Diet, nutrition intake, and metabolism in populations at high and low risk for colon cancer. Binding of bile salts to dietary residues.

The binding of glycocholic and glycochenodeoxycholic acids to dried defatted residues of homogenized diets consumed by four dietary groups has been measured. The four groups were true vegetarian Seventh-day Adventists (SDA), lacto-ovo vegetarian SDA, nonvegetarian SDA, and the general population. Glycocholic acid was bound to the same extent (7 to 9%) by all four dietary residues. The true vegetarian SDA residues bound significantly more glycochenodeoxycholic acid than those of either lacto-ovo vegetarian SDA (p less than 0.001) or nonvegetarian SDA (p less than 0.001). The general population residue bound significantly more glycochenodeoxycholic acid than did those of nonvegetarian SDA (p less than 0.001). Binding of glycochenodeoxycholic acid was significantly correlated with dietary neutral detergent fiber (p less than 0.001), hemicellulose (p less than 0.01) and cellulose (p = 0.01). There was no correlation between the binding of glycochenodeoxycholic acid and dietary lignin, pectin, or cutin.

Diet, nutrition intake, and metabolism in populations at high and low risk for colon cancer. Relationship of diet to serum lipids.

Serum cholesterol, high-density lipoprotein cholesterol, and triglycerides of three groups of Seventh-day Adventists (SDAs)--true vegetarians, lacto-ovo vegetarians, and nonvegetarians--and the general population were measured and related to age, sex, and diet. True vegetarian SDAs had the lowest cholesterol levels while cholesterol levels of the other three groups were similar. Triglyceride levels were highest in the true vegetarian SDAs and lowest in general population. Cholesterol levels rose with increasing age while percentage of high-density lipoprotein cholesterol fell. Female SDAs in all three dietary groups had higher cholesterol levels than males. In all four groups percentage of high-density lipoprotein cholesterol was higher in females than in males. In the male subjects, cholesterol levels varied linearly and inversely with carbohydrate intake. Protein and fat intake in true vegetarian SDAs and lacto-ovo vegetarian SDA groups were lower than in the nonvegetarian SDA and general population groups. The differences in protein and fat intake were reflected in elevations in serum cholesterol levels. In the female subjects, cholesterol levels were also inversely correlated with carbohydrate intake but not as distinctly as in the males. True vegetarian SDA females ingested less protein and fat than the other three groups and exhibited lower serum cholesterol levels. Cholesterol levels in lacto-ovo vegetarian SDA, nonvegetarian SDA, and general population female subjects were similar and did not reflect differences in protein or fat intake. The true vegetarian dietary lifestyle resulted in lowest cholesterol levels, however, if it was breeched to the least extent, cholesterol levels rose. Thus, intake of skim, low fat, or whole milk resulted in similar serum cholesterol levels as did low or high egg consumption.

Diet, nutrition intake, and metabolism in populations at high and low risk for colon cancer. Comparison of serum hexosaminidase levels.

Elevated levels of serum hexosaminidase (beta-2-acetamido-2-deoxy-D-glucoside; N-acetamidodeoxy-D-glucohydrolase, EC 3.2.1.30)(HEX) have been found in patients with cancer. In view of the reported low levels of colon cancer among Seventh-day Adventists (SDA) we determined levels of total HEX, and its heat-labile (HEX-A) and heat-stable (HEX-B) isozymes in vegetarian SDA, lacto-ovo vegetarian SDA, nonvegetarian SDA, and the general public. Lowest levels of total HEX and highest percentage of HEX-B were found in vegetarian SDA. The levels in the other three groups were comparable, and these differences were seen at all age levels. Female subjects exhibited significantly lower total HEX levels than the males but the percentage of HEX-B was the same.

Influence of whole or skim milk on cholesterol metabolism in rats.

Male Wistar rats were fed commercial ration and given whole milk, skim milk, or water to drink. After 3 weeks the control group showed the greatest weight gain. Rats given whole milk had the smallest livers. Serum cholesterol levels were significantly lower in rats fed either whole or skim milk, but other serum lipids were unaffected. Liver triglyceride levels were lowest in the rats on skim milk. Activities of hepatic fatty acid synthetase, hydroxymethyl-glutaryl coenzyme A reductase and cholesterol 7alpha-hydroxylase were similar in the two milk-fed groups and considerably lower than in the controls.

Dietary fiber and intestinal adaptation: effects on lipid absorption and lymphatic transport in the rat.

Adult male rats fed defined diets containing various fiber supplements or cholestyramine for 4 wk were surgically provided with lymphatic drainage catheters and starved overnight. After duodenal administration of a standard lipid test emulsion, absorption rates and lipoprotein distributions of cholesterol and oleic acid were determined. Prefeeding diets containing cellulose or alfalfa had no significant effect on oleic acid absorption. Diets containing pectin, guar gum, metamucil, mixed fibers (Fibyrax), or cholestyramine caused decreased lymphatic recovery in the initial period; except for the metamucil diet, no decrease was caused in the 24-h recovery, suggesting delayed but not impaired absorption. Fatty acid distribution among lipoproteins and chylomicron size were not altered by diet. All supplements caused a significant reduction in cholesterol absorption during the initial period, and cholesterol absorption remained depressed in animals prefed pectin, guar gum, mixed fibers, metamucil, and cholestyramine.

Cholesterol vehicle in experimental atherosclerosis. Part 15. Randomized butter and randomized lard.

Randomized lard and butter oil were conpared with native lard and butter oil for their effects on cholesterol-induced atherosclerosis in rabbits. In each experiment there was also a group fed corn oil. The diets contained 2% cholesterol and 6% fat and were fed for eight weeks. Randomization of either butter or lard had virtually no effect as regards their atherogenic potential when fed as part of a diet containing 2% cholesterol. The corn oil-containing diet was less atherogenic than any of the other fats.

Flordipine, a calcium channel blocker, which does not influence lipidemia or atherosclerosis in cholesterol-fed rabbits.

Data relating to the effects of calcium channel blockers on experimental atherosclerosis in rabbits are inconsistent with most studies finding no effect on either serum lipids or atherosclerosis. We have administered flordipine (5, 15 or 45 mg/kg/day) for 10 weeks to rabbits fed 1% cholesterol and 4% corn oil. At no level of treatment was there an effect on serum or liver lipids or on aortic sudanophilia.

Cholesterol vehicle in experimental atherosclerosis. Part 16. Effect of peanut oil on pre-established lesions.

Rabbits were fed an atherogenic diet (2% cholesterol and 6% corn oil) for 8 weeks and then divided into groups of equal average serum cholesterol levels. One group was autopsied, and the others were returned to cholesterol-free diets consisting of commercial laboratory ration or ration augmented with 6% corn oil, peanut oil or PGF, a fat designed to resemble peanut oil minus arachidic and behenic acids. The animals were maintained on the diets for 8 more weeks. On all regimens, severity of atherosclerosis was exacerbated. The extent of exacerbation was significantly less in rabbits fed corn oil than in the others. The extent of exacerbation of lesions appears to be a function of the level of unsaturation of the dietary fats.

Experimental atherosclerosis in rabbits fed cholesterol-free diets. Part 7. Interaction of animal or vegetable protein with fiber.

Rabbits were maintained for 10 months on a semipurified, cholesterol-free atherogenic regimen. All diets contained sucrose (40%) and hydrogenated coconut oil (14%). The protein (25%) was either casein or soya protein and the fiber (15%) was either wheat straw, alfalfa, or cellulose. Within either protein group the order for induction of cholesteremia was cellulose=wheat straw greater than alfalfa. For atherogenesis, the effect was cellulose greater than wheat straw greater than alfalfa Soya-wheat straw or soya-cellulose diets were less cholesteremic and atherogenic than their casein counterparts. When alfalfa was the fiber, the two types of protein were almost equivalent. Our results show that casein may be more cholesteremic and atherogenic than soya protein under certain conditions (cellulose or wheat straw as fiber) but the addition of alfalfa to the diet renders the two proteins equivalent.

Experimental atherosclerosis in rabbits fed cholesterol-free diets.

Rabbits were fed a semipurified, cholesterol-free atherogenic diet containing 40% sucrose, 25% casein, 14% fat, 15% fiber, 5% salt mix and 1% vitamin mix. The fats were corn oil (CO), palm kernel oil (PO), cocoa butter (CB), and coconut oil (CNO). The rabbits were bled at 3, 6, and 9 months and killed at 9 months. Serum lipids of rabbits fed CO were unaffected. Serum cholesterol levels (mg/dl) at 9 months were: CO -- 64; PO -- 436; CB -- 220; and CNO -- 474. HDL-cholesterol (%) was: CO -- 37; PO -- 8.6; CB -- 25.1; and CNO -- 7.0. Average atherosclerosis (arch + thoracic/2) was: CO -- 0.15; PO -- 1.28; CB -- 0.53; and CNO -- 1.60. Cocoa butter (iodine value 33) is significantly less cholesterolemic and atherogenic than palm oil (iodine value 17) or coconut oil (iodine value 6). The difference between the atherogenic effects of cocoa butter and palm oil may lie in the fact that about half of the fatty acids of palm oil are C 16 or shorter, whereas 76% of the fatty acids of cocoa butter are C 18 or longer.

Experimental atherosclerosis in rabbits fed cholesterol-free diets. Part 12. Comparison of peanut and olive oils.

The atherogenicity of peanut oil is well established as is the fact that the structure of the component triglycerides of peanut oil influences its atherogenicity. This study was carried out to determine if the relative saturation of peanut oil was partly responsible for the observed effects. Rabbits were fed a semipurified, cholesterol-free diet containing 14% of North American peanut oil (iodine value, 100), South American peanut oil (iodine value, 110) or olive oil (iodine value, 83) for 8 months. Rabbits fed olive oil exhibited higher levels of serum and liver lipids than did the two peanut oil-fed groups but significantly lower levels of aortic atherosclerosis. The findings confirm earlier observations that the structure of a fat can have an affect on its atherosclerogenic potential that is independent of its level of unsaturation.

Experimental atherosclerosis in rabbits fed cholesterol-free diets. 13. Interaction of proteins and fat.

The atherogenic and cholesterolemic effects of animal protein vis-a-vis plant protein are well documented. Virtually all the studies were carried out using diets high in saturated fat, such as coconut oil. In order to determine if the same effects were seen with less saturated fat, we have compared atherogenic effects of an animal protein (casein) with those of a plant protein (soybean protein isolate) fed with partially hydrogenated soybean oil (PHS) (iodine value 72) or soybean oil (iodine value 134) as part of a cholesterol-free semipurified diet. After 6 months only rabbits fed casein-PHS exhibited elevated levels of plasma and liver cholesterol and triglycerides and atherosclerosis. Rabbits fed soy protein-PHS had slightly higher plasma cholesterol and triglycerides than did those fed soy protein and soybean oil, but values in both groups were in the normal range. The different effects of animal and plant protein on lipidemia and atherosclerosis can be influenced by dietary fat and appear to be dependent on fat saturation.

Experimental atherosclerosis in rabbits fed cholesterol-free diets. Part 9. Beef protein and textured vegetable protein.

Rabbits were fed a semipurified diet containing 40% sucrose, 25% protein, 15% fiber and 14% tallow. The proteins fed were beef (B), textured vegetable protein (TVP) and casein (C). One diet contained beef-TVP (1 : 1) and in another a soy carbohydrate fraction, spent flakes, was added to the diet; it provided 2.2% protein and 10.5% fiber. TVP provided 6.4% soluble carbohydrate and 10.5% fiber. The diets were fed from 8 months. Diets containing beef protein or casein gave significantly higher serum cholesterol levels and atherosclerosis and significantly lower serum HDL-cholesterol than did the other 3 diets. The beef-TVP (1 : 1) diet gave low serum cholesterol (67% below beef) levels and atherosclerosis (47% below beef). This effect is probably due to the protein. The diet containing spent flakes gave low serum cholesterol levels (44% below beef) and atherosclerosis (45% below beef). This effect is attributed to the different fiber. The lowest serum cholesterol levels and least severe atherosclerosis were observed in the rabbits fed TVP.

Cholesterol vehicle in experimental atherosclerosis. Part 18. Comparison of North American, African and South American peanut oils.

Peanut oils were obtained from the United States (NAPNO), Africa (APNO), and South America (SAPNO) and their effects on atherosclerosis in rabbits fed 2% cholesterol were determined. The major differences among the oils were in the content of oleic (NAPNO, 48.9%; APNO, 58.6%; SAPNO, 36.4%) and linoleic (NAPNO, 29.6%; APNO, 21.7%; SAPNO, 41.1%) acids. In a series of 4 experiments it was found that South American peanut oil was 7% more atherogenic than African peanut oil and 18% more atherogenic than North American peanut oil. American peanut oil was 14% more atherogenic that corn oil (CO). South American peanut oil gave highest serum and liver lipid levels. The differences in atherogenicity may be due to the structure of the triglycerides of the various peanut oils.

Effects of casein and soy protein on hepatic and serum lipids and lipoprotein lipid distributions in the rat.

Rats fed a semipurified diet containing casein developed higher levels of circulating triglycerides and cholesterol than animals fed a soy protein-containing diet. The increased serum lipid levels in non-fasted rats were associated largely with the d less than 1.006 g/ml lipoprotein particles (e.g. chylomicrons or very low density-like lipoproteins). In addition, casein-fed rats exhibited higher levels of circulating insulin and depressed hepatic 7 alpha-hydroxylase levels compared to soy-fed rats. Supplementation of the casein diet with arginine, to give an arginine/lysine ratio comparable to that in the soy diet, resulted in a reduction of d less than 1.006 g/ml lipids, a reduction in serum insulin levels and an elevation in hepatic 7 alpha-hydroxylase activity. Supplementation of the soy diet with lysine also resulted in modification of these parameters toward those observed with casein diets, albeit the effects were less dramatic. The results suggest that the hyperlipidemia associated with feeding casein-based diet is associated with decreased rates of clearance of chylomicron-like lipoproteins and their component triglycerides and cholesterol. Furthermore, this is largely prevented by addition of arginine to diets containing casein as the sole protein source.

Conjugated linoleic acid suppresses the growth of human breast adenocarcinoma cells in SCID mice.

Conjugated linoleic acid (CLA), which is mainly derived from dairy products, has been shown both in vitro and in animal models to have strong anti-tumor activity. Particular effects were observed on the growth and metastatic spread of transplantable mammary tumors. In this study, we examined the effect of dietary CLA on the growth of human breast adenocarcinoma cells in severe combined immunodeficient (SCID) mice. Mice were fed 1% CLA for two weeks prior to subcutaneous inoculation of 10(7) MDA-MB468 cells and throughout the study. Dietary CLA inhibited local tumor growth by 73% and 30% at 9 and 14 weeks post-inoculation, respectively. Moreover, CLA completely abrogated the spread of breast cancer cells to lungs, peripheral blood, and bone marrow. These results indicate the ability of dietary CLA to block both the local growth and systemic spread of human breast cancer via mechanisms independent of the host immune system.

Age-related changes in the lipid metabolism of Fisher 344 rats.

Lipid metabolism of male Fisher 344 rats aged 2-24 months was studied. Serum and liver cholesterol levels did not display the age-related gradual increase seen in other rat strains. An increase in the serum plus liver cholesterol pool from 2 to 6 months was followed by a plateau through 18 months and then another increase at 24 months of age. The triglyceride pool increased from 2 to 6 months and then remained unchanged through 24 months of age. Cholesterol synthesis from acetate decreased 50% between 2 and 9 months and fell only slightly through 24 months of age. Assay of 3-hydroxy-3-methyl glutaryl Coenzyme A (HMG-CoA) reductase showed a similar pattern but did not decrease further after 9 months of age. Cholesterol 7alpha hydroxylase activity was not significantly altered by age. These age- and strain-related differences present an opportunity for a comparative study of the aging process using the parameters of lipid metabolism as indicators.

Lectin may contribute to the atherogenicity of peanut oil.

Peanut oil is unexpectedly atherogenic for rats, rabbits, and primates. The lesions it produces are more fibrous than fatty. The mechanism underlying the atherogenicity of peanut oil has been elusive. Randomization of peanut oil reduces significantly its atherogenic properties, but native and randomized peanut oils have similar rates of lipolysis, and rats fed the two oils absorb and transport lipids in a similar fashion. Peanut oil differs from other oils in having a relatively high lectin content, and the randomization process markedly reduces the lectin content as well. The biologically active lectin of peanut oil has an affinity for glycoproteins found specifically on arterial smooth muscle cells. Peanut lectin has been shown to stimulate growth of smooth muscle and pulmonary arterial cells. Vigorous washing of peanut oil reduces its lectin content by 46%. Compared to rabbits fed cholesterol and peanut oil, rabbits fed cholesterol and washed peanut oil exhibited less severe atherosclerosis in the aortic arch (by 9%) and in the thoracic aorta (by 31%). The data suggest that peanut oils' endogenous lectin may contribute significantly to its atherogenic properties.

Linoleic acid amides: effect on cholesteremia and atherosclerosis.

Several of a series of linoleic acid amides have been reported to inhibit cholesterol-induced atherosclerosis in rabbits. The three amides which have been studied to the greatest extent are (in order of increasing activity) N-cyclohexyl linoleamide (AC23), N(alpha methylbenzyl) linoleamide (AC223), and N[aplha-phenyl-beta-(p-tolyl)ethyl] linoeamide (AC 485). We have found AC223 to inhibit cholesterol absorption in rats and to slightly inhibit exogenous but not endogenous cholesteremia in rabbits. In a fiber-free diet, AC223 reduces serum cholesterol and liver triglyceride levels. Rats were also fed a basal semipurified diet with and without AC223. Fecal excretion of labeled exogenous (as [ (14)C] cholesterol) or endogenous (as [14 C] mevalonolactone) steroid was 44 and 43% higher in drug treated groups. The mechanism of hypocholesteremic action of the linoleamides appears to involve inhibition of cholesterol absorption.

Influence of dietary fiber on lipids and aortic composition of vervet monkeys.

A semipurified, cholesterol-free diet containing 40% carbohydrate can produce aortic sudanophilia or aortic atherosclerosis in vervet monkeys (Cercopithecus aethiops pygerethrus) depending on the particular carbohydrate fed. Four groups of vervet monkeys (three males and three females per group) were fed semipurified diets containing lactose. Two of the groups were also fed 15% cellulose (C) or 15% cellulose plus 0.1% cholesterol (CC); the two other groups were fed 15% pectin (P) or 15% pectin plus 0.1% cholesterol (PC). The average serum total cholesterol and low density lipoprotein cholesterol levels over the entire feeding period (mg/dl +/- SEM) were, for C, 156 +/- 14 and 95 +/- 5; for P, 173 +/- 15 and 112 +/- 8; for CC, 187 +/- 27 and 122 +/- 21; and for PC, 155 +/- 11 and 108 +/- 7. Cholesterol levels at autopsy (mg/dl +/- SEM) were, for C, 103 +/- 6; for P, 108 +/- 16; for CC, 92 +/- 9; and for PC, 106 +/- 7. Aortic sudanophilia (percentage of area) was, for C, 5.9 +/- 2.7; for P, 13.5 +/- 9.4; for CC, 5.3 +/- 2.1; and for PC, 21.6 +/- 10.3. Dietary pectin led to more severe sudanophilia (increased by 129% in the absence of cholesterol and by 308% in its presence) than did cellulose. Analysis of aortic glycosaminoglycans (GAG) revealed that dermatan sulfate levels fell in both cholesterol-fed groups, and chondroitin sulfate fell in aortas of group CC. Heparan sulfate levels were unaffected by cholesterol feeding. Hexuronic acid, galactosamine and hexosamine levels were elevated in the pectin-fed monkeys, but levels were unaffected by dietary cholesterol.(ABSTRACT TRUNCATED AT 250 WORDS)