Influence of dietary protein type and iron source on the absorption of amino acids and minerals

Urinary concentrations of mineral elements and their predictors in pregnant women in Jinan, China

BACKGROUND

The essential mineral elements play important roles in proper growth, development and maintenance of physiological homeostasis of an organism. Women are at greater risk of mineral deficiency during pregnancy. However, the predictors of mineral element levels in pregnant women remain unclear. This study was conducted to determine the urinary levels of calcium (Ca), iron (Fe), copper (Cu), manganese (Mn) and selenium (Se) in women during early pregnancy and to explore the predictors of urinary exposure to each mineral element and high co-exposure to mineral element mixture.

METHODS

298 pregnant women in first trimester were recruited when they attended antenatal care in a hospital in Jinan, Shandong Province, China. We collected their spot urine samples and questionnaire data on their sociodemographic characteristics, lifestyle habits, food and dietary supplement intake, and residential environment. The concentrations of Ca, Fe, Cu, Mn and Se in all urine samples were measured. LASSO regression, multiple linear regression and binary logistic regression were used to analyze the predictors affecting mineral element levels.

RESULTS

The geometric means of creatinine-corrected Ca, Fe, Cu, Mn and Se concentrations were 99.37 mg/g, 1.75 µg/g, 8.97 µg/g, 0.16 µg/g and 16.83 µg/g creatinine, respectively. Factors that influenced the concentrations of individual mineral element were as follows: (1) Se and Ca concentrations increased with maternal age; (2) women taking tap water as family drinking water had higher Ca levels and those taking polyunsaturated fatty acids intermittently had higher Cu levels; (3) Fe was adversely related to consumption frequency of barbecued foods; (4) Pregnant women with more frequent consumption of shellfish/shrimp/crab and living near green spaces or parks had higher Mn exposure, and those with higher frequency of meat consumption had lower Mn exposure. In addition, maternal age and the frequency of egg consumption were associated with odds of exposure to a mixture of high Ca, Fe, Cu and Se.

CONCLUSIONS

The pregnant women in this study had comparable concentrations of urinary Cu and Se but lower concentrations of Ca, Fe and Mn compared with those in other areas. Predictors of urinary mineral elements included maternal age (Se and Ca), type of domestic drinking water (Ca), consumption frequency of barbecued food (Fe), polyunsaturated fatty acid use (Cu), the presence of urban green spaces or parks near the home and frequency of meat and shellfish/shrimp/crab intake (Mn). Moreover, maternal age and egg consumption frequency were significant predictors of high-level co-exposure to urinary Ca, Fe, Cu and Se.

Basal diet and indigestible marker influence apparent digestibilities of nitrogen and amino acids of cottonseed meal and soybean meal in pigs

This study was to determine the apparent ileal nitrogen (N) and amino acid digestibilities of cottonseed meal (CSM) and soybean meal (SBM) in simple carbohydrate-based and more complex wheat-based diets. Twenty five Large White × Landrace boars (40.9 kg) were randomly allocated to one of 5 dietary treatments: a wheat diet, 40% CSM in either a sugar:starch (1:1) or wheat-based diet, or 40% SBM in either a sugar:starch or wheat-based diet for 14 d. All diets contained vitamins, minerals, and contained acid-insoluble ash (AIA) and Cr2O3 as indigestible markers. Rations were offered (1,800 g/pig per d) in 3 meals/d on d 1 - 11 and 8 meals/d on d 12 - 13. On d 14, the pigs were fed hourly for 8 h. After the 8th meal, pigs were anaesthetised with isoflurothane, and ileal and faecal digesta sampled from the terminal ileum and rectum before lethal injection of barbiturate. Apparent ileal digestibility (AID) of N was greater (12.1%) when CSM was fed in the wheat-based diet as compared to the simple carbohydrate-based diet, whereas apparent ileal N digestibility of SBM was slightly lower (-4.5%) in the wheat-based diet as compared to the sugar:starch-based diet. Apparent ileal amino acid digestibility generally respondeds similarly to N. Therefore, while there was a wide difference in apparent N and amino acid digestibilities of SBM and CSM when they were fed in the sugar:starch-based diets, these differences were less apparent when they were fed the wheat-based diet. There was an apparent net release of N into the hindgut of pigs fed CSM in both base diets. Conversely, there was quite substantial apparent digestion of N in the hindgut of pigs fed SBM in both base diets. The use of Cr2O3 as an indigestible marker resulted in lower apparent ileal and faecal digestibilities than using AIA, particularly for diets containing CSM. These data demonstrate that the basal diet and choice of indigestible marker can substantially influence the estimate of apparent N digestibility, this response can differ for different protein meals.

Study of Nutritive Utilization of Protein and Magnesium in Rats with Resection of the Distal Small Intestine. Beneficial Effect of Goat Milk

The search for diets to improve the nutritive utilization of protein and magnesium in malabsorption syndrome led us to study goat milk, because of its particular nutritional characteristics, and to compare it with cow milk, which is most commonly consumed. We studied the nutritive utilization of protein and magnesium in transected rats (control) and in rats with resection of 50% of the distal small intestine. The diets used were the standard diet recommended by the American Institute of Nutrition and diets based on lyophilized goat or cow milk. The consumption of goat milk produces better protein efficiency ratio and food conversion efficiency values, particularly in rats with intestinal resection, together with a higher nutritive utilization of protein. Magnesium apparent digestibility coefficient is not modified by intestinal resection in rats fed with goat milk-based diet, on the contrary to the standard and cow milk diets. Magnesium apparent digestibility coefficient is greater for the goat milk group, which is reflected in the greater quantity of this mineral stored in bone. These results demonstrate the beneficial effect of goat milk on the nutritive utilization of protein and on magnesium bioavailability, especially in animals with resection of the distal small intestine.