This study compared the effects of supplementation with a polyphenol-rich pomace from strawberry (US) and a strawberry pomace without most of these compounds (PS) on gastrointestinal, blood, and tissue biomarkers in rats fed diets differing in carbohydrate contents for 4 wk. The diets were: corn starch (group CS), high fructose (60% by weight; group F), starch with 7.7% of either US or PS (groups CS+US and CS+PS, respectively), and high fructose with 7.7% of either US or PS (groups F+US and F+PS, respectively). An interaction (P < 0.05) was observed between diet type and strawberry preparation, showing that upon fructose feeding, US had a greater effect than PS on lowering serum insulin, liver total cholesterol, and conjugated dienes. Additionally, the F+US group had lower serum FFA than the F+PS group (P < 0.05). The extraction of polyphenols diminished the physiological effect associated with strawberry intake, suggesting that the fiber component of the pomace was also active in reducing metabolic complications following fructose feeding to rats.

The objective of the study was to compare the effects of experimentally induced type 1 or type 2 diabetes (T1D or T2D) on the functional, structural and biochemical properties of mouse peripheral nerves. Eight-week-old C57BL/6 mice were randomly assigned into three groups, including the control (CTRL, chow-fed), STZ (streptozotocin (STZ)-injected), and HFD (high-fat diet (HFD)-fed) group. After 18-weeks of experimental treatment, HFD mice had higher body weights and elevated levels of plasma lipids, while STZ mice developed hyperglycemia. STZ-treated mice, after an extended period of untreated diabetes, developed motor and sensory nerve conduction-velocity deficits. Moreover, relative to control fibers, pre- and diabetic axons were lower in number and irregular in shape. Animals from both treatment groups manifested a pronounced overexpression of nNOS and a reduced expression of SOD1 proteins in the sciatic nerve, indicating oxidative–nitrosative stress and ineffective antioxidant protection in the peripheral nervous system of these mice. Collectively, STZ- and HFD-treated mice revealed similar characteristics of peripheral nerve damage, including a number of morphological and electrophysiological pathologies in the sciatic nerve. While hyperglycemia is a large component of diabetic neuropathy pathogenesis, the non-hyperglycemic effects of diabetes, including dyslipidemia, may also be of importance in the development of this condition.

The present 4-week study on growing Wistar rats was aimed at assessing the potential advantages of dietary supplementation with apple pomace containing both fibre and polyphenols, which enables nutritional exploitation of the physiological traits of both compounds. A total of twenty-four rats, assigned to the control (C), group fed with a diet supplemented with 14 % of processed apple pomace (A) and group fed with a diet supplemented with 15 % unprocessed apple pomace (AP) groups, were fed the following iso-fibrous diets: control, ethanol-extracted and unprocessed apple pomaces (low and high level of dietary polyphenols, i.e. 0·002 and 0·018 %, respectively). To measure the animal response, parameters describing the caecal fermentation, antioxidative status and lipoprotein profile of rats were assessed. Both dietary apple pomaces were found to significantly (P# 0·05) decrease caecal pH and ammonia concentration, microbial b-glucuronidase activity as well as to increase caecal SCFA concentration in comparison to the control diet. The unprocessed pomace did not suppress caecal fermentation. Unlike the extracted one, the dietary apple pomace rich in polyphenols significantly (P#0·05 v. C group) increased erythrocyte superoxide dismutase activity and serum antioxidant capacity of lipid-soluble substances and significantly (P#0·05 v. C group) decreased amounts of thiobarbituric acid-reactive substances in liver tissue. Moreover, the 4-week administration of the AP diet to rats evoked a significant decrease in serum glucose concentration (P# 0·05 v. C and A groups).In conclusion, the results demonstrated that the polyphenol-rich fibre complexes from apple pomace exerted positive effects on gastrointestinal physiology and antioxidant status of rats.