Social disparities in musculoskeletal disorders and associated mental malaise: findings from a population-based survey in France.

AIMS: Various types of musculoskeletal disorders (MSDs) have comorbid mental disorders, which may in turn have a negative influence on disease course and role impairment, but the contribution of social factors to this type of comorbidity is a much under-researched area. This study investigates whether there is a socially patterned association of MSDs with different dimensions of mental malaise. METHODS: The sample included 3,368 economically active participants aged 18-64 years, randomly selected from the Lorraine region in north-eastern France. Information was provided through a post-mailed questionnaire on fatigue, sadness/depression (Duke questionnaire) and cognitive disability during the last eight days. RESULTS: MSDs were significantly more prevalent in manual workers, clerks and other occupations than in upper and intermediate professionals, and similar occupational disparities were found for cognitive disability, fatigue and sadness/ depression. Stratifying the sample, we found the occupational disparities in cognitive disability to be much stronger among participants suffering from MSDs than among participants not suffering from MSDs, and the occupational disparities in fatigue and sadness/depression to be limited to the subsample of subjects suffering from MSDs. CONCLUSIONS: The findings demonstrate that the association of MSDs with mental malaise is much stronger in the lower occupational groups than in the higher groups. Given that psychological factors are implicated in disease prognosis and in the development of disabilities, awareness of the social dimension of the association and treatment of the comorbid mental disorders could open a promising avenue for reducing social inequalities in disability related to MSDs.

Ex vivo study of incorporation into adipocytes and lipolysis-inhibition effect of polycyclic aromatic hydrocarbons.

We have previously shown that benzo[a]pyrene (B[a]P) administrated at extremely low dose can cause weight gain in mice and that the increase in adipose tissue mass is due to inhibition of beta-adrenergic stimulation of lipolysis. Moreover we have suggested that in addition to its endocrine properties, adipose tissue act as a reservoir for many chemical carcinogens including Polycyclic Aromatic Hydrocarbons (PAHs). In this paper we show that B[a]P as well as the two C4 PAHs, pyrene and phenanthrene can bioaccumulate into adipocytes in a similar manner, but that at the difference of B[a]P, have no impact on epinephrine-induced lipolysis. On the basis of this ex vivo study, we therefore suggest that B[a]P may play a central role in carcinogenesis not only by inducing cancer through its mutagenic properties, but also by increasing the bioaccumulation capacity of the adipose tissue mass.

Behaviour of dioxin in pig adipocytes.

Due to their lipophilic properties, dioxins can be integrated into the lipidic vacuole of adipocytes (fat cells). The aim of this study was to determine the kinetics of incorporation and release of 3H-labelled palmitic acid and 14C-labelled 2,3,7,8-TCDD in isolated adipocytes from pigs. The incorporation of 2,3,7,8-TCDD and palmitic acid was found to be concomitant under conditions of lipogenesis, under the effect of increasing quantities of insulin and in the presence of glucose. Release of these two compounds was found to be dependant on a lipolytic agent (epinephrine). These results suggest the risk of a strong increase of 2,3,7,8-TCDD, induced by lipolysis, in the blood of animals or humans previously exposed to this dioxin.

In vitro allergenicity of peanut after hydrolysis in the presence of polysaccharides.

BACKGROUND: Peanut is a major allergenic product. Manufacturing processes used in food industries to improve the physicochemical properties of food-based peanut (stabilization, texturization), could cause a modification of the digestibility of peanut proteins and, consequently, their allergenicity. OBJECTIVE: This study aimed at examining the influence of polysaccharides, i.e., gum arabic, low methylated pectin (LMP) and xylan, on the in vitro hydrolysis of peanut protein isolate (PPI) and the in vitro allergenicity of the digestion products. METHODS: PPI was hydrolysed during a two-step in vitro hydrolysis by pepsin, followed by a trypsin/chymotrypsin (T/C) mixture performed in dialysis bags with molecular weight cut-offs (MWCO) of 1000 or 8000 Da. SDS-PAGE electrophoresis and immunoblotting were assessed on the peptic and T/C digestion products in (retentates) and out of the dialysis bags (dialysates). RESULTS: Hydrolysis by all of the digestive enzymes showed retention of some proteins in the dialysis bags in the presence of gum arabic and xylan. The retentates were recognized by IgG and IgE, particularly peptides <20 kDa. The IgE binding with peptides of retentate containing xylan from the dialysis bag with an MWCO of 1000 Da was reduced. The immunoreactivity of hydrolysis products in dialysates was considerably reduced by polysaccharides, regardless of the dialysis bag. CONCLUSION: Reduction of PPI hydrolysis was probably due to non-specific interactions between polysaccharides and peptides. In retentates, IgE-binding epitopes were reduced by digestion and the presence of xylan. In dialysates, they were reduced by all of the polysaccharides. This work highlights the possibility of modulating this food allergy through optimized formulation.

[Food allergy: effect of proteins-lipids and proteins-polysaccharides interactions]. / Allergénicité alimentaire: importance des interactions protéines-lipides et protéines-polysaccharides.

The most widely used ingredients in food formulation are proteins, lipids and polysaccharides. Proteins-lipids and proteins-polysaccharides interactions play a key role in the structure, stability, sensorial and nutritional properties of formulated foods. The objective of the present study is to highlight the importance of proteins-lipids and proteins-polysaccharides interactions, on the immuno-reactivity of allergenic proteins. Two models have been studied, on the one hand refined and not refined oils (soya and sunflower) and soya lecithin, on the other hand mixtures based on peanut proteins and polysaccharides (arabic gum, pectin, xylan). STUDY OF OILS: We have extracted proteins, using a PBS buffer, from refined and not refined oils from soya, sunflower and from soya lecithin, determined protein concentrations and identified allergenic proteins using SDS-PAGE electrophoresis and immuno-blotting. Phospholipids are determined by atomic absorption spectrometry. The protein determination and SDS-PAGE show the presence of a higher amount of proteins in not refined oils and lecithin as compared to refined oils. An important amount of proteins associated to phospholipids are eliminated by degumming on the form of lecithin. On the other hand, residual proteins from refined oils are accompanied by phospholipids. Immuno-blots reveal the presence of a 56 kDa allergen in oils issued from soya seeds and soya lecithin, and the presence of a 67 kDa allergen in oils issued from sunflower seeds. We conclude that the presence or elimination of proteins, especially allergens from oils is linked to amphiphilic association to phospholipids. STUDY OF PEANUT PROTEINS-POLYSACCHARIDES MIXTURES: We have digested in vitro proteins in a dialysis bag using a multi-enzymatic method and characterized proteins and peptides using SDS-PAGE electrophoresis and immuno-blotting. Our results confirm that peanut proteins alone are digested by proteases and that a number of large peptides still have epitopes recognized by anti-peanut proteins antibodies. Our results also show that the presence of polysaccharides changes the peptidic profile after digestion and that, depending on the polysaccharide type, smaller or larger peptides can be obtained in the dialysis bag. Smaller peptides are obtained using pectin whereas larger peptides are obtained using arabic gum and xylan. In the latter case, an increasing amount of peptides reacts to antibodies. Our first observations clearly show the need to better understand modifications of proteins allergenicity induced by the presence of other ingredients such as polysaccharides and lipids, in relation to technological treatments.

Beta-lactoglobulin/polysaccharide interactions during in vitro gastric and pancreatic hydrolysis assessed in dialysis bags of different molecular weight cut-offs.

The effects of gum arabic, low methylated (LM) pectin or xylan at levels of 0 and 50 wt.% on beta-lactoglobulin (beta-lg) digestibility were studied as well as the interactions between the two macromolecules during in vitro hydrolysis. The proteolysis was performed in a system involving a two-step hydrolysis: either pepsin alone, or pepsin followed by a trypsin/chymotrypsin (T/C) mixture in dialysis bags with molecular weight cut-offs (MWCO) 1000 or 8000 Da. Digestibility was estimated by the N release and by a SDS-PAGE electrophoresis of retentates from the two dialysis bags after hydrolysis. Turbidimetric measurements monitored the structural evolution of mixtures during the two-step hydrolysis. Results showed that beta-lg was almost resistant to peptic digestion and that polysaccharides increased the N release despite a reduction of pepsin activity. This is due to the formation of electrostatic complexes between polysaccharides and beta-lg, which reduced beta-lg aggregation, increasing its solubility. The polysaccharides reduced significantly the beta-lg T/C digestibility as determined using a dialysis bag with a MWCO 1000 Da, without a modification of their enzymatic activities. No significant effect of polysaccharides on the beta-lg digestibility was detected using the dialysis bag with a MWCO 8000 Da. The electrophoresis pattern did not show differences in the profile of retentates in relation with the dialysis bag used. This suggests that non-specific interactions could occur during the second step of hydrolysis between polysaccharides and amino acids or peptides smaller than 8000 Da.

Effects of different levels of gum arabic, low methylated pectin and xylan on in vitro digestibility of beta-lactoglobulin.

Plant hydrocolloids used in the food industry to improve texture and stability of food, such as dairy products, can reduce protein digestibility and, consequently, modify the bioavailability of amino acids. We studied the in vitro hydrolysis at 37 degrees C of beta-lactoglobulin (beta-lg) in mixed dispersions containing either gum arabic or low-methylated pectin or xylan at levels of 0, 1, 10, 20, 30, and 50% weight. Proteolysis used either pepsin alone by progressive reduction of pH during proteolysis or pepsin followed by trypsin and chymotrypsin in two different dialysis bags with a molecular weight (MW) cutoff of 1000 or 8000 Da. Results showed that beta-lg was almost resistant to pepsin digestion and that the three plant hydrocolloids inhibited significantly beta-lg digestibility as determined using dialysis bag with a 1000-Da MW cutoff. Among the three polysaccharides used, xylan showed a digestibility decrease greater than that obtained with gum arabic and low-methylated pectin. On the other hand, no significant effect of polysaccharides on the in vitro beta-lg digestibility was detected using the dialysis bag with an 8000 Da MW cutoff. This mainly suggests that peptides with MW in the range 1000 to 8000 Da may interact with polysaccharides more than peptides and proteins with a greater molecular weight to decrease the protein digestibility, and that the nature of the polysaccharides plays a role in the interaction.

Obesity is associated with decreasing levels of the circulating soluble leptin receptor in humans.

OBJECTIVE: Leptin plays a major role in the regulation of body weight. It circulates in both free and bound form. One of the leptin receptor isoforms exists in a circulating soluble form that can bind leptin. In the present study, we measured the soluble leptin receptor (SLR) levels in lean and obese humans. We investigated the relationship between plasma SLR levels, plasma leptin levels and the degree of obesity. We also examined whether SLR concentrations could be modulated by fat mass loss induced by a 3 month weight-reducing diet. SUBJECTS: A total of 112 obese (age 18-50 y; body mass index (BMI) 30-44 kg/m2; 23 men and 89 women), 38 overweight (age 19-48 y; BMI 25-29 kg/m2; 10 men and 28 women) and 63 lean (age 18-50 y; BMI 17-24 kg/m2; 16 men and 47 women) humans. MEASUREMENTS: A direct double monoclonal sandwich enzyme-linked immunosorbent assay (ELISA) was used for the quantitative measurement of the soluble human leptin receptor. Leptin was measured by radioimmunoassay (RIA). Body composition was assessed by biphotonic absorptiometry DEXA (dual energy X-ray absorptiometry). RESULTS: We observed that the SLR is present in human plasma (range 10-100 ng/ml). SLR levels were lower in obese and overweight than lean subjects (28.7+/-8.8, 40.2+/-14.9, 51.2+/-12.5 ng/ml, respectively) and were inversely correlated to leptin and percentage of body fat (r=-0.74 and r=-0.76; respectively; P<0.0001). The ratio of circulating leptin to SLR was strongly related to the percentage of body fat (r=0.91; P<0.0001). Interestingly a gender difference was observed in SLR levels, which were higher in obese and overweight men than in obese and overweight women. In obese subjects after a 3 month low-calorie diet, SLR levels increased in proportion to the decrease in fat mass. In the gel filtration profile, SLR coeluted exactly with the bound leptin fractions. CONCLUSION: Obesity, in humans is associated with decreasing levels of the circulating soluble leptin receptor (SLR). The relationship of SLR with the degree of adiposity suggests that high SLR levels may enhance leptin action in lean subjects more than in obese subjects.

The cholesterol-lowering property of soybeans fed to rats is related to the fasting duration.

Numerous factors affect plasma cholesterol and, therefore, represent potential interferences with the specific effects of diet on lipid metabolism. After casein intake, serum cholesterol levels depend on many experimental conditions in rats, such as the type of casein, the presence or absence of cholesterol in the diet, the age and strain of rat, the diet composition, the nutritional status. The effect of fasting duration on selected parameters was studied in adult male Wistar rats fed a 20% casein and 1% cholesterol-based diet. No changes were observed in total serum, lipoproteins-B and HDL cholesterol and in triglyceride values after an 8 h-fast compared to non-fasted animals. A significant decrease was induced in total and lipoproteins-B cholesterol with a 12 h-fast. A prolonged fast resulted in a significant decrease in these parameters and in triglycerides and in HDL-cholesterol levels. Fasted animals fed heated soybean meal instead of casein did not display a marked decrease in serum lipids. It appeared that the fasting effect was more marked in animals fed casein than in animals fed soybeans. These results showed the importance of experimental conditions such as nutritional status of animals when blood samples are taken in studies of the hypocholesterolemic effect of soy protein compared to casein.

Effects of soybean (Glycine max) germination on biologically active components, nutritional values of seeds, and biological characteristics in rats.

We briefly reviewed the effects of soybean germination on biologically active components, nutritive value of seed and biological characteristics in rats. The purpose of this review is to evaluate the effects of soybean germination on nutritional values of seeds and the potential importance for the use of germinated soybeans, from a contemporary conception, in food preparation as well as on soybean possible influence in optimal health. Germination induced a substantial increase in the content of saponin, oestrogenic compounds and almost all phytosterols, particularly beta-sitosterol of seeds. Lecithin content increased slightly and gradually during germination process. Lipase and alpha-galactosidase activities increased whereas lipoxygenase activities reduced after a short period of germination (< or = 72 h). Therefore, the substantial odour and flavour scores of germinated soybean flour were improved. Germinated seeds were also beneficial to heat penetration, their thermolabile antinutritional factors were easier to inhibit than those of dry beans, also the seeds did not require a long cooking time to be palatable. Duration of the germination process greatly influenced the nutritional value and palatability of seeds and biological characteristics in rats. In rat bioassay, one-day germination of soybeans induced a significant increase of daily body weight gain, daily protein intake in rats and protein efficiency ratio (PER) of seed meal. Palatability of seeds was also improved whereas a 5-day germination resulted in a decrease of PER of seed meal (less than the value of unheated seeds) and induced thyroid enlargement in rats. A vapour thermal treatment (100 degrees C, 20 min) eliminated thyroid-active agents and improved PER of seed meal, food intake and final weight of rats. Well prepared germinated soybeans can be used as a good alternate to animal proteins for more balanced nutritional diet. Development of food products from germinated soybean may be another way to further increase the versatility and utility of soybeans for both developing and industrialized countries, as germination induced the modification of certain specific biologically active components, palatability and nutritive value of seeds.

Dietary intakes, eating style and overweight in the Stanislas Family Study.

OBJECTIVES: To describe the eating patterns of members of French families and to assess the relationships between dietary intakes, eating style and overweight. DESIGN: Cross-sectional analysis of nutritional and behavioural characteristics. SUBJECTS: 1,320 members of 387 families (age 11-65y) attending the Centre for Preventive Medicine for a routine medical check-up. MEASUREMENTS: Individual body weight and height were measured. Food intake was assessed using a three day dietary record. Eating style was measured using the French validated version of the Dutch Eating Behaviour Questionnaire. RESULTS: In each of the four groups (men, women, boys and girls), dietary restraint was positively correlated with overweight (P< or =0.001) and associated with lower energy intakes (P < or = 0.05-P < or = 0.001). A negative association between energy intake and overweight was found in girls only (P< or =0.001). In all cases, overweight and dietary restraint exaggerated any existing macronutrient imbalance in energy intake (ie higher protein and fat contributions, lower carbohydrate contribution). Emotional eating was positively correlated to body mass index in women only (P< or =0.01). External eating was mainly a characteristic of children (P< or =0.001). CONCLUSION: As in overweight subjects, clear relationships were found in this sample of general population between dietary intakes and eating style. The population will be followed up for 10y. In the long term, these results should have implications in the prevention of obesity.

Composition of pulp, skin and seeds of prickly pears fruit (Opuntia ficus indica sp.).

The proximate composition of pulp, skin and seeds of prickly pear cactus (Opuntia ficus indica) was investigated and is reported on a dry weight basis. The most abundant component of the pulp and skin was ethanol-soluble carbohydrates. Pulp contained glucose (35%) and fructose (29%) while the skin contained essentially glucose (21%). Protein content was 5.1% (pulp), 8.3% (skin) and 11.8% (seeds). Starch was found in each of the three parts of the fruit. Pulp fibers were rich in pectin (14.4%), skin and seeds were rich in cellulose (29.1 and 45.1%, respectively). Skin was remarkable for its content of calcium (2.09%) and potassium (3.4%). Prickly pear is a neglected nutritional source which should be more widely used because of its potential nutrient contribution.

[Chronobiology, nutrition and metabolism]. / Chornobiologie, nutrition et métabolisme.

The "nutrition" function is fulfilled by a succession of physiologic actions of which the first is eating and the last is the intracellular metabolism of nutrients. These actions involve not only sensory processes subjected to neurocentral regulation but also peripheral metabolic, and hormonal processes. The physiologic "nutrition" function involves a number of parameters for which fundamental rhythms have been demonstrated, such as eating behaviors, intra- and extracellular metabolisms, hormone secretions and their effects on target organs, and use of food and nutrients. Each of these rhythms can be demonstrated under physiologic conditions but can be modified by environmental factors (temperature, light, seasons, physical and mental activity), disease states (many diseases can produce profound alterations in nutritional regulation processes), and drugs. Interactions between these rhythms also exist; for instance, eating behavior rhythms can be modified by sociocultural pressures and this can, in turn, modify the fundamental rhythms of biologic parameters. The unit of time that allows the study of these rhythms varies: in addition to circadian and ultradian rhythms, weekly (cisaseptian) and annual (circannual) cyclical changes should be taken into account when investigating human nutrition.

Accessibility of human apolipoprotein B-100 epitopes in insulin-dependent diabetes: relation with the surface lipid environment of atherogenic particles.

The physicochemical modifications (composition and conformation) of lipoproteins containing apolipoprotein B-100 (apo B-100) were studied in normocholesterolaemic adequately controlled Type 1 insulin-dependent diabetic patients. Thirty-one normocholesterolaemic (serum cholesterol < 6.50 mmol/l) diabetic male patients and 31 age-and body mass index-adjusted healthy normolipaemic male controls were studied. Cholesterol and choline-containing phospholipids were measured in total serum and in two lipoprotein subfractions containing or not apo B (LpB and LpnoB respectively). These subfractions were separated by precipitation with concanavalin A. Total apo B-100 and two lipoprotein particles defined according to their apo B-100 epitope accessibility were determined using respectively anti-apo B polyclonal and two monoclonal antibodies that reacted with specific epitopes on the apo B molecule. Despite a classical lipid profile (cholesterol and triglyceride levels), which was quite normal in plasma from patients as compared to controls, a depletion of choline-containing phospholipid content in serum and more specifically in LpB particles was observed in diabetic patients. Decreased cholesterol content was also observed in LpB particles. Immunological analysis demonstrated an increased number of lipoprotein particles (a condition previously related to coronary artery disease) and decreased immunoaccessibility of a conformationally expressed apo B-100 epitope. These conformational changes were correlated with modifications of the surface phospholipid environment of LpB particles. It is concluded that subtle abnormalities in the composition and conformation of atherogenic apo-B-containing lipoproteins occur in Type 1 diabetes mellitus. These structural modifications may be one factor accounting for the increased rate of atherosclerosis in diabetes, despite the existence of a normal classical lipid profile.

Internal validation of a French version of the Dutch eating behaviour questionnaire.

This study is the first part of the validation of a French version of the Dutch Eating Behaviour Questionnaire (DEBQ), among a population of obese and normal-weight patients. The questionnaire was administered to 166 subjects. Construct validity was assessed by orthogonal factor analysis with a varimax procedure and reliability was measured by Cronbach's alpha coefficient. Results showed the presence of three major factors ("emotional", "restrained" and "external eating") with loadings similar to those of the original questionnaire. A high internal consistency was found in the different scales. This study clearly demonstrates the factorial validity and the reliability of a French version of the DEQB.

Relationships between macronutrient intake, handicaps, and cognitive impairments in free living elderly people.

It is still unknown what if any relationships exist between intake of macronutrients by the elderly, and their functional or cognitive handicaps, particularly for free living elderly people. We investigated 226 men and 215 women, aged 65 or more, free living and in good health. They were randomly selected in the département of Bas-Rhin, after stratification for age, sex and residence (rural or urban). Handicaps and cognitive functions of each subject were assessed with the Géronte scale and the Mini-Mental State Examination (MMSE), respectively. Food intake was measured by a three-day record. A multiple correspondence analysis concluded that functional parameters and macronutrient intakes were rather independent. The relationships found were detailed by a backward stepwise logistic regression. In men, alcohol intake was associated with an improvement in functional and cognitive parameters, and polyunsaturated fatty acids with the capacity to move outside the home. In women, lipid intake increased the MMSE score. Overweight in women was linked with better functional and cognitive performances, and in men with the capacity to move outside the home. In both sexes, age worsened the score of functional and cognitive parameters. In conclusion, macronutrient intakes and functional or cognitive parameters were found to be mutually independent; this suggests that macronutrient deficiencies are of little importance in the worsening functional or mental autonomy of the elderly. The relationships found between functional variables and alcohol or polyunsaturated fatty acid intakes in men, and lipid intakes in women, and overweight in both sexes might evidence a better state of health.

Increased erythrocyte aggregation in insulin-dependent diabetes mellitus and its relationship to plasma factors: a multivariate analysis.

Red blood cell aggregation in vitro (kinetics and shear resistance) was studied in 13 healthy controls and 13 type I (insulin-dependent) diabetic patients free of severe degenerative complications who were matched for age, sex, and body mass index. Measurements were performed with a device that analyzes the laser light backscattered by a blood suspension. Both the velocity of rouleau formation and the cohesion of the rouleau network were significantly increased in diabetic patients. Plasma viscosity and whole-blood viscosity measured at low shear rate (0.95 s-1) were also significantly elevated in the diabetic group. Multivariate analyses of the whole population sample and the diabetic patients confirmed the influence of plasma proteins on the kinetics of aggregation. Fibrinogen levels, which were close to normal, affected mainly the shear resistance of the aggregates. Triglyceride and apolipoprotein (apo) B levels and indexes of metabolic control or protein glycation (fasting blood glucose and fructosamine) also appeared to influence markedly both the kinetics of rouleau formation and the cohesion of the rouleau networks. These rheological abnormalities occurred in diabetic patients before the appearance of any severe degenerative complications. We suggest that these rheological abnormalities are linked to plasma or erythrocyte factors, and are not due to angiopathy.

[Effects of treatments (heat and fermentation by Rhizopus oligosporus sp-T3) of sweet white lupin seeds on certain factors of its nutritional use]. / Effets des traitements (chauffage et fermentation par Rhizopus oligosporus sp-T3) de la graine de lupin blanc doux sur certains facteurs de son utilisation nutritionnelle.

For improving the nutritional value and functional properties of sweet white lupin (SWL), a solid fermentation process using Rhizopus oligosporus was developed for the preparation of lupin products. A comparison of the effects of soaking + thermal treatment and fermentation was made from 3 lupin products: non-treated lupin seeds (SWLnt), heated lupin seeds (steamed at 100 degrees C for 30 min) (SWLh), and fermented lupin products (SWLf) from SWLh on chemical characteristics and protein efficiency ratio (PER) in rats. The major effect of soaking and thermal treatment is a loss of protein solubility and available lysine (from 3.02 +/- 0.18 g/16 g N to 2.3 +/- 0.25). Fermentation leads to a modification, of amino acid composition and to an increase in available lysine compared to heating (2.90 +/- 0.12 g/16 g N). The nutritional quality of SWLnt is low (PER = 0.83 +/- 0.09), thermal treatment decreases it (0.58 +/- 0.18) and fermentation compensates heating effect (0.74 +/- 0.25). It is suggested that the modifications of nutritional quality depends on the availability of lysine rather than on the variations of the levels of other amino acids.

Effect of different kinds of dietary casein on blood cholesterol and triglycerides in pair fed rats.

After casein intake, serum cholesterol levels are dependent on many experimental conditions in rats. The effect of the method of casein preparation was assessed in Wistar rats pair-fed for 4 wk with three identical diets differing only by the type of casein used. Compared with dietary casein and Na caseinate, ingestion of lipid- and vitamin-free casein resulted in higher liver weights (4.35 +/- 0.23 vs. 3.89 +/- 0.30 and 3.90 +/- 0.25 g) and fasting serum cholesterol levels (0.55 +/- 0.13 vs. 0.49 +/- 0.09 and 0.44 +/- 0.09 g/L). Compared with the two other casein diets, ingestion of Na caseinate produced the lowest fasting serum triglyceride levels (0.62 +/- 0.13 vs 0.74 +/- 0.12 and 0.73 +/- 0.13 g/L). Peptic digestibility of caseins used might be a regulating factor of serum cholesterol levels in Wistar rats.

Effects of the nature of dietary proteins, lecithin and methionine on rat plasma lipids.

In order to study the complex interrelationships between on the one hand, dietary proteins, lecithin and methionine and, on the other, blood cholesterol and triglyceride levels, groups of .10 rats were fed for six weeks with diets only differing by the nature of proteins which comprised 10% of the diet. These diets were composed of egg white, heated soybean flour, casein, heated soybean flour supplemented with 1% methionine, or with 4% of the lipids replaced by soybean lecithin, heated 5-day germinated soybean supplemented or not with 1% methionine and casein with 4% of the lipids replaced by lecithin. Egg white caused no change in blood cholesterol compared to heated soybean meal (0.955 +/- 0.18 vs 0.83 +/- 0.14), but caused a significant increase in blood cholesterol levels compared to casein (0.955 +/- 0.18 vs 0.81 +/- 0.11 g/l). No effect was found on blood triglycerides levels. Lecithin caused no change when it partially replaced lipids in the soybean or casein diets thought it increased triglycerides with the casein diet (1.16 +/- 0.31 vs 0.84 +/- 0.24 g/l). Supplementation of the heated soybean diet with 1% methionine led to an increase in blood triglycerides (0.85 +/- 0.26 vs 1.18 +/- 0.34 g/l). After germination, this effect disappeared. The effects of the type of protein, partial replacement of dietary lipids by lecithin and supplementation with methionine are discussed.