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The effect of diet supplemented with 5% and 15% cellulose or with 15% fiber isolated from red beet (Beta vulgaris var. rubra) on the development of alimentary hypercholesterolemia and chemically induced colon carcinoma was studied in male Wistar rats. Hypercholesterolemia was induced by a diet containing 0.3% of cholesterol and colon carcinoma was induced by treatment with dimethylhydrazine (20 mg/kg, 12 doses applied s.c. in one-week intervals). Fibrous matter isolated from red beet contained 89% fiber, of which 9% was in water soluble form. Animals were killed 14 weeks after the application of dimethylhydrazine (i.e. 26 weeks after starting on the diets). Red beet fiber diet (and not the increased cellulose intake) caused a reduction of serum cholesterol and triacylglycerol levels (by 30 and 40%, respectively) and a significant increase in the fraction of cholesterol carried in HDL. This diet induced also a significant decrease (almost by 30%) of cholesterol content in aorta. Higher cellulose content in the diet and even more so the administration of red beet fiber caused a significant reduction of conjugated dienes content in plasma, erythrocytes and in liver. Also observed were increases in the activities of superoxide dismutase and catalase in erythrocytes and in colon and activities of glutathione peroxidase and glutathione-S-transferase in liver. The presence of both higher cellulose content and red beet fiber in the diet significantly reduced the incidence of precancerous lesions--aberrant crypt foci--in the colon. The diet containing red beet fiber did not affect significantly the incidence of colon tumours although the number of animals bearing tumours was reduced by 30%.

The effect of dried tomato, grape and apple pomace (5% in diet) on the cholesterol levels in serum and selected organs was studied in male Wistar rats fed a cholesterol diet (0.3%) shortly after weaning. Pomace of individual fruits contained 47.2, 67.0 and 46.2 g of total dietary fiber per 100 g of dry matter for tomato, grape and apple pomace, respectively. Corresponding values for the soluble components of the fiber were 10.3, 14.7 and 26.0%. None of the tested products affected the serum cholesterol levels. Tomato and apple pomace significantly reduced cholesterol level in liver by 15% and 11%, respectively, and all tested pomace species reduced cholesterol content in heart (by 18-21%). Triacylglycerol content was affected only by tomato pomace and solely in the heart. Cholesterol absorption measured by dual-isotope ratio method, was not significantly affected by the pomace, however, all products strongly reduced (up to the half of the original value) the activity of HMG-CoA reductase in liver and increased the fractional catabolic rate of plasma cholesterol (by 60-120%). All tested pomace reduced plasma levels of conjugated dienes and tomato and grape pomace exhibited this effect also in the liver. All tested pomace reduced the activities of antioxidant enzymes superoxid dismutase, catalase and glutathione peroxidase in erythrocytes (by 34-56%).

Wistar rats fed a semisynthetic diet containing 0.3% cholesterol and supplemented with 5% dried whole oyster mushroom ( Pleurotus ostreatus ) had reduced serum and liver cholesterol levels by 32 and 55%, respectively, at the end of 8th week of the experiment. The reduction of cholesterol was due to the decreased cholesterol content in very-low-density lipoproteins (VLDL) and in low-density lipoproteins (LDL). Cholesterol concentration in high-density lipoproteins (HDL) increased significantly by 34%. Animals fed the oyster mushroom diet had elevated level of fecal excretion of neutral sterols by 32% and the excretion of bile acids by 55%. Activity of cholesterol 7α-hydroxylase (a rate-limiting enzyme of cholesterol catabolism) was enhanced by 33% and the activity of lecithin: cholesterol acyltransferase was also increased by 13%.

In Wistar rats fed after weaning a semisynthetic diet containing 0.3% cholesterol (C), the addition of 4% dried whole oyster mushroom ( Pleurotus ostreatus ) led to a reduced level of serum and liver C at the end of the 10 th week of the experiment by 25, resp. 33%. The level of serum triacylglycerols was not influenced by the mushroom, but was significantly reduced by 13% in liver. The decrease in serum C level is a consequence of the decreased C concentration in very-low-density lipoproteins (VLDL) and in low-density lipoproteins (LDL). Content of C in high-density lipoproteins (HDL) was not influenced by the mushroom. Dietary Pleurotus ostreatus increased the fractional turnover rate of LDL (by 28%) and HDL (by 31%) as determined by the analysis of decay curves of 125 I-labelled lipoproteins. The increase in rate of LDL and HDL catabolism is one of the decisive mechanisms which mediates the hypocholesterolemic effect of mushroom in rat.

In male rats fed a diet containing 1.5% cholesterol and 5% of dried mushroom (Pleurotus ostreatus) a significantly reduced accumulation of cholesterol in serum (by 45%) and the liver (by 15%) was observed at the end of the 12th week of the experiment. The decrease in serum cholesterol level by more than 90% is a consequence of the decreased cholesterol concentration of very-low-density lipoproteins (VLDL) and of low-density lipoproteins. Consumption of P. ostreatus reduces the total VLDL entry into the circulation by 19% and accelerates (by 49%) fractional turnover rate of VLDL.

We studied the effect of the edible mushroom Pleurotus ostreatus (4% in diet containing 1% of cholesterol) on serum and liver lipids in female rats with hereditary enhanced sensitivity to alimentary cholesterol. We found that the consumption of the mushroom-containing diet prevented serum cholesterol increase which was manifested at the end of the 4th week of the experiment. At the end of the 7th week of the experiment the cholesterolemia was lowered by almost 40% as compared with control animals kept on the same diet but without the mushroom. The decrease in serum cholesterol levels is a consequence of the decreased cholesterol concentrations of very-low-density lipoproteins and of low-density lipoproteins.

The addition of 10% dried fruiting bodies of the oyster mushroom (Pleurotus ostreatus) to the diet containing 1% of cholesterol reduced serum cholesterol levels by 65% and cholesterol content in the liver, heart, long extensor muscle and aorta of male rabbits (Chinchilla) by 60; 47; 25 and 79%, respectively. Oyster mushroom diet reduced the content of conjugated dienes by 60-70% in the plasma, erythrocytes and liver. However, it did not significantly affect the activities of antioxidant enzymes. Oyster mushroom diet reduced significantly the incidence of atherosclerotic plaques as estimated by sudanophilia (absence of a positive reaction in 3 of 5 animals) as well as plaque size (26% vs. 2% of the area with a positive reaction in control and oyster mushroom-treated animals, respectively). While all animals on control diet showed atherogenic changes in the aorta, oyster mushroom diet prevented the development of these changes in three animals. Fatty streaks and fibromatous plaques were found in the remaining two animals from this group. The oyster mushroom prevented the formation of atheroma plaques (found in three cases from the control diet group) and reduced the incidence of segmental injury of the coronary artery and of focal fibrosis of the myocardium. The oyster mushroom caused lower incidence of foam cells in all types of lesions.

The addition of 10% dried fruiting bodies of oyster mushroom (Pleurotus ostreatus) to the diet containing 1% of cholesterol reduced serum cholesterol levels by 65% and cholesterol content in liver, heart, long extensor muscle and aorta of male rabbits (Chinchilla) by 60, 47, 25 and 80%, respectively. The decrease in total serum cholesterol was affected primarily (by 70%) by reduced cholesterol content in very-low-density lipoproteins (VLDL) while the contribution of high density lipoproteins (HDL) cholesterol increased by a factor of 3. Oyster mushroom diet reduced by 60-70% the content of conjugated dienes in plasma, erythrocytes and liver, however, it did not affect significantly the activities of antioxidant enzymes. Oyster mushroom diet reduced significantly the incidence of atherosclerotic plaques as estimated by sudanophilia (absence of positive-reaction in 3 of 5 animals) as well as plaque size (26% vs. 2% of the area with positive reaction in control and oyster mushroom-treated animals, respectively). While all animals on control diet showed atherogenic changes in aorta, oyster mushroom diet prevented the development of these changes in three animals. Fatty streaks and fibromatous plaques were found in the remaining two animals from this group. Oyster mushroom prevented the formation of atheroma plaques (found in three cases from the control diet group) and reduced the incidence of segmental injury of coronary arteria and of focal fibrosis of myocardium. Oyster mushroom caused lower incidence of foam cells in all types of lesions.

The effect of dried tomato, grape and apple pomace (5% in diet) on the cholesterol levels in serum and selected organs was studied in male Wistar rats fed a cholesterol diet (0.3%) shortly after weaning. Pomace of individual fruits contained 47.2, 67.0 and 46.2 g of total dietary fiber per 100 g of dry matter for tomato, grape and apple pomace, respectively. Corresponding values for the soluble components of the fiber were 10.3, 14.7 and 26.0%. None of the tested products affected the serum cholesterol levels. Tomato and apple pomace significantly reduced cholesterol level in liver by 15% and 11%, respectively, and all tested pomace species reduced cholesterol content in heart (by 18-21%). Triacylglycerol content was affected only by tomato pomace and solely in the heart. Cholesterol absorption measured by dual-isotope ratio method, was not significantly affected by the pomace, however, all products strongly reduced (up to the half of the original value) the activity of HMG-CoA reductase in liver and increased the fractional catabolic rate of plasma cholesterol (by 60-120%). All tested pomace reduced plasma levels of conjugated dienes and tomato and grape pomace exhibited this effect also in the liver. All tested pomace reduced the activities of antioxidant enzymes superoxid dismutase, catalase and glutathione peroxidase in erythrocytes (by 34-56%).

It is generally accepted that lowering of serum cholesterol levels reduces the risk of atherosclerosis. Identification and characterization of natural substances with hypocholesterolemic activity useful in dietetic prevention or treatment of hypercholesterolemia is still relevant in countries with persistent progression of hypercholesterolemia. Addition of oyster mushroom (Pleurotus ostreatus), an industrially produced wood-rotting fungus, to the diet effectively reduced cholesterol accumulation in serum and liver of rats fed a cholesterol diet. The aim of a series of experiments was to explain the biochemical mechanism of this effect.Male Wistar rats fed a cholesterol (0.3%) diet shortly after weaning for a period of 8-10 weeks were used in the experiments. The addition of 5% of dried oyster mushroom to the diet had following effects: reduction of cholesterol level both in serum (5.12 +/- 0.55 vs. 3.44 +/- 0.16 mmol/l, p0.02) and liver (241 +/- 12 vs. 113 +/- 11 mmol/kg, p0.001); redistribution of cholesterol in favour of high-density lipoproteins; reduced production of very-low-density lipoproteins (135 +/- 7 vs. 96.5 +/- 5 mumol/h/kg, p0.001); reduced cholesterol absorption (61.2 +/- 2 vs. 53 +/- 2%, p0.02) and reduced HMG-CoA activity in liver (137 +/- 16 vs. 86 +/- 9 pmol/min/mg proteins, p0.02). Simultaneously, an increase in 7 alfa-hydroxylase activity in liver (17 +/- 1 vs. 22 +/- 1 pmol/min/mg proteins. p0.02) and bile acid excretion (7 +/- 0.9 vs. 11 +/- 0.5 mg/day/rat, p0.02) was observed. (Values shown are means +/- SEM.)Biochemical mechanism of hypocholesterolemic effect of oyster mushroom on cholesterol-fed rats includes reduced production of cholesterol-rich very-low-density and low-density lipoproteins which principally determine cholesterol levels in serum. This effect is related to decreased absorption and biosynthesis of cholesterol together with increase in cholesterol catabolism and excretion of degradation products-bile acids.

The effect of the diet containing 5% of powdered oyster mushroom (Pleurotus ostreatus) or an equivalent amount of mushroom ethanolic extract on cholesterol content in serum and liver, on its distribution in lipoproteins, absorption and turnover was studied in male Wistar rats (initial body weight about 70 g) fed a diet with 0.3% cholesterol. 12 weeks of feeding with whole oyster mushroom or mushroom extract reduced cholesterol level in serum by 52 and 33%, respectively. However, cholesterol content in liver was reduced only by whole oyster mushroom (by 20%). Diminished serum cholesterol level was mediated in 60% by reduction of cholesterol in very-low-density lipoproteins. Both whole oyster mushroom and mushroom extract increased the concentration of cholesterol in high-density lipoproteins. Consuming whole oyster mushroom decreased cholesterol absorption (estimated by dual-isotope plasma ratio method) by nearly 16% while no significant effect of mushroom extract could be demonstrated. Feeding the diet containing whole oyster mushroom or its extract reduced the half-times of decay curve of cholesterol-4-14C by 29 and 35%, respectively and reciprocally increased the fractional catabolic rate of plasma cholesterol.

The effect of dried oyster mushroom (Pleurotus ostreatus) on cholesterol (C) content in serum, in lipoproteins and in liver, and on the activity of 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase in liver microsomes, was studied in male rats (strain Wistar, initial body weight 75 g) fed on low-cholesterol (9 mg/100 g) and high-cholesterol (0.3%) diets. Addition of 5% oyster mushroom to both diets reduced significantly the C-content in serum (by 30%), in very-low- and low-density lipoproteins (in a 1:1 ratio to the decrease of total serum C) and in liver (by 50%), as well as the activity of HMG-CoA reductase (by more than 30%).

Oyster mushroom (Pleurotus ostreatus) is a wood-rotting mushroom industrially grown in Slovakia and other countries on ligno-cellulosic substrates. We have shown in a series of experiments that the addition of 5% of dried oyster mushroom fruiting bodies to diet of experimental animals efficiently reduced the accumulation of cholesterol in serum and liver that was induced either nutritionally or by stimulation of endogenous lipid production. With the aim to study an alternative application of oyster mushroom in the diet and to characterize active substances in more detail, we compared the hypocholesterolemic activity of the whole oyster mushroom with its extracts in aqueous ethanol and with the extraction residues

The effect of adding 5% powdered oyster mushroom (Pleurotus ostreatus) during 12 weeks on kinetic parameters of cholesterol metabolism was studied in male rats (Wistar, initial body weight 85 g) fed a semisynthetic diet containing 0.3% of cholesterol. The plasma cholesterol decay curve (examined for the final 29 days of the experiment after a single dose of cholesterol-4-14C) was evaluated by mathematical analysis using a two-pool model of plasma cholesterol metabolism. The oyster mushroom in the diet reduced the half-times of both exponentials resulting in lower calculated values (by 28%) of total entry of cholesterol into the body cholesterol pool (absorption+endogenous synthesis) and lower sizes of both pools (with slower and faster cholesterol exchange). The rate of cholesterol exchange between the pools was enhanced and the rate of total clearance of cholesterol from the system (metabolic turnover rate of cholesterol i.e. the rate of degradation and excretion of cholesterol from the organism) was enhanced by 50%. The oyster mushroom diet effectively prevented the progress of hypercholesterolaemia (decrease by 38%) and cholesterol accumulation in liver (decrease by 25%) that were induced by the cholesterol diet.

The content of cholesterol in the serum and liver of male Wistar rats fed, for the period of 8 weeks shortly after weaning, a diet containing 0.3% of cholesterol was reduced by 33 and 27% by the addition of 5% of dried oyster mushroom powder. Although the level of serum triacylglycerols was not affected by oyster mushroom, their content in liver of rats on mushroom diet was reduced by 41%. Very-low-density lipoproteins and low-density lipoproteins participated by 55 and 38%, respectively, in the total reduction of serum cholesterol. Cholesterol content in high-density lipoproteins was not significantly affected by oyster mushroom. Cholesterol absorption as determined by dual-isotope plasma ratio method was significantly reduced by 14% with oyster mushroom diet. Similarly, this diet increased by 42% the fractional catabolic rate of cholesterol determined by the analysis of decay curve of [4−14C]cholesterol.

In the conditions of physiological nutrient content and variable amino-acid mixtures made of casein K, gluten G and KG combination (1:1, standard diet), the 10-week effect of amino acids (until the age of 105 days, end of maturation stage) was investigated in growing rats with respect to protein utilization (net protein ratio) and to the values of lipid parameters at the end of the experiment (cholesterol, triacylglycerols, atherogenic indexes, cholesterol distribution into lipoprotein classes). A significant decrease in NPR for gluten, an insignificant decrease for casein in the growth period are related to the amino acid score of limiting amino acids--they determine rate of proteosynthesis and potential biological value--amount percentage of amino acids of the given diet for plastic processes of proteins (AS for KG 69, for K 67, for G 28; BHp for KG 83.1, for K 70.0, for G 54.1). Since day 105 amino acid utilization is balanced in all groups, hence it does not depend upon the quality of aminograms (lower rate of proteosynthesis in comparison with the growth period, for which the values of limiting amino acids are sufficiently high). Significantly decreased values of cholesterolemia and triacylglycerolemia for gluten food, insignificantly higher values for casein food, are in direct correlations with the values of Lys/Arg, Met/Arg, Met, Lys, and in indirect correlations with Arg and Arg+Glu+Gly. Distribution of HDL-cholesterol as a cholesterol percentage in HD lipoproteins is higher by 8.7% for gluten and all atherogenic indexes are significantly decreased in contrast to casein food, in which a slight decrease in HDL-cholesterol and insignificantly higher atherogenic indexes were recorded.