Watermelon & Hepatic Gene Expression
A recent study has found that the consumption of watermelon may positively impact hepatic gene expression and upregulate lipid metabolism in obese mice. The current Western diet, often characterized by intake of high levels of saturated fats, cholesterol, and refined carbohydrate, has been shown to contribute to the development of non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH), both associated with excessive fat accumulation in the liver.
Previous evidence from animal studies suggests that vitamins and phytonutrient compounds from fruit may support the regulation of several key proteins (transcription factors) related to lipid metabolism, hepatic fat deposition, apoptosis of hepatocytes, and inflammation, thereby protecting against NAFLD, NASH, and some of the negative metabolic consequences of the Western diet.
Earlier studies specific to watermelon, consumed alongside a high-fat diet, in male mice, have reported improved fat metabolism, blood glucose regulation, and lowered inflammation associated with the consumption of this fruit. While there are minimal human studies, results assessing the impact of watermelon intake on factors associated with overweight and obesity are also promising. This may be attributable to the variety of nutrients found in watermelon, including dietary fiber, vitamin C, vitamin E, β-carotene, lycopene, and flavonoids.
The aim of this study was to assess the impact of different watermelon compounds on hepatic gene expression and lipid metabolism. Over a 10-week period, mice were fed either a low-fat diet, high-fat diet (control diet), or a high-fat diet plus either the flesh, rind or skin of the watermelon. RNA sequencing was then performed.
The results demonstrated mice in all three watermelon groups exhibited positively altered hepatic gene expression with upregulation of lipid metabolism pathways alongside downregulated inflammatory and vasoconstriction pathways compared to mice in the high-fat diet control group. The researchers also report that while each part of the watermelon positively impacted hepatic transcription, they delivered differing results and potential mechanisms of action, perhaps as a result of the unique phytochemical composition of each part of the watermelon.
The researchers concluded that mice fed components of watermelon reflective of typical levels of human consumption exhibited positive hepatic gene expression linked to improved lipid metabolism. In addition, it was noted that the study utilized powdered watermelon extracts rather than fresh produce, which may offer the potential for watermelon byproducts to be used as cost-effective components of nutraceuticals in the future. They also postulated that the processing used to create watermelon extracts for the study may have reduced their nutritional value and that the fresh fruit may offer additional or more pronounced benefits.