Brief reportDietary phytic acid prevents fatty liver by reducing expression of hepatic lipogenic enzymes and modulates gut microflora in rats fed a high-sucrose diet
Introduction
Phytic acid (PA; myo-inositol hexaphosphoric acid), a ubiquitous plant component, has been traditionally considered an antinutrient [1]. However, it has been demonstrated that dietary PA prevents fatty liver caused by a high-sucrose (HSC) diet in rats [2]. To our knowledge, no information exists on whether suppression of hepatic activities of lipogenic enzymes by PA intake in rats fed the HSC diet is associated with changes in gene expression of hepatic lipogenic enzymes.
When PA is administered as a dietary supplement, it is suggested that undigested PA or partially digested inositol phosphates accumulate in the gastrointestinal tract of monogastric animals such as humans and rodents [3], [4]. The presence of undigested products of PA in the gut may have beneficial effects on the gut microflora, similar to those associated with dietary fiber or oligosaccharides [5]. Several lines of evidence suggest a role for the gut microbiota in the etiology of nonalcoholic fatty liver disease [6]. It is possible that the preventive effect of PA on fatty liver due to the HSC diet may be related to modulation of gut microflora.
It has been demonstrated that dietary PA modulates characteristics of the colonic environment in rats fed a high-fat diet [7]. The present study was conducted to examine whether dietary PA affects the gene expression of hepatic lipogenic enzymes and to investigate the relation between anti-fatty liver activity of PA and gut microflora in rats fed the HSC diet.
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Materials and methods
Male Sprague Dawley rats were purchased, maintained, and housed as previously described [8]. The rats were assigned to three groups of six rats each randomized by weight. Compositions of the high-starch (HSR), the HSC and the HSC plus 1.02% dodecasodium PA (Sigma Chemical Co., St Louis, MO, USA) diets were described elsewhere [2]. Previous studies indicated that at around 1%, PA perfectly prevents fatty liver due to the HSC diet or xenobiotic intake in rats [2], [9], [10]. Experimental diets
Results
Final body weight did not differ among the three groups (Table 1). Food intake was slightly increased in rats fed the HSC diet compared with those fed the HSR diet. Compared with the HSR diet, the HSC diet significantly increased the levels of hepatic weight, total lipids and triacylglycerol, and the activities and gene expression of hepatic lipogenic enzymes (P < 0.05; Table 1). These increases were clearly suppressed by dietary PA (P < 0.05; Table 1). PA intake elevated the fecal ratio of
Discussion
To our knowledge, this is the first study to report that the preventive effect of dietary PA on fatty liver induced by the HSC diet is mediated through the downregulation of expression of hepatic lipogenic enzymes. As previously explained, gut microflora including Lactobacillus spp. and Clostridium spp. regulates hepatic lipogenesis and fat storage [6], [14], [15]. This study also provides the first evidence that dietary PA increases the fecal ratio of Lactobacillus spp. and depresses the
Conclusion
PA doses used in this study were relatively higher than in human consumption via food, because some human populations may consume up to ∼1 g/d of PA [1]. However, we previously found that supplementation with as little as ∼0.05% PA in the diet could downregulate the high levels of hepatic lipids and hepatic activities of lipogenic enzymes due to the HSC diet in rats [10]. It is possible that dietary PA may be useful to improve fatty liver induced by an HSC, mineral-sufficient diet in humans.
References (16)
Effects of dietary myo-inositol or phytic acid on hepatic concentrations of lipids and hepatic activities of lipogenic enzymes in rats fed on cornstarch or sucrose
Nutr Res
(1997)- et al.
Effect of dietary phytase on the digestion of phytate in the stomach and small intestine of humans
J Nutr
(1988) - et al.
Phytate breakdown and apparent absorption of phosphorus, calcium and magnesium in germfree and conventionalized rats
Nutr Res
(1996) - et al.
Dietary phytic acid modulates characteristics of the colonic luminal environment and reduces serum levels of proinflammatory cytokines in rats fed a high-fat diet
Nutr Res
(2014) - et al.
Consumption of a resistant protein, sericin, elevates fecal immunoglobulin A, mucins, and cecal organic acids in rats fed a high-fat diet
J Nutr
(2011) - et al.
Dietary inositol hexakisphosphate, but not myo-inositol, clearly improves hypercholesterolemia in rats fed casein-type amino acid mixtures and 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane
Nutr Res
(2008) - et al.
Effects of dietary carbohydrate and myo-inositol on metabolic changes in rats fed 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT)
J Nutr Biochem
(2003) - et al.
Beneficial effects of protease preparations derived from Aspergillus on the colonic luminal environment in rats consuming a high-fat diet
Biomed Rep
(2015)
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This research was supported in part by a Grant-in-Aid (no.15, G-9, 2015) from The Tojuro Iijima Foundation for Food Science and Technology in Japan. YO designed and supervised the study. AS and YO performed the animal experiments. All three authors contributed to the analysis of data and the interpretation of the results, wrote the draft of the manuscript, and critically reviewed it. The authors have no conflicts of interest to declare.