The availabilities of nutrients from a representative rural Mexican diet (RMD) and a representative urban Mexican diet (UMD) were evaluated by balance experiments in sixteen Mexican women. Compared with UMD, the plant-based RMD led to a higher number of defaecations and higher faecal excretion of dry matter, fat, nitrogen and energy. Apparent digestibility of N from RMD was only 67% compared with 90% from UMD. N balance was 0.4 and 2.6 g/d with RMD and UMD respectively (P < 0.001). Apparent digestibility of energy was 89 and 95% from RMD and UMD respectively (P < 0.001). Calculation of the metabolizable energy (ME) using Atwater's (Atwater & Bryant, 1900) general factors overestimates the determined ME in RMD by 8%. The Food and Agriculture Organization/World Health Organization/United Nations University (World Health Organization, 1985) recommended factors for correction of digestibility of fibre intake overestimate energy and protein absorption from RMD. The diets provided similar amounts of zinc, and its apparent absorption from RMD was 0.5 mg/d (4.6%) and its balance was 0.1 mg/d. This compared with values for UMD of 1.6 mg/d (16%) and 1.2 mg/d respectively. Iron intake was higher from RMD (17.4 v. 11.6 mg/d; P < 0.01), but apparent absorption was 17 v. 35% and balance was 2.7 and 3.8 mg/d (P < 0.001) for RMD and UMD respectively. RMD also contained more calcium (745 v. 410 mg/d) but apparent absorption from RMD was negative (−136 v. 15 mg/d) and balance was more negative (−197 v.−77 mg/d; P < 0.05). Thus, the content of these minerals is not low in the rural diet but their bioavailabilities are poor.

Whole-body protein synthesis, estimated by the irreversible loss rate procedure, and hind-leg protein metabolism determined by arterio-venous techniques were monitored in response to three nutritional conditions (approximately 0.6, 12 and 1.8 x energy maintenance (M)) in ten wether lambs (33 kg average live weight). In all lambs and treatments measurements were based on radiolabelled phenylalanine, but the terminal procedures (five at 0.6 x M and five at 1.8 x M) also included infusion of [1-13C]leucine; this permitted comparison of amino acids catabolized (leucine) and non-metabolized (phenylalanine) by the hind-limb tissues. Whole-body protein synthesis increased with intake and the relationship with energy expenditure was slightly lower than that reported previously for pigs and cattle. The efficiency of protein retention: protein synthesis did not exceed 0.25 between the two intake extremes. Effects of intake on amino acid oxidation were similar to those observed for cattle. Hind-limb protein synthesis also increased significantly (P < 0.001) in response to intake. Estimates of protein gain, from net uptake values, indicated that the tissues made a greater proportional contribution to total protein retention above M and to protein loss below M, emphasizing the role played by muscle tissue in providing mobile protein stores. The rates of protein synthesis calculated depended on the selection of precursor (blood) metabolite, but rates based on leucine always exceeded those based on phenylalanine when precursor from the same pool was selected. The incremental efficiency of protein retained: protein synthesis was apparently unity between 0.6 and 1.2 x M but 0.3 from 1.2 to 1.8 x M. Blood flow through the iliac artery was also proportional to intake. Leucine and oxo-acid catabolism to carbon dioxide increased with intake such that the metabolic fate of the amino acid was distributed in the proportion 2:1 between protein gain and oxidation. The rates of oxidation were only 1–3% the reported capacity of the rate-limiting dehydrogenase enzyme in muscle, but sufficient enzyme activity resides in the hind-limb adipose tissue to account for such catabolism

The objective of the present experiment was to define the form of the relationship between varying levels of energy intake at constant, high protein intake and the performance of young pigs. By doing so it was expected that we could distinguish between four models that predict the pig's responses to its diet as rates of protein and lipid retention. Forty young pigs were assigned at 12 kg live weight either to an initial slaughter group (n 8) or to one of four allowances of starch intake at a constant intake of a high-protein feed (with 345 g crude protein (nitrogen x 6.25)/kg food). Half the pigs were killed after 4 weeks and half after 8 weeks on the treatments; at each slaughter point on each treatment half the pigs were entire males and half were females. Increasing the intake of starch (energy) resulted in significant increases in the rates of live weight, empty-body, protein and lipid gains of pigs slaughtered at both stages. There was no minimum positive lipid: protein ratio in the gain of the pigs. Male pigs deposited more protein and less lipid than females but this effect of sex on protein and lipid retention was seen only on the two highest allowances of starch intake. The calculated efficiency of protein utilization increased with increasing starch intake up to a maximum of 0.81, when probably the energy: protein in the diet became non-limiting. The results led to the rejection of two of the models that predict the rates of protein and lipid retention as responses to protein and energy intake, but the two remaining models could not be rejected, at least qualitatively.

The effects of dietary casein and soyabean-protein isolate (SPI) on gastric emptying and small intestinal transit were observed in rats fed on an 80 g casein or 80 g SPI/kg diet. After a 24 h fast, rats were given 2 g of both the test diets containing 10 g guanidinated casein/kg diet as a marker protein. The amounts of the marker protein remaining in the stomach of the rats fed on the casein or SPI diet were similar and decreased to about 50% after 20min. The emptying rate then slowed, especially in the casein group, so that the amount leaving the stomach after 1 h in the SPI group was slightly higher (P < 0.05). The small intestinal transit of chyme was estimated by a bolus injection of colloidal carbon suspension or of colloidal carbon and 3H-labelled polyethylene glycol through an implanted duodenal catheter 6 min before death. The average value of transit at 12, 20, 40 and 60 min after feeding of SPI diet was about 25% faster than that after casein diet. The transit velocity of the SPI group was also faster than that of the non-protein group 40 min after feeding. These findings reveal that SPI enhances the small intestinal transit of the liquid phase of chyme. There was no correlation between the gastric emptying of homoarginine and small intestinal transit. This result suggests that the small intestinal transit of lumen contents is controlled by the dietary protein regardless of the gastric emptying of protein.

Plasma concentrations of endothelium-associated proteins (EAP) (plasma fibronectin (PFN), angio-tensin-converting enzyme, factor VIII-related antigen (F VIII-R:Ag)) and tissue plasminogen activator and serum thyroid hormone concentrations were studied in nine patients with anorexia nervosa (AN), before and after weight gain. Before weight gain (-35.9 (se 2.3)% of standard body-weight) PFN was significantly reduced and F VIII-R:Ag was significantly increased in AN patients compared with the concentrations in control subjects (211.5 (se 14.9) v. 274.7 (se 16.6) μg/ml, P < 0.05; 129.2 (se 14.1) v. 88.2 (se 9.7)%, P <0.05 respectively). Serum triiodothyronine (T3) and free T3 levels were also significantly lower before weight gain in AN patients (0.85 (se 0.07) v. 1.53 (se 0.08) nmol/l, P < 0.001; 2.57 (se 0.23) v. 5.31 (se 0.34) pmol/l, P < 0.001 respectively), although serum thyroxine (T4), free T4, and thyrotropin concentrations were within the normal range throughout the study periods. Following weight gain, PFN and F VIII-R: Ag concentrations normalized as did the thyroid hormone levels. The incremental changes in PFN levels correlated significantly with those in serum thyroid hormone concentrations (T3, r 0.79, P <0.01; free T3, r 0.84, P < 0.01). These findings suggest that PFN levels may be directly related to serum T3 concentrations in AN patients.

The contents of dopamine (DA) and serotonin (5-HT) and their metabolites were measured in rat substantia nigra and corpus striatum following dietary changes, including restriction of protein content (low-protein diet; LPD) and the contents of several large neutral amino acids (isoleucine, leucine, methionine, phenylalanine, tryptophan and valine) for 25 d. The LPD produced an increase in the concentration of tyrosine (TYR) in the two regions of the brain studied. This effect was also observed with all amino acid deficiencies studied except for valine in the substantia nigra, tryptophan in the striatum and phenylalanine in both regions. Likewise, the concentration of 5-hydroxyindolacetic acid (5-HIAA), the main metabolite of 5-HT, increased in the substantia nigra but not in the striatum after LPD, as well as with all the amino acid deficiencies studied, with the exception of tryptophan deficiency. In this case there was a dramatic effect on all components of the serotoninergic system, with decreases in the concentration of tryptophan (TRP; precursor), 5-HT and 5-HIAA. This behaviour clearly shows an interrelationship between precursor (TRP) availability and 5-HT synthesis and metabolism. With valine deficiency, dopaminergic and serotoninergic systems demonstrated opposite effects in the substantia nigra and the corpus striatum, and the behaviour of the two monoamines was also opposite within each structure. The significance of these changes is discussed.

The objective of the experiment was to define the form of the relationship between varying levels of protein and energy intake and the performance of young pigs. Forty-four young pigs were assigned at 12 kg live weight for 6 weeks either to an initial slaughter group (n 8) or to one of the nine feeding treatments (n 4); three allowances of a high-protein food with 355 g crude protein (nitrogen × 6.25; CP)/kg (P1, P2, P3) at three levels of feeding (L, M and H). Each feeding level was met by supplementing the allowance of feed P with the appropriate amount of starch and each treatment had two males and two females. The rate of protein deposition was not affected by feeding level at the two lowest allowances of basal feed P (P1 and P2), but it increased with increasing the feeding level for the pigs on treatment P3. Males deposited more protein than females, but this effect was more pronounced with treatment P3. The rate of lipid deposition increased with each increase in the level of feeding and decreased with increasing the allowance of feed P. The calculated efficiency of protein utilization (ep) was expressed as a function of the energy: protein ratio in the feed (MJ metabolizable energy/kg digestible CP). The best model to describe the relationship was a linear-plateau model, with the maximum value for ep of 0.814 at 73 MJ/kg. This relationship provided the basis of a model that could predict the response of a growing pig to its diet as rates of protein and lipid retention

The effects of protein restriction on Δ9 desaturase (EC 1.14.99.5) activity were studied in growing rats. A control group was fed on a balanced diet (200 g casein/kg; BD) for 28 d. The experimental group was fed on the low-protein diet (20 g casein/kg; LP) for 26 d, then refed the balanced diet (BD-R) for 2 d. Rats were born to and suckled from normally fed dams. The enzyme activity was measured after 2 and 14 d of LP, and 26 d of LP plus 2 d of BD-R, by incubations in vitro of hepatic microsomal pellets with [1-14C]stearic acid. The results indicated a decreased Δ9 desaturase activity after 2 and 14 d of LP of -33 and -43% respectively. Refeeding for 2 d was sufficient to super-repair this activity (+ 66%). The fatty acid composition of total liver lipids and microsomal phosphatidylethanolamines (PE) and phosphatidylcholines (PC) were also investigated; 18:0 decreased in total liver lipids at 14 d of LP, when 18:1n-9 increased. Stearic acid (18:0) increased in PC at 2 d of LP and in PE at 14 d of LP; oleic acid (18:1n-9) did not change. Therefore, it is concluded that a defect occurred in the bioconversion of 18:0 into 18:1n-9 by Δ9 desaturation during protein depletion. As oleic acid is accumulated in total liver lipids during LP, we speculate that this is due to a decreased oxidation or transport of this fatty acid

The activity of liver cystathionase (EC 4.4.1.1) was decreased after 3 d of stress induced by surgery. The rate of l-cysteine synthesis from l-methionine was significantly higher in isolated hepatocytes from controls than in hepatocytes from rats suffering from surgical stress. The half-life of l-[2(n)-3H]methionine was significantly higher in rats submitted to surgical stress than in controls. Plasma l-methionine: l-cystine ratio was higher in stressed rats than in controls. l-cystine uptake was significantly increased in the surgically-stressed rats when compared with the controls. All these facts are consistent with the hypothesis that the observed inhibition of cystathionase is physiologically important and thatl-cysteine might be considered as an essential amino acid in cases of surgical stress.

Subcutaneous melatonin implants were administered to castrated hand-reared male red deer (Cervus elaphus) during a 63 d period in spring, after which effects on voluntary feed intake (VFI), rumen pool size, rumen capacity (i.e. volume) and heart rate were measured on four occasions, evenly spread over a 12-month period, with the deer individually fed indoors on a diet of lucerne (Medicago sativa) chaff. Blood samples for hormone determinations were taken at intervals throughout the study. Day-time plasma melatonin concentration was approximately 5 pg/ml in control animals, whereas during melatonin administration it increased to 60–150 pg/ml and declined to 30 pg/ml by 142 d after the last implantation. Melatonin administration markedly depressed plasma prolactin concentration during the period of implantation, but thereafter plasma prolactin concentration rose in the treated animals during autumn and winter, whilst it declined in control animals over this period. VFI, rumen pool size and heart rate in control animals attained highest values in summer and lowest values in winter, showing a pronounced seasonal cycle. Melatonin administration depressed all these values in late spring and summer and increased all the values in autumn and winter, relative to control animals, and appeared to move the cycles by approximately 6 months. Melatonin-treated animals showed maximum values for all these measurements during winter. The castrated male deer showed little seasonal change in live weight, which was not affected by melatonin administration. The findings support the view that melatonin probably mediates the effect of daylength on digestive function in red deer. Rumen capacity remained relatively constant throughout the year, but rumen pool size as a proportion of rumen capacity increased with increasing VFI.

To determine the effects of dietary protein level on cardiac and hepatic mitochondrial oxidative phosphorylation, chicks were fed on semi-purified diets of different protein levels (7, 25, 43 and 61% of metabolizable energy content) for 7, 14 and 21 d. All diets were formulated to contain equivalent fat, mineral and vitamin contents on a gross energy basis. Cardiac and hepatic mitochondrial oxidative phosphorylation rates were assessed polarographically with pyruvate and malate as substrates. Cardiac mitochondria isolated from chicks fed on a 43 or 61% protein-energy diet for 7 d exhibited significantly reduced ADP:oxygen (ADP:O) ratios when compared with mitochondria isolated from chicks fed on a lower-protein-energy diet. Feeding low- (7%) protein-energy diets for 14 d resulted in a relatively increased ADP:O ratio in the heart. Responses of ADP:O ratios to protein level in hepatic mitochondria showed more dependency on protein level than in heart muscle; at all feeding periods the ADP:O ratio decreased with an increase in protein level. As a result, ATP synthesized in the liver, expressed as nmol/mg mitochondrial protein per min, significantly decreased with increased dietary protein level. A parallel correlation was observed, in chicks fed on diets with different levels of protein, between ADP:O ratio for liver mitochondria and body fat. These results suggest that the reduction in oxidative phosphorylation in the heart and liver of animals fed on a higher protein-energy diet may partly contribute to the depression of body fat.

Adult male Syrian hamsters were fed on a high-fat diet with or without access to boiled coffee. Plasma total, low-density-lipoprotein- and high-density-lipoprotein-cholesterol and triacylglycerol concentrations were increased by the coffee and very-low-density-lipoprotein-cholesterol concentrations were lowered. It is concluded that the Syrian hamster is a suitable animal model in which to study the hypercholesterolaemic effect of coffee

The effects of zero-erucic acid rapeseed oil and rapeseed oil-containing margarine on plasma fatty acid composition and serum cholesterol were studied in butter users (n 43). Compliance to the substitution was followed by fatty acid analysis of total plasma and plasma phospholipids. The amount of substitute fats represented, on average, 21% of total fat and 8% of total energy intake. Changes in the relative fatty acid composition of plasma phospholipids indicated further fatty acid metabolism, and were closely related to the serum cholesterol level. The reduction in saturated fatty acids led to a significant increase in the proportion of n-3 and n-6 polyunsaturated fatty acids (PUFA) with the rapeseed oil diet, whereas the margarine caused a significant rise in n-6 PUFA only. The increase in the proportions of the two PUFA families occurred in accordance with their competitive order, most completely with the rapeseed oil diet. When butter was replaced by rapeseed oil, low-density-lipoprotein-cholesterol decreased by an average of 9.1% without a reduction in high-density-lipoprotein-cholesterol. During margarine substitution the reduction was 5.2%, on average. Of the plasma phospholipids, α-linolenic acid and the linoleic:stearic acid ratio, but not oleic acid, were the components most significantly correlated with serum cholesterol levels or the decrease in these levels. The results show that rapeseed oil can act primarily as a source of essential fatty acids, rather than that of monoenes, in the diet of butter users.

The present study reports results from two investigations to determine effects of a 6-week period of moderate n-3 fatty acid supplementation (2.7 g/d) on fasting and on postprandial triacylglycerol and metabolic hormone concentrations in response to standard test meals. In the first study postprandial responses were followed for 210 min after an early morning test meal challenge; in the second study responses to an evening test meal were followed during the evening and overnight for a total period of 12 h. In both studies postprandial triacylglycerol responses to the test meals were significantly reduced after compared with before fish-oil supplementation. In the second study the triacylglycerol peak response seen between 200 and 400 min in subjects studied before supplementation with fish oils was almost completely absent in the same subjects after 6 weeks of n-3 fatty acid supplementation. Analysis of fasting concentrations of metabolites and hormones was carried out on the combined data from the two studies. There were no significant differences in total, low-density-lipoprotein- or high-density-lipoprotein-cholesterol concentrations during fish-oil supplementation, although there was considerable individual variation in cholesterol responses to the supplement. Concentrations of Apo-B and Apo-A1 were unchanged during supplementation with fish oils. Fasting and early morning postprandial GIP concentrations were lower in subjects taking fish oils, possibly due to acute effects of fish-oil capsules taken on the evening before the studies. In both studies fasting insulin and glucose and postprandial insulin concentrations remained unchanged following fish-oil supplementation. The results do not support the view that triacylglycerol-lowering effects of n-3 fatty acids are due to modulation of insulin secretion mediated via the enteroinsular axis. Further studies are required to determine the precise mechanism by which fish oils reduce both fasting and postprandial triacylglycerol concentrations.

The influence of dietary copper on lipid composition, phospholipid-fatty acid and protein profiles and fluidity of the erythrocyte membranes of rats is reported. In general Cu deficiency in rats induced some changes in the phospholipid-fatty acid profile of erythrocyte membranes when compared with Cu-adequate animals. Stearic (18:0) and docosadienoic (22:2n-3) acids contents, for example, were significantly increased (P < 0.001) while oleic (18:1n-9) and linolenic (18:3n-3) acid contents were significantly depressed (P < 0.001) as a result of Cu deficiency. Moreover the cholesterol:phospholipids molar ratio and the cholesterol (mol):membrane proteins (mg) ratio in Cu-deficient rats were, to different degrees, significantly lower than in animals fed on Cu-adequate diets. In addition, diets deficient in Cu led to a reduction in erythrocyte membrane fluidity (P < 0.001) as assessed by the intramolecular excimer fluorescence of 1,3-di(1-pyrenyI) propane. However, no significant alteration in the phospholipid:protein ratio was observed as a result of differences in dietary treatment. The pattern of erythrocyte membrane proteins obtained with sodium dodecyl sulphate-polyacrylamide gel electro-phoresis did not seem to be influenced by Cu-deficient diets.

The faecal and ileal true protein digestibilities of the raw pea (Pisum sativum) varieties finale and frijaune and the ileal true protein digestibility of steam-processed common beans (Phaseolus vulgaris) were measured in piglets using the 15N-dilution technique. The faecal true protein digestibility of both pea varieties was about 97. The ileal true protein digestibility was between 93 and 95, indicating that the pea protein is almost completely enzymically digested in the small intestine. The faecal apparent protein digestibility was 85 for both varieties while at the ileal level it was 79 and 74 respectively. The lower ileal apparent protein digestibility of peas can be attributed completely to the excretion of endogenous protein. The ileal apparent protein digestibility of toasted common beans was about zero (–4); the ileal true protein digestibility was about 66. This indicates that the protein of the common bean, although toasted, was highly resistant to enzymic digestion. It was calculated that per kg ingested bean protein, 340 g undigested bean protein and 700 g endogenous protein passed the terminal ileum. The results of the present study explain why in previous experiments a strongly reduced weight gain and even weight loss was observed in piglets fed on raw and toasted common beans.

Seven non-anaesthetized pigs (mean body-weight 64.6 kg) were used to study the intestinal absorption and hepatic metabolism of glucose and amino acids (AA) using carbohydrate solutions (maltose dextrin; 440 g/2 l), containing 110 g of either an enzymic milk-protein hydrolysate (PEP) with a large percentage of small peptides (about 50% with less than five AA residues) and very few free AA (8%) or a mixture of free AA (AAL) with an identical pattern, infused intraduodenally. Each pig was previously fitted under anaesthesia with electromagnetic flow probes around the portal vein and the hepatic artery, and with permanent catheters in the portal vein, carotid artery, one hepatic vein and the duodenum. Each solution was infused for 1 h after a fasting period (18 h) and each pig received both solutions at 8 d intervals. The observation period lasted 8 h. For most AA (his, lys, phe, thr, arg, tyr, pro) the absorption rate after infusion of PEP was significantly higher than after that of AAL during the 1st hour, but the differences quickly disappeared. After 8 h, the only differences concerned his and tyr (PEP > AAL) and met, glu and asp (AAL > PEP). There was a large uptake of blood AA by gut-wall cells, higher after AAL infusion than after PEP infusion, particularly for branched-chain AA (BCAA). The absorption of ammonia-nitrogen after both infusions was equivalent to two-thirds of urea-N passing from blood to intestinal tissues and lumen. Glucose absorbed within 8 h represented only 76% (PEP) or 69% (AAL) of the infused amounts. The cumulative hepatic total AA (TAA) uptake increased from 13 to 27% of the infused amounts between the 1st and the 8th hour after PEP infusion, and from 8 to 31% after AAL infusion. Most essential AA were largely taken up by the liver, with the exception of met (PEP) and thr and of BCAA, which were poorly retained for both solutions; there was a high uptake of ala and gly, and a release of asp, glu, and gln. Urea-N released by the liver within 8 h was equivalent to 23–25% absorbed amino-N and to around 1.5 times ammonia-N taken up by the liver within 8 h. Glucose was highly taken up by the liver during the first hours then released, the total uptake within 8 h representing about half the absorbed amount. There was a lactate release tending to be higher after PEP than after AAL infusion and a liver pyruvate release identical for both solutions. From calculations of net non-catabolic metabolism in the liver the possible synthesis of liver proteins within 8 h may be estimated at 35 g for both solutions. The cumulative peripheral TAA uptake increased from 12 to 27% of the infused amounts between the 1st and 8th hour after PEP and from 9 to 11% after AAL infusion. At 8 h after the infusion the larger uptake concerned BCAA, arg, glu and asp and there was a marked release of gln, gly and ala for both solutions; the peripheral balance was zero for met (PEP) or characterized by a release of phe and thr (AAL). Thus, protein synthesis seemed only to be possible with the aid of plasma proteins synthesized in the liver. The 8 h peripheral balance of glucose, lactate and pyruvate was characterized by the same level of uptake for both solutions. The time-course of AA absorption, depending on the physicochemical structure of nitrogenous mixtures present in the digestive tract, had an influence on the pattern of liver and peripheral AA uptake.

The glycaemic index (GI) and the triacylglycerol response were measured in thirty non-insulin-dependent diabetes mellitus patients given 50 g portions of five different conventional Indian meals containing semolina (Triticum aestivum) cooked by two different methods, or combinations of semolina and pulse (black gram dhal (Phaseolus mungo), green gram dhal (Phaseolus aureus) or Bengal gram dhal (Cicer arietum)). There were no significant differences among meals in mean GI except for meals based on roasted semolina or semolina-black gram dhal. Compared with the blood glucose response for a 50 g glucose load, only meals based on steam-cooked semolina and semolina-Bengal gram dhal elicited a significantly lower response at 1 h postprandially, and only meals based on semolina-black gram dhal at 2 h postprandially. No significant differences were found among the meals in the triacylglycerol response

Indian River male broiler chickens growing from 7 to 28 d of age were fed on diets containing energy: protein values varying from 43 to 106 MJ/kg protein and containing 0 or 1 mg triiodothyronine (T3)/kg diet to study effects on growth, metabolic hormone concentrations and in vitro lipogenesis. In vitro lipid synthesis was determined in liver explants in the presence and absence of ouabain (Na+, K+-transporting ATPase (EC 3.6.1.37) inhibitor) to estimate the role of enzyme activity in explants synthesizing lipid. Growth and feed consumption increased (P < 0.01) when the energy: protein value decreased from 106 to 71 MJ/kg protein; however, both variables decreased as the value was further decreased from 53 to 43 MJ/kg protein. Triiodothyronine depressed (P < 0.01) growth, but not food intake. Large energy:protein diets (> 53 MJ/kg protein) and dietary T3 lowered (P < 0.01) plasma growth hormone. Large energy:protein diets (> 53 MJ/kg protein) increased (P < 0.01) lipogenesis, plasma growth hormone (GH) and decreased plasma insulin-like growth factor 1 (IGF-1). Also, T3 decreased plasma GH, IGF-1 in vitro lipogenesis. Ouabain inhibited a greater proportion of in vitro lipogenesis in those explants synthesizing fat at a high rate. Both dietary T3 and in vitro ouabain decrease lipogenesis, but, when combined, the effects are not cumulative

Thirty-eight male volunteers participated in a double-blind cross-over trial evaluating the effect of replacing the usual sources of saturated fat in the Dutch diet (animal fats and hydrogenated oils) by palm oil, which is virtually free of cholesterol and trans-fatty acids, on serum lipids, lipoproteins and apolipoproteins. Maximum (about 70%) replacement had no significant effect on serum total cholesterol or most lipoprotein fractions, but resulted in an 11% increase in serum high-density-lipoprotein (HDL)2-cholesterol relative to the control (P2 = 0.01). The palm-oil diet also caused an 8% decrease in low-density-lipoprotein (LDL):HDL2+HDL3-cholesterol ratio (P2 = 0.02) as well as a 9% decrease in triacylglycerols in the low-density-lipoprotein fractions (P2 = 0.01). Palm oil consumption resulted in a 4% increase in serum apolipoprotein AI (P2 = 0.008) and a 4% decrease in apolipoprotein B (P2 = 0.01) relative to the control diet; the B:AI apolipoprotein ratio was decreased by 8% (P2 < 0.0001). These results were not significantly affected by the different lipoprotein E phenotypes of the volunteers. Although the observed differences were relatively modest, the present study, nonetheless, indicates that dietary palm oil, when replacing a major part of the normal fat content in a Dutch diet, may slightly reduce the lipoprotein- and apolipoprotein-associated cardiovascular risk profiles