Increased bioavailability of hesperetin-7-glucoside compared with hesperidin results in more efficient prevention of bone loss in adult ovariectomised rats

Hesperidin (Hp), a citrus flavonoid predominantly found in oranges, shows bone-sparing effects in ovariectomised (OVX) animals. In human subjects, the bioavailability of Hp can be improved by the removal of the rhamnose group to yield hesperetin-7-glucoside (H-7-glc). The aim of the present work was to test whether H-7-glc was more bioavailable and therefore more effective than Hp in the prevention of bone loss in the OVX rat. Adult 6-month-old female Wistar rats were sham operated or OVX, then pair fed for 90d a casein-based diet supplemented or not with freeze-dried orange juice enriched with Hp or H-7-glc at two dose equivalents of the hesperetin aglycone (0·25 and 0·5%). In the rats fed 0·5%, a reduction in OVX-induced bone loss was observed regarding total bone mineral density (BMD):+7·0% in OVX rats treated with Hp (HpOVX) and +6·6% in OVX rats treated with H-7-glc (H-7-glcOVX) v. OVX controls (P<0·05). In the rats fed 0·25% hesperetin equivalents, the H-7-glcOVX group showed a 6·6% improvement in total femoral BMD v. the OVX controls (P<0·05), whereas the Hp diet had no effect at this dose. The BMD of rats fed 0·25% H-7-glc was equal to that of those given 0·5% Hp, but was not further increased at 0·5% H-7-glc. Plasma hesperetin levels and relative urinary excretion were significantly enhanced in the H-7-glc v. Hp groups, and the metabolite profile showed the absence of eriodictyol metabolites and increased levels of hesperetin sulphates. Taken together, improved bioavailability of H-7-glc may explain the more efficient bone protection of this compoun

Effects of plant food potassium salts (citrate galacturonate or tartrate) on acid–base status and digestive fermentations in rats

Potassium (K) organic anion salts, such as potassium citrate or potassium malate in plant foods, may counteract low-grade metabolic acidosis induced by western diets, but little is known about the effect of other minor plant anions. Effects of K salts (chloride, citrate, galacturonate or tartrate) were thus studied on the mineral balance and digestive fermentations in groups of 6-week-old rats adapted to an acidogenic/5 % inulin diet. In all diet groups, substantial amounts of lactate and succinate were present in the caecum, besides SCFA. SCFA were poorly affected by K salts conditions. The KCl-supplemented diet elicited an accumulation of lactate in the caecum; whereas the lactate caecal pool was low in rats fed the potassium tartrate-supplemented (K TAR) diet. A fraction of tartrate (around 50 %) was recovered in urine of rats fed the K TAR diet. Potassium citrate and potassium galacturonate diets exerted a marked alkalinizing effect on urine pH and promoted a notable citraturia (around 0·5 μmol/24 h). All the K organic anion salts counteracted Ca and Mg hyperexcretion in urine, especially potassium tartrate as to magnesuria. The present findings indicate that K salts of unabsorbed organic anions exert alkalinizing effects when metabolizable in the large intestine, even if K and finally available anions (likely SCFA) are not simultaneously bioavailable. Whether this observation is also relevant for a fraction of SCFA arising from dietary fibre breakdown (which represents the major organic anions absorbed in the digestive tract in man) deserves further investigation

Effect of potassium salts in rats adapted to an acidogenic high-sulfur amino acid diet

Low-grade metabolic acidosis, consecutive to excessive catabolism of sulfur amino acids and a high dietary Na:K ratio, is a common feature of Western food habits. This metabolic alteration may exert various adverse physiological effects, especially on bone, muscle and kidneys. To assess the actual effects of various K salts, a model of the Westernised diet has been developed in rats: slight protein excess (20 % casein); cations provided as non-alkalinising salts; high Na:K ratio. This diet resulted in acidic urine (pH 5·5) together with a high rate of divalent cation excretion in urine, especially Mg. Compared with controls, K supplementation as KCl accentuated Ca excretion, whereas potassium bicarbonate or malate reduced Mg and Ca excretion and alkalinised urine pH (up to 8). In parallel, citraturia was strongly increased, together with 2-ketoglutarate excretion, by potassium bicarbonate or malate in the diet. Basal sulfate excretion, in the range of 1 mmol/d, was slightly enhanced in rats fed the potassium malate diet. The present model of low-grade metabolic acidosis indicates that potassium malate may be as effective as KHCO3 to counteract urine acidification, to limit divalent cation excretion and to ensure high citrate concentration in urine

Contribution of various dietary constituents to the acid base status : Interest of animal models of latent metabolic acidosis

International audienceThe potential role of large intestine Animal models of metabolic acidosis are generally based on drastic treatments and are poorly suitable as models of latent metabolic acidosis (LMA). Specific rodent diets have been evaluated as LMA models, together with their responsiveness to dietary alkalinizing factors. Using this model, the possibility to obtain LMA states with moderate levels of protein intake was identified, pointing to the critical role of anions in the mineral moiety of the diet.fermentations to acid-base control has also been examined with this model

Contribution of various dietary constituents to the acid base status : Interest of animal models of latent metabolic acidosis

Open Access JournalInternational audienceThe potential role of large intestine Animal models of metabolic acidosis are generally based on drastic treatments and are poorly suitable as models of latent metabolic acidosis (LMA). Specific rodent diets have been evaluated as LMA models, together with their responsiveness to dietary alkalinizing factors. Using this model, the possibility to obtain LMA states with moderate levels of protein intake was identified, pointing to the critical role of anions in the mineral moiety of the diet.fermentations to acid-base control has also been examined with this model

Comparison of native or reformulated chicory fructans, or non-purified chicory, on rat cecal fermentation and mineral metabolism

International audienceChicory inulin has been identified as an effective prebiotic to promote active fermentation and lactobacilli proliferation in the large intestine, and to enhance calcium (Ca) digestive absorption and deposition in bones. The aim of this study was to compare, in a growing rat model, the effects on digestive fermentations and mineral metabolism of diets containing 7.5% inulin, using either a purified native inulin ((NAT)Inulin) or a reformulated inulin ((REF)Inulin, based on a combination of short- and long chain fructans) or dehydrated chicory. All the inulin diets elicited a marked enlargement of the cecum and acidification of the cecal contents (P < 0.01) and these diets promoted succinic acid rich fermentation together with substantial amounts of short-chain fatty acids (SCFA), especially butyrate. After 1 month of adaptation, all the inulin diets strongly enhanced Ca absorption compared to controls (P < 0.01), but this effect was no more observed after 3 months of adaptation. Magnesium (Mg) absorption was stimulated by the inulin diets after 1 and 3 months experiment. Bone parameters were significantly affected by the chicory diet (enhanced distal bone mineral density and breaking load) whereas the purified inulin diets were less effective. In conclusion, with the present model, both (NAT)Inulin and (REF)Inulin exerted similar effects as to (1) cecal fermentation and profile of end-products of bacterial metabolism, (2) stimulation of Ca and Mg digestive absorption and (3) overall effects on bone parameters. The particular effects of the chicory crude fractions on digestive fermentation and bone parameters suggest possible synergisms between inulin-type fructans and other nutrients

When nutrition interacts with osteoblast function: Molecular mechanisms of polyphenols

ReviewInternational audienceRecent research has provided insights into dietary components that may optimise bone health and stimulate bone formation. Fruit and vegetable intake, as well as grains and other plant-derived food, have been linked to decreased risk of major chronic diseases including osteoporosis. This effect has been partially attributed to the polyphenols found in these foods. Thus, it has been suggested that these compounds may provide desirable bone health benefits through an action on bone cell metabolism. The present review will focus on how some polyphenols can modulate osteoblast function and reports which cellular signalling pathways are potentially implicated. However, to date, despite numerous investigations, few studies have provided clear evidence that phenolic compounds can act on osteoblasts. Polyphenols cited in the present review seem to be able to modulate the expression of transcription factors such as runt-related transcription factor-2 (Runx2) and Osterix, NF-kappa B and activator protein-1 (AP-1). It appears that polyphenols may act on cellular signalling such as mitogen-activated protein kinase (MAPK), bone morphogenetic protein (BMP), oestrogen receptor and osteoprotegerin/receptor activator of NF-kappa B ligand (OPG/RANKL) and thus may affect osteoblast functions. However, it is also important to take in account the possible interaction of these compounds on osteoclast metabolism to better understand the positive correlation reported between the consumption of fruit and vegetables and bone mass

Dietary restriction alters bone density and femoral biomechanics in aged male rats

International audienc

Dose response of hesperidin, a citrus flavonoid, on bone mass in young intact rats

International audienc