We hypothesize that defatting is an important factor that can determine the beneficial effects of flaxseeds on rats with diet-induced disorders. The experiment lasts 8 weeks and is conducted on Wistar rats allocated to four groups as follows: a control group fed with a standard diet; a high-fat (HF) group fed with a diet containing 21% fat and 0.1% cholic acid as a stimulator of lipid absorption; an HF group fed a diet supplemented with 1% native flaxseeds; and an HF group fed a diet supplemented with 1% defatted flaxseeds. In the HF group, several unfavourable changes in the gut and lipid metabolism are observed. Supplementation of the HF diet with native flaxseeds prevent an increase in colonic β-glucuronidase activity, whereas dietary defatted flaxseeds increase mucosal disaccharidase activities in the small intestine (sucrose, maltase and lactase). Regardless of the form of supplementation, dietary flaxseeds increase bacterial glycolytic activity in the distal intestine and decrease hepatic fat, especially triglyceride, accumulation. Both flaxseed forms decrease lipid peroxidation in the kidneys and increase the blood HDL cholesterol concentration with the native form being more efficient in the former and the defatted form being more efficient in the latter. The lipid-modulating effects of defatted flaxseeds are associated with reduced hepatic expression of peroxisome proliferator-activated receptor α, which is not the case in terms of native flaxseeds. Dietary supplementation with a relatively small amount of flaxseeds can exert beneficial effects on gut functions and lipid metabolism in rats, and these effects are affected by defatting to some extent.

Background There is a tendency to search for new, unconventional plant oils with health-promoting properties, preferably unrefined, which besides having an interesting fatty acid profile contain a high level of biologically active compounds. This review is focused on selected berry seed oils as potential cardioprotective food supplements, that is, strawberry, red raspberry, and blackcurrant seed oil, and their chemical composition and nutritional quality. Main text Berry seed oils are rich in essential fatty acids both from n-6 and n-3 family. The content of polyunsaturated fatty acids in selected oils was reported as follows (as percentage of total fatty acids): red raspberry seed oil, 85% (linoleic acid, 54%; α-linolenic acid, 32%); blackcurrant seed oil, 81.5% (linoleic acid, 48%; α- and γ-linolenic acid, 30%); and strawberry seed oil, 78% (linoleic acid, 42%; α-linolenic acid, 36%). Worthy of notice is also the presence of γ-linolenic acid in blackcurrant seed oil (approximately 17%). In addition, the seed oils are abundant in other bio-active compounds, such as sterols, tocols, and phenolic compounds. Except for blackcurrant seed oil, health-promoting aspects of the proposed seed oils have not been extensively investigated in in vivo studies. But, there are available studies on laboratory rats suggesting cardioprotective properties of these oils. Especially, a potent triglyceride-lowering effect of blackcurrant, strawberry, and raspberry seed oil was visible. The tested berry seed oils also ameliorated the inflammatory state in the organism and the liver fat content. Nevertheless, the consumption of the berry seed oils, especially together with an unbalanced diet, induced also some unfavorable changes in the organism. Conclusion The proposed berry seed oils can be considered edible and potentially cardioprotective supplements; however, there is a need for extensive in vivo researches that could confirm their properties, check the safety of their consumption, and allow to select the most suitable ones.

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