Small Amounts Of Cholesterol Research Articles

THE COMPONENT COMPOSITION OF THE PHYTOSTEROLS OF THE AERIAL PART OF THE HORSETAIL VAR-IEGATED ЕQUISÉTUM VARIEGATUM SCHLEICH. EX. WEB. GROWING IN NORTH-EAST YAKUTIA

It is known that phytosterols have high immunomodulating, hypocholesterolemic and oncoprotective activity and are widely used in medicine. In addition, the plants containing them are used in feed of farm animals as dietary supplements that stimulate growth and the immune system. Promising, but poorly studied, sources of these biologically active compounds may be plants of the class Horsetails (Equisetopsida), grown under extreme conditions of sharply continental climate of Yakutia. The steric composition of the aerial part of the variegated horsetail (Equisétum variegatum) was studied for the first time during the summer and autumn vegetation. It is shown that the composition of the main free sterols includes β-sitosterol, campesterol, stigmasterol, isofucosterol, as well as a small amount of cholesterol. The total amount of free and bound sterols in the tissues of the aerial part of this species is about 0.5 mg/g dry weight or 2% of the total content of all lipid components. Moreover, the content of free sterols in the aerial part of variegated horsetail is an order of magnitude higher than the content of sterol esters in these tissues. Peculiarities of the seasonal (autumn-summer) dynamics of changes in the relative contents of stigmasterol, campesterol and isofucosterol and the absolute total content of sterols in the aerial part of variegated horsetail are revealed.

Lipid-Dependent Gating of Kv Channels and Excitability Change of Cerebellar Purkinje Neurons in an NPC1 Model Mouse

Recent studies of Kv channels in different membrane systems with altered ratios between phospholipids and nonphospholipids support our lipid-dependent gating hypothesis that the nonphospholipids favor the conformational switch of the voltage sensor domains of a Kv channel to a resting state. To enable more precise control of lipid composition in an artificial membrane and avoid possible solvent contamination or phase separation of lipids in bilayer membranes, we constructed a bead-supported unilamellar membrane (bSUM) and used it to define a more quantitative relationship between nonphospholipid content and change in the gating property of a voltage-gated potassium channel. In the bSUMs, we were able to show for the first time that a small amount of cholesterol (∼10 molar %) in a phospholipid membrane in a fluidic phase exerts a strong inhibitory effect on a KvAP channel, suggesting that the Kv channels might be highly sensitive to change in membrane cholesterol content. To test this prediction in a physiological system where lipid metabolic defects cause significant neurological disorders, we analyzed the neuronal excitability in a mouse model for the Niemann-Pick disease type C, an NPC1-I1061T knockin mice. Systematic comparison of five different groups of cerebellar Purkinje neurons from both knockin mice and control animals revealed a significant decrease in the firing frequency of action potentials in the tonic-burst firing Purkinje neurons of the NPC1 mice, which appears to be consistent with the predicted cholesterol effects on Kv channels. Detailed studies of the gating properties in these Purkinje neurons are being conducted to understand the underlying mechanism. Our data support a potential connection among cholesterol content in cell membranes, cholesterol-dependent gating of voltage-gated K channels and change in neuronal excitability in CNS neurons.

Combined effect of synthetic protein, Mini-B, and cholesterol on a model lung surfactant mixture at the air–water interface

The overall goal of this work is to study the combined effects of Mini-B, a 34 residue synthetic analog of the lung surfactant protein SP-B, and cholesterol, a neutral lipid, on a model binary lipid mixture containing dipalmitolphosphatidylcholine (DPPC) and palmitoyl-oleoyl-phosphatidylglycerol (POPG), that is often used to mimic the primary phospholipid composition of lung surfactants. Using surface pressure vs. mean molecular area isotherms, fluorescence imaging and analysis of lipid domain size distributions; we report on changes in the structure, function and stability of the model lipid-protein films in the presence and absence of varying composition of cholesterol. Our results indicate that at low cholesterol concentrations, Mini-B can prevent cholesterol's tendency to lower the line tension between lipid domain boundaries, while maintaining Mini-B's ability to cause reversible collapse resulting in the formation of surface associated reservoirs. Our results also show that lowering the line tension between domains can adversely impact monolayer folding mechanisms. We propose that small amounts of cholesterol and synthetic protein Mini-B can together achieve the seemingly opposing requirements of efficient LS: fluid enough to flow at the air–water interface, while being rigid enough to oppose irreversible collapse at ultra-low surface tensions.

Effect of serum, cholesterol and low density lipoprotein on the functionality and structure of lung surfactant films.

Lung surfactant is a complex mixture of lipid and protein, responsible for alveolar stability, becomes dysfunctional due to alteration of its structure and function by leaked serum materials in disease. Serum proteins, cholesterol and low density lipoprotein (LDL) were studied with bovine lipid extract surfactant (BLES) using Langmuir films, and bilayer dispersions using Raman spectroscopy. While small amount of cholesterol (10 wt%) and LDL did not significantly affect the adsorption and surface tension lowering properties of BLES. However serum lipids, whole serum as well as higher amounts of cholesterol, and LDL dramatically altered the surface properties of BLES films, as well as gel-fluid structures formed in such films observed using atomic force microscopy (AFM). Raman-spectroscopic studies revealed that serum proteins, LDL and excess cholesterol had fluidizing effects on BLES bilayers dispersion, monitored from the changes in hydrocarbon vibrational modes during gel-fluid thermal phase transitions. This study clearly suggests that patho-physiological amounts of serum lipids (and not proteins) significantly alter the molecular arrangement of surfactant in films and bilayers, and can be used to model lung disease.

Seasonal changes in minor membrane phospholipid classes, sterols and tocopherols in overwintering insect, Pyrrhocoris apterus

Ectotherm animals including insects are known to undergo seasonal restructuring of the cell membranes in order to keep their functionality and/or protect their structural integrity at low body temperatures. Studies on insects so far focused either on fatty acids or on composition of molecular species in major phospholipid classes. Here we extend the scope of analysis and bring results on seasonal changes in minor phospholipid classes, lysophospholipids (LPLs), free fatty acids, phytosterols and tocopherols in heteropteran insect, Pyrrhocoris apterus. We found that muscle tissue contains unusually high amounts of LPLs. Muscle and fat body tissues also contain high amounts of β-sitosterol and campesterol, two phytosterols derived from plant food, while only small amounts of cholesterol are present. In addition, two isomers (γ and δ) of tocopherol (vitamin E) are present in quantities comparable to, or even higher than phytosterols in both tissues. Distinct seasonal patterns of sterol and tocopherol concentrations were observed showing a minimum in reproductively active bugs in summer and a maximum in diapausing, cold-acclimated bugs in winter. Possible adaptive meanings of such changes are discussed including: preventing the unregulated transition of membrane lipids from functional liquid crystalline phase to non-functional gel phase; decreasing the rates of ion/solute leakage; silencing the activities of membrane bound enzymes and receptors; and counteracting the higher risk of oxidative damage to PUFA in winter membranes.

Sterol/steroid metabolism and absorption in a generalist and specialist caterpillar: Effects of dietary sterol/steroid structure, mixture and ratio

Insects cannot synthesize sterols de novo, so they typically require a dietary source. Cholesterol is the dominant sterol in most insects, but because plants contain only small amounts of cholesterol, plant-feeding insects generate most of their cholesterol by metabolizing plant sterols. Plants almost always contain mixtures of different sterols, but some are not readily metabolized to cholesterol. Here we explore, in two separate experiments, how dietary phytosterols and phytosteroids, in different mixtures, ratios, and amounts, affect insect herbivore sterol/steroid metabolism and absorption; we use two caterpillars species – one a generalist (Heliothis virescens), the other a specialist (Manduca sexta). In our first experiment caterpillars were reared on two tobacco lines – one expressing a typical phystosterol profile, the other expressing high amounts/ratios of stanols and 3-ketosteroids. Caterpillars reared on the control tobacco contained mostly cholesterol, but those reared on the modified tobacco had reduced amounts of cholesterol, and lower total sterol/steroid body profiles. In our second experiment, caterpillars were reared on artificial diets containing known amounts of cholesterol, stigmasterol, cholestanol and/or cholestanone, either singly or in various combinations and ratios. Cholesterol and stigmasterol-reared moths were mostly cholesterol, while cholestanol-reared moths were mostly cholestanol. Moth tissue cholesterol concentration tended to decrease as the ratio of dietary cholestanol and/or cholestanone increased. In both moths cholestanone was metabolized into cholestanol and epicholestanol. Interestingly, M. sexta generated much more cholestanol than epicholestanol, while H. virescens did the opposite. Finally, total tissue steroid levels were significantly reduced in moths reared on diets containing very high levels of cholestanol. We discuss how dietary sterol/steroid structural differences are important with respect to sterol/steroid metabolism and uptake, including species-specific differences.

Neutral Sterols of Cephalic Glands of Stingless Bees and Their Correlation with Sterols from Pollen

Sterols are essential molecules in the membrane lipid composition and precursors of important sterol hormones that regulate many developmental processes. Insects are unable to synthesize sterolsde novoand, thus, all phytophagous insects depend on an exogenous source of sterols for growth, development, and reproduction. The sterol requirements of social bees are not fully known due to the fact that there is no well-defined diet available throughout the year with regard to floral resources. Our study aimed to characterize the sterols present in pollen stored inMelipona marginataandMelipona scutellariscolonies, as well as evaluating their presence in the mandibular, hypopharyngeal, and cephalic salivary gland secretions. We analyzed the chemical composition of pollen stored in the colonies and the composition of the cephalic glands of workers in three adult functional phases (newly emerged, nurses, and foragers) by gas chromatography and mass spectrometry. The results showed that the pollen analyzed contained campesterol, stigmasterol, sitosterol, isofucosterol, lanosterol, and small amounts of cholesterol. The glands showed the same compounds found in the pollen analyzed, except lanosterol that was not found inM. scutellarisglands. Surprisingly, cholesterol was found in some glands with relative ratios greater than those found in pollen.

Molecular etiology of a dominant form of type III hyperlipoproteinemia caused by R142C substitution in apoE4

We have used adenovirus-mediated gene transfer in apolipoprotein (apo)E(-/-) mice to elucidate the molecular etiology of a dominant form of type III hyperlipoproteinemia (HLP) caused by the R142C substitution in apoE4. It was found that low doses of adenovirus expressing apoE4 cleared cholesterol, whereas comparable doses of apoE4[R142C] greatly increased plasma cholesterol, triglyceride, and apoE levels, caused accumulation of apoE in VLDL/IDL/LDL region, and promoted the formation of discoidal HDL. Co-expression of apoE4[R142C] with lecithin cholesterol acyltransferase (LCAT) or lipoprotein lipase (LPL) in apoE(-/-) mice partially corrected the apoE4[R142C]-induced dyslipidemia. High doses of C-terminally truncated apoE4[R142C]-202 partially cleared cholesterol in apoE(-/-) mice and promoted formation of discoidal HDL. The findings establish that apoE4[R142C] causes accumulation of apoE in VLDL/IDL/LDL region and affects in vivo the activity of LCAT and LPL, the maturation of HDL, and the clearance of triglyceride-rich lipoproteins. The prevention of apoE4[R142C]-induced dyslipidemia by deletion of the 203-299 residues suggests that, in the full-length protein, the R142C substitution may have altered the conformation of apoE bound to VLDL/IDL/LDL in ways that prevent triglyceride hydrolysis, cholesterol esterification, and receptor-mediated clearance in vivo.

Composition and bioactivity of secretion from Stauronematus compressicornis (Fabricius)

We analyzed the composition and studied the bioactivity of secretion from the poplar sawfly, Stauronematus compressicornis (Fabricius). A leaf-sandwich method was applied to test the bioactivity of the secretion. Coomassie brilliant blue, gas chromatography (GC) and other methods were used to analyze and carry out protein assays, amino acid analyses, fatty acid and cholesterol detection of the secretion. Results show that the secretion had a significant antifeeding effect on 4th instar larvae of the armyworm (Pseudaletia separata Walker). Dissolved in 0.27 mol·L−1 HCl, 0.1 mol·L−1 NaOH and 0.05 mol·L−1 Na2HPO4 separately, the secretions had antifeeding rates ranging from 22.7% to 49.6%. Meanwhile, the weights of the secretion-treated insects were significantly lower than those of the control. Biochemical detection showed that the proteins contained in the secretion were composed of 16 amino acids. The secretion also contained small amounts of cholesterol and fatty acids, which included lauric acid, myristic acid, myristoleic acid, seventeen carbonic acids and oleic acid.

Effect of Cholesterol and Other Additives on Viscosity, Self-Diffusion Coefficient, and Intramolecular Movements of Oleic Acid

It has been empirically known that cholesterol largely increases the viscosity of oleic acid. To clarify the mechanism of the effect of cholesterol on the intermolecular and the intramolecular (segmental) movements of oleic acid in the liquid state, we measured density, viscosity, IR, 1H NMR chemical shift, self-diffusion coefficient, and 13C NMR spin-lattice relaxation time for the liquid samples of oleic acid containing a small amount of cholesterol. Furthermore, the above measurements were also carried out for the samples of oleic acid containing a small amount of cholestanol, cholestane, cholesteryl oleate, ethanol, or benzene. Cholesterol, possessing one OH group and one double bond in its molecular structure, largely increased the viscosity and reduced the self-diffusion and the intramolecular movement of oleic acid. Cholestanol, possessing one OH group but not a double bond, and cholesteryl oleate, not possessing an OH group, also reduced the self-diffusion and the intramolecular movement; cholestane, not possessing an OH group, slightly reduced the self-diffusion and the intramolecular movements. In contrast with these sterols, ethanol and benzene reduced the viscosity and increased the self-diffusion and the intramolecular movements. In addition, cholesterol and ethanol, both having one OH group, promoted the upfield shift of the 1H NMR signal of the carboxyl group of oleic acid; IR difference spectra for the cholesterol/oleic acid system quite resemble those for the ethanol/oleic acid system. These results suggest that oleic acid makes a complex with cholesterol as well as with ethanol. On the basis of the formation of the complex, we have revealed the role and the functional mechanism of cholesterol to the intermolecular and the intramolecular movements of oleic acid in the liquid state.

Lipid Homeostasis and Lipoprotein Secretion in Niemann-Pick C1-deficient Hepatocytes

Niemann-Pick C (NPC) disease is a fatal inherited disorder characterized by an accumulation of cholesterol and other lipids in late endosomes/lysosomes. Although this disease is considered to be primarily a neurodegenerative disorder, many NPC patients suffer from liver disease. We have investigated alterations that occur in hepatic lipid homeostasis using primary hepatocytes isolated from NPC1-deficient mice. The cholesterol content of Npc1(-/-) hepatocytes was 5-fold higher than that of Npc1(+/+) hepatocytes; phospholipids and cholesteryl esters also accumulated. In contrast, the triacylglycerol content of Npc1(-/-) hepatocytes was 50% lower than of Npc1(+/+) hepatocytes. We hypothesized that the cholesterol sequestration induced by NPC1 deficiency might inhibit very low density lipoprotein secretion. However, this process was enhanced by NPC1 deficiency and the secreted particles were enriched in cholesteryl esters. We investigated the mechanisms responsible for these changes. The synthesis of phosphatidylcholine, cholesteryl esters, and cholesterol in hepatocytes was increased by NPC1 deficiency and the amount of the mature form of sterol response element-binding protein-1 was also increased. These observations indicate that the enhanced secretion of lipoproteins from NPC1-deficient hepatocytes is due, at least in part, to increased lipid synthesis.

Paired helical filaments contain small amounts of cholesterol, phosphatidylcholine and sphingolipids

By using qualitative and quantitative high-performance thin layer chromatography (hpTLC) we found lipids associated with purified Alzheimer's (AD) paired helical filaments (PHF) in an amount of 1.4+/-0.2% of the total anhydrous mass. Compared to normal brain tissue these lipids have an unusual lipid class composition. The most prominent lipid classes were phosphatidylcholine (PC), cholesterol (CH), galactocerebrosides (GC) and sphingomyelin (SM). In addition, the use of micro high-performance liquid chromatography (HPLC) in combination with matrix-assisted laser desorption and ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) allowed the determination of the molecular species of the polar membrane lipid classes present in PHF. The lipid pattern of intracellular PHF shows many characteristics of the conserved lipid pattern previously described for extracellular amyloid fibrils, suggesting similarities in their pathway of formation.

A Molecular View of Cholesterol-Induced Condensation in a Lipid Monolayer

We investigate the intermolecular interactions in a mixed phospholipid/cholesterol monolayer using the surface-specific technique of vibrational sum frequency generation. This technique allows us to monitor the conformational and orientational order in the phospholipid as the surface pressure and cholesterol content are varied. We find a disproportionally large increase in phospholipid molecular order upon addition of relatively small amounts of cholesterol, a witness to the condensation effect at the molecular level.

Eruptive xanthomata in uncontrolled diabetes

with a two-week history of worsening symptoms of thirst, polyuria and lethargy presented to the admissions department feeling generally unwell. Five days previously he had visited his general practitioner who had made a diagnosis of diabetes mellitus and treated the patient for a presumed urinary tract infection. The patient had an otherwise unremarkable medical history, he did not take any regular medications or abuse alcohol and his grandfather was the only family member with type 2 diabetes. The patient had small, yellow nodules located across his torso and upper arms (figure 1). He said that these nodules, ranging from 2–4 mm in diameter, had appeared over the preceding week or so. The rest of the examination, including fundoscopy, was normal. Routine blood biochemistry was undertaken: liver and thyroid function tests as well as urea and creatinine were normal. Abnormal results included a random glucose sample of 22.5 mmol/L, sodium 120 mmol/L and total cholesterol 24.7 mmol/L. Subsequent testing found that his high density lipoprotein (HDL) cholesterol was 2.2 mmol/L, triglycerides were 96.0 mmol/L and upon close inspection, the serum was noticeably lipaemic; and the lipid content was clearly visible after settling the specimen bottle in the fridge (figure 2). The patient commenced insulin therapy (Humalog Mix 25; 36 & 18 units) and was seen by both the diabetes nurse specialist and the dietitian for education and advice. After six weeks he was seen in the Outpatients Clinic and his blood biochemistry had improved: total cholesterol 7.8 mmol/L, HDL cholesterol 1.1 mmol/L, triglycerides 19.4 mmol/L and HbA1C 6.6%. Eruptive xanthomata or xanthoma diabeticorum appear in patients who have greatly elevated serum triglycerides, very low density lipoproteins (VLDLs) and chylomicrons. The lesions themselves consist of mainly triglycerides and small amounts of cholesterol. In severe cases, fundoscopy may reveal lipaemia retinalis, when blood vessels of the retina appear milky due to exudation of abnormal triglyceride-rich plasma. The low sodium in this patient was a spurious result due to

Inhibition of protein translocation across the endoplasmic reticulum membrane by sterols.

Cholesterol and related sterols are known to modulate the physical properties of biological membranes and can affect the activities of membrane-bound protein complexes. Here, we report that an early step in protein translocation across the endoplasmic reticulum (ER) membrane is reversibly inhibited by cholesterol levels significantly lower than those found in the plasma membrane. By UV-induced chemical cross-linking we further show that high cholesterol levels prevent cross-linking between ribosome-nascent chain complexes and components of the Sec61 translocon, but have no effect on cross-linking to the signal recognition particle. The inhibiting effect on translocation is different between different sterols. Our data suggest that the protein translocation machinery may be sensitive to changes in cholesterol levels in the ER membrane.

A Thermodynamic Study of the Effects of Cholesterol on the Interaction between Liposomes and Ethanol

The association of ethanol with unilamellar dimyristoyl phosphatidylcholine (DMPC) liposomes of varying cholesterol content has been investigated by isothermal titration calorimetry over a wide temperature range (8–45°C). The calorimetric data show that the interaction of ethanol with the lipid membranes is endothermic and strongly dependent on the phase behavior of the mixed lipid bilayer, specifically whether the lipid bilayer is in the solid ordered (so), liquid disordered (ld), or liquid ordered (lo) phase. In the low concentration regime (<10 mol%), cholesterol enhances the affinity of ethanol for the lipid bilayer compared to pure DMPC bilayers, whereas higher levels of cholesterol (>10 mol%) reduce affinity of ethanol for the lipid bilayer. Moreover, the experimental data reveal that the affinity of ethanol for the DMPC bilayers containing small amounts of cholesterol is enhanced in the region around the main phase transition. The results suggest the existence of a close relationship between the physical structure of the lipid bilayer and the association of ethanol with the bilayer. In particular, the existence of dynamically coexisting domains of gel and fluid lipids in the transition temperature region may play an important role for association of ethanol with the lipid bilayers. Finally, the relation between cholesterol content and the affinity of ethanol for the lipid bilayer provides some support for the in vivo observation that cholesterol acts as a natural antagonist against alcohol intoxication.

An AFM Study of Lipid Monolayers. 2. Effect of Cholesterol on Fatty Acids

In this study the effect of cholesterol in Langmuir−Blodgett monolayers of fatty acids of varying chain lengths was investigated by atomic force microscopy (AFM). Domain formation due to lateral phase separation was studied at different lipid compositions and surface pressures. A small amount of cholesterol is miscible with palmitic acid (C16:0) and forms a flat monolayer while excess cholesterol forms a rougher cholesterol-rich phase. No miscibility was observed in monolayers of lignoceric acid (C24:0) and cholesterol. For the ternary mixed monolayer (palmitic acid, lignoceric acid, and cholesterol) the two fatty acids formed separate domains and the miscibility of cholesterol in the two phases showed behavior corresponding to that of the binary fatty acid−cholesterol systems. From the shape, size, and height differences of the domains one can conclude that the driving force to minimize the interfacial length between different phases is reduced in the presence of cholesterol. This can be attributed to line active properties of cholesterol.

Eustigmatophyte microalgae are potential sources of C 29 sterols, C 22–C 28n-alcohols and C 28–C 32n-alkyl diols in freshwater environments

The neutral lipids of three freshwater microalgae from the class Eustigmatophyceae were examined to investigate possible algal sources of lipids in lacustrine sediments. The major neutral lipids in Eustigmatos vischeri (Hulbert) Taylor, Vischeria helvetica (Vischer et Pascher) Taylor and Vischeria punctata Vischer were sterols, long-chain alcohols and alkyl diols. The distributions of long-chain n-alkanols and n-alkenols were very similar in each species, but there were small interspecies differences in the proportions of alkyl diols. Saturated alcohols ranged from 14:0 to 28:0 (both present in trace amounts), with 22:0 as the major alkanol. The latter has previously been reported to be the major n-alcohol in some lacustrine sediments. C 16–C 30 monounsaturated alcohols were more abundant: 26:1 and 28:1 were the major constituents. The sterol distributions consisted predominantly of 24-ethylcholesterol with small amounts of cholesterol, 24-methylcholesterol, 24-ethylcholesta-5,22 E-dien-3β-ol and isofucosterol. These results add to the growing list of microalgae that contain a high proportion of 24-ethylcholesterol, which is more typically associated with higher plants. The long-chain alkyl diols ranged from C 28 to C 32: the major constituents were the C 28 1,13-diol and C 30 and C 32 1,15 diols which occurred together with smaller amounts of other positional isomers. C 30 and C 32 alkyl diols have been found in marine eustigmatophytes of the genus Nannochloropsis, and these new results confirm that the same class of compounds occurs in freshwater eustigmatophytes.

Clogging the arteries

Atherosclerosis is a leading cause of mortality in North America and Europe. Several research groups have developed models of Chlamydia pneumoniae respiratory infection in rabbits and have observed pathological changes consistent with atherosclerotic vascular disease. Muhlestein et al.[1]now report the effects of C. pneumoniae respiratory infection followed by antibiotic (azithromycin) treatment on the development of atherosclerosis in rabbits. All the rabbits were fed a diet supplemented with small amounts of cholesterol, an established method of accelerating atherosclerosis. The degree of intimal atheromatous involvement was determined by the measure of maximal intimal thickness, the percentage of luminal circumference involved and the plaque area index. The average of these measurements was significantly higher in the infected untreated rabbits than in the infected antibiotic-treated rabbits and the uninfected controls. These results argue the causal nature of C. pneumoniae infection in the development of atherosclerosis, and thus heart disease, as well as the therapeutic role of antibiotic therapy. Interestingly, the response to infection was not uniform among the infected untreated rabbits (40% showed prominent atherogenesis, while 60% did not), suggesting that there is variability in the ability of the bacteria to establish an infection or in the host response to combat such an infection. Muhlestein et al.[1]point out the limitations of their study: they did not determine whether cholesterol supplementation was important or whether other doses or other antibiotics would have the same anti-atheromatous effect. They also note that, as with any model, this rabbit model is not identical to that of the human disease and any extrapolations must be made with caution.

Reduction of serum cholesterol and low-density lipoprotein cholesterol levels in a juvenile population after isocaloric substitution of whole milk with a milk preparation (skimmed milk enriched with oleic acid)

Objective: To study the effects of serum lipid levels by isocaloric substitution of whole milk intake in a group of children with a milk preparation (fat-free milk enriched with oleic acid containing a small amount of cholesterol) that is frequently consumed in our community. Design: A crossover clinical trial was carried out with random selection. There were 88 children of both sexes, ranging in age from 3 to 9 years, selected at a Primary Care Center. The children were divided into two homogeneous groups. The first group consumed whole milk for the first 7-month study period, whereas the second group drank the milk substitute. At the end of the first test period, serum lipid levels were measured. Then the type of diet was reversed: Group 1 children consumed the milk substitute whereas Group 2 children drank whole milk. The rest of their intake did not vary throughout the study. At the end of the second 7-month period we measured serum lipid levels again. The levels of serum lipid evaluated were total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, Apoprotein A1, Apoprotein B, and lipoprotein (a). For the statistical analysis the nonpaired and paired t tests were used. Results: The mean level of cholesterol after taking whole milk was 4.53 mmol/L (175.26 mg/dl), and the mean level after taking the milk preparation was 4.2 mmol/L (162.65 mg/dl), which indicates a 7.2% decrease. The mean level of low-density lipoprotein cholesterol after whole milk intake was 2.73 mmol/L (106.1 mg/dl), whereas after consuming the milk preparation it was 2.47 mmol/L (96.1 mg/dl), which indicates a decrease of 9.5%. Triglycerides were reduced from 0.83 mmol/L (73.53 mg/dl) after whole milk to 0.72 mmol/L (63.79 mg/dl) after the milk substitute, which suggests a 13.25% decrease. High-density lipoprotein cholesterol, apoprotein A1, apoprotein B, and lipoprotein (a) did not undergo any significant change. Conclusions: To reduce serum levels of total cholesterol and low-density lipoprotein cholesterol, without reducing caloric intake, it may be beneficial to substitute the whole milk customarily consumed by children with a milk preparation of fat-free milk enriched with oleic acid. (J Pediatr 1998;132:85-9)