Bartholomeus Belonje

Manganese content of soy or rice beverages is high in comparison to infant formulas

Objective: Well-meaning but inadequately informed parents may perceive plant-based beverages such as soy beverages (SB) or rice beverages (RB) as an alternative to infant formula. Manganese (Mn) is an essential mineral nutrient found at high levels in plants such as soy and rice. Excessive Mn exposure increases the risk of adverse neurological effects. Methods: We analysed, by atomic absorption spectrometry, the Mn content of 36 SB, 5 RB, 6 evaporated milks (EM), 14 soy-based infant formulas (SF) and 16 milk-based infant formulas (MF), obtained from commercial outlets in Ottawa, Canada. Results: SB had the highest levels of Mn (16.5 ± 8.6 μg/g dry wt, mean ± s.d.), followed by RB (9.9 ± 1.7 μg/g dry wt). Mn levels of individual SB/RB ranged from 2 to 17 times the mean Mn content of SF (2.4 ± 0.7 μg/g dry wt) and 7 to 56 times that of MF (0.70 ± 0.35 μg/g dry wt). EM contained very little Mn (0.02 ± 0.03 μg/g dry wt). Calculated mean Mn intakes from SB/RB by infants up to 6 months of age, assuming complete substitution of these products (0.78 L/day), approached the Tolerable Upper Intake Level (UL) for 1–3 year olds (no UL for Mn is available for infants under 1 year of age). Expressed as μg Mn/100 kcal, SB/RB exceeded the range derived from ULs and typical energy intakes of 1–3 year olds. Conclusions: SB/RB should not be fed to infants because they are nutritionally inadequate and contain Mn at levels which may present an increased risk of adverse neurological effects if used as a sole source of nutrition.

Elemental composition of anatomically distinct regions of rat liver.

Experiments were conducted to test the commonly held assumption that analysis of a portion of rat liver is representative of the elemental concentration of the whole organ. Male Sprague-Dawley rats (initial body weight approximately 250 g) fed a chow diet or weanling male Long-Evans rats (initial body weight approximately 50 g) fed a semipurified diet with or without copper in the mineral premix were sacrificed after 4 wk on their respective diets and livers were dissected into seven portions representing major anatomical divisions of this organ. Elemental analyses by atomic absorption spectroscopy (calcium, magnesium, iron, zinc, copper, manganese), atomic emission spectroscopy (sodium, potassium), or colorimetric assay (phosphorus) demonstrated no statistically significant differences in composition of these nine elements among anatomical regions of liver. Dietary copper deficiency led to equivalently reduced copper concentration in all portions of rat liver and did not cause any other significant alterations in liver composition of these nine elements within the 4 wk of these studies. These results confirm the validity of the common assumption that analysis of a portion of rat liver can be representative of the elemental composition of the whole organ. This conclusion will allow more analyses to be performed on fewer animals, thereby reducing animal use and reagent costs without sacrificing analytical accuracy.

Prevention of nephrocal cinosis in male and female rats by providing fluoride and additional magnesium in the diet

Nephrocalcinosis (NC) was observed in young Charles River (CD) Sprague Dawley rats fed for six weeks a purified diet containing 20% protein from casein and 3% Bernhart-Tomarelli (11) or 3.5% AIN-76 (12) salt mixtures, but not in rats fed a stock diet which contained 0.54% Cl, 0.27% Mg and 40 mg/kg F. Females were more susceptible than males. The addition of 50 mg fluoride (as sodium fluoride) per kg prevented NC in all the males (kidney Ca, mg/g dry weight: median, 0.40; range, 0.30–0.46) but not in all the females (0.49, 0.25–1.86), the corresponding figures for stock diet fed rats being: male; 0.26, 0.25–0.28; female; 0.34, 0.28–0.58. Doubling the level of fluoride did not reduce NC further. Increasing the dietary level of chloride to 0.54% (equal to that in the stock diet) in the presence of 50 mg/kg fluoride resulted in kidney calcium levels which were not significantly different from those in female rats fed fluoride alone. Nephrocalcinosis was prevented in both males and females when the diet contained levels of chloride and magnesium equal to those in the stock diet and 50 mg/kg fluoride, irrespective of whether Bernhart-Tomarelli or AIN-76 salt mixture was added to the diet. Magnesium added at 0.27% level with 50 mg/kg fluoride also was equally effective in preventing kidney calcification. Any dietary change did not have any significant effect on liver or heart calcium level.

Lead concentration in the livers of Canadians

SummaryLiver specimens were collected at 114 (83 males and 31 females) autopsies on accident victims and on 4 stillborn infants in seven Canadian Cities. The age of the individuals ranged from newborn to 89 years with about 70% being 19–65 years. The level of lead in the samples was determined by atomic absorption spectroscopy using a carbon rod atomizer. The concentration of lead in liver was low (μg/g: Mean, 0.37, Median 0.28) at birth and during infancy. In the stillborn infants it ranged from 0.30 to 0.77 (Mean 0.51). Male adults had an average level of 1.78 (Median 1.41) whereas in adult females the corresponding values were 0.65 and 0.57. The liver lead concentration peaked at about the end of the fourth decade in adult males. There was no indication of any regional differences.