Effects of protein level, methionine supplementation and carbohydrate type of the diet on liver lipid and plasma free threonine contents in the lactating rat

Eight groups of 13-15 female rats were fed purified diets after littering. Four groups received a low protein (8% casein) diet (groups 8) and the others, a normal protein (20% casein) diet (groups 20). Carbohydrates were supplied either as starch (groups S) or as starch plus 40% fructose (groups F). Half the animals received a 0.4% methionine supplementation (groups M). Four or five dams per group were sacrificed on days 2, 7 and 14 after littering. The diet intake was increased by methionine supplementation, substitution of starch for fructose and increased protein content, mainly during the second week of lactation. This influenced weight variation of the dams and litter growth. On all days, the plasma levels of cholesterol esters, triglycerides and phospholipids were positively correlated with the dietary protein level. On days 7 and 14, the liver neutral lipid content was increased in rats fed the low protein diets supplemented with methionine (groups 8SM and 8FM) and the normal protein diets containing 40% fructose (groups 20F and 20FM). The plasma free threonine content was positively correlated with the protein level in the diet. On day 14, rats fed a low protein diet had a threonine deficiency, except those in groups 8S and 8F. The plasma free threonine content of these rats was not reduced, possibly due to an impaired utilization of this amino acid. The liver lipidosis observed during lactation, in contrast to that observed during growth with a low protein diet, was not due to a threonine deficiency.     

Increased plasma homocysteine concentration in rats from a low casein diet

Rats were fed on a 10% casein (10C) diet, 30% casein (30C) diet, 10C+0.5% methionine diet, or 30C+0.5% methionine diet for 14 d to investigate the relationship between the dietary protein level and plasma homocysteine concentration. The plasma homocysteine concentration was significantly higher in the rats fed on the 10C diet than in the rats fed on the 30C diet, and this phenomenon persisted even under the condition of methionine supplementation. The activity of hepatic cystathionine beta-synthase (CBS) was significantly lower in the rats fed on the 10% casein diets than in the rats fed on the 30% casein diets, irrespective of methionine supplementation. This is the first demonstration of a low-protein diet increasing the plasma homocysteine concentration in experimental animals. It is suggested that the decreased CBS activity might be associated, at least in part, with the hyperhomocysteinemia caused by the low-casein diet.     

Increased Plasma Homocysteine Concentration in Rats from a Low Casein Diet

Rats were fed on a 10% casein (10C) diet, 30% casein (30C) diet, 10C+0.5% methionine diet, or 30C+0.5% methionine diet for 14 d to investigate the relationship between the dietary protein level and plasma homocysteine concentration. The plasma homocysteine concentration was significantly higher in the rats fed on the 10C diet than in the rats fed on the 30C diet, and this phenomenon persisted even under the condition of methionine supplementation. The activity of hepatic cystathionine β-synthase (CBS) was significantly lower in the rats fed on the 10% casein diets than in the rats fed on the 30% casein diets, irrespective of methionine supplementation. This is the first demonstration of a low-protein diet increasing the plasma homocysteine concentration in experimental animals. It is suggested that the decreased CBS activity might be associated, at least in part, with the hyperhomocysteinemia caused by the low-casein diet.     

54Mn absorption and excretion in rats fed soy protein and casein diets

Rats were fed diets containing either soy protein or casein and different levels of manganese, methionine, phytic acid, or arginine for 7 days and then fed test meals labeled with 2 microCi of 54Mn after an overnight fast. Retention of 54Mn in each rat was measured every other day for 21 days using a whole-body counter. Liver manganese was higher (P less than 0.0001) in soy protein-fed rats (8.8 micrograms/g) than in casein-fed rats (5.2 micrograms/g); manganese superoxide dismutase activity also was higher in soy protein-fed rats than in casein-fed rats (P less than 0.01). There was a significant interaction between manganese and protein which affected manganese absorption and biologic half-life of 54Mn. In a second experiment, rats fed soy protein-test meals retained more 54Mn (P less than 0.001) than casein-fed rats. Liver manganese (8.3 micrograms/g) in the soy protein group was also higher than that (5.7 micrograms/g) in the casein group (P less than 0.0001), but manganese superoxide dismutase activity was unaffected by protein. Supplementation with methionine increased 54Mn retention from both soy and casein diets (P less than 0.06); activity of manganese superoxide dismutase increased (P less than 0.05) but liver manganese did not change. The addition of arginine to casein diets had little effect on manganese bioavailability. Phytic acid affected neither manganese absorption nor biologic half-life in two experiments, but it depressed liver manganese in one experiment. These results suggest that neither arginine nor phytic acid was the component in soy protein which made manganese more available from soy protein diets than casein diets.     

Meat meal in the diet of the early-weaned pig IV. The supplementation of diets with tryptophane,lysine and methionine

Two experiments were conducted with 72 pigs between 28 and 56 days of age to study the effect of tryptophane supplementation on their performance when fed on diets containing wheat and meat meal.In the first experiment, pigs were fed on a basal diet (Diet 1) or on the same diet supplemented with calcium dihydrogen phosphate (Diet 2), bone meal (Diet 3) or bone meal plus tryptophane (Diet 4), all to 3.1% calcium. The weight gains of the pigs (315 g day^?1) fed on Diet 3 were significantly lower than that of the pigs fed on the other three diets (363 g day^?1). The feed conversion ratios showed a similar trend. Diet 3 contained 0.16% tryptophane while the other diets contained 0.18–0.19% tryptophane. The crude protein, lysine and methionine contents of all diets were similar.In the second experiment, a basal diet containing meat meal and bone meal was supplemented with tryptophane, lysine plus methionine or all three amino acids. Feed intake was increased by all amino acid supplements. Weight gains were improved significantly (57%) by the addition of all three amino acids to the diets, but the improvements due to tryptophane alone (28%) or methionine plus lysine (35%) were not significant. Tryptophane supplementation alone or with lysine plus methionine increased the nitrogen retention of the pigs.It was concluded that the requirement for tryptophane of pigs between 28 and 56 days of age was greater than 0.16% of diets containing wheat and meat meal.     

Effect of various levels of supplementation with sodium pivalate on tissue carnitine concentrations and urinary excretion of carnitine in the rat

In previous studies, sodium pivalate has been administered to rats in their drinking water (20 mmoles/L; equivalent to 0.3% of the diet) as a way to lower the concentration of carnitine in tissues and to produce a model of secondary carnitine deficiency. Although this level of supplementation results in a marked decrease in carnitine concentration in a variety of tissues, it does not produce the classical signs of carnitine deficiency (i.e., decreased fatty acid oxidation and ketogenesis). The present study was designed (1) to determine if increasing the level of pivalate supplementation (0.6, 1.0% of the diet) would further reduce the concentrations of total and free carnitine in rat tissues without altering growth or food intake, and (2) to examine the effect of length of feeding (4 vs. 8 weeks) on these variables. Male, Sprague-Dawley rats were randomly assigned to either a control (0.2% sodium bicarbonate) or experimental diet (0.3, 0.6, 1.0% sodium pivalate) for either four or eight weeks. Animals (n = 6/group) were housed in metabolic cages; food and water were provided ad libitum throughout the study. Supplementation with sodium pivalate did not alter water intake or urine output. Ingestion of a diet containing 1.0% pivalic acid decreased food intake (g/day; P < 0.05), final body weight (P < 0.007), and growth rate (P < 0.001) after four weeks. The concentration of total carnitine in plasma, heart, liver, muscle, and kidney was reduced in all experimental groups (P < 0.001), regardless of level of supplementation or length of feeding. The concentration of free carnitine in heart, muscle, and kidney was also reduced (P < 0.001) in rats treated with pivalate for either four or eight weeks. The concentration of free carnitine in liver was reduced in animals supplemented with pivalate for eight weeks (P < 0.05), but no effect was observed in livers from rats treated for four weeks. Excretion of total carnitine and short chain acylcarnitine in urine was increased in pivalate supplemented rats throughout the entire feeding period (P < 0.001). Free carnitine excretion was increased during Weeks 1 and 2 (P < 0.01), but began to decline during Week 3 in experimental groups. During Weeks 6 and 8, free carnitine excretion in pivalate supplemented rats was less than that of control animals (P < 0.01). In summary, no further reduction in tissue carnitine concentration was observed when rats were supplemented with sodium pivalate at levels greater than 0.3% of the diet. Food intake (g/day) and growth were decreased in rats fed a diet containing 1.0% sodium pivalate. These data indicate that maximal lowering of tissue carnitine concentrations is achieved by feeding diets containing 0.3% sodium pivalate or less.     

Down-regulation of rat liver beta-adrenergic receptors by cysteine

Down-regulation of hepatic beta-adrenergic receptors was indicated by a 56% decrease in the specific activity of 125I-iodocyanopindolol bound to rat liver membrane preparations from rats fed diets containing 15% of casein supplemented with cysteine, instead of methionine or unsupplemented. Down-regulation of hepatic beta-adrenergic receptors by cysteine appears to be mediated through an effect of cysteine on the tissue concentration of S-adenosyl methionine (SAM). The liver tissue concentration of SAM in rats fed cysteine-supplemented diets decreased 53% compared to those fed diets supplemented with methionine. The decrease in liver SAM in rats fed the diet supplemented with cysteine appears to reflect a non-competitive inhibition of methionine adenosyl-transferase by cysteine. Lineweaver-Burk plots demonstrated a dose-related Vmax response to cysteine but did not change the apparent Km at any concentration tested.     

Effects of supplemental methionine and lysine on the nutritional value of housefly larvae meal (Musca domestica) fed to rats

The performance and blood composition of rats fed housefly larvae meal supplemented with, or without, methionine and lysine, or fed at high concentration were investigated. Rats fed supplemental methionine alone achieved highest body weight gain (P < 0.05). Dietary supplementation of both methionine and lysine or high dietary concentration of larvae meal depressed (P < 0.05) rat feed intake. The blood composition of rats was superior (P < 0.05) on methionine-supplemented larvae meal. Additional amino acids from larvae elicited higher (P < 0.05) serum proteins, cholesterol and triglyceride; however, other blood biochemical profiles were lower (P < 0.05) than in the unsupplemented group. In conclusion, housefly larvae meal seemed deficient in methionine and it benefited the rat tremendously to supplement with this amino acid: however, additional lysine and high dietary inclusion of larvae meal as sole protein source appeared nutritionally inconsequential.     

Effects of Arginine and Methionine on the Growth Depression of Rats Fed Diets High in Glycine

In order to determine if the growth retardation by dietary exceess glycine could be prevented by the addition of arginine and/or methionine, weanling rats were fed a 25% casein diet (standard) or a 10% casein diet (low protein diet) with a supplement of several combinations of glycine, arginine, or methionine.

The changes in body weight, urinary creatinine, and kidney transamidinase activity were determined. The growth depression effect by excess glycine was prevented considerably in animals receiving standard diet and completely in animals receiving low protein diet by the addition of arginine and methionine to the high glycine diets.

The total urinary creatinine was increased by the supplement of both glycine and arginine, while the growth rate was not invariably raised and kidney transamidinase activity had a tendency to decrease.     

Iodothyronine deiodinase activity in methionine-deficient rats fed selenium-deficient or selenium-sufficient diets

We examined the effect of methionine deficiency on iodothyronine 5’-deiodinase activity in selenium-deficient rats or selenium-sufficient rats fed sodium selenate or selenomethionine. Forty-two weanling male Wistar rats were divided into six groups and pair fed the respective purifiedl-amino acid-based diets for 4 wk.l-methionine concentrations in the diet were 8.0 g/kg for sufficient rats, and 2.0 g/kg for deficient rats. Selenium concentrations in the diet were 0.5 mg/kg (as sodium selenate or selenomethionine) for selenium-sufficient rats and less than 0.005 mg/kg for selenium-deficient rats. Type I 5’-deiodinase activities were significantly lower in liver and higher in kidney of methionine-deficient rats than in those of methionine-sufficient rats fed either the selenium-sufficient or the selenium-deficient diets. The type I 5’-deiodinase activity in brain was significantly lower in the methionine-deficient rats than in the methionine-sufficient rats fed the selenium-deficient diet. Type II 5’-deiodinase activity in brain was significantly higher in the methionine-deficient rats than in the methionine-sufficient rats fed selenium-sufficient diet as sodium selenate. Both thyroxine and 3,3’,5-triiodothyronine concentrations in plasma were significantly higher in the methionine-deficient rats than in the methionine-sufficient rats. It is suggested that the methionine deficiency affects the 5’-deiodinase activity and thyroid hormones level in the rats.     

Body weight deficit in the absence of reduction in cerebrum weight and nucleic acid content in progeny of swine restricted in protein intake during pregnancy

Fifty-six castrated male progeny of crossbred (Chester White x Landrace x Large White x Yorkshire) dams fed an adequate diet (control, C), a control diet fed at one-third of C (restricted, R), or diets severely deficient in protein (PF) or restricted in nonprotein calories (RCal) were killed at age 25 weeks. Dams were fed their respective diets in the following regimens: C, 1.8 kg (6000 kcal daily) throughout pregnancy; R, 0.6 kg of C diet daily for 70 days, then 1.8 kg of C daily to parturition at about 114 days; PF, 1.8 kg of a "protein-free" diet (less than 0.2% protein) throughout pregnancy; RCal, 0.6 kg daily (2000 kcal) of a diet containing three times the concentration of protein, minerals, and vitamins provided by the C diet for 70 days, then 1.8 kg of C daily to parturition. All dams were fed an adequate diet ad libitum through a 28-day lactation. Castrated male progeny were assigned to one of two replicates based on birth date and fed a corn-soybean meal diet ad libitum from weaning to age 25 weeks, supplemented from age 10 to 12 weeks with 0, 110, or 220 mg/kg of thyroprotein (iodinated casein). Cerebrum weight was unaffected by maternal diet, despite a significant (P less than 0.001) reduction in body weight of progeny of PF dams compared with other groups, resulting in a higher relative cerebrum weight in progeny of PF dams than in progeny of C, R, and RCal dams. Absolute and relative weights of RNA, DNA, and total protein in cerebrum were unaffected by maternal diet. Thyroprotein supplementation to the diet of the progeny had no effect on cerebrum weight or its protein or nucleic acid content. It is concluded that maternal protein deprivation but not restriction of feed or nonprotein calorie intake to one-third of recommended allowance during gestation results in stunting of body weight in young adult progeny but does not affect cerebrum weight, cerebrum cell number (DNA), or protein synthetic activity (RNA), or RNA-to-protein ratio.     

Soluble neutral and acid maltases in the suckling-rat intestine. The effect of cortisol and development

The 100000g supernatants from 13-day-old suckling-rat intestinal homogenates contained 43.5% of the total intestinal maltase activity, compared with 7.1% in weaned adult rats aged 40 days. The soluble maltase activity was separated on Sepharose 4B into two quantitatively equal fractions at pH6.0, one containing a maltase with a neutral pH optimum and the other a maltase with an acid pH optimum. The neutral maltase was shown to be a maltase-glucoamylase identical with membrane-bound maltase-glucoamylase in molecular weight, heat-sensitivity, substrate specificity, K(m) for maltose and K(i) for Tris. The soluble enzyme was induced by cortisol, but the ratio of the soluble to bound enzyme fell during induction. Solubility of the neutral maltase was not accounted for by the action of endogenous proteinases under the preparative conditions used. It is postulated that the soluble neutral maltase is a membrane-dissociated form of the bound enzyme and that the relationship between these two forms is modulated by cortisol. The acid maltase generally resembled acid maltase of liver, muscle and kidney. It was shown to be a maltase-glucoamylase with optimal activity at pH3.0, and molecular weight of 136000 by density-gradient centrifugation. At pH3.0 its K(m) for maltose was 1.5mm. It was inhibited by turanose (K(i)=7.5mm) and Tris (K(i)=5.5mm) but not by p-chloromercuribenzoate or EDTA. Some 55% of its activity was destroyed by heating at 50 degrees C for 10min. The acid maltase closely resembled beta-glucuronidase and acid beta-galactosidase in its distribution in the intestine, response to tissue homogenization in various media, and decrease in activity with cortisol treatment and weaning, indicating that it was a typical lysosomal enzyme concentrated in the ileum.     

Changes in Creatine and Urea Formation in Rats Fasted and Fed Low Protein Diets

Changes in the time course of the urinary excretion of creatinine, creatine and urea, and the activities of kidney transamidinase and liver urea-cycle enzymes were investigated in rats fasted and fed on a 10% casein diet and 10% casein diets supplemented with 10% glycine and/or 1.4% arginine.

The urinary total-creatinine of the fasted rats increased extremely during fasting for 7 days, while that of the animals given the 10% casein diet supplemented with glycine and arginine rose exceedingly on the 3rd day and thereafter no significant change was observed. Most of the increase of total-creatinine could be accounted for by the increase of creatine. The activity of kidney transamidinase in the fasted rats decreased in the 3rd day and thereafter kept nearly constant. The transamidinase activity of rats fed on the 10% casein diet after giving a protein-free diet for 5 days increased in the 3rd day. An inverse relation was observed between the urinary creatine and the transamidinase activity. The urinary urea increased in the rats fasted or fed on the 10% casein diets with the supplement of glycine and/or arginine. In fasting, the activities of liver urea-cycle enzymes, except arginase, had a tendency of increasing with the lapse of time. The arginase activity remained more or less constant. The reason of the extreme increase of urinary creatine during starvation was discussed.     

Effects of alginates and sodium carrageenates mixed with soy proteins on the coefficient of protein efficiency

Male 21 d-old Wistar rats, were fed for 4 wk with diets containing casein or soybean proteins (10%) with 0.5, 1, 2 or 3% sodium alginate or sodium carrageenan or without any alginate or carrageenan. Daily protein intake and weight gain of casein-fed rats were not significantly different (P less than 0.05) from those of rats fed soybean meal with alginate, whatever the dose received. Rats fed 3% carrageenan in soybean meal had significantly higher feed intake than that of rats fed casein. At the levels studied, alginate had no effect on the Protein Efficiency Ratio (PER), but carrageenan did. The addition of increased quantities of carrageenan to soybean meal followed by heating the mixture led to a progressive and significant decrease in PER at all levels of carrageenan compared to casein feeding. The addition of 3% carrageenan to heated soybean meal, corresponding to 0.62% of meal diet, led to a significant decrease in PER. These results confirm the precipitating role of carrageenans on proteins.     

Effect of Glutathione on Lipogenesis in Liver Slices from Rats Fed on Low Casein Diet

To study the mechanism of fatty infiltration in the liver due to added sulfur-containing amino acids to low casein diet, the effect of sulfur-containing amino acids and glutathione (GSH) on the incorporation of acetate-l-¹⁴C into lipid fractions were studied in liver slices from rats fed on 8% casein diet (Basal diet) with or without added methionine (Met).

The liver acetyl Co A carboxylase activities of rats on basal diet with or without added Met were similar.

Addition of Met, cystine or cysteine to the incubation medium had little effect on lipogenesis of slices. On addition of GSH to liver slices from rats fed on basal diet, lipid formation increased appreciably. On the other hand, addition of GSH to liver slices from rats fed on Met supplemented diet showed no accelerative effect on lipogenesis.

Addition of GSH to the incubation medium of liver slices from rats fed on basal diet tended to reduce the incorporation of acetate into the phospholipid fraction and to increase into the fatty acid fraction of liver slices.

The content of liver GSH was lower in rats on basal diet than in those on Met supplemented diet. The higher GSH level in rats on Met supplemented diet may be one factor causing fatty infiltration in the liver of these animals.     

Muscle and liver protein synthesis and degradation in growing rats fed a raw field bean (Vicia faba L.) diet

Body weight gain, food intake, gastrocnemius muscle and liver weight, protein and RNA content, as well as the fractional rates of muscle and liver protein synthesis (ks, according to the method of constant infusion of L-[14C]tyrosine), growth (kg) and degradation (kd), along with RNA activity (g of protein synthesized per day/g RNA) of both organs, were determined in growing male rats fed ad libitum over a period of 10 days on 18.7% protein diets containing either casein (5% of methionine added) (control) or the raw legume field bean (Vicia faba L.) as the sole sources of protein. It has been found that as compared to control rats, those fed the raw legume diet exhibited a significant reduction in the rate of growth, muscle RNA, ks, kg, kd and RNA activity, and a significant increase in liver ks, kd and RNA activity. All differences were statistically significant at least at the 5% level. The possible nature of these findings is discussed.     

Effects of a high soy protein diet on intestinal polyamines and ornithine decarboxylase activity in rats

This study was performed to determine whether intestinal luminal polyamine concentrations are affected by a high soy protein diet when compared with a high casein diet or a normoprotein casein diet. We also determined the effects of these diets, with differences in polyamines content, on mucosal polyamines and ornithine decarboxylase (ODC) activity to assess cell proliferation. Three groups of eight male Wistar rats were fed either a 50% soy protein diet, a 50% casein diet, or an 18% casein diet as a control. After 4 weeks of feeding, both intestinal content and mucosa were recovered. Polyamines were assayed by high performance liquid chromatography. ODC activity was measured by the release of (14)CO(2) from (14)C-L-ornithine. Luminal putrescine and cadaverine concentrations were higher in the jejunum than in the ileum, suggesting an absorptive process. The highest concentrations of intestinal polyamines were observed in rats fed the soy protein diet (P < 0.05). Only minor differences were observed in mucosal polyamines according to the diets. ODC activity was also higher in the intestinal mucosa of rats fed the high soy protein diet (P < 0.05). These results suggest that intestinal luminal polyamine concentrations and ODC activity are modulated by the dietary protein source.     

Depletion of delta 9 desaturase (EC 1.14.99.5) activity in lactating rat during protein restriction

The effects of protein restriction on the activity of delta9 desaturase (EC 1.14.99.5) were investigated in lactating rats. A control group was fed a balanced diet (20% casein) for 14 days, whereas the experimental groups were fed a low-protein diet (8% casein), supplemented with or without L-methionine (0.4%), for 14 days. The enzyme activity was measured by incubations of hepatic microsomal pellets with (1-14C) stearic acid. Results showed a decreased delta9 desaturase activity, after 2,7 and 14 days of depleted diet, of -50, -40 and -33% respectively, compared with control. The supplementation of the low-protein diet with 0.4% methionine, which favours food consumption as well as growth, did not improve the altered delta9 desaturase activity. Our data evidenced that delta9 desaturase activity is depleted by protein restriction during lactation, when the protein needs are high for the biosynthesis of animal tissues. This change has to be considered as a sign of depressed delta9 desaturase biosynthesis or modifications of enzymatic properties, or both.     

High-Casein Diet Suppresses Guanidinoacetic Acid-Induced Hyperhomocysteinemia and Potentiates the Hypohomocysteinemic Effect of Serine in Rats

To determine the effect of dietary protein level on experimental hyperhomocysteinemia, rats were fed 10% casein (10C) and 40% casein (40C) diets with or without 0.5% guanidinoacetic acid (GAA) for 14 d. In addition, rats were fed 10C + 0.75% methionine (10CM) and 40C + 0.75% methionine (40CM) diets with or without 2.5% serine for 14 d to determine the relationship between the dietary protein level and intensity of the hypohomocysteinemic effect of serine. GAA supplementation markedly increased the plasma homocysteine concentration in rats fed with the 10C diet, whereas it did not increase the plasma homocysteine concentration in rats fed with the 40C diet. Although serine supplementation significantly suppressed the methionine-induced enhancement of plasma homocysteine concentration, the decreased plasma homocysteine concentration was significantly lower in rats fed with the 40CM diet than in rats fed with the 10CM diet. The hepatic cystathionine β-synthase and betaine-homocysteine S-methyltransferase activities were significantly higher in rats fed with the 40C or 40CM diet than in rats fed with the 10C or 10CM diet, irrespective of supplementation with GAA and serine. These results indicate that the high-casein diet was effective for both suppressing GAA-induced hyperhomocysteinemia and potentiating the hypohomocysteinemic effect of serine, probably through the enhanced activity of homocysteine-metabolizing enzymes.     

Effects of moderate riboflavin deficiency on lipid metabolism in rats

Dietary riboflavin intake of the people in Taiwan has been inadequate, while the fat intake has been increasing remarkably in recent years. Therefore, the effects of a moderate riboflavin deficiency on lipid metabolism in growing young rats fed diets containing 10, 25, or 40 percent calories of fat for 5 weeks were studied. The riboflavin deficiency status of the rats was certified by increased activity coefficients of erythrocyte glutathione reductase. Serum total lipids and cholesterol levels were significantly lower (P less than 0.05) in the medium fat-riboflavin deficient group. In the high fat-riboflavin deficient group, the growth and dietary intake were depressed and the liver weight/100 g body weight increased markedly (P less than 0.001). The liver total lipids, triglycerides, cholesterol and lipid peroxides of the high fat-riboflavin deficient group showed significant increases (P less than 0.025, P less than 0.025, P less than 0.05 and P less than 0.025 respectively), as compared with the pair-fed control groups. However, the increases were not significant in the medium fat and the low fat groups. The present study indicates that a high fat-riboflavin deficient diet would have adverse effects on lipid metabolism.