2. Bioavailibility and Effect on Lipid Metabolism of Crude β- Carotene Extract from Sweet Potato Leaves and Synthetic β- Carotene in Rats Fed Different High Fat Diets Recently clinical trials indicate that an increasing relative risk of death from cardiovascular disease following synthesized beta-carotene supplement. We are interested in the problem whether synthetic beta-carotene is suitable for use as a dietary supplement. The purpose of this study was to investigate the effects of different sources of beta-carotene and lipids on lipid metabolism and beta-carotene availability in rats. Forty adult male Wistar rats were randomly divided into five groups with the variables including the sources the sources of beta-carotene (synthetic and natural beta-carotene crude extract from sweet potato leaves ) and lipids (soybean oil and lard ). Diets and water were given ad libitum, and was 10g/kg cholesterol added in diets for forty days. The results showed that for (-carotene concentration in the serum and liver, the synthetic (-carotene groups were significantly higher than the beta-carotene extract groups (P<0.05). Comparison of the effect of different lipids under the same beta-carotene source indicated that, the lard groups were significantly higher in beta-carotene concentration than the soybean oil groups. Different sources of beta-carotene and lipid fed did not affect the serum and liver retinol concentration in both the soybean oil-fed groups and the lard- fed groups (P>0.05). The effects on lipid metabolism were as follows: The synthetic beta-carotene groups had significantly higher ratio between high density lipoprotein cholesterol (HDL-C) and low density lipoprotein cholesterol (LDL-C) than the beta-carotene extract groups (P<0.05), the beta-carotene extract groups is the most significant. Besides, the synthetic beta-carotene groups and the beta-carotene extract groups could both cause liver

3. Bioavailibility and Effect on Lipid Metabolism of Crude β- Carotene Extract from Sweet Potato Leaves and Synthetic β- Carotene in Rats Fed Different High Fat Diets total cholesterol content decreasing, and the beta-carotene extract groups is the most significant. The synthetic beta- carotene groups serum and liver acyltriglyceride concentration are significant higher than the beta-carotene extract groups. The rat serum, liver and adrenal gland beta- carotene concentration in the synthetic beta-carotene groups are all the lard group significant higher than the soybean oil group. Under the injection of soybean oil, the beta- carotene extract group serum and liver acyltriglyceride concentration are significant lower than the synthetic beta-carotene group, but the groups under the lard injection are not statistically different. The effects on fatty acid were as follows: Among the soybean oil groups, the serum and liver linoleic acid (18:2,n-6) ratios were significantly higher in the synthetic beta-carotene groups than in the beta-carotene extract groups (P<0.05); and Among the lard groups the serum and liver oleic acid (18:1,n-9) ratios were significantly higher in the synthetic beta-carotene groups than in the beta-carotene extract groups (P<0.05). These results suggest that ingestion of beta-carotene crude extract from sweet potato leaves, as compared to injestion of the synthetic beta-carotene, has the benefit of decreasing serum lipids. Except this, the lard diet could cause more beta-carotene deposit in the liver and increase beta-carotene bioavailability.