Kappaphycus alvarezii as a Food Supplement Prevents Diet-Induced Metabolic Syndrome in Rats

Abstract

The red seaweed, Kappaphycus alvarezii, was evaluated for its potential to prevent signs of metabolic syndrome through use as a whole food supplement. Major biochemical components of dried Kappaphycus are carrageenan (soluble fiber ~34.6%) and salt (predominantly potassium (K) 20%) with a low overall energy content for whole seaweed. Eight to nine week old male Wistar rats were randomly divided into three groups and fed for 8 weeks on a corn starch diet, a high-carbohydrate, high-fat (H) diet, alone or supplemented with a 5% (w/w) dried and milled Kappaphycus blended into the base diet. H-fed rats showed symptoms of metabolic syndrome including increased body weight, total fat mass, systolic blood pressure, left ventricular collagen deposition, plasma triglycerides, and plasma non-esterified fatty acids along with fatty liver. Relative to these obese rats, Kappaphycus-treated rats showed normalized body weight and adiposity, lower systolic blood pressure, improved heart and liver structure, and lower plasma lipids, even in presence of H diet. Kappaphycus modulated the balance between Firmicutes and Bacteroidetes in the gut, which could serve as the potential mechanism for improved metabolic variables; this was accompanied by no damage to the gut structure. Thus, whole Kappaphycus improved cardiovascular, liver, and metabolic parameters in obese rats.

Keywords: Kappaphycus alvarezii; carrageenan; inflammation; metabolic syndrome; obesity; potassium; red seaweed; salt.

Figure 1

Effects of Kappaphycus on inflammation (top row—“in”) and collagen deposition (middle row—“cd”) in the heart using hematoxylin and eosin stain and picrosirius red stain, respectively, in C rats (A,D), H rats (B,E), and HR rats (C,F). Effects of Kappaphycus on inflammation and fat deposition (bottom row—“fv”) in the liver using hematoxylin and eosin stain in C rats (G), H rats (H), and HR rats (I).

Figure 2

Effects of Kappaphycus on structure and inflammation in ileum (top row) and colon (bottom row) using hematoxylin and eosin stain in C rats (A,D), H rats (B,E), and HR rats (C,F). “in”—inflammation.

Figure 3

Effect of Kappaphycus on gut microbiota diversity profiles. (A) Heat map of bacterial species abundance. Abundance values for each species were plotted as a percentile with the most abundant species represented in bright red, the 50th percentile species represented in purple and the lowest value in pink. (B) The relative abundance of each phylum presented as a percentage of the total population for each treatment group. (C) Shannon diversity index. The index was determined from the means of abundance for each treatment group. (D) Relative abundance of species that were differentially regulated by diet. Only species whose mean abundance for the C diet group was equal to or higher than 1% were plotted in order to enhance confidence. C, corn starch diet-fed rats; H, high-carbohydrate, high-fat diet-fed rats; HR, high-carbohydrate, high-fat diet-fed rats supplemented with dried and milled whole Kappaphycus.