Oral intake of the microalgae Nannochloropsis oceanica, Chlorella vulgaris, or Phaeodactylum tricornutum improves metabolic conditions in hypercaloric-fed mice

• Intake of N. oceanica , C. vulgaris, or P. tircornutum had no adverse effects. • N. oceanica reduced Western-style diet (WSD)-induced excess liver fat. • P. tircornutum and N. oceanica reduced liver damage induced by the WSD. • All microalgae affected gut microbial composition and reduced LPS translocation. Diet-induced metabolic load is associated with excess body weight and liver steatosis. Here, selected microalgae, known to contain bioactive nutrients, were studied for beneficial metabolic effects in a mouse model of liver steatosis. Adult mice (8 per group) were fed either a Western-style diet (WSD) or a control diet +/− 15 % of the microalgae Chlorella vulgaris (CV), Nannochloropsis oceanica (NO), or Phaeodactylum tricornutum (PT) for 12 weeks. We evaluated liver fat content and liver damage, as well as fecal microbiota and lipopolysaccharide (LPS) translocation. NO supplementation to a WSD reduced the grade of liver steatosis (from 17 % to 4.7 %, p < 0.002), the liver damage score (p < 0.001), and LPS translocation (p < 0.001). PT had similar effects on liver damage score (p < 0.001) and LPS translocation (p < 0.001). CV supplementation reduced LPS translocation (p < 0.001). In conclusion, dietary supplementation of microalgae may be a novel sustainable approach to combat metabolic loads.