（Medical college ; University of Wasit, Iraq）
Hypercholesterolemia is the most important risk factor for cardiovascular diseases. In this study, we explored the effect of probiotics from functional milk on serum cholesterol levels in hypercholesterolemic subjects. This study included 26 subjects with serum total cholesterol 5.17–7.76 mmol/L. They did not consume milk containing any probiotics for a 2-week prestudy period. After this period, they receive either 300 g of functional milk for 4 weeks as a substitution for milk. Blood lipids were measured at the beginning and at the end of intervention. Consuming probiotics from functional milk caused a significant decrease in serum total cholesterol (5.97±0.77 vs 5.20±0.43 mmol/L, P= 0.023, P <0.05). However, there were no significant changes in blood lipid indices after receiving functional milk. Probiotics from functional milk had a cholesterol-lowering effect in hypercholesterolemic subjects.
Keyword: Probiotics; functional milk; total cholesterol; hypercholesterolemia.
Introduction
Hypercholesterolemia is the most important risk factor for cardiovascular disease. This prevalence of hypercholesterolemia is estimated to be 11.1% worldwide [1]. Dietary and lifestyle adjustments have a profound impact on controlling hypercholesterolemia.
Probiotics are living microorganisms that, when consumed in sufficient amounts, have a healthy effect on the host. Some studies have shown that probiotics have a beneficial effect in the prevention and treatment of certain diseases. It has been demonstrated to have many beneficial effects to humans, like improving gut health, immunity and prevention of harmful microorganisms, antihypertensive and anti-oxidant effects, anti-cancer properties, improving arthritis, reducing dermatitis and allergy symptoms, preventing gastrointestinal diseases, tooth carry, osteoporosis and obesity [2, 3].
In addition to these known effects, it was reported that probiotics from milk had a hypocholesterolemic effect. Thereafter, a series of studies have been performed to elucidate the effect of fermented dairy products on serum cholesterol, but the cholesterol-lowering effect of probiotics has not yet been established. The results of these studies included a significant reduction in serum cholesterol through a constant value to an increase in cholesterol concentration. The results of these contradictions may be due to different experimental designs, different amounts of fermented milk consumed, and differences in probiotic cultures and lactic acid bacteria strains used in these studies [4, 5].
In the present study, we examined the role of probiotics from functional milk lowing cholesterol. We attempted to know the clinical effects of functional milk on hypercholesterolemic population
Method and Materials
Subjects
26 volunteers were recruited. Prior to inclusion, blood samples were drawn to select subjects with mild to moderate hypercholesterolemia (total cholesterol between 5.17 and 7.76 mmol/L). Subject with coronary heart disease, diabetes, hypothyroidism, nephrotic syndrome and obesity (body mass index >30 kg/m2) was excluded. Lipid-lowering drugs or pharmaceuticals known to affect the blood lipid metabolism were not allowed to use. The study was approved by the university ethics committee and all subjects gave consent to participate.
Study Design
It was a single-blind study with treatment periods lasting 4 weeks and followed by a washout period of 2 weeks. Before starting, all the subjects followed a 2-week prestudy period during which they were asked not to consume any yogurt or milk containing probiotics. After this prestudy period, the subjects received a dose of 3*100 g/day functional milk for 4 weeks.
Subjects were not informed about the type of the functional milk they received (single-blind). They were advised not to change their exercise or eating habits during the whole study period and there was a checkup every week by telephone to ask about compliance and side effects.
Anthropometric measurements, collection of blood samples after overnight fasting and a 3-day dietary record were done after the prestudy period and at the end of the 4 weeks’ intervention in the study periods. A nutritionist (one of the researchers) instructed the subjects to record their food intake prior to the beginning of the study and their records were checked.
Biochemical Assays
Blood samples were drawn in the morning after 10~12h fasting, and put at room temperature and centrifuged for 10 min at 2,000 u/min. The resulting serum was stored at –80°C until analysis. Serum total cholesterol, HDL-C and triacylglycerol were measured enzymatically (Pars Azmoon, Tehran, Iran) on a Selectra II autoanalyzer (Vita Lab, Helsinki, Finland). LDL-C was calculated according to Friedewald’s formula.
Statistical Analysis
All the data are expressed as mean±SD. Comparisons between two groups were analyzed by Student t test. Statistical analysis was performed with SPSS version 20 (SPSS, Inc, Chicago, IL) and values of P <0.05 were considered statistically significant.
Results
A total of 26 subjects were recruited, of which were 10 males and 16 females. Characteristics of the participants included in the study are listed in Table 1.
There were 16 women (71.5%) and 10 men (28.5%). Mean (±SD) of age and BMI were 48.5 (±6.0) years and 25.6 (±2.4) kg/m2 respectively. Physical activity level and smoking status were constant during the research. There were no significant changes in weight and BMI during the study (data not shown). The baseline levels of total cholesterol, LDL-C, HDL-C, triacylglycerol in included participants are 5.97±0.77, 3.61±0.54, 1.06±0.41, 2.36±1.40 mmol/L.
The effects of probiotic functional milk on blood lipid indices are shown in Table 2. Probiotics from functional milk consumption caused a significant decrease (5.97±0.77 vs 5.20±0.43 mmol/L, P= 0.023) in serum total cholesterol, with a net change 0.70±0.34 (Table 2). However, there were no significant reductions in other serum lipids level after probiotics functional milk treatment.
Discussion
We examined the hypocholesterolemic effect of probiotics from functional milk with and our study had a special design: before the study, yogurt or other fermented dairy products were excluded from the diet in order to delete their possible effects on blood lipids. The results indicate that the probiotics from functional milk causes a significant reduction in serum total cholesterol in mildly to moderately hypercholesterolemic subjects.
Previous studies have compared the effects of probiotics and traditional yogurt on plasma lipid mass spectrometry in women with normal cholesterol. Several lipid parameters were altered during the study in probiotic and control yoghurts. Therefore, no significant differences between the groups were observed. They concluded that regular consumption of probiotics and conventional yogurt for 4 weeks had a positive effect on lipid mass spectrometry in healthy women's plasma [6].
In the study of dairy products fermented with various Lactobacillus acidophilus strains, there was no effect on serum cholesterol. The probiotic functional milk we used in this study contained Streptococcus thermophilus and Lactobacillus delbrueckii subspecies. In addition, we can conclude that the cholesterol-lowering effect of probiotics from functional milk is completely related to the presence of Lactobacillus acidophilus or Lactococcus lactis and/or both because they have an acid and bile High resistance [7 ,8]. Possible mechanisms by which these bacteria lower cholesterol may include inhibition of cholesterol absorption by the small intestine by bacterial cells in combination with cholesterol and bile acids, or promotion of excretion and assimilation of the effects of lactic acid bacteria on cholesterol after binding of bile acids to lactic acid bacteria cells [9, 10].
Because of the large amount of yogurt added to the diet and the uncontrolled fat content of these diets, it is difficult to explain many of the findings on the cholesterol-lowering effects of yogurt. Therefore, they are not comparable to our research. In one well-designed study, 480 g/day of yogurt lasting for 4 weeks, there was no effect on blood lipids in men with normal blood lipids [11]. The use of plain yogurt as a control yogurt had no effect on blood lipids. The significant reduction in LDL-C deficiency after consumption of probiotic yogurt in this study may be due to the small sample size and the inability to achieve optimal statistical power. Therefore, another study of more samples may be accompanied by a significant reduction in LDL-C. In addition, the dose of probiotics is another focus [12].
In a study of the dose-response effect of probiotic bacteria on blood lipids, Larsen et al. [13] randomly assigned 75 healthy young adults to 5 groups receiving either placebo or a mixture of the two probiotics in the concentration of 108, 109, 1010 or 1011 CFU/day during 3 weeks. No overall dose-response effect on the blood lipids was found. The strain of bacteria is a key in producing health benefits. If a strain of bacteria has no cholesterol-reducing effect, using a higher dose will not be effective. Overall, the suggested dose of probiotic bacteria is 108–1011 CFU/day according to the strain of bacteria or the type of the disease [14]. So, 100 g of probiotic dairy product should contain 106–109 CFU/g of the probiotic bacteria at the time of consumption. In the present study, the probiotic yogurt contained the lowest number of bacteria suggested previously. Since the probiotic culture we applied in this study caused a reduction in serum total cholesterol, we predict that higher counts of these bacteria probably have more potential to lower total and LDL-C in hypercholesterolemic subjects.
Conclusion
Probiotics from functional milk caused a significant reduction in serum total cholesterol and we expect that using a greater sample size and a higher dose of probiotics in functional milk will be accompanied by a significant reduction in LDL-C. So, consumption of probiotics from functional milk is probably beneficial for hypercholesterolemic patients.
Reference
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论文作者:Abstract
论文发表刊物:《航空军医》2019年第01期
论文发表时间:2019/4/16
标签：collection论文; overnight论文; Anthropometric论文; measurements论文; fasting论文; rsquo论文; nutritionist论文; 《航空军医》2019年第01期论文;