Effects of Omega-3-Rich Pork Lard on Serum Lipid Profile and Gut Microbiome in C57BL/6NJ Mice

Abstract

Background and aims: Hyperlipidemia is a risk factor for cardiovascular diseases. This study is aimed at investigating the effects of consuming omega-3-rich pork lard on the serum lipid profile and gut microbiome of the mice model.

Methods and results: We divided 23 C57BL/6NJ males (16-week-old) into 3 groups, and each group received either a control diet, a high-fat diet of coconut oil (coconut oil), or a high-fat diet of omega-3-rich pork lard (omega lard) for 28 days. Thereafter, fasting serum lipids and fecal microbiomes were analyzed. The serum cholesterol, triglyceride, and LDL levels of the omega lard-treated group were significantly reduced compared to the coconut oil-treated group (P < 0.05). However, the microbiome analysis revealed a significant increase in the abundance of Lachnospiraceae in the omega lard-treated group compared to the coconut oil-treated group (P < 0.05). Furthermore, Spearman's correlation analysis revealed that the increased serum lipid content was positively correlated with the abundance of Bacteroidaceae (P < 0.05) and negatively correlated with the abundance of Lachnospiraceae (P < 0.05).

Conclusions: These findings suggested that omega-3-rich pork lard altered the serum lipid profile and gut microbiome in the mice model. Practical Application. The excellent protection offered by omega-3-rich pork lard against hyperlipidemia indicated that pork lard could be used as alternative cooking oil for health-conscious individuals. It could also be introduced as a functional ingredient for patients with hyperlipidemia.

Figure 1

Differences in body weight, dietary intake, and organ weight. The differences in body weight (a), change in body weight (b), accumulated dietary intake(c), accumulated calorie intake (d), relative liver weight (e), and relative visceral fat weight (f) of all groups are shown. Control, coconut oil, and omega lard refer to the control, coconut oil-fed, and omega lard-fed groups, respectively. Body weight and change in body weight were estimated at the end of the experiment (four weeks). The accumulated dietary and calorie intakes were estimated daily. Liver and visceral fat tissues were harvested at the end of the experiment, and their weights were measured relative to the body weight of the mice. The number of mice was 8, 7, and 8 in the control, coconut oil-fed, and omega lard-fed groups, respectively. Data are presented as mean ± SEM. Uppercase letters and asterisk indicate significant differences between groups (P < 0.05).

Figure 2

Differences in serum lipid profile and liver and kidney function enzymes. The differences in the levels of glucose, cholesterol, triglycerides, LDL, HDL, BUN, creatinine, ALT, and AST are shown. Control, coconut oil, and omega lard refer to the control, coconut oil-fed, and omega lard-fed groups, respectively. All parameters were analyzed using serum samples collected at the end of the experiment (four weeks). Data are presented as mean ± SEM. The number of mice was 8, 7, and 8 in the control, coconut oil-fed, and omega lard-fed groups, respectively. The serum level of each parameter is shown on the y-axis and the groups are indicated on the x-axis. Asterisks indicate significant differences between groups (P < 0.05).

Figure 3

Hepatic macrovesicular steatosis. The histopathological staining of liver tissues showing hepatic macrovesicular steatosis in the control group at 10x (a) and 40x (b), coconut oil-fed group at 10x (c) and 40x (d), omega lard-fed group at 10x (e) and 40x (f) and the hepatic macrovesicular steatosis scores (g). Increased incidences of hepatic macrovesicular steatosis were observed in both the coconut oil- and omega lard-fed groups compared to the control group. The hepatic macrovesicular steatosis scores were consistent, showing a slightly increased incidence of steatosis in both the coconut oil- and omega lard-fed groups. No significant difference between the coconut oil- and omega lard-fed groups was observed (chi-square test, P < 0.05). The number of mice is presented on the y-axis and the severity of hepatic macrovesicular steatosis on the x-axis. Liver tissues were harvested from all animals at the end of the experiment (four weeks). The number of animals was 8, 7, and 8 in the control, coconut oil-fed, and omega lard-fed groups, respectively.

Figure 4

Microbiota analysis. Principal component analysis (PCA) of the fecal microbiome (a) is shown. Control, coconut oil, and omega lard represent the control, coconut oil-fed, and omega lard-fed groups, respectively. All feces samples were collected at the end of the experiment (four weeks). The number of animals was 8, 7, and 8 in the control, coconut oil-fed, and omega lard-fed groups, respectively. The PCA of the fecal microbiome was performed using Bray–Curtis measurements. The control, coconut oil-fed, and omega lard-fed groups are represented by red, blue, and yellow circles, respectively. The relative abundance of bacterial families in the fecal microbiome (b) is shown, where each bacterial family is indicated by a different color. The comparison of the relative abundance of bacterial families in the fecal microbiome between the groups is shown for Lachnospiraceae, Bacteroidaceae, Peptococcaceae, and Burkholderiaceae (c). The abundance (%) of the bacterial population is indicated on the y-axis and the groups on the x-axis. Data are presented as mean ± SEM. Asterisks indicate significant differences between groups (P < 0.05).

Figure 5

Correlation between microbiome and serum lipid content. Spearman's correlations between fecal microbiome and levels of different serum lipids are shown. ^∗ indicates P < 0.05 and ^∗∗ indicates P < 0.01.