Written by, Renata Filiaci, MS Health and Wellness

Introduction

The Western diet consists of the overconsumption of saturated fat, refined grains, and excessive sugar and protein, and lack of consumption of whole foods. This diet started during and following the Industrial era when processed foods became a staple item in the modern family’s home. Since this change, chronic illness and disease have become a public health threat partially due to the consumption of the Western diet. Over 65% of the United States population is either overweight or obese, which is leading to many other severe illnesses, such as type 2 diabetes, cardiovascular disease, hypertension, high-risk cholesterol concentrations, and cancer (Cordain, Eaton, Sebastian, Mann, Lindeberg, Watkins, O’Keefe, & Brand-Miller, 2005).

The consumption of the Western diet has also been linked to liver disease. The liver is a valuable role in maintaining positive homeostasis. The liver aids in digestion and purifying blood from harmful chemicals as well as storing and processing nutrients, which makes it critical for survival (Marieb & Hoehn, 2016). The liver continuously recirculates its blood and components by entering the gut and being reabsorbed back into the liver, indicating that what a person puts into their stomach is associated with liver health. To have positive liver function, the gut and liver have to maintain a healthy balance in components, which should be low in saturated fat, refined grains, and excess sugar and protein (Jena, Sheng, Liu, Kalanetra, Mirsoian, Murphy, French, Krishnan, Mills, & Wan, 2017).

An article was written by authors Mollahosseini, Daneshzad, Rahimi, Yekaninejad, Maghbooli, and Mirzaei (2017) discussing the relationship between eating a fruit and vegetable based diet and reducing liver enzymes, which could eliminate the potential risk of developing related liver diseases. The researchers conducted a cross-sectional study analyzing how consuming vegetables and fruits have a higher association with reducing liver enzymes as well as oxidative stress. Vegetables have a high amount of antioxidant properties and bioactive compounds which are known to promote good health and prevent certain diseases, which is valuable for liver maintenance (Mollahosseini, Daneshzad, Rahimi, Yekaninejad, Maghbooli, & Mirzaei, 2017; National Cancer Institute, 2018). The purpose of this literature review is to establish a connection between consuming a plant-based diet and using plant-based medicinal protocols as an effective treatment for liver disease.

Results

In a study done by Jena, Sheng, Liu, Kalanetra, Mirsoian, Murphy, French, Krishnan, Mills, and Wan (2017), the researchers related the consumption of the Western diet and the increase in hepatic inflammation in mice. Farnesoid X receptor (FXR) mice were fed either a control diet or a Western diet for ten months. FXR is lessened in patients suffering from liver cirrhosis and liver cancer. FXR is a member of the nuclear receptor family that regulates bile acid synthesis and transfer as well as lipid and glucose metabolism from the liver to gut back to the liver (Claudel, Staels, & Kuipers, 2005). The mice that were fed a Western diet had severe steatohepatitis, reduced firmicutes (good gut bacteria), and increased proteobacteria (harmful bacteria). An imbalance in bacteria can cause problems in the liver to gut component transferring as well as promote chronic disease (Jena, Sheng, Liu, Kalanetra, Mirsoian, Murphy, French, Krishnan, Mills, & Wan, 2017).

Associating the Western diet with a diet high in saturated fat, the authors in this experiment, Kim, Choi, Jang, and Park (2013), evaluated and compared mice fed a high fat diet to those fed carvacrol-supplemented diet (CSD). Carvacrol is a food additive used for flavoring and foodstuffs, which is from the essential oils of many herbs including, Origanum, Satureja, Thymbra, Thymus, and Coridothymus species. It is noted from previous studies that carvacrol has demonstrated positive effects on inflammation, cancer, oxidants, and hepatotoxic induced rats. The mice were either fed a normal diet (control), high-fat diet, or CSD for ten weeks; there was no difference in amount of consumption. Liver tissues, weight, plasma, protein, and hepatic biochemistries were assessed. The mice that were fed CSD had reduced high-fat induced hepatic steatosis as well as significantly lower levels of hepatic triglycerides, free fatty acids, total cholesterol, and cholesteryl ester. CSD has been recorded to promote the metabolism of lipids and fatty acids in the liver by modulating the gene expression of SIRT1-AMPK pathway, which help break down fat and protein, as well as inhibit the gene expressions of proinflammatory cytokines with no harmful effects (Kim, Choi, Jang, & Park, 2013).

The authors, Calleja, Vieites, Montero-Meterdez, Torres, Faus, Gil, and Suarez (2012), examined the antioxidant effect of b-caryophyllene (CAR) on rat liver. Due to their phytochemical makeup, explicitly focusing on the bioactive compound terpenoid, plant-based foods and diets have a low-molecular lipophilic disposition, which reduces the risk of chronic diseases. CAR, a component of the essential oil from many vegetables, fruits, herbs, and plants, is reported to have antioxidant activity as well as protection and inhibition against liver fibrosis and lipid peroxidation. Rats were treated with carbon tetrachloride, which induced liver damage. The day before initial carbon-tetrachloride poisoning, rats were fed CAR treatment, plus other terpene compounds, which was based upon prior dosing in other studies; however, the concentration came out to be between 50-200 micrograms. CAR treatment had the best results; with CAR treatment, higher inhibitory action against lipid peroxidation occurred, carbon tetrachloride was suppressed, and bilirubin levels were reduced. Also recorded after CAR treatment was the reduction of liver fibrosis and oxidative stress on the liver (Calleja, Vieites, Montero-Meterdez, Torres, Faus, Gil, & Suarez, 2012).

The aim of this study performed by Hossain, Lee, Park, Birhanu, Mechesso, Park, Park, Lee, Youn, and Park (2018) was to evaluate the use of fermented Cucurbita moshata (pumpkin) extract (FCME) and its effect on treating obesity and nonalcoholic fatty liver disease in obese mice. Pumpkin is rich in many bioactive compounds, such as polysaccharides, vitamins, mineral salts, carotene, and other essential nutrients. The constituent, polysaccharide, plays a fundamental role in reducing inflammation and maintaining a favorable metabolism by increasing the serum insulin levels, reducing the levels of blood glucose, and improving glucose tolerance, which correlates with being antidiabetic. The mice were split into groups depending on diet, including a control group, a high-fat diet group, and groups where mice were fed a high-fat diet with either 0.1%, 0.3%, or 0.5% of FCME. Supplementing the diet with FCME significantly reduced adipose tissue mass, liver enzymes and plasma lipids in obese mice as well as suppressed body weight gain by controlling and regulated plasma lipids and liver enzymes (Hossain, Lee, Park, Birhanu, Mechesso, Park, Park, Lee, Youn, & Park, 2018).

The buildup of lipids and triglycerides, due to overconsumption of fats and imbalance in lipid metabolism, can influence the development of many liver related diseases, such as hyperlipidemia, which is associated with the progression of nonalcoholic fatty liver disease. The authors, Bouazza, Bitam, Amiali, Bounihi, Yargui, and Koceir (2015), calculated the effects of fruit vinegars on liver damage and oxidative stress in high fat diet (HFD) fed rats. Due to the constituent polyphenols in vinegar, it is known for its antibiotic, antioxidant, and anti-inflammatory effects; specifically, attributing these effects with fruit vinegars, such as pomegranate, prickly pear, and apple, they could have hepatoprotective abilities. There were five groups of rats: the control fed a standard diet, rats fed a HFD, rats fed HFD and pomegranate vinegar, rats fed HFD and prickly pear vinegar, and rats fed HFD and apple vinegar. After seven months of observation, treatment with fruit vinegars decreased body weight gain, total cholesterol, triglycerides, lipoprotein-cholesterol (LDL), and lipid profile while increasing high-density apoliprotein-cholesterol (HDL) and antioxidant activity against infiltration of disease (Bouazza, Bitam, Amiali, Bounihi, Yargui, & Koceir, 2015).

High amounts of glucose, which are apparent in the consumption of the Western diet, aids in lipid accumulation, further affecting the metabolism of lipids in the liver. This is attributed to liver disease, specifically the growth of nonalcoholic fatty liver disease and liver cancer. The study provided by Yuk, Kim, Yang, Sung, Jeong, and Lee (2018) investigates the effects of nobiletin on high glucose-induced lipid accumulation in HepG2 cells for 24 hours. Nobiletin is a flavonoid present in citrus peels; flavonoids aid in proper metabolism. Similarly to CSD, nobiletin exhibited reduction of the gene expression SREBP-1c via AMPK pathway, which helps break down fat and protein, resulting in reduced lipogenesis and lipid accumulation (Yuk, Kim, Yang, Sung, Jeong, & Lee, 2018).

In a study performed by Li, Liu, Wang, Chen, Zhang, and Kang (2018), the authors assessed the consumption of hemp seed and Sonchus oleraceus (the HB diet) and its effect on age-related metabolic syndrome and lifespan in mice. Current food production and the Western diet are being linked to chronic disease, which is causing health practitioners to look at other options, such as eating plant-based foods. Both hemp seed and Sonchus oleraceus have highly beneficial components, such as antioxidants, omega-3 fatty acids, anti-inflammation properties, essential nutrients, and anti-aging activity. Hemp seed is high in plant protein, and Sonchus oleraceus stimulates protein synthesis. There were two groups of female mice, a control group which was fed the Western diet as desired and the experimental group which was fed the HB diet as desired for three months. After the procedure, the liver and spleen were then taken from the mice for histological analysis to determine hepatic lipid accumulation, fatty acid composition, glucose, cholesterol and triglyceride levels, and lipid peroxidation. Mice who were fed the control diet had enlarged, aged livers with increased lipid and triglyceride content as well as increased hepatic inflammation due to its high levels in protein, saturated fat, and sugar. The mice that were fed the HB diet had the complete opposite response; oxidative stress and inflammation were decreased in the liver with less hepatic lipid, cholesterol, and triglyceride accumulation (Li, Liu, Wang, Chen, Zhang, & Kang, 2018).

In a research study by Bolsinger, Landstrom, Pronczuk, Auerbach, and Hayes (2017), the authors examined the correlation between a low glycemic diet and its protection against metabolic syndrome and type 2 diabetes mellitus (T2DM) in Nile rats. Metabolic syndrome and T2DM are associated with the increase in non-alcoholic fatty liver disease, liver cancer, and liver cirrhosis. The Nile rat was chosen for its susceptibility in having metabolic syndrome which transitions to T2DM. The rats were then split up into groups including a control diet group and a low glycemic diet group, which were fed lentils to determine the relationship between disease and dietary fiber, caloric density, macronutrient composition, glycemic index, and glycemic load. Though the low glycemic group had increased diet intake, this group resulted in lower plasma lipids and insulin as well as reduced caloric intake and adipose accumulation. The lentils are also high in fermentable dietary fiber, which lowered blood glucose levels as well as promoted favorable gut flora metabolism in the rats (Bolsinger, Landstrom, Pronczuk, Auerbach, & Hayes, 2017).

Discussion

After thorough research, a primarily plant-based diet as a treatment for liver disease lacked in evidence; however, trials showing the use of plant-based medicinal protocols as management for liver disease support the notion that a plant-based diet is favorable in the treatment of liver disease. Throughout each study, the use of the plant-based material as treatment showed blood lipid control, indicating that plants aid in treating obesity and diabetes, which can prevent further liver degradation, such as nonalcoholic fatty liver disease, liver cirrhosis, and liver cancer.

Both essential oil use of b-caryophyllene (CAR), fermented Curcubita moshata (pumpkin), and carvacrol supplemented diet (CSD) prove to inhibit and protect the liver from fibrosis and inflammation due to their antioxidant activity in the liver, which could show the possibility that explicitly eating a diet high in vegetables and fruits is the way to treat liver disease. Similarly, the supplemental HB diet provides incite that plant protein and omega-3 fatty acids work together in preventing an enlarged liver, oxidative stress, and cholesterol build up, which could lessen the risk of diabetes-related liver disease. By eating plant protein, there is less chances of saturated fat and a buildup of lipids because plant protein and healthy fats metabolize together. Also, if switching to a plant-based diet is too rigorous of a change, the benefits of including essential oils in the diet work as an opportunistic agent in controlling liver health.

By modulating gene expression of lipid metabolism and inhibiting the gene expressions of pro-inflammatory cytokines shows, CSD and nobiletin can potentially reduce the risk of developing genetic liver related diseases as well as reverse and reduce further degradation from previously developed liver diseases, such as diabetes mellitus, nonalcoholic fatty liver disease, and liver fibrosis or cirrhosis. Also, CSD could be taken in place of liver disease medications, which could adversely affect the body and deplete nutrients, because there are no harmful effects when consumed. Moreover, CSD works as anti-inflammatory agent, which will work by reducing and protecting against inflammation in the liver.

Fruit vinegars can do numbers to the liver as determined by the reduction of total cholesterol, triglycerides, lipoprotein-cholesterol (LDL), and lipid profile while increasing high-density apoliprotein-cholesterol (HDL) in high fat diet fed rats, which promotes the hepatoprotective effect. Pairing the consumption of fruit vinegars with a plant-based diet could eliminate the development of disease altogether. Also, fruit vinegars decreased body weight gain in the rats which can help regulate possible excess weight gain in obese persons attributing to the decrease in risk of developing liver diseases associated with obesity while being hepatoprotective.

The Western diet proves to influence liver disease in mice and rats as well as promote the risk of mortality. The Western diet consists of saturated fat, refined grains, and excess sugar. By switching choice in carbohydrate intake to consuming unrefined grains and legumes, which are high in omega-3 fatty acids and dietary fiber, this combination can help lower blood glucose levels and prevent further lipid buildup while maintaining insulin production in patients with metabolic syndrome and T2DM. Considering 65% of the United States is obese, which leads to reduced metabolic activity and T2DM, this correlation is tremendous for the health industry because it could maintain and control patients with diabetes as well as prevent further liver disease from occurring while reversing liver damage.

The limitation of this literary review was the result of lack of studies focusing specifically on a plant-based diet being effective treatment. Each study primarily focused on plant-based material or extract as treatment, but not on exclusively consuming a plant-based diet. Though the studies on plant-based options and medicines were proven effective and functional, more research is necessary in determining whether eating solely plants is the best choice for the treatment of liver disease.

Conclusions

The evidence provided supports that consuming a plant-based diet and using plant-based medicinal protocols are useful as the treatment for liver disease. Since the liver and gut are connected by blood transfer and reabsorption, the liver plays an essential role in digestion, purification, and metabolism, which correlates it with absorbing a diet low in unhealthy substances, such as the foods associated with the Western diet. The Western diet consists of a diet high in saturated fat, sugar, refined grains, and protein and low in vegetables, fruits, legumes, and unrefined grains, which were only determined as beneficial for liver health. As a result of their dietary fiber content, antioxidant and nutrient dense properties, high fatty acid components, and low-glycemic activity, a diet abundant in plant-based foods are essential.

References

Bolsinger, J., Landstrom, M., Pronczuk, A., Auerbach, A., & Hayes, K. C. (2017). Low glycemic load diets protect against metabolic syndrome and Type 2 diabetes mellitus in the male Nile rat. The Journal of Nutritional Biochemistry, 42, 134-148. https://doi.org/10.1016/j.jnutbio.2017.01.007

Bouazza, A., Bitam, A., Amiali, M., Bounihi, A., Yargui, L., & Koceir, E. A. (2015). Effect of fruit vinegars on liver damage and oxidative stress inhigh-fat-fed rats. Pharmaceutical Biology, 54(2), 1-6. DOI: 10.3109/13880209.2015.1031910

Calleja, Vieites, Montero-Meterdez, Torres, Faus, Gil, & Suarez. (2012). The antioxidant effect of b-caryophyllene protects rat liver from carbon tetrachloride-induced fibrosis by inhibiting hepatic stellate cell activation. British Journal of Nutrition, 2013(109), 394–401 doi:10.1017/S0007114512001298

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