**1. Introduction**

442 Lipid Metabolism

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Probiotics are dened as viable microorganisms that exhibit benecial effects on the health of the host [1]. Now, probiotics are known to possess physiological functions such as inhibition to pathogens, assisting digestion, immunoregulatory activity and antitumor activity [2]. Here, we discuss the effects of probiotic on lipid metabolism from seven main aspects including history, antioxidant effect, impact on lipoprotein, microflora view, hormones, receptors and new mechanisms.

#### **1.1. Past and present**

As early as in 1974, Mann and Spoerry observed that inhabitants from African Maasai tribes maintained a lower level of blood lipids due to a high fermented milk intake [3]. Further perspective suspected that live Lactobacilli included in fermented milk may contribute to reducing cholesterol [4]. The cholesterol-reducing effect of probiotic has become more apparent with the discovery of bile salt deconjugating and cholesterol assimilating ability of *Lactobacillus* [5] [6]. Thereafter, a set of screening procedures both *in vitro* and *vivo* was established for evaluation of cholesterol-reducing probiotics [7]. Many probiotic strains mostly *L. acidophilus* were screened out with cholesterol-reducing property [8].

A new study by Lye et al showed that there existed ve possible probiotic mechanisms including assimilation of cholesterol during growth, binding of cholesterol to cellular surface, disruption of cholesterol micelle, deconjugation of bile salt and bile salt hydrolase (BSH) activity [9]. Now with the development of molecular biology, we can judge cholesterol-lowering effect firstly by detection of BSH gene and its expression in a probiotic genome. A recent study by Sridevi et al showed that *Lactobacillus buchneri* ATCC 4005 exhibited a great cholesterol-lowering property through an optimal condition of bile salt hydrolase production [10]. In conclusion from a meta-analysis, administration of probiotic can exect benefits on total cholesterol and LDL-cholesterol level of human [11].

© 2013 Zhang and Zhang, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

There are some reports that fermented soy milk by probiotics also showed favorable function of regulating lipids level [12]. The advantages of fermented soy milk are that undesirable soybean oligosaccharides can be hydrolysed which provide nutritional components for probiotic and a large variety of peptides and amino acids are produced as well as active aglycon form of isoflavones [13]. An improved cholesterol profile was observed with daily intake of a probiotic soy product [14]. It seems possible that living probiotics and functional isoflavones cooperated in regulating lipid profile.

The Effect of Probiotics on Lipid Metabolism 445

[25]

[26]

[28]

[32]

catalase activity [24]

status [27]

oxidation [30]

blood cells [31]

Strains Model Antioxidant effects Renferences

Rats with colon carcinogenesis

High fructose fed rats

*Lactobacillus fermentum* ME-3 human Enhanced total antioxidative

High-Fat and cholestero-l fed rat

Iron overloade-d mice

VSL#3 ob/ob mice Lower fatty acid beta-

*L. acidophilus* rats Higher GSH-Px activity in red

Lipoprotein transport play an important role in accumulation of host lipopolysaccharide level (LPS) [33]. Studies by Cani et al showed that elevated LPS level was considered as a trigger factor involved in the pathogenesis of obesity and metabolic risk via innate immune mechanism [34]. LPS-binding protein (LBP) and lipoproteins exert a synergistic effect on

Several fermented milk containing probiotics were demonstrated to reduce low-density lipoprotein cholesterol(LDL-c) level and very-low-density lipoprotein cholesterol (VLDL-c) in animal and human [26] [36] [37].Recently, *L. casei* Shirota had been proved a plasma LBPlowering effect in obesity mice and *L. reuteri* NCIMB 30242 yoghurt could improve ApoB-100 level in hypercholesterolaemic subjects, suggesting that probiotic possess LPS-reducing

human An increase of SOD and

Lower plasma lipid peroxidation levels and higher plasma total antioxidant levels

Lower values of TBARS and higher values of glutathione in liver and pancreatic tissues

An increase in total radical trapping antioxidant potential (TRAP) and a decrease in conjugated dienes in plasma

A significant decrease of lipid

Inhibition of hemolysis of red blood cell under the condition of vitamin E dificient

peroxide in the colonic mucosa [29]

Probiotic yoghurt containing *Lactobacillus acidophilus* LA-5 and *Bifidobacterium* BB-12

*Bacillus polyfermenticus* 

Probiotic dahi containing *Lactobacillus acidophilus* and *Lactobacillus casei*

*Bacillus polyfermenticus* SCD

*Streptococcus thermophilus* YIT 2001

*L .rhamnosus* SBT 2257 rats

**Table 1.** Antioxidative effects of probiotics

**3. Impact on lipoprotein** 

reducing the toxic LPS level[35].

function to delay the obesity risk [38] [39].
