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1.
Eur J Nutr ; 41(1): 19-26, 2002 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-11990004

RESUMEN

BACKGROUND: We found in preliminary studies with hamsters that citrus peels have a cholesterol lowering effect comparable to that of pectin extracted from these peels. AIM OF THE STUDY: We wanted to examine whether the cholesterol lowering effect of the peels could be completely accounted for by the pectin in the peels. METHODS: We fed cholesterol enriched (0.1 %,w/w) semipurified diets containing 3% (w/w) of cellulose, lemon peels, lemon pectin, and the waste stream material of the lemon peels to hybrid F1B hamsters for a period of 8 weeks. The waste stream of the lemon peels is the left over after extraction of the lemon pectin. RESULTS: Feeding the semipurified diets resulted in an increase of plasma cholesterol levels in all the dietary groups after 2 and 4 weeks on the diets. Cholesterol concentrations in the cellulose fed hamsters continued to increase after 4 weeks on the diet, whereas cholesterol levels in the other groups had reached a plateau. As a consequence, the plasma cholesterol levels in the hamsters fed the peels (5.59 +/- 0.74 mmol/L, mean +/- SD, n = 14), pectin (5.19 +/- 0.48 mmol/L), or waste stream (5.53 +/- 0.94 mmol/L) were lower than those in the hamsters fed cellulose (6.71 +/- 1.52 mmol/L) after 8 weeks on the diets. Differences in total plasma cholesterol were reflected in differences in both VLDL and LDL cholesterol concentration, but this effect was more distinct for the VLDL. There was no effect of the type of fiber on HDL cholesterol levels. Liver cholesterol concentrations paralleled. the concentrations of plasma cholesterol and the liver cholesterol concentrations in the hamsters fed the peels (3.57+/- 1.01 micromol/g liver, mean +/- SD, n = 14), pectin (4.86 +/- 1.42), and the waste stream (4.96 +/- 1.89) were lower than those in the cellulose group (7.19 +/- 2.32). The hamsters fed the peels, pectin, or waste stream tended to have a higher excretion of fecal bile acids and neutral sterols then the cellulose fed hamsters. CONCLUSION: The results of this study suggest that lemon peels and the waste stream of the lemon peels are as effective in lowering plasma and liver cholesterol in hamsters as the pectin extracted from the peels and that also compounds other than pectin are probably responsible for the cholesterol lowering effect of the citrus peels.


Asunto(s)
Anticolesterolemiantes/farmacología , Antidiarreicos/farmacología , Colesterol/sangre , Citrus , Hipercolesterolemia/sangre , Hipercolesterolemia/tratamiento farmacológico , Pectinas/farmacología , Triglicéridos/sangre , Residuos , Análisis de Varianza , Animales , Cricetinae , Hígado/efectos de los fármacos , Masculino , Mesocricetus
2.
Nahrung ; 46(2): 83-6, 2002 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-12017997

RESUMEN

We fed cholesterol-enriched (0.1% w/w) semipurified diets containing 3% of lemon pectin or 3% of the polygalacturonic acid regions fraction (smooth regions fraction) of the lemon pectin to hybrid F1B hamsters for a period of 8 weeks. A control group was fed cellulose and a positive control group was fed psyllium. The feeding of the semipurified diets resulted in an increase of plasma cholesterol levels in all the dietary groups when compared with initial values. The hamsters fed the psyllium, pectin, or the polygalacturonic acid regions fraction had significantly (P < 0.05) lower plasma cholesterol levels than the cellulose fed group throughout the experimental period. Plasma cholesterol levels in the hamsters fed the psyllium, pectin, or polygalacturonic acid regions fraction were not significantly different. Liver cholesterol concentrations were also lower in the hamsters fed the psyllium, pectin, or the polygalacturonic acid regions fraction than in the hamsters fed the cellulose, but this effect reached statistical significance only in the hamsters fed the polygalacturonic acid regions fraction. The results of these studies suggest that the polygalacturonic acid regions of the pectin molecule is responsible for the cholesterol-lowering properties of the pectin.


Asunto(s)
Anticolesterolemiantes/farmacología , Colesterol/sangre , Pectinas/química , Pectinas/farmacología , Animales , Anticolesterolemiantes/administración & dosificación , Celulosa/administración & dosificación , Celulosa/farmacología , Colesterol/análisis , Colesterol en la Dieta/administración & dosificación , Cricetinae , Hígado/metabolismo , Masculino , Mesocricetus , Pectinas/administración & dosificación , Psyllium/administración & dosificación , Psyllium/farmacología
3.
Ann Nutr Metab ; 44(5-6): 223-8, 2000.
Artículo en Inglés | MEDLINE | ID: mdl-11146328

RESUMEN

We fed cholesterol-enriched (1% cholesterol and 0.2% cholic acid) semipurified diets containing either 3% cellulose or psyllium to 2 groups of female Wistar rats for a period of 8 weeks. The feeding of the cholesterol-enriched semipurified diets resulted in a progressive increase in plasma cholesterol levels in both groups during the 8 weeks of the experiment. The rats fed psyllium, however, had significantly lower plasma cholesterol concentrations than the animals fed cellulose throughout the experimental period (at 8 weeks, 8.92 +/- 4.42 and 16.47 +/- 8 mmol/l, respectively, means +/- SD, n = 14, p < 0.01). Most of the plasma cholesterol in both groups at the end of the study was located in the very low-density lipoprotein (VLDL) fraction (91%) and differences in total plasma cholesterol concentrations were predominantly reflected in differences in VLDL cholesterol. Plasma triglyceride concentrations were not significantly different between the 2 groups. Liver cholesterol concentrations paralleled the concentrations of plasma cholesterol and were significantly lower (p < 0.001) in the psyllium-fed rats (90.31 +/- 13.81 micromol/g liver) than in the cellulose-fed rats (60.49 +/- 15.25 micromol/g liver). Substitution of psyllium for cellulose resulted in an increase in the excretion of fecal bile acids by 26%, and this increase was predominantly caused by an increased excretion of beta-muricholic acid and the bile acids derived from beta-muricholic acid (omega-muricholic acid and hyodeoxycholic acid).


Asunto(s)
Anticolesterolemiantes/administración & dosificación , Colesterol/sangre , Psyllium/administración & dosificación , Animales , Colesterol en la Dieta/administración & dosificación , Colesterol en la Dieta/efectos adversos , VLDL-Colesterol/sangre , Heces/química , Femenino , Lípidos/sangre , Hígado/metabolismo , Ratas , Ratas Wistar
4.
J Nutr ; 128(11): 1944-9, 1998 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-9808647

RESUMEN

We fed semipurified diets containing pectin with either a high or low in vitro viscosity at a level of 3 g/100 g air-dried diet to hamsters for 8 wk. A control group was fed cellulose and a positive control group was fed psyllium. The pectins used were a calcium-sensitive pectin (CS-pectin) that has a high viscosity and a noncalcium-sensitive pectin (NCS-pectin) that has a low viscosity. In the presence of calcium, CS-pectin has a more than 80-fold higher viscosity than NCS-pectin which offered the opportunity to investigate the possible role of viscosity in the hypolipidemic properties of pectin. The hamsters fed CS-pectin or psyllium had considerably lower plasma cholesterol concentrations (3.69 +/- 0.44 and 4.21 +/- 0.45 mmol/L, respectively, mean +/- SD, n = 14) than those fed NCS-pectin (5.03 +/- 1.15 mmol/L) or cellulose (5.72 +/- 1. 04 mmol/L). Differences in total plasma cholesterol were reflected in both high density lipoprotein and very low density lipoprotein cholesterol. There was no effect of fiber on low density lipoprotein cholesterol levels. Liver cholesterol concentrations paralleled the plasma cholesterol levels and were 9.91 +/- 2.48 micromol/g of liver for the CS-pectin group, 15.03 +/- 5.75 for the psyllium group, 17. 69 +/- 10.66 for the NCS-pectin group, and 25.57 +/- 9.23 for the cellulose group. Fecal bile acid and neutral steroid excretion tended to be higher in the hamsters fed CS-pectin than in their counterparts fed NCS-pectin. The hamsters fed psyllium had significantly greater fecal excretions of bile acids than the hamsters fed cellulose, CS-pectin or NCS-pectin, whereas the excretion of fecal neutral sterols tended to be lower. Plasma cholesteryl ester transfer protein activity was significantly lower in the hamsters fed CS-pectin than in those fed NCS-pectin. The results of this study suggest that the viscosity of pectins may determine their cholesterolemic effect.


Asunto(s)
Proteínas Portadoras/sangre , Colesterol/sangre , Colesterol/metabolismo , Dieta , Glicoproteínas , Hígado/metabolismo , Pectinas/farmacología , Animales , Ácidos y Sales Biliares/metabolismo , Calcio/farmacología , Celulosa/farmacología , Proteínas de Transferencia de Ésteres de Colesterol , HDL-Colesterol/sangre , LDL-Colesterol/sangre , VLDL-Colesterol/sangre , Cricetinae , Heces , Masculino , Mesocricetus , Pectinas/administración & dosificación , Psyllium/farmacología , Triglicéridos/sangre , Viscosidad
5.
J Nutr ; 123(3): 578-85, 1993 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-8463858

RESUMEN

The effects of the type of dietary fat (180 g/kg diet) and of calcium phosphate (CaHPO4) supplementation (25 vs. 225 mmol/kg diet) on luminal solubility of fatty acids and bile acids, cytotoxicity of fecal water and intestinal epitheliolysis were studied in rats. In rats fed the low and high calcium phosphate diets, fecal excretion of fatty acids diminished in the order palm oil > milk fat > corn oil. Palm oil also caused the highest concentration of fatty acids measured in fecal water followed by milk fat and corn oil when fed at both calcium phosphate levels. The differences in concentrations of luminal surfactants in fecal water of rats fed the three fat diets resulted in a fat type-dependent cytotoxicity of fecal water, with that of palm oil-fed rats the most cytotoxic. The concentrations of fatty acids as well as bile acids in fecal water were, however, significantly lowered by calcium phosphate supplementation in rats fed all types of dietary fat. This reduction in concentration of fecal water surfactants resulted in a lower cytotoxicity of fecal water. The concentration of surfactants in fecal water and cytotoxicity were correlated by multiple regression analysis (R = 0.89). Intestinal epitheliolysis measured as alkaline phosphatase activity in fecal water was lowered comparably to the reduction in cytotoxicity by supplemental calcium phosphate. Intestinal epitheliolysis and cytotoxicity of fecal water were correlated (r = 0.92, P < 0.001). The type of dietary fat and the amount of dietary calcium phosphate influence the concentrations of surfactants in fecal water and consequently affect cytotoxicity of fecal water and intestinal epitheliolysis.(ABSTRACT TRUNCATED AT 250 WORDS)


Asunto(s)
Agua Corporal/metabolismo , Fosfatos de Calcio/farmacología , Neoplasias del Colon/etiología , Grasas de la Dieta/administración & dosificación , Heces , Fosfatasa Alcalina/metabolismo , Animales , Ácidos y Sales Biliares/química , Ácidos y Sales Biliares/metabolismo , Fosfatos de Calcio/administración & dosificación , Fosfatos de Calcio/uso terapéutico , Muerte Celular/efectos de los fármacos , División Celular/efectos de los fármacos , Colon/patología , Neoplasias del Colon/patología , Neoplasias del Colon/prevención & control , Grasas de la Dieta/efectos adversos , Epitelio/patología , Ácidos Grasos/química , Ácidos Grasos/metabolismo , Masculino , Aceite de Palma , Aceites de Plantas/administración & dosificación , Aceites de Plantas/efectos adversos , Ratas , Ratas Wistar , Solubilidad
6.
Cancer Res ; 53(4): 784-9, 1993 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-8428359

RESUMEN

Bile acids and fatty acids may promote colon cancer by inducing colonic hyperproliferation. Dietary calcium inhibits the promoting effects of bile acids and fatty acids, possibly by precipitating these surfactants and lowering their cytolytic activity. Because bile acids and fatty acids are products of fat digestion, their effects may be dependent on the type of dietary fat. The effects of the type of dietary fat (energy percentage, 40) and of CaHPO4 supplementation (25 versus 225 mumol/g diet) on the luminal solubility of surfactants, cytolytic activity, epitheliolysis, and in vivo colonic proliferation were studied in rats using Western high-risk diets. The different types of commercially available fats were butter, saturated margarine, and polyunsaturated margarine. Supplemental calcium drastically increased fecal fatty acid excretion, the effect being dependent on the type of fat, and slightly stimulated fecal bile acid excretion. Soluble surfactant concentrations were drastically decreased by calcium supplementation with all three types of dietary fat. Consequently, cytolytic activity of fecal water was decreased by supplemental calcium. These luminal effects of calcium resulted in a lower intestinal epitheliolysis. The compensatory proliferation of the colonic epithelium was decreased by supplemental CaHPO4 for the butter and saturated margarine diets. Despite CaHPO4-dependent decreases in luminal effects and epitheliolysis, no significant decrease in proliferation on the polyunsaturated margarine diet was observed. Multiple regression analysis of soluble surfactants with cytolytic activity (R = 0.76), epitheliolysis (R = 0.74), and colonic proliferation (R = 0.84) showed highly significant associations. Cytolytic activity and epitheliolysis as well as epitheliolysis and proliferation were highly correlated (r = 0.97 and r = 0.88, respectively; n = 36) for control and CaHPO4-supplemented diets, suggesting cause-and-effect relationships. It is concluded that the antiproliferative effect of dietary calcium is mediated by the precipitation of luminal surfactants and is dependent on the type of dietary fat.


Asunto(s)
Ácidos y Sales Biliares/análisis , Calcio de la Dieta/farmacología , Ácidos Grasos Insaturados/efectos adversos , Ácidos Grasos/análisis , Heces/química , Mucosa Intestinal/citología , Triglicéridos/efectos adversos , Animales , Ácidos y Sales Biliares/metabolismo , Mantequilla/efectos adversos , División Celular/efectos de los fármacos , Ácidos Grasos/metabolismo , Ácidos Grasos Insaturados/administración & dosificación , Mucosa Intestinal/efectos de los fármacos , Masculino , Margarina/efectos adversos , Ratas , Ratas Wistar , Triglicéridos/administración & dosificación
7.
Cancer Res ; 53(2): 248-53, 1993 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-8417817

RESUMEN

Dietary calcium supplementation inhibits hyperproliferation of rectal epithelium, possibly by precipitating luminal surfactants and thus preventing their cell-damaging effects. Therefore, we studied the effects of supplemental dietary calcium (35.5 mmol/day) on composition and cytolytic activity of fecal water and on the release of the epithelial marker alkaline phosphatase in 12 healthy volunteers. Fecal water was isolated by low-speed centrifugation. Cytolytic activity was determined as lysis of human erythrocytes by fecal water. Intestinal alkaline phosphatase activity in fecal water was measured with the use of the uncompetitive inhibitor L-phenylalanine. Supplemental calcium increased soluble calcium and decreased soluble P(i). The logarithm of the concentration product of calcium and phosphate was linearly dependent on pH. These observations indicate formation of insoluble calcium phosphate. Supplemental calcium did not alter the total bile acid concentration in fecal water but significantly decreased the ratio of more hydrophobic to more hydrophilic bile acids from 3.3 to 2.3. Calcium also significantly decreased the concentration of fatty acids (from 2.9 to 2.1 mM). Consistent with these decreases in hydrophobic surfactants, calcium decreased the cytolytic activity of fecal water from 47 +/- 9 to 27 +/- 8% (n = 12, P < 0.05). Analogous to the decrease in cytolytic activity, the release of the epithelial marker alkaline phosphatase was also lowered by supplemental calcium. We conclude that supplemental dietary calcium decreases luminal cytotoxic surfactant concentrations and thus inhibits luminal cytolytic activity and the release of the epithelial marker alkaline phosphatase as an indicator of intestinal epitheliolysis. This mechanism may explain how dietary calcium could decrease epithelial cell proliferation.


Asunto(s)
Calcio/farmacología , Heces/química , Mucosa Intestinal/metabolismo , Adulto , Fosfatasa Alcalina/metabolismo , Ácidos y Sales Biliares/metabolismo , Calcio/metabolismo , Ácidos Grasos/metabolismo , Hemólisis , Humanos , Concentración de Iones de Hidrógeno , Magnesio/metabolismo , Masculino , Fosfatos/metabolismo , Esteroles/metabolismo , Agua/metabolismo
8.
Am J Physiol ; 261(6 Pt 1): G907-12, 1991 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-1767851

RESUMEN

The effects of dietary steroid and CaHPO4 supplementation on the solubility of bile acids and cytotoxicity of fecal water were studied in rats. Dietary steroid supplementation increased the bile acid concentration of both feces and fecal water. CaHPO4 supplementation produced a slight increase in total fecal bile acid concentration but resulted in a drastic decrease in soluble bile acid concentration. Cytotoxicity of fecal water on control and steroid-supplemented diets decreased with CaHPO4 supplementation analogous to the decrease in soluble bile acid concentration. The concentrations of precipitated Ca and Pi were highly correlated (r greater than 0.90) with the concentration of precipitated bile acids and with inhibition of cytotoxicity. However, there was no significant correlation between the logarithms of soluble calcium and soluble bile acids, indicating that solubility of bile acids is not determined by soluble calcium. Concentrations of calcium and phosphate in fecal water indicated the formation of insoluble calcium phosphate in the intestine. Thus dietary CaHPO4 causes a decrease in soluble bile acid concentration, which is probably due to the formation of an insoluble bile acid calcium phosphate complex. Consequently, cytotoxicity of fecal water is inhibited, which might have implications for the protective effect of dietary calcium with regard to colonic cancer in humans.


Asunto(s)
Fosfatos de Calcio/farmacología , Citotoxinas , Heces , Animales , Ácidos y Sales Biliares/metabolismo , Calcio de la Dieta , Eritrocitos/citología , Femenino , Hemólisis , Humanos , Ratas , Ratas Endogámicas , Esteroides/farmacología
9.
Gastroenterology ; 99(6): 1653-9, 1990 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-2121581

RESUMEN

It has been suggested that supplemental dietary calcium decreases hyperproliferation of colonic epithelial cells because calcium precipitates and thus inactivates luminal bile acids. Therefore, 12 healthy men were studied before and after dietary calcium supplementation (35.5 mmol/day) to quantify intestinal associations of calcium, phosphate, and bile acids. The supplemental dietary calcium was almost completely (95%) recovered, mainly in feces. Calcium increased the fecal excretion of both phosphate (31%) and bile acids (53%) and decreased the ratio of dihydroxy to trihydroxy bile acids in duodenal bile almost twofold. In vitro studies showed that precipitation of glycodeoxycholic acid was caused by the formation of insoluble calcium phosphate. Water-soluble and calcium-associated amounts of phosphate and bile acids in feces were measured by resolubilization studies, using the calcium chelator ethylenediaminetetraacetate. In both the control and calcium periods, significant amounts of phosphate (80% and 90%) and bile acids (33% and 50%) were calcium-associated. Moreover, the calcium-induced increments in fecal phosphate and bile acids were completely calcium-associated. Calcium decreased the amount of water-soluble phosphate but not of bile acids. These results indicate that supplemental calcium stimulates formation of insoluble calcium phosphate in the intestinal lumen and thus increases binding of luminal bile acids.


Asunto(s)
Ácidos y Sales Biliares/metabolismo , Calcio de la Dieta/farmacología , Calcio/metabolismo , Mucosa Intestinal/metabolismo , Fosfatos/metabolismo , Ácidos y Sales Biliares/orina , Calcio/orina , Ácido Edético , Heces , Humanos , Masculino , Fosfatos/orina
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