/- 0.14 to 4.78 +/- 0.14 mmol/L (P < 0.0001 for all changes). Hormone replacement therapy did not affect the relative change in HDL cholesterol. Plasma glucose, insulin, hemoglobin A(1C,) free fatty acid, and apo B concentrations did not change significantly. During the ad libitum 15%-fat diet, participants lost 4.6 +/- 0.4 kg. Plasma triacylglycerol and LDL cholesterol returned to baseline values (1.77 +/- 0.12 and 3.31 +/- 0.08 mmol/L, respectively), whereas HDL cholesterol and apo A-I remained low (1.40 +/- 0.08 and 4.82 +/- 0.18 mmol/L, respectively). HDL cholesterol and apo A-I concentrations stabilized in subjects who were not receiving hormone replacement therapy but continued to decline in women who were receiving hormone therapy. CONCLUSIONS: The ad libitum 15%-fat diet resulted in significant weight loss. The euenergetic but not the ad libitum diet caused hypertriacylglycerolemia. HDL cholesterol decreased during both low-fat diets.     

Comparison between the effects of dietary saturated (16:0), monounsaturated (18:1), and polyunsaturated (18:2) fatty acids on plasma lipoprotein metabolism in cebus and rhesus monkeys fed cholesterol-free diets.

Cebus and rhesus monkeys were fed cholesterol-free diets providing 40% of energy as fat for 6-wk periods. The fats were high-linoleic acid safflower oil (HLSO), high-oleic acid safflower oil (HOSO), or palm oil (PO), rich in polyunsaturated (18:2), monounsaturated (18:1), or saturated (16:0) fatty acids, respectively. In cebus monkeys, plasma cholesterol concentrations during HLSO intake were 17-19% lower than those during HOSO or PO intake, attributed to a decrease in high-density lipoprotein (HDL). Plasma triglyceride (TG) and low-density-lipoprotein (LDL) cholesterol concentrations were comparable during all dietary treatments. Sixty-eight percent of total LDL catabolism was receptor mediated in all dietary groups and this was associated with similar apolipoprotein B pool sizes and fractional catabolic rates. Rhesus monkeys revealed similar cholesterol concentrations (total, LDL, and HDL) during all dietary treatments. TG concentrations during PO intake were 34% and 63% higher than those during HOSO and HLSO intakes, respectively. Hence, dietary 16:0 and 18:1 produce similar effects on LDL and HDL metabolism in normocholesterolemic primates.     

Replacing 40% of dietary animal fat with vegetable oil is associated with lower HDL cholesterol and higher cholesterol ester transfer protein in cynomolgus monkeys fed sufficient linoleic acid

This study was designed to evaluate whether replacing approximately 40 g/100 g dietary animal fat with vegetable oil would improve plasma lipids and lipoproteins when diets contained prudent levels of total saturated acid (SFA), monounsaturated acid (MUFA) and PUFA. Using a cross-over design, male Cynomolgus monkeys (n = 10) were fed purified diets containing a mixture of fats. For the diet based on animal fat (AF-diet), approximately 85 g/100 g of the total fat was derived from pork fat, and approximately 40 g/100 g of this was replaced with olive oil for the vegetable oil-based diet (VO-diet). Thus, the fat content of the VO diet comprised 50% pork fat and 35% olive oil. The remaining 15% of the total fat (for both diets) was safflower oil. Both diets provided approximately 30% of total energy (%en) from fat, <10%en SFA and approximately 6-7%en from PUFA. Monkeys were rotated through two 7-wk feeding periods, during which time plasma lipids and lipoproteins were evaluated. Compared with the AF diet, plasma total cholesterol (TC) concentrations tended to be lower ( approximately 10%) after monkeys consumed the VO diet (3.18 +/- 0.83 vs. 3.52 +/- 0.93 mmol/L, P = 0.099), and this was due entirely to a significant 12% reduction in HDL cholesterol (1.53 +/- 0.41 vs. 1.73 +/- 0.47, mmol/L, P = 0.0009). Although plasma lipoprotein compositional analyses revealed no significant differences in either lipoprotein composition or the estimated particle diameters, the measurement of cholesterol ester transfer protein (CETP) using (3)H-cholesterol ester-labeled HDL revealed that the lower HDL cholesterol (HDL-C) when monkeys consumed the VO diet was associated with a 31% increase in transfer (P = 0.04). However, despite the changes in HDL-C, the TC/HDL-C ratio did not differ between monkeys after the two diet treatments. Regression analyses of data from these monkeys revealed a significant correlation between the dietary 16:0/18:2 ratio and plasma HDL-C. These data suggest that within the context of currently recommended prudent diets, it may be possible to manipulate HDL-C beneficially. Whether a similar effect would occur in humans warrants investigation.     

Growth and lipid metabolism responses in rats fed different dietary fat sources

An experiment with male albino rats was conducted to examine the effect of dietary fat sources on growth performance and apparent digestibility of total fat and fatty acids. The effect on plasma and organ cholesterol concentrations as well as lipoproteins cholesterol and fatty acid profile of hepatic phospholipids was also examined. Forty 3 week old rats were fed purified diets containing 0.041% cholesterol and 7% fat (wt/wt) from soy oil (SO), or cow ghee (GH), or 25% fish oil (FO) plus soy oil (SF) or 25% fish oil plus 75% ghee (GF), or 50% soy oil plus 50% ghee (SG) for a period of 35 days. Final body weight, weight gain, organ weights and feed efficiency ratio showed no significant differences (P < 0.05) among the dietary treatments. The apparent digestibility of total dietary fat and saturated fatty acids in the animals fed diet containing cow ghee only or in combination with fish oil or soy oil was significantly lower than the other dietary groups. Consumption of ghee with combination of fish oil or soy oil lead to significant improvement in the fat apparent digestibility of dietary fat. Total cholesterol and triglyceride concentrations of plasma and organs as well as lipoprotein cholesterol levels were higher in animals fed diets containing ghee. For rats fed diet containing cow ghee in combination with fish oil or soy oil, the cholesterol content of total plasma, lipoprotein fractions (VLDL, LDL and HDL) and organs was decreased significantly. Furthermore, dietary fats altered the fatty acids composition of hepatic phosphlipid fatty acids composition. Feeding dietary fish oil reduced arachidonic acid (20:4) and increased linoleic acid (18:2) and eicosapentaenoic acid (20:5) contents. The reduction in the arachidonic acid was being more pronounced in animals fed dietary ghee with combination of fish oil.     

Growth and lipid metabolism responses in rats fed different dietary fat sources

An experiment with male albino rats was conducted to examine the effect of dietary fat sources on growth performance and apparent digestibility of total fat and fatty acids. The effect on plasma and organ cholesterol concentrations as well as lipoproteins cholesterol and fatty acid profile of hepatic phospholipids was also examined. Forty 3 week old rats were fed purified diets containing 0.041% cholesterol and 7% fat (wt/wt) from soy oil (SO), or cow ghee (GH), or 25% fish oil (FO) plus soy oil (SF) or 25% fish oil plus 75% ghee (GF), or 50% soy oil plus 50% ghee (SG) for a period of 35 days. Final body weight, weight gain, organ weights and feed efficiency ratio showed no significant differences (P < 0.05) among the dietary treatments. The apparent digestibility of total dietary fat and saturated fatty acids in the animals fed diet containing cow ghee only or in combination with fish oil or soy oil was significantly lower than the other dietary groups. Consumption of ghee with combination of fish oil or soy oil lead to significant improvement in the fat apparent digestibility of dietary fat. Total cholesterol and triglyceride concentrations of plasma and organs as well as lipoprotein cholesterol levels were higher in animals fed diets containing ghee. For rats fed diet containing cow ghee in combination with fish oil or soy oil, the cholesterol content of total plasma, lipoprotein fractions (VLDL, LDL and HDL) and organs was decreased significantly. Furthermore, dietary fats altered the fatty acids composition of hepatic phospholipid fatty acids composition. Feeding dietary fish oil reduced arachidonic acid (20:4) and increased linoleic acid (18:2) and eicosapentaenoic acid (20:5) contents. The reduction in the arachidonic acid was being more pronounced in animals fed dietary ghee with combination of fish oil.     

广州40～65岁居民膳食脂肪酸构成与血脂关系的研究

目的:分析广州中老年人膳食脂肪和脂肪酸构成(饱和脂肪酸:单不饱和脂肪酸:多不饱和脂肪酸,SFA:MUFA:PUFA,S:M:P)与血脂的关系。方法:招募40~65岁广州市民,用食物模具量化的食物频数问卷和三日膳食回顾调查对象每日摄入食物种类和数量,计算能量和营养素摄入量。结果:(1)188名男性,367名女性进入本研究。男女能量摄入分别为9.7±2.24和8.48±2.04MJ/d,脂肪供能比分别为28.3%±7.2%和30.4%±6.1%,S:M:P分别为1:1.5:0.9和1:1.5:1.1。(2)脂肪供能比≤30%(n=333)者总胆固醇(TC)、低密度脂蛋白(LDL)、甘油三酯(TG)水平均显著低于脂肪供能比>30%(n=222)者。(3)脂肪供能20%~30%时,不同S:M:P三组间的血脂水平无差异。(4)脂肪供能比30%~45%时,S:M:P为1:1.5:1的Ⅱ组TC、LDL水平均显著低于S:M:P为1:1.2:0.7的Ⅰ组和1:1.8:1.4的Ⅲ组。结论:与脂肪供能比>30%的膳食相比,脂肪供能比≤30%的膳食更有利于维持血脂正常;脂肪供能比≤30%时,不同S:M:P可能对血脂没有显著影响;而脂肪供能比为30%~45%,S:M:P为1:1.5:1的膳食比1:1.2:0.7和1:1.8:1.4的膳食更有利于维持血脂正常。     

Optimal macronutrient balance.

There is at present a justifiable debate as to the optimum level of total dietary fat which will reduce the risk of obesity without an elevation of plasma triacylglycerol or a depression of plasma HDL-cholesterol. Total plasma cholesterol and LDL-cholesterol levels are lowered and risk of fatal myocardial infarction is lowered when either saturated or trans-unsaturated fatty acids are replaced isoenergetically by either monounsaturated or polyunsaturated fatty acids. The triacylglycerol-raising and HDL-lowering effects of low-fat high-carbohydrate diets can be overcome with low intakes of n-3 polyunsaturated fatty acids and moderate exercise. Whilst a reduction in dietary fat is being attained in many countries, the reduction is uniform across all fatty acids, leaving dietary fat composition unchanged. The ability of low-fat diets to reduce cholesterol and cause a fall in body weight is not influenced by the carbohydrate ratio starch: sugars in the diet. However, weight-gain susceptibility to high intakes of dietary fat and the plasma cholesterol responsiveness to diet are considerably influenced by common genetic polymorphisms.     

Boys from populations with high-carbohydrate intake have higher fasting triglyceride levels than boys from populations with high-fat intake

Experimentally, high-carbohydrate diets have been shown to elevate triglycerides, but it has not been established whether this rise is permanent or transient. The authors approached this question by studying 719 boys from worldwide populations with marked differences in long-term carbohydrate intake. Fasting serum triglycerides, total cholesterol and high density lipoprotein (HDL) cholesterol concentrations were measured in boys aged 8 and 9 years from 12 countries--eight in Europe, three in Africa, and one in Asia. A standardized protocol was used for obtaining fasting blood and for the preparation, storage and transport of serum, and all measurements were made in one laboratory. Published values were used for the United States. Mean values for lipid levels per country were compared with the percentage of daily energy intake consumed as carbohydrate or fat, as determined by survey. Boys from populations with higher carbohydrate and lower fat intake had lower low density lipoprotein (LDL) cholesterol levels (univariate regression coefficient (+/- standard error, -0.028 +/- 0.009 mmol/liter for each percent of energy from carbohydrate; p less than 0.01, n = 13), but they also had higher fasting triglycerides (0.010 +/- 0.002 mmol/liter for each percent of energy from carbohydrate; p less than 0.01, n = 13) and lower HDL cholesterol levels (-0.022 +/- 0.003 mmol/liter for each percent of energy from carbohydrate; p less than 0.001, n = 13). These trends agree with results from epidemiologic studies within populations and from controlled dietary trials, and suggest that in normolipidemic healthy subjects, high-carbohydrate, low-fat diets cause higher triglyceride levels than diets that are higher in fats and oils.     

Effects of the National Cholesterol Education Program's Step I and Step II dietary intervention programs on cardiovascular disease risk factors: a meta-analysis

BACKGROUND: Plasma lipid and lipoprotein responses have been variable in dietary intervention studies. OBJECTIVE: The objective of this study was to evaluate the effects of the National Cholesterol Education Program's Step I and Step II dietary interventions on major cardiovascular disease risk factors using meta-analysis. DESIGN: MEDLINE was used to select 37 dietary intervention studies in free-living subjects published from 1981 to 1997. RESULTS: Step I and Step II dietary interventions significantly decreased plasma lipids and lipoproteins. Plasma total cholesterol (TC), LDL cholesterol, triacylglycerol, and TC:HDL cholesterol decreased by 0.63 mmol/L (10%), 0.49 mmol/L (12%), 0.17 mmol/L (8%), and 0.50 (10%), respectively, in Step I intervention studies, and by 0.81 mmol/L (13%), 0.65 mmol/L (16%), 0.19 mmol/L (8%), and 0.34 (7%), respectively, in Step II intervention studies (P < 0.01 for all). HDL cholesterol decreased by 7% (P = 0.05) in response to Step II but not to Step I dietary interventions. Positive correlations between changes in dietary total and saturated fatty acids and changes in TC and LDL and HDL cholesterol were observed (r = 0.59, 0.61, and 0.46, respectively; P < 0.001). Multiple regression analyses showed that for every 1% decrease in energy consumed as dietary saturated fatty acid, TC decreased by 0.056 mmol/L and LDL cholesterol by 0.05 mmol/L. Moreover, for every 1-kg decrease in body weight, triacylglycerol decreased by 0.011 mmol/L and HDL cholesterol increased by 0.011 mmol/L. Exercise resulted in greater decreases in TC, LDL cholesterol, and triacylglycerol and prevented the decrease in HDL cholesterol associated with low-fat diets. CONCLUSION: Step I and Step II dietary interventions have multiple beneficial effects on important cardiovascular disease risk factors.     

Weight loss is correlated with an improved lipoprotein profile in obese postmenopausal women

BACKGROUND: Changes in plasma lipid and lipoprotein distributions that occur after menopause increase the risk of cardiovascular disease in women, especially in those who are overweight. OBJECTIVE: The purpose of this study was to evaluate the impact of a nine-month weight reduction program on plasma lipids, dietary intake and abdominal fat obesity. DESIGN: A partial crossover design was used to study a weight loss treatment consisting of Phentermine hydrochloride (Fastin, SmithKline Beecham Pharmaceuticals, Philadelphia, PA) therapy plus a low energy diet (5040 kJ/d). Forty-seven obese, postmenopausal Caucasian women (BMI of 30-38 kg/m2) were randomized into two groups, both of which received drug and diet treatment over six months. However, Group I started the intervention program three months later than Group II. Plasma total, HDL and LDL cholesterol and triacylglycerol were measured, body composition was assessed by anthropometry and dual energy x-ray absorptiometry, and food frequency records were collected at four timepoints. RESULTS: Over nine months, women in Group II reduced body weight (14.4%), lowered plasma concentrations of LDL cholesterol (14% to 26%) and triacylglycerol (15%) and raised plasma HDL cholesterol concentration (15%). These plasma lipid changes decreased the total cholesterol/HDL cholesterol ratio from 4.3 to 3.2. All subjects decreased abdominal fat measurements and energy and cholesterol intakes, as well as percentage of energy derived from total and saturated fat during the study. Most subjects also increased dietary fiber consumption. CONCLUSION: Both weight loss and diet modifications are associated with an improved plasma lipid profile in obese postmenopausal women.     

The effect of diet on plasma lipids, lipoproteins, and coronary heart disease

The role that diet plays in the management of plasma lipid levels is discussed in this review. It has long been recognized that saturated fatty acids and cholesterol raise the plasma cholesterol level whereas polyunsaturated fatty acids lower it. Recently, the effects of other dietary constituents in the management of plasma lipid levels have been established. In particular, monounsaturated fatty acids, soluble fiber, and vegetarian diets favorably affect plasma lipid levels. Overweight and obesity adversely affect plasma lipid levels. Omega-3 fatty acids are hypotriglyceridemic, and high carbohydrate diets low in saturated fatty acids are hypocholesterolemic. Further work is required to establish the long-term consequences of alcohol and coffee consumption on the plasma lipid response. A variety of alternative dietary strategies can be employed in conjunction with traditional dietary recommendations (i.e., reduce total fat, especially saturated fatty acids and dietary cholesterol) for the management of plasma lipid levels. The expected plasma total cholesterol (specifically low-density-lipoprotein cholesterol) reduction is approximately 10% to 20% when dietary saturated fatty acids and cholesterol are decreased to less than or equal to 7% of calories and less than or equal to 200 mg of cholesterol per day. Further dietary modifications, such as increasing soluble fiber, may lead to additional reductions of 1% to 10% in plasma total cholesterol.     

An eight-month controlled study of a low-fat high-fibre diet: effects on blood lipids and blood pressure in healthy young subjects.

The effects on blood lipids and blood pressure of a diet corresponding to present Nordic Nutrition Recommendations, i.e. less than 30% of energy from fat and with a fibre content exceeding 3 g/MJ, were studied in 18 men and 12 women (mean age, 24 years) under strict dietary control over 8 months. Blood sampling, blood pressure and body weight measurement were performed at four occasions on their habitual diet and once a month during the intervention period. An age-matched control group (17 men, 8 women) was followed with monthly measurements parallel to the intervention group. The habitual diets, assessed by 7-day records, showed an average fat content corresponding to 36% of energy. Initial levels of total cholesterol and HDL cholesterol (X +/- SD) were 4.21 +/- 0.61 and 1.23 +/- 0.23 mmol/l for the men in the intervention group; 4.35 +/- 0.79 and 1.21 +/- 0.26 mmol/l for the male controls; 4.61 +/- 0.59 and 1.46 +/- 0.31 mmol/l for the women in the intervention group and 4.48 +/- 0.64 and 1.48 +/- 0.29 mmol/l for the female controls. Significantly decreased levels of total cholesterol and HDL cholesterol throughout the experimental period were seen for both sexes in the intervention group. Total cholesterol fell 0.49 mmol/l (95% CI: 0.41-0.56) in the male subjects and 0.49 mmol/l (95% CI: 0.39-0.59) in the female subjects. The fall in HDL cholesterol was 0.16 mmol/l (95% C: 0.13-0.18) and 0.18 mmol/l (95% CI: 0.12-0.23), respectively. Total cholesterol changes were independent of initial values. All subjects were normotensive at the start of the study with an average blood pressure of 122/68 mmHg for men and 112/68 mmHg for the women. Systolic blood pressure dropped gradually and significantly in the male subjects of the intervention group. A minimum of 6 mmHg below initial values was noted after six months of dietary intervention. No significant changes in dietary intake and blood lipids were observed in the control group. Thus, changes of present dietary habits of young healthy Danish subjects to an intake in accordance with the Nordic Nutrition Recommendations 1989 will favourably affect suggested risk factors for disease.