Lipid profile of mice fed a high‐fat diet supplemented with a wax ester‐rich marine oil

Abstract

Oil extracted from the marine copepod Calanus finmarchicus contains the long chain omega‐3 fatty acids eicosapentaenoic acid and DHA in addition to stearidonic acid (18:4n‐3). Unlike other marine lipids, the fatty acids in this oil are esterified with long chain fatty alcohols as wax esters. The aim of this study was to examine the fate of the wax esters in oil from C. finmarchicus when given as a 2% supplement in a high fat diet to C57BL/6J mice for 11 weeks. The study confirmed that feeding mice a high fat diet supplemented with a small amount of oil containing wax esters reduced the body weight gain. During digestion, wax esters were hydrolyzed and the fatty acids absorbed since the fatty acid composition of the adipose tissue and liver reflected the enrichment with the Calanus oil. The composition of the liver lipids demonstrated elongation and desaturation of the C18 omega‐3 fatty acids from the feed and accumulation of longer chained omega‐3 fatty acids. Elevated levels of FFA and FAOH in the feces suggest that the absorption process, not the hydrolysis, could be a rate limiting step in utilization of small amounts of wax esters included in high fat diets in mice.Practical applications: The limited amount of available fish oil has led to extensive search for alternative sources of long‐chain PUFA. One suggestion is to harvest at lower trophic levels, like small crustaceans, which may be abundantly present in the oceans. In this investigation, we have studied the effects of including the astaxanthin‐rich oil from the marine copepod C. finmarchicus in a high fat diet in mice. This oil is different from other marine oils since most of the fatty acids are esterified to long‐chain fatty alcohols, not in TAG, and that stearidonic acid is the major omega‐3 fatty acid present. The results provide knowledge and understanding of aspects related to digestion and possible physiological effects of including small amounts of marine wax esters in diets.The lipid class composition in the feces from mice fed a high fat diet or a high fat diet supplemented with a wax ester rich oil were similar except for the pronounced amount of fatty alcohols in feces of the latter.