Supplementation with Sea Vegetables Palmaria mollis and Undaria pinnatifida Exerts Metabolic Benefits in Diet-Induced Obesity in Mice

ABSTRACT Background Sea vegetables are rich sources of nutrients as well as bioactive components that are linked to metabolic health improvement. Algal polysaccharides improve satiety and modulate gut microbiota while proteins, peptides, and phenolic fractions exert anti-inflammatory, antioxidant, and antidiabetic effects. Objective We tested the hypothesis that dietary supplementation with either Pacific dulse (Palmaria mollis, red algae) or wakame (Undaria pinnatifida, brown algae) could remediate metabolic complications in high-fat diet-induced obesity. Methods Individually caged C57BL/6J mice (n = 8) were fed ad libitum with either a low-fat diet (LFD), 10% kcal fat; high-fat diet (HFD), 60% kcal fat; HFD + 5% (wt:wt) dulse (HFD + D); or HFD + 5% (wt:wt) wakame (HFD + W) for 8 weeks. Food intake and weight gain were monitored weekly. Glucose tolerance, hepatic lipids, fecal lipids, and plasma markers were evaluated, and the gut microbiome composition was assessed. Results Despite the tendency of higher food and caloric intake than the HFD (P = 0.04) group, the HFD + D group mice did not exhibit higher body weight, indicating lower food and caloric efficiency (P < 0.001). Sea vegetable supplementation reduced plasma monocyte chemotactic protein (MCP-1) (P < 0.001) and increased fecal lipid excretion (P < 0.001). Gut microbiome analysis showed that the HFD + D group had higher alpha-diversity than the HFD or LFD group, whereas beta-diversity analyses indicated that sea vegetable–supplemented HFD-fed mice (HFD + D and HFD + W groups) developed microbiome compositions more similar to those of the LFD-fed mice than those of the HFD-fed mice. Conclusion Sea vegetable supplementation showed protective effects against obesity-associated metabolic complications in C57BL/6J male mice by increasing lipid excretion, reducing systemic inflammatory marker, and mitigating gut microbiome alteration. While the obese phenotype development was not prevented, metabolic issues related to lipid absorption, inflammation, and gut microbial balance were improved, showing therapeutic promise and warranting eventual mechanistic elucidations.

Antiobesogenic Potential of Seaweed Dulse (Palmaria palmata) in High-fat Fed C57BL/6 J Mice (P21-014-19)

Objectives The growing obesity challenge around the world continues to warrant interventions that could mitigate disease onset and progression. This study aimed to evaluate the potential of seaweed supplementation using dulse (Palmaria palmata) and wakame (Undaria pinnatifida), in improving caloric management and insulin resistance, and mitigating inflammation and gut microbiome shifts in diet-induced obesity in C57BL/6 J mice. Methods Twenty-four individually-caged C57BL/6 J mice were fed ad libitum with a high-fat diet (HFD) with and without seaweed inclusion, and another 8 mice for low-fat control (n = 8). Freeze-dried dulse and wakame were incorporated in the test diets at 5% inclusion level. Glucose tolerance test was performed during week 4 to assess insulin resistance state of test animals. After 9 weeks, fresh fecal samples were collected from all 32 mice prior to necropsy. These were used for the gut microbiome analysis using MiSeq. Fecal triglyceride levels were determined using Infinity Triglycerides Kit while plasma Monocyte Chemoattractant Protein-1 (MCP-1) was quantified using ELISA. Results Despite higher feed intake, dulse-fed mice had lower feed efficiency, indicating less weight gain from same amount of diet. This group also showed improved early-phase insulin response compared to HFD and wakame-fed groups. Plasma inflammatory marker MCP-1 levels were also significantly reduced in dulse-fed mice. While liver triglyceride levels were not affected with the dietary inclusion, fecal samples showed that there was higher lipid being excreted in dulse-fed group. This suggests that caloric excess and inflammatory progression may have been mitigated by increased lipid excretion in the feces. Gut microbiome analysis showed that dulse-fed mice retained microflora composition that is comparable to those fed with low-fat diet. Conclusions Our work reveals that dulse supplementation improved obesity and associated metabolic parameters by increasing lipid excretion, improving early-phase insulin response, and mitigating both inflammation and gut microbiome shifts associated with HFD, more effectively than wakame. These provide initial evidences that dietary inclusion of dulse holds therapeutic promise in mitigating diet-induced obesity. Funding Sources Oregon State University Agricultural Research Foundation. Supporting Tables, Images and/or Graphs