Lipids, lipoproteins and fatty acid composition in obese adolescents undergoing a very low calorie diet

Sixteen obese adolescents (mean +/- SD age: group I 12.5 +/- 2.1 and group II 12.0 +/- 2.5 years) were treated at least 3 weeks with two different very low calorie diet (VLCD) regimens. The VLCD in group I contained 33g proteins, 25.5g carbohydrates and 0.7g fat (240 kcal, 1004KJ) and in group II 44g protein, 33g carbohydrates and 0.9g fat (320 kcal, 1339KJ). After the 3 weeks treatment total serum cholesterol decreased from 180 +/- 34 mg/dl in group I and 184 +/- 34 mg/dl in group II respectively, to 125 + 16 mg/dl and 120 + 22 mg/dl. This fall was mainly due to the highly significant decrease of LDL-cholesterol. VLDL-cholesterol, HDL-cholesterol and triglycerides in group I remained almost unchanged. In group II triglycerides increased significantly from 81 +/- 19 mg/dl to 104 +/- 19 mg/dl and HDL-cholesterol decreased slightly. The LDL-C HDL-C- ratio in both groups improved considerably. Fatty acid composition of the serum lipids changed only slightly: In total serum linoleic acid levels declined slightly in group I and remained constant in group II. Linoleic acid content in cholesterylesters declined moderately in group I from 37.5 +/- 5.6% to 34.8 +/- 5.6% whereas arachidonic acid increased slightly in both groups. In phospholipids, oleic acid declined in both groups significantly, linoleic acid declined significantly in group I and arachidonic acid increased in group I significantly. Similar changes occurred in triglycerides. After 3 weeks treatment with a practically fat free alimentation no biochemical signs of essential fatty acid deficiency could be detected.     

Effects of including a ruminally protected lipid supplement in the diet on the fatty acid composition of beef muscle

Enhancing the polyunsaturated fatty acid (PUFA) and decreasing the saturated fatty acid content of beef is an important target in terms of improving the nutritional value of this food for the consumer. The present study examined the effects of feeding a ruminally protected lipid supplement (PLS) rich in PUFA on the fatty acid composition of longissimus thoracis muscle and associated subcutaneous adipose tissue. Animals were fed ad libitum on grass silage plus one of three concentrate treatments in which the lipid source was either Megalac (rich in palmitic acid; 16 : 0) or PLS (soybean, linseed and sunflower-seed oils resulting in an 18 : 2n-6:18 : 3n-3 value of 2.4:1). Treatment 1 contained 100 g Megalac/kg (Mega, control); treatment 2 (PLS1) contained 54 g Megalac/kg with 500 g PLS/d fed separately; treatment 3 (PLS2) contained no Megalac and 1000 g PLS/d fed separately. The PLS was considered as part of the overall concentrate allocation per d in maintaining an overall forage:concentrate value of 60:40 on a DM basis. Total dietary fat was formulated to be 0.07 of DM of which 0.04 was the test oil. Total intramuscular fatty acids (mg/100 g muscle) were decreased by 0.31 when feeding PLS2 compared with Mega (P<0.05). In neutral lipid, the PLS increased the proportion of 18 : 2n-6 and 18 : 3n-3 by 2.7 and 4.1 on diets PLS1 and PLS2 v. Mega, respectively. Similar responses were noted for these fatty acids in phospholipid. The amounts or proportions of 20 : 4n-6, 20 : 5n-3 or 22 : 6n-3 were not influenced by diet whereas the amounts and proportions of 22 : 4n-6 and 22 : 5n-3 in phospholipid were decreased with inclusion of the PLS. The amounts of the saturated fatty acids, 14 : 0, 16 : 0 and 18 : 0, in neutral lipid were on average 0.37 lower on treatment PLS2 compared with Mega. Feeding the PLS also decreased the proportion of 16 : 0 in neutral lipid. The amount of 18 : 1n-9 (P=0.1) and the amount and proportion of 18 : 1 trans (P<0.01) were lower on treatments PLS1 and PLS2 in neutral lipid and phospholipid. Conjugated linoleic acid (cis-9, trans-11) was not influenced by diet in the major storage fraction for this fatty acid, neutral lipid. The PUFA:saturated fatty acids value was increased markedly (x2.5) with inclusion of the PLS (P<0.001) while the Sigman-6 : n-3 value increased slightly (x1.2; P=0.015). The results suggest that the protected lipid used, which was rich in PUFA, had a high degree of protection from the hydrogenating action of rumen micro-organisms. The PLS resulted in meat with a lower content of total fat, decreased saturated fatty acids and much higher 18 : 2n-6 and 18 : 3n-3. The net result was a large shift in polyunsaturated: saturated fatty acids, 0.28 v. 0.08, on feeding PLS2 compared with Mega, respectively.     

The impact of the changing fatty acid profile of fats on diet assessment and health

We are transiting a time in which advances in plant molecular biology and genetics have resulted in a remarkable array of oils and fats that have a modified fatty acid profile, compared to the parent stock variety. The rapid evolution of modified oils and fats poses challenges for keeping nutrient databases current as well as deciphering what new fats/oils are used, from the standpoint of diet assessment and, in particular, collecting accurate dietary data. The expanding array of modified fats and oils has been designed to have greater shelf stability due to an increase in monounsaturated fat and enhanced health benefits due to a reduction in trans fat. The effects of oilseeds reduced in alpha-linolenic acid (ALA) on health outcomes need to be evaluated since diets rich in ALA have many health benefits.     

Changes in the maternal essential fatty acid profile during early pregnancy and the relation of the profile to diet

BACKGROUND: Although the pattern of the essential fatty acids (EFAs) changes considerably from week 10 of pregnancy to term, no information is available on changes in EFA concentrations in the early stages of pregnancy. OBJECTIVE: The main objectives were to assess the EFA status, particularly that of 22:6n-3, in women during the first 10 wk of pregnancy and to investigate the relation of EFA status to dietary EFA intake during this period. DESIGN: Healthy women (n = 24) planning to become pregnant were recruited. The fatty acid composition of plasma and erythrocyte phospholipids was determined before and at weeks 4, 6, 8, and 10 of pregnancy. Food intake was assessed at entry into the study and at week 10 of pregnancy by using food-frequency questionnaires. RESULTS: A small but nonsignificant increase in dietary intake of 22:6n-3 was found. The plasma phospholipid content of 22:6n-3 (% by wt) increased continuously during the first 10 wk of pregnancy. At week 10 of pregnancy, the plasma percentages of 16:0, 20:3n-6, and 20:4n-6 had increased significantly, whereas the percentages of the 18-24-carbon saturated fatty acids, 18:2n-6, and the ratio of n-6 to n-3 fatty acids had dropped significantly. The composition of erythrocyte phospholipids showed changes similar to those observed in plasma. CONCLUSIONS: Maternal plasma and erythrocyte phospholipid 22:6n-3 concentrations start to increase in very early pregnancy, which cannot be explained by changes in dietary intake alone. This rise probably represents early maternal adaptations to meet the requirements of highly proliferating and differentiating tissues at this stage of fetal development.     

孕期不同膳食模式对膳食脂肪酸含量及母初乳脂肪酸组成的影响

【目的】研究中国两种不同膳食模式地区膳食脂肪酸(fatty acid,FA)含量的差异,并探讨这种差异对母初乳脂肪酸组成的影响。【方法】对传统内陆膳食(常州)和海洋膳食(温州)地区孕晚期孕妇进行7d膳食调查,根据《2002中国食物成份数据》中的食物脂肪酸含量数据计算出膳食脂肪酸含量;并通过随访这些孕妇收集5d母初乳样本,采用高效毛细气相色谱分析技术检测5d母初乳的脂肪酸组成。【结果】常州与温州两地孕母摄入的膳食种类存在差异,温州地区孕母摄入的海洋食品远大于常州地区。常州地区孕母膳食脂肪酸中亚油酸(linoleic acid,LA)和α-亚麻酸(α-linolenic acid,ALA)含量均高于温州地区;而二十二碳六烯酸(docosahexaenoic acid,DHA)和二十碳五烯酸(eicosap-entaenoic acid,EPA)含量均低于温州地区;花生四稀酸(arachidonic acid,AA)含量则未见显著差异。两地膳食脂肪酸组成中LA、ALA、AA以及DHA的差异同样反应在5d母初乳中,但两地5d母初乳中的EPA含量差异无显著性。【结论】膳食模式不同的两个地区,其孕母的膳食脂肪酸含量存在差异,且这种差异可在母初乳脂肪酸组成中得到体现。     

Effects of a normolipidic diet containing trans fatty acids during perinatal period on the growth, hippocampus fatty acid profile, and memory of young rats according to sex

ObjectiveTo investigate whether dietary trans fatty acids (TFAs) are incorporated in the hippocampus and its effects on the growth and aversive and spatial memories of young rats.MethodsWistar rat offspring whose mothers were fed with normolipidic diets containing soybean oil (soy group) or hydrogenated vegetable oil (trans group) during gestation and lactation were used. Male and female pups received the same diets as their mothers until the end of behavioral testing. The composition of fatty acids in the total lipids of the diets and hippocampus was quantified by gas chromatography. The results were evaluated by Student’s t test or analysis of variance followed by the Bonferroni correction.ResultsThe trans male and female body weights were higher during lactation and after weaning, with trans males having the lower body weight of the two. There was incorporation of 0.11% and 0.17% of TFAs in the hippocampi of male and female rats, respectively. During passive avoidance test, there was no significant difference. In the water maze test, there was no significant difference between male groups in the training and retention phases, except on day 4, when there was a significant decrease in latency in trans males. Trans females were worse on day 2 only and showed an improvement in spatial memory during the probe trial.ConclusionThe TFAs were incorporated in small amounts in the hippocampus and did not affect aversive memory. However, spatial memory was modified in young rats fed with a diet rich in TFAs. These findings suggested that, in addition to the TFA content of the diet provided, it is important to consider the provision of essential fatty acids and the ω-6/ω-3 ratio.     

Reassessment of trans fatty acid availability in the US diet

This report updates our 1984 estimate of the amount of trans fatty acids available for consumption in the US diet, namely 7.6 g.person-1.d-1, for 1989. Compared with 1984 data, we found essentially no change in 1989 for the per capita availability of trans fatty acids from total food service fats and oils. The 1989 value we obtained for industrial fats and oils is somewhat higher than the value we reported for 1984, in part because more complete data were available for 1989. In contrast, however, since 1984 the per capita availability of trans fatty acids from household salad and cooking oils, household shortenings, and all margarines and spreads (retail, food service, and industrial) has decreased. Overall, our reassessed (1989) value for total trans fatty acid availability is 8.1 g.person-1.d-1, which is similar to our original estimate. This total may increase slightly (approximately 0.3 g.person-1.d-1) as a result of the recent switch by many establishments from the use of tallow to partially hydrogenated vegetable oils for frying.     

The Mediterranean diet: effects on proteins that mediate fatty acid metabolism in the colon

A Mediterranean diet appears to have health benefits in many domains of human health, mediated perhaps by its anti-inflammatory effects. Metabolism of fatty acids and subsequent eicosanoid production is a key mechanism by which a Mediterranean diet can exert anti-inflammatory effects. Both dietary fatty acids and fatty acid metabolism determine fatty acid availability for cyclooxygenase- and lipoxygenase-dependent production of eicosanoids, namely prostaglandins and leukotrienes. In dietary intervention studies and in observational studies of the Mediterranean diet, blood levels of fatty acids do reflect dietary intakes but are attenuated. Small differences in fatty acid levels, however, appear to be important, especially when exposures occur over long periods of time. This review summarizes how fat intakes from a Greek-style Mediterranean diet can be expected to affect fatty acid metabolizing proteins, with an emphasis on the metabolic pathways that lead to the formation of proinflammatory eicosanoids. The proteins involved in these pathways are ripe for investigation using proteomic approaches and may be targets for colon cancer prevention.     

Manipulating the fatty acid composition of muscle and adipose tissue in beef cattle

Enhancing the n-3 polyunsaturated fatty acid (PUFA) content of beef is important in view of the generally saturated nature of fatty acids in ruminant meats and the negative effect this can have on human health. This study examined the effects of different sources of dietary n-3 PUFA on the performance of steers and the fatty acid composition of m. longissimus thoracis muscle and associated subcutaneous adipose tissue. Animals were fed ad libitum on grass silage plus one of four concentrates (60:40 forage:concentrate on a DM basis) containing differing sources of lipid: Megalac (16:0), lightly bruised whole linseed (18:3n-3), fish oil (20:5n-3 and 22:6n-3) and a mixture of linseed and fish oil (1:1, on an oil basis). Diets were formulated so that total dietary oil intake was 6 %, approximately half of which was from the experimental test oil. Linseed feeding not only increased the levels of 18:3n-3 in muscle phospholipid from 9.5 to 19 mg/100 g muscle but also enhanced the synthesis of 20:5n-3, the level of which increased from 10 to 15 mg/100 g muscle. Linseed also increased the proportion of 18:3n-3 in muscle neutral lipid and in adipose tissue lipids by a factor of 1.64 and 1.75 respectively. Fish oil feeding doubled the proportion of 20:5n-3 and 22:6n-3 in muscle phospholipids. The proportion of 18:1 trans in muscle neutral lipid was higher on the n-3 PUFA diets than the control diet, 0.04 and 0.02 respectively. Despite the implied modification to rumen metabolism, lipid source did not affect feed intake, growth rate, cold carcass weight or carcass fatness, but carcass conformation score was higher on fish oil treatments (P < 0.05). However, total muscle fatty acid content was not different between treatments and ranged from 3.5-4.3 % of tissue weight. The increase in n-3 PUFA in the meat produced by feeding linseed or fish oil lowered the n-6:n-3 ratio but had little effect on the P:S ratio.     

Maternal diet and exercise: effects on long-chain polyunsaturated fatty acid concentrations in breast milk

BACKGROUND: Long-chain polyunsaturated fatty acids (LC-PUFA) are essential for infant growth and development. The amount of long-chain PUFA in breast milk depends on maternal diet and body stores. Because exercise increases mobilization and utilization of fatty acids, maternal activity may also influence the amount of LC-PUFA in breast milk. OBJECTIVE: To investigate the effects of exercise on alpha-linolenic acid (LNA), linoleic acid (LA), docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and arachidonic acid (AA) concentrations in maternal plasma and breast milk and to determine if lactating women consume adequate amounts of LC-PUFA to compensate for those used for energy during exercise. DESIGN: LC-PUFA in plasma and breast milk were measured at 12 weeks postpartum in exercising and sedentary women. Dietary intake was recorded for 3 days. A subsample of women participated in exercise and rest sessions to examine the acute effects of exercise on breast milk LC-PUFA. RESULTS: There were no differences in dietary intake between the two groups. Mean intake (+/-standard error of the mean) of LA was 11.05+/-1.39 and 9.34+/-0.97 and LNA was 0.96+/-0.12 and 0.82+/-0.09 g/day by the sedentary and exercise groups, respectively. These amounts are close to the Adequate Intakes of LA and LNA for lactation (13 and 1.3 g/day, respectively). No differences were found in LC-PUFA in plasma and breast milk between groups. After 30 minutes of exercise, there was a trend for an increase in LA and LNA concentrations in breast milk, with no change in DHA, EPA, and AA concentrations. CONCLUSIONS: These results suggest that women consuming adequate amounts of LC-PUFA can exercise moderately without decreasing the LC-PUFA in their breast milk.     

Isomeric fatty acids and tumorigenesis: a commentary on recent work

This article critically reviews the existing, although limited, literature concerning trans fatty acids and tumorigenesis. Neither epidemiological nor experimental studies published to date have demonstrated any valid association between trans fatty acid ingestion and tumorigenesis. A recent study showed that under controlled conditions, a fat with a high content of trans fatty acids did not promote the development of mammary tumors induced in rats by 7,12-dimethylbenz[a]anthracene to any greater extent than did a comparable fat with a high content of cis fatty acids. In addition, in this study a high trans fat was less tumor promoting than was a blend of fats that simulated the dietary fat composition of the United States and had a lower level of trans fatty acids. Another study using comparable cis and trans fats demonstrated that the high trans fat did not affect the growth and metastasis of implanted mammary tumors in mice relative to the high cis fat. Also, two recent studies reported no significant difference in the development of induced colon tumors in rats fed diets high in cis or trans fatty acids. The results of these and other studies are consistent with the conclusion that trans fatty acids are not uniquely related to tumor development.     

Maternal intake of flaxseed-based diet (Linum usitatissimum) on hippocampus fatty acid profile: implications for growth, locomotor activity and spatial memory

Objective

To investigate flaxseed as a partial source of protein and an exclusive source of lipids and fibers in the development of the central nervous system by analyzing hippocampal fatty acid composition and cognitive and locomotor functions.

Methods

Experimental diets were given to dams during preconception, pregnancy, and lactation and to their pups after weaning. Female Wistar rats were separated into three groups according to experimental diet: a control group (CG) and a flaxseed group (FG), fed ad libitum diets, and a modified control group (MCG), pair-fed with the FG. After weaning, the pups received their mothers’ diets. After 30 d, eight males from each group were tested in a Morris water maze to assess learning, memory, and motor function.

Results

The offspring of FG dams showed a lower body mass than CG dams, probably due to non-nutritional factors and an imbalance between ω-3 and ω-6 fatty acids of the seed, and displayed a higher concentration of α-linolenic acid, possibly suggesting inhibition of arachidonic acid synthesis. The content of docosahexaenoic acid in the hippocampus was higher in the FG followed by the MCG compared with the CG. Hippocampal docosahexaenoic acid content correlated with better spatial memory performance in the FG, whereas arachidonic acid content correlated with longer time in solving the task.

Conclusion

Flaxseed during perinatal and postweaning periods improves spatial memory to the detriment of growth. These findings indicate that there must be caution in encouraging the maternal intake of flaxseed during pregnancy and lactation.     

Altered hepatic metabolism of free fatty acid in rats fed a threonine-imbalanced diet

The effects of a threonine-imbalanced diet (8% casein supplemented with 0.3% methionine, TI) on the ketone body production and the secretion rate of lipids were examined in the isolated perfused rat liver. Feeding a TI diet compared to an 8% casein (C) diet resulted in an enlargement of liver, presumably due to 2-4-fold accumulation of triglyceride. Serum triglyceride likewise increased significantly in rats fed a TI diet. No significant difference was found in the other lipid components both in serum and liver. When the livers from rats fed C or TI diets were isolated and perfused in the presence of an exogenous oleate substrate, the TI diet decreased the ketone body production and conversely increased the secretion rate of triglyceride, suggesting an inverse relationship between rates of ketogenesis and triglyceride secretion. The proportion of oleate in the perfusate triglyceride obtained at the end of perfusion was comparable between the C and TI groups, whereas in the post-perfused liver it was higher in the former than in the latter, suggesting a stimulatory effect of the TI diet on the secretion of the oleate in the form of triglyceride. These results indicate that altered hepatic metabolism of long-chain free fatty acids between the pathways of oxidation and esterification is one of the causative factors for triglyceride accumulation in the liver produced by threonine imbalance.     

Withdrawal of red meat from the usual diet reduces albuminuria and improves serum fatty acid profile in type 2 diabetes patients with macroalbuminuria

BACKGROUND: Replacement of red meat in the diet with chicken has reduced the urinary albumin excretion rate (UAER) and serum cholesterol in microalbuminuric type 2 diabetes patients. The effects of withdrawing red meat are unknown in the more advanced stages of diabetic nephropathy. OBJECTIVE: Our objective was to assess the effects of replacing red meat in the usual diet (UD) with chicken (CD) and of consuming a lactovegetarian low-protein diet (LPD) on renal function, fatty acid, and lipid profile in macroalbuminuric type 2 diabetes patients. DESIGN: A crossover controlled trial was conducted in 17 type 2 diabetes patients with macroalbuminuria (24-h UAER > or = 200 microg/min). Each patient followed the UD, CD, and LPD in a random order for 4 wk. After each diet, glomerular filtration rate, UAER, serum fatty acid, lipid profile, glycemic control, anthropometric indexes, and blood pressure were measured. RESULTS: UAER [median CD: 269.4 (range: 111-1128) microg/min; LPD: 229.3 (76.6-999.3) microg/min; UD: 312.8 (223.7-1223.7) microg/min; P < 0.01] and mean (+/-SD) non-HDL cholesterol (CD: 3.92 +/- 0.99 mmol/L; LPD: 3.92 +/- 0.93 mmol/L; UD: 4.23 +/- 1.06 mmol/L; P = 0.042) were lower after CD and LPD than after UD. Compared with the UD, an increase in serum total polyunsaturated fatty acids was also observed (CD: 39.8 +/- 2.6%; LPD: 39.7 +/- 4.4%; UD: 37.3 +/- 3.1%; P = 0.029). CONCLUSION: In macroalbuminuric patients with type 2 diabetes, withdrawing red meat from the diet reduces the UAER.     

Enrichment of n‐3 fatty acids and conjugated linoleic acid in beef: ProSafeBeef

ProSafeBeef is a 5‐year integrated project funded by the European Commission under the sixth Framework Programme. The overall aim is to advance beef safety and quality across Europe and the work programme spans seven integrated “pillars”. Pillar 3 is concerned with producing safe beef and beef products with enhanced nutritional and eating quality characteristics. A particular focus is on the development of strategies to enhance the concentrations in beef of those fatty acids considered to be of benefit to human health, without causing a detrimental effect on the appearance, shelf‐life or eating quality of the beef. There is accumulating evidence of the importance of long‐chain n‐3 (omega‐3) polyunsaturated fatty acids (PUFAs) for human health and disease prevention, and also evidence from experimental studies that has shown anticarcinogenic, antiatherogenic, and anti‐obesity effects of two isomers of conjugated linoleic acid (CLA). Based on this evidence, the major focus of research efforts to improve the nutritional value of beef has been on increasing the concentration of the n‐3 PUFAs and CLA. Considerable progress has been made within pillar 3 of ProSafeBeef to meet this aim, primarily by manipulating the diet of cattle. Fundamental information on ruminal lipid metabolism and on the control and/or prevention of ruminal hydrogenation of dietary lipids arising from research within ProSafeBeef will facilitate the production of beef with a ‘healthier’ fatty acid profile. Moreover, strategies will be defined for industry on how to optimise nutritional and sensory properties and oxidative quality of beef products, by combining the nutritional enhancement made in the live animal together with target levels of functional ingredients to be added during processing.