EFFECT OF PHYTOSTEROL SUPPLEMENTED HEALTH FOOD (YOGHURT) ON LDL LEVELS -A PILOT STUDY

An investigation was carried out to study the effect of phytosterol supplemented health food (yoghurt) on LDL cholesterol and total cholesterol levels. Phytosterols are defined as plant sterols and plant stanols. Phytosterols lower total and LDL blood cholesterol by preventing cholesterol absorption from the intestine, so they have been known as blood cholesterol-lowering agents for over the last half century. Phytosterols are naturally found in fruits, vegetables, nuts and principally oils. Dietary phytosterol intakes normally range from 160 to 400mg/day with variations depending on food culture and major food sources. Recent studies have shown that maximum cholesterol-lowering benefits are achieved at doses of 2-3 g per day. Therefore today’s use implies the need for enriched functional food products, which give enough phytosterols intake thereby contributing to lowering LDL cholesterol levels. Milk is a naturally available animal food consumed by all ages. In tropical countries, milk is fermented and consumed as it is merited with dietetic and therapeutic value. Yoghurt prepared with Streptococcus thermophilus & Lactobacillus bulgaricus is a fermented milk product similar to curds and consumed in European countries for good health. In yoghurt the proteins, carbohydrates and fats are predigested by bacterial cultures, hence it is more easily digested than milk. It also contains significantly higher free amino acids and peptides compared to milk. A study was therefore, undertaken with the objective of developing suitable technology for the preparation of yoghurt, incorporated with phytosterol powder at different levels (2, 2.5 and 3%), to identify the most acceptable product and to evaluate shelf life and physico-chemical properties. Finally the effect of supplementation of phytosterol incorporated yoghurt on total cholesterol and LDL cholesterol levels in human subjects was studied. Yoghurt above 2% of phytosterol concentration was not found to be acceptable as it increased grainy mouth feel and grainy texture. Therefore yoghurt with 2% phytosterol content was selected for further study. The products were stored in plastic cups (PET) and stored at refrigerator temperature of 4 o C for carrying out shelf life studies for 15 days. Total Bacterial Count (TBC) and Total Mold count (TMC) was assessed on 0 day, 10 th day and 15 th days of storage. These microbial analyses results suggested that control and experimental yoghurts were safe for consumption upto 15 days without any spoilage. Physico-chemical and nutritional properties like pH, colour, titrable acidity, TSS, protein, fat, calcium and dietary fiber were analyzed for control and phytosterol incorporated yoghurt using standard methods of AOAC. The colour value of control and experimental yoghurts were mainly determined in the form of lightness, hue and brightness. The scores for colour were highest for experimental sample than control sample. Statistically significant difference (p<0.05) was observed for colour between in control and phytosterol incorporated (Experimental) sample. Control and experimental yoghurt showed pH of 4.61 and 4.44 respectively. The acidity of control and experimental yoghurts were 0.89 % and 0.84 %, respectively. The TSS of control and experimental yoghurts were 18.96 and 20.23 respectively. Control and experimental yoghurt (2% phytosterol incorporated) were supplemented to human subjects after approval of ethical committee. 16 male subjects with in the age range of 23-28 years were selected for the study. They were divided into control group (n=6) and experimental group (n=10) respectively. Control group was fed with only plain yoghurt without phytosterols and experimental group was fed with phytosterol incorporated yoghurt. Total time taken for supplementation was 30 days and the lipid profile was analysed on the 0 th day and 30 th day. The blood samples were collected on 12 hr fasting status on 0 day and 30 th day. The serum was used for analysing the lipid profile. The nutrient analysis of control and experimental yoghurt showed that phytosterol incorporated yoghurt was a good source of calcium, 120 mg in control and in experimental 119 mg. Protein content was 3.80 g/100 g in control yoghurt and 3.87 g/100 g in experimental yoghurt. As the yoghurt was made from toned milk, fat content was 3.10 g % and 3.23 g % in control and experimental yoghurts respectively. Dietary fibre content of control yoghurt was found to be 3.40 g % and in experimental 3.25 g % which could be due to addition of guar gum. Physico chemical composition of the experimental product did not differ much from the control. The mean total cholesterol levels were 216.05±14.90 mg/dl on 0 day which reduced to 214.15±14.85 mg/dl on 30 th day in control subjects. There was a significant reduction (215.90±10.52 mg/dl on 0 day to 206.60±11.49 mg/dl on 30 th day) in the mean total cholesterol levels in the experimental subjects who were fed with 2% phytosterol incorporated yoghurt daily at lunch time for a period of 30 days indicating that supplementation with phytosterol would bring desirable reduction in the total cholesterol levels. The percent reduction in total cholesterol in experimental group was 4.16% compared to 0.87% in the control group. A reduction in tryglyceride levels was 1.25% of control group where as there was 4.67% reduction in the experimental group. Similarly the HDL cholesterol levels was increased significantly from 39.73±1.89 mg/dl on 0 day to 40.30±1.92 mg/dl on 30 th day in experimental subjects. A reduction in VLDL cholesterol levels was 1.27 % of control group where as there was 4.67 % reduction in the experimental group. Similarly the reduction in LDL cholesterol levels was 1.42 % of control group where as there was 5.88 % reduction in the experimental group. In the present study, phytosterol incorporated yoghurt supplemented for 30 days, reduced the LDL cholesterol from 134.65 mg/dl to 126.72 mg/dl. The per cent change in experimental LDL cholesterol was 5.88%. If could be postulated that if the supplementation time could be increased to 2 to 3 months and dose of the phytosterol powder in the yoghurt be increased to 2.5 or 3%, it could further reduce of the total cholesterol and LDL cholesterol content.