Diet supplementation with the macroalgae Laurencia glandulifera and Dictyopteris membranacea limits postprandial hyperglycemia and alters intestinal microbiome in mice.

BACKGROUND: Development of obesity and type 2 diabetes largely depends on dietary habits that concomitantly affect the gut microbiome resulting in dysbiosis. Several dietary supplements have been suggested to suppress development of diabetes, partly via changes in the gut microbiome. Earlier research has shown that secondary metabolites from the marine algae Laurencia glandulifera and Dictyopteris membranacea, possess anti-inflammatory properties suppressing intestinal inflammation in vivo. Since these algae are part of the local community diet, we aimed to investigate their potential use as dietary supplements with beneficial effect in preventing early obesity and development of glucose intolerance. Their impact in modulating the gut microbiome was also evaluated, being readily affected by diet. METHODS: We utilized the mouse model of diet-induced type 2 hyperglycemia applying a 4-week early obesity protocol, supplementing animal feed with dried mass of the marine algae Laurencia glandulifera and Dictyopteris membranacea. Intestinal microbiome changes were assessed using 16S sequencing, inflammatory profile was examined by measuring cytokine, chemokine and adipokine in serum and adipose tissue, whereas glucose intolerance was verified by glucose tolerance test. RESULTS: Dietary supplementation with either of the two algae limited postprandial hyperglycemic spikes and induced colonization of distinct microbiota, partially reversing some of the changes induced by high fat diet, including reducing colonization of Helicobacter and promoting colonization of beneficial species Dubosiella and Akkermansia. In addition, both algae significantly reduced expression of the proinflammatory cytokines IL-6, IL-12 and chemokines cxcl1 and cxcl2 in the adipose tissue. L. glandulifera reduced weight gain of mice during the early stages of the model, whereas D. membranacea did not, although mice from both groups exhibited reduced leptin expression. CONCLUSION: These findings suggest that dietary supplementation with L. glandulifera or D. membranacea promotes beneficial changes in the gut microbiome and suppresses metabolic inflammation and postprandial hyperglycemia at the early stages of obesity, paving the way to further elucidate the underlying mechanism.