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Many investigators have reported changes in mineral status with age but conflicting observations were done concerning mineral absorption. This study was conducted to clarify the effect of aging on intestinal absorption and status of minerals, using a stable isotope approach. To do so, 40 rats of different ages: 9, 22, 44, and 88 weeks were fed with a semi-purified diet for a total of 30 days. At the beginning of the 4th week, the rats received a stable isotope solution containing (44)Ca, (25)Mg, (67)Zn, and (65)Cu. Individual feces and urine were then collected during 4 consecutive days in order to measure stable isotopes by inductively coupled plasma/mass spectrometry (ICP/MS) and blood and tissues were sampled for mineral status determination. Intestinal absorption of (44)Ca and (67)Zn considerably decreased with age, whereas intestinal (25)Mg absorption decreased only moderately and intestinal (65)Cu absorption was unaffected. Plasma and bone calcium (Ca) were not modified with age whereas urinary Ca excretion considerably increased. Plasma and erythrocyte magnesium (Mg) levels were unaffected with age whereas urinary Mg excretion and Mg bone level decreased. Plasma zinc (Zn) level decreased and bone Zn level increased with age whereas red blood cell and liver Zn level and urinary Zn excretion remained unchanged. Plasma Cu level increased with age whereas liver and bone Cu levels and urinary Cu excretion remained unchanged. These results show that the effect of aging on the intestinal mineral absorption and status differ largely according to the mineral considered. Further studies are required under different nutritional conditions to explore the underlying mechanisms during aging and to adjust a better nutrition of the elderly.

Background: Inulin-type fructans or chains with mainly beta[2-1] linked fructose molecules escape the ingestion procedure in the small intestine and are fermented by the microflora, and are known to increase colonic absorption of minerals in animals. The fermentation rate in the large bowel into short-chain fatty acids depends on the molecular mass and the structure of these food ingredients. It is thought that this colonic fermentation is the basis for the reported increase in mineral absorption., Aim of the Study: The purpose of the present study was twofold: a) to compare different types of fructans that differ in the sugar chain length and in chain branching; b) to determine the potential synergistic effect of a combination of inulin-type fructans with different chain lengths., Methods: For this purpose, 50 adult male Wistar rats weighing 170 g each were used in this study. The rats were distributed into 5 groups and fed for 28 days a fiber-free basal purified diet or diet containing 10 % oligofructose (OF) (DP(av) 4), or 10 % HP-inulin (DP(av) 25), a blend of 50 % OF and 50 % HP-inulin, or a branched-chain inulin., Results: During the first period, the rats went into a gradual adaptation, during which the rats received 2.5 % for 1 week and then 5 % for 1 week of the tested products. During the last 4 days of the experiment, feces and urine were monitored for mineral balance study. The animals were then sacrificed and blood, cecum and tibia were sampled for mineral status assessment. Our results showed that the ingestion of all the tested fructans led to a considerable cecal fermentation. All tested compounds increased the intestinal absorption and balance of Mg significantly. Interestingly, in the present experimental set-up, all tested compounds increased the intestinal absorption and balance of Ca numerically, but only the blend OF + HP-inulin increased apparent intestinal absorption and balance of Ca significantly., Conclusions: The different types of fructans studied in the present experiment seem to have similar activity on mineral absorption. However, the combination of OF and HP-inulin showed synergistic effects on intestinal Ca absorption and balance in rats. Further studies with other combinations of fructans need to be done to extend these findings.

Background: Previous studies indicated that dietary Mg-deficiency in rats results in a marked pro-inflammatory effect. Since magnesium (Mg) frequently acts as a natural calcium (Ca) antagonist, the possibility exists that the pro-inflammatory effect of Mg-deficiency may be a consequence of a reduced extracellular Mg(2+)/Ca(2+) antagonism., Aim of the Study: Thus, the aim of the study was to assess whether dietary Ca-deficiency improves the abnormal inflammatory response of Mg-deficient rats., Materials and Methods: Weaning male Wistar rats were randomly divided into 4 groups according to the dietary Mg and Ca as follows: Mg-adequate Ca-adequate (control), Mg-adequate Ca-deficient, Mg-deficient Ca-adequate, Mg-deficient Ca-deficient. Animals were fed the appropriate diets for 8 days., Results: Mg-deficient Ca-adequate rats as compared to controls displayed the usual decrease in plasma Mg, whereas the plasma Ca concentration was unaffected. The classical symptoms of inflammation including hyperemia, increased number of blood leukocytes and increased spleen weight were observed. In addition, these animals also showed an increase in heart lipid peroxidation and in plasma triglyceride concentration. In Mg-deficient rats, Ca-deficiency induced hypocalcemia and offered a significant protection against the pro-inflammatory effect of Mg-deficiency. This was evidenced by lower inflammation scores, prevention of leukocytosis and of spleen enlargement. The protective effects of Ca-deficiency on the inflammatory response in Mg-deficiency was accompanied by significant reduction in lipid peroxidation and by a normalization of plasma triglyceride concentration., Conclusion: All together, the results suggest that Ca is implicated in the inflammatory response of experimental Mg-deficiency and that oxidative stress and hypertriglyceridemia are the results of the acute phase response following Mg-deficiency in rats.

Weanling Wistar rats were pair-fed for 9 days a control or a calcium-deficient diet. After a 12-hour fast the rats were injected intraperitoneally with glucose (250 mg/100 g body weight), and blood was collected 15, 30 and 60 minutes after the injection. Before injection, calcium (9.7 +/- 0.2 mg/100 ml), glucose and insulin plasma levels were identical in the control and deficient animals, although calcium-deficient animals showed a small but significant increase in blood plasma magnesium levels. Blood glucose levels were higher in the calcium-deficient rats than in control rats 15 to 30 minutes after the glucose injection (15.4 +/- 1.4 vs. 9.7 +/- 0.4 mM, P less than 0.01, 30 minutes after). Plasma insulin levels were significantly lower 15 minutes after the glucose injection (24 +/- 4 vs. 73 +/- 8 microU/ml; P less than 0.01). Calcium deficiency is therefore associated with a decreased response to the glucose tolerance test in the absence of any change in the blood plasma calcium levels.

Abstract Background previous studies have shown that non-digestible inulin-type fructan intake can increase intestinal mineral absorption in both humans and animals. However, this stimulatory effect on intestinal absorption may depend on experimental conditions such as duration of fermentable fiber intake, mineral diet levels and animals' physiological status, in particular their age. Objectives the aim of this study was to determine the effect of inulin intake on Ca and Mg absorption in rats at different age stages. Methods eighty male Wistar rats of four different ages (2, 5, 10 and 20 months) were randomized into either a control group or a group receiving 3.75% inulin in their diet for 4 days and then 7.5% inulin for three weeks. The animals were fed fresh food and water ad libitum for the duration of the experiment. Intestinal absorption of Ca and Mg was determined by fecal monitoring using stable isotopic tracers. Ca and Mg status was also assessed. Results absorption of Ca and Mg was significantly lower in the aged rats (10 and 20 mo) than in the young and adult rat groups. As expected, inulin intake increased Ca and Mg absorption in all four rat groups. However, inulin had a numerically greater effect on Ca absorption in aged rats than in younger rats whereas its effect on Mg absorption remained similar across all four rat age groups. Conclusion the extent of the stimulatory effect of inulin on absorption of Ca may differ according to animal ages. Further studies are required to explore this effect over longer inulin intake periods, and to confirm these results in humans.