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Given evidence of a hypocholesterolemic effect in rats, soy protein compared with casein showed the following effects on cholesterol dynamics: a) lower cholesterol absorption and greater fecal steroid excretion, b) more rapid turnover of serum cholesterol, c) a marked size reduction of the rapidly exchangeable cholesterol pool (pool A) through a significant increase in the removal rate in that compartment without influencing the production rate, and d) greater hepatic sterogenesis both in vitro and in vivo. In contrast, the amino acid mixture equivalent to soy protein compared with casein-type mixture showed: a) no effects on cholesterol absorption and fecal steroid excretion, b) no effects on the turnover of serum cholesterol, c) the reduction of pool A size as a result of decreased production, and d) the reduction of hepatic steroidogenesis in vitro, but not in vivo. These results indicate that decreased intestinal absorption of cholesterol, and increased fecal steroid excretion are primarily responsible for the antihypercholesterolemic effect of soy protein compared with casein. The fecal loss of steroids far outweighs the activation of hepatic steroidogenesis. In the case of the soy protein-type amino acid mixture, the depression of hepatic cholesterol synthesis seems accountable for reducing serum cholesterol levels.

D-Psicose, a C3 epimer of D-fructose, is known to lower body weight and adipose tissue weight and affect lipid metabolism. The precise mechanism remains unknown. It has been reported that D-psicose has a short half-life and is not metabolized in the body. To determine how D-psicose modifies lipid metabolism, rats were fed diets with or without 3% D-psicose for 4 weeks. Rats were decapitated without fasting every 6 h over a period of 24 h. Changes in serum and liver lipid levels, liver enzyme activity, and gene expression were quantified in experiment 1. Rats fed D-psicose had significantly lower serum insulin and leptin levels. Liver enzyme activities involved in lipogenesis were significantly lowered by the D-psicose diet, whereas gene expression of a transcriptional modulator of fatty acid oxidation was enhanced. In experiment 2, feeding the D-psicose diet gave significantly lower body weight (389 ± 3 vs 426 ± 6 g, p < 0.05) and food intake (23.8 ± 0.2 vs 25.7 ± 0.4 g/day, p < 0.05) compared to the control diet. Rats fed the D-psicose diet gave significantly higher energy expenditure in the light period and fat oxidation in the dark period compared to rats fed the control diet, whereas carbohydrate oxidation was lower. In summary, these results indicate that the D-psicose diet decreases lipogenesis, increases fatty acid oxidation, and enhances 24 h energy expenditure, leading to d-psicose's potential for weight management.

The HFC diet induced hepatic features of NASH and eventually progressed cirrhosis in Sprague-Dawley rats within 9 weeks.

Ingestion of high-fructose corn syrup (HFCS) is associated with the risk of both diabetes and obesity. Rare sugar syrup (RSS) has been developed by alkaline isomerization of HFCS and has anti-obesity and anti-diabetic effects. However, the influence of RSS on glucose metabolism has not been explored. We investigated whether long-term administration of RSS maintains glucose tolerance and whether the underlying mechanism involves hepatic glucokinase translocation. Wistar rats were administered water, RSS, or HFCS in drinking water for 10 weeks and then evaluated for glucose tolerance, insulin tolerance, liver glycogen content, and subcellular distribution of liver glucokinase. RSS significantly suppressed body weight gain and abdominal fat mass (p < 0.05). The glucose tolerance test revealed significantly higher blood glucose levels in the HFCS group compared to the water group, whereas the RSS group had significantly lower blood glucose levels from 90 to 180 min (p < 0.05). At 30, 60, and 90 min, the levels of insulin in the RSS group were significantly lower than those in the water group (p < 0.05). The amount of hepatic glycogen was more than 3 times higher in the RSS group than that in the other groups. After glucose loading, the nuclear export of glucokinase was significantly increased in the RSS group compared to the water group. These results imply that RSS maintains glucose tolerance and insulin sensitivity, at least partly, by enhancing nuclear export of hepatic glucokinase.

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1. The effect of variation in arginine: lysine on the relative cholesterolaemic effects of dietary soya-bean protein and casein was studied. Male rats received semi-purified diets containing soya-bean protein isolate or casein supplemented respectively with varing amounts of lysine or arginine for 40 d and blood samples were taken after a 5 h fast.2. Neither the addition of arginine to casein nor lysine to soya-bean protein modified the intrinsic effect of these proteins on serum cholesterol.3. Serum triglyceride levels tended to rise with increasing amounts of lysine supplementation. The opposite trend was obtained with arginine supplementation.4. Casein caused an increase in the concentration of serum insulin, but not glucagon. The glucagon level was increased proportionately with increasing amounts of arginine, while the addition of lysine showed no effect. The effects of added amino acids on serum insulin were inconclusive.5. There was a parallel increase in serum apo E and glucagon in response to arginine supplementation, while lysine supplementation increased serum apo E. 6. Thus, arginine:lysine was more effective in regulating serum triglyceride than serum cholesterol. Insulin was associated with different effects of these proteins on serum lipids.

I. The effect of the soya-bean protein isolate and casein, both given zoo g/kg diet for 3-4 weeks, on serum cholesterol was compared in male rats.2. Soya-bean protein exerted a hypocholesteraemic effect only in a cholesterol-free low-fat (10 g maize oil/kg) diet, when the lowering action appeared independent of the strain of the rat or the feeding pattern.The results obtained with diets containing cholesterol or higher levels of fats or both showed no definite pattern of response.3. Although the decrease in serum cholesterol appeared greater in a-lipoproteins than in ,&lipoproteins, the proportion of the former to total cholesterol remained almost unchanged. The concentration of serum apo A-1 was significantly lower in rats given the vegetable protein.4. Rats given soya-bean protein excreted significantly more neutral sterols. 5.The serum amino acid pattern did not reflect the difference in dietary protein. Addition of cholesterol to the diets modified the serum aminogarm, the decrease in threonine being most marked in both protein groups.6. This study shows that the hypocholesteraemic action of soya-bean protein is easily modified by the type of diet.