Excretion of volatile nitrosamines in a rural population in relation to food and drinking water consumption.

Urinary excretion of volatile nitrosamines was assessed in 59 non-smokers living in a rural county of Québec, Canada. Water and food intakes were measured by means of a 24-hour recall. Nitrates were analyzed in the tap water of all participants (geometric mean=2.0 mg nitrate-N/L) and dietary intakes of nitrate and vitamins C and E were estimated via a validated Canadian food database. Urine was collected over the same 24-hour period and analyzed for nitrates by hydrazine reduction and for volatile nitrosamines by gas-chromatography/mass spectrometry. N-Nitrosopiperidine (NPIP) was found in urine samples from 52 of the 59 subjects. Geometric mean of NPIP urinary excretion was 67 ng/day and maximum value was 1045 ng/day. No other volatile nitrosamine was detected. There was a correlation between urinary nitrate excretion and total nitrate intake (r=0.71, P < 0.001). However, no relationship was found between urinary NPIP excretion and either nitrate excretion, dietary or water nitrate intakes. NPIP excretion was significantly correlated to coffee intake (r=0.40, P=0.002) and this relation was not modified by vitamin intake. We conclude that nitrate intake is not related to nitrosamine excretion in this rural population. The influence of coffee consumption on NPIP excretion deserves further attention.

Sources of nitrate exposure in residents of rural areas in Quebec, Canada.

Nitrate exposure was investigated in a group of 187 people using well water and living in four areas of rural Quebec (Canada) with intensive agricultural activities. Nitrate intake was evaluated using a 24-h dietary recall and a food frequency questionnaire, in conjunction with a validated food database and measurements of nitrate concentrations in private wells. The total internal dose was estimated by means of the 24-h urinary nitrate excretion, while taking into account risk factors for endogenous nitrate formation. Mean (geometric) 24-h urinary nitrate excretion was 16.9 mg N for the 100 people with low groundwater contamination (mean nitrate concentration=0.18 mg N/l) and 23.3 mg N in the 87 individuals with moderate groundwater contamination (mean nitrate concentration=7.1 mg N/l). A multivariate analysis revealed that dietary nitrate intake during the last 24 h was the principal source of exposure, followed by water intake during the last 24 h. The Quetelet index was also a significant predictor of urinary excretion. The total predictive model explained only 29% of the variability in urinary nitrate excretion (R2=0.286). Neither the inflammatory status as indicated by elevated C reactive protein, the presence of Helicobacter pylori antibodies nor the occurrence of diarrhea during the last 24 h prior to urine collection were associated with urinary nitrate excretion. In conclusion, food and to a lesser extent water contribute to nitrate exposure in this rural setting with moderate water contamination. Better predictors of endogenous nitrate production are needed to improve our ability to model nitrate body burden and estimate associated health risks.

Binding capacity of various fibre to pesticide residues under simulated gastrointestinal conditions.

The purpose of this study was to compare the effect of the nature and quantity of various dietary fibre (cellulose, hemicellulose, pectin, lignin) in diets on the binding capacity to pesticides azinphos-methyl (AZM), chlorpropham (CLP), chlorothalonil (CKL), permethrin (PER) as estimated by solubility under conditions of pH and temperature simulating those in the gastrointestinal tract (incubated at pH 2 for 30 min at 37 degrees C, then at pH 7 for 60 min). The ratios of fibre to pesticides were determined in omnivorous diets. In this model, the binding capacity of lignin was equal to hemicellulose for PER, AZM and CLP, but it was significantly higher for CKL. Hemicellulose bound more CKL, AZM and CLP than did cellulose. Although pectin appreciably decreased all pesticides, its effect was lower than other fibres with one exception--cellulose-CKL. In the presence of equal amounts of fibre, lignin exerted the most significant effect on pesticide solubility. Hemicellulose and cellulose bind to the same extent PER and AZM. The effect of pectin was significant only on CKL and AZM when compared to the control.

Influence of inhaled corticosteroids and dietary intake on bone density and metabolism in patients with moderate to severe asthma.

OBJECTIVES: Compare the effect of high doses of inhaled corticosteroids on bone loss in subjects with moderate to severe asthma or mild asthma, and examine the influence of dietary intake on bone metabolism. DESIGN: A survey on the effects of corticotherapy and nutrition on bone density was conducted in 74 subjects currently being treated for asthma in the asthma clinic of Hôpital Laval (Sainte-Foy, Quebec, Canada). Fifty-eight subjects completed the study (attrition rate = 15%). MAIN OUTCOME MEASURES: In all subjects expiratory volumes were determined and urinary analysis was conducted for hydroxyproline, calcium, phosphorus, and cortisol levels. Osteocalcin, calcium, phosphorus, cortisol, alkaline phosphatase, and gamma-glutamyltransferase levels were measured in blood samples. Bone density of the lumbar spine was determined by means of dual-energy x-ray absorptiometry. Nutrition evaluation was based on a 3-day food diary analyzed using progiciel Nutri 91. The nutritional parameters examined were calcium; phosphorus; magnesium; zinc; vitamins A, C, and D; protein; total fiber; oxalates; energy; caffeine; and alcohol in relation to bone density. SUBJECTS: Thirty-one patients with moderate to severe asthma who had been taking more than 1,000 micrograms beclomethasone per day or the equivalent for more than 2 years and 27 patients with mild asthma who were taking less than 500 micrograms beclomethasone per day or the equivalent. STATISTICAL ANALYSES PERFORMED: Four-factor analysis of variance with hierarchized interactions of four levels, Duncan's test, Pearson correlation coefficients. RESULTS: Blood levels of osteocalcin and protein intake were lower in patients with moderate to severe asthma than in those with mild asthma (P < .05). Significant correlations (P < .02) were observed between bone density and calcium intake (r = .40), phosphorus intake (r = .35), protein intake (r = .30), and serum alkaline phosphatase level (r = -.30). Bone density was not significantly different between the two groups of patients with asthma. APPLICATIONS: A follow-up of patients with asthma who are taking inhaled corticosteroids is needed to assess bone density, osteocalcin levels, and dietary intakes of calcium. Verify if osteocalcin level decreases over time in patients with moderate to severe asthma, monitor possible modifications in bone density, and verify if the correlation between dietary calcium and bone density is maintained.

The hypercholesterolemic effect of cod protein is reduced in the presence of high dietary calcium.

To determine the respective and interactive effects of dietary protein source and calcium level on serum, hepatic, and fecal lipid levels, 48 male New Zealand rabbits were fed purified diets varying in the source of dietary protein, namely casein, cod protein, or soy protein, at an adequate (7 mg Ca/g diet) or a high (14 mg Ca/g diet) concentration of calcium in a 3 x 2 factorial design for 28 days. Dietary proteins interacted with dietary calcium to modulate serum and low density lipoprotein (LDL) cholesterol. When combined with the adequate-calcium diet, code protein induced higher levels of serum and LDL cholesterol than casein and soy protein, induced lower serum and LDL cholesterol than when associated with an adequate concentration of calcium. These results indicate that the hypercholesterolemic effect of cod protein is reduced in the presence of high dietary calcium. Moreover, fecal lipid content was inversely correlated with serum total (p = 0.06) and LDL (p = 0.04) cholesterol in rabbits fed cod protein diets only. An increased formation of insoluble calcium phosphate in the intestine, which may result in lower fat intestinal absorption and serum cholesterol levels, may have been responsible for the decrease in serum and LDL cholesterol in rabbits fed cod protein with high dietary calcium.

Effects of dietary fibre mixtures on glucose and lipid metabolism and on mineral absorption in the rat.

Four diets containing different mixtures of dietary fibre (DF) were tested in the rat to verify the effects of fibre source and fibre level on plasma glucose, insulin and lipids and on apparent intestinal absorption of minerals. Diets Puri5 and Puri 10 contained 5 and 10% of total DF from pectin and cellulose. Diets Bran 5 and Bran 10 supplied 5 and 10% DF from oat bran and wheat bran. A fifth diet with 5% cellulose was used as a control. Ten rats were fed each diet for 4 weeks. On days 3, 17 and 28, feces were collected and analyzed for Fe, Zn, Ca and Mg. On day 29, blood samples were collected in portal vein and abdominal aorta in fasted and fed rats from each group. All diets had similar effects on plasma insulin and triglycerides. Compared to Bran diets, Puri diets induced higher portal glucose (p < 0.01) and lower plasma cholesterol (p < 0.03) in fed rats. The apparent absorption of Fe, Zn and Mg was higher (p < 0.05) in rats fed Puri diets than in those fed Bran diets. For Ca, the difference was significant only on day 3. In this study, only the apparent absorption of Fe was affected (p < 0.01) by fibre level (5 > 10%). This indicates that in fibre mixtures, the source rather than the amount of fibre generally affects absorptive and metabolic parameters.

Extent of damage to amino acid availability of whey protein heated with sugar.

The effect of heat treatments, at various water activities (aW), on digestibility and on the availabilities of amino acids of whey protein samples in the presence of lactose was estimated by an in vitro digestion method with continuous dialysis. Four aW (0.3, 0.5, 0.7 and 0.97), three temperatures (75, 100 and 121 degrees C) and three heating periods (50, 500 and 5000 s) were selected. The initial lysine:lactose molar ratio was 1:1. Amino acid profiles showed that excessive heating of whey (121 degrees C, 5000 s) destroyed a significant proportion of cystine at all aW, lysine at aW 0.3, 0.5 and 0.7, and arginine at aW 0.5 and 0.7. At aW 0.3, 0.5 and 0.7, protein digestibility decreased (P less than 0.05) as the temperature increased from 75 to 121 degrees C for a heating period of 5000 s, and as the heating time was prolonged, from 500 to 5000 s at 121 degrees C. Excessive heating also decreased (P less than 0.05) the availabilities of all amino acids at aW 0.3, 0.5 and 0.7. The availabilities of lysine, proline, aspartic acid, glutamic acid, threonine, alanine, glycine and serine were particularly affected. Severe heating at aW 0.97 did not seem to favour the Maillard reaction, but the availabilities of cystine, tyrosine and arginine were decreased, probably as a result of structural modifications of the protein upon heating. Heating whey protein concentrates in the presence of lactose not only affected lysine, but also impaired enzymic liberation of other amino acids, according to the severity of heat treatments and aW.

Zinc and Calcium Solubility from Instant Tea and Coffee With and Without the Addition of Milk.

The effect of tea and coffee, with and without milk, on the solubility of added zinc and calcium after a sequential pH change to 2 and 6 was investigated. The addition of milk did not decrease the solubility of endogenous zinc or calcium in tea but did in coffee. Liquid tea decreased (P<0.01) the solubility of added zinc but not of added calcium. However, the addition of milk to tea containing added zinc and calcium decreased (P<0.01) the solubility of both elements. This decrease reached a plateau after 100 or 150 ml of milk was added to 100 or 50 ml of tea, respectively. In coffee, when the minerals were added, the solubility of zinc did not depend on the presence of milk, whereas the solubility of calcium decreased proportionally to the amount of milk added (P<0.05).