Isabelle Galibois

Lack of effect of dietary conjugated linoleic acids naturally incorporated into butter on the lipid profile and body composition of overweight and obese men

BACKGROUND Dietary conjugated linoleic acid (CLA) is known to reduce atherosclerosis, plasma total and LDL-cholesterol concentrations, and body fat accumulation in several animal species. Of the few studies that investigated the effects of CLA supplementation in humans, all used commercially formulated oral supplements made from a mixture of CLA isomers. OBJECTIVE We compared the effects on plasma lipoproteins and body composition of the consumption of a modified butter naturally enriched with CLA (CLA-B: 4.22 g CLA/100 g butter fat) by the addition of sunflower oil to the diet of dairy cows with the consumption of a control butter (CON-B) that was low in CLA (0.38 g CLA/100 g butter fat). DESIGN In a crossover design study including an 8-wk washout period, 16 men [x +/- SD age: 36.6 +/- 12.4 y; body mass index (in kg/m2): 31.2 +/- 4.4] were fed each of the 2 experimental isoenergetic diets, providing 15% of energy as protein, 45% as carbohydrates, and 40% as lipids, of which >60% was derived from experimental fats, for 4 wk. RESULTS Consumption of the CLA-B diet induced a significantly (P < 0.05) smaller reduction in plasma total cholesterol and in the ratio of total to HDL cholesterol (-0.02 mmol/L and -0.00, respectively) than did consumption of the CON-B diet (-0.26 mmol/L and-0.34, respectively). Abdominal adipose tissue area measured by computed tomography showed no difference in accumulation of either visceral or subcutaneous adipose tissue after the 2 experimental diets. CONCLUSION These results suggest that a 10-fold CLA enrichment of butter fat does not induce beneficial metabolic effects in overweight or obese men.

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.

Sequential release of amino acids and peptides during in vitro digestion of casein and rapeseed proteins

Abstract An in vitro proteolysis method was used to study the kinetics of digestion of casein and rapeseed proteins. After a pepsin predigestion, the protein sources were submitted to a 24-hour pancreatin hydrolysis, with the continuous removal of digestion products by dialysis. Dialysates were collected at 3-hour intervals, and analysed for content of nitrogen, amino acids and low molecular weight peptides. At the end of the experimental period, casein had a higher overall digestibility (97%) than rapeseed (83%). The difference was mostly due to a high rate of digestion during the first 3 hours for casein, as nitrogen release was similar for both proteins at subsequent intervals. Much more variation was observed in individual amino acid digestibility. In casein, arginine, tyrosine and methionine were the most rapidly released, being more than 95% digested after 12 hours. In rapeseed, the amino acids were generally hydrolysed more gradually. Only tyrosine and methionine were more than 95% released by 24 hours. In general, highly digestible amino acids were mostly released as free amino acids. But differences were also noted between proteins for the distribution of individual amino acids in low molecular weight peptides. With casein, isoleucine, valine and threonine were found in large proportion in peptides, and arginine was mostly released as a free amino acid. With rapeseed, histidine was preferentially released in peptides, while methionine appeared mostly in the free form from 6 to 12 hours. These findings give new insight into the effect of protein nature upon the kinetics and form of release of digestion products. Differences in sequential hydrolysis also suggest that subsequent absorption and utilisation of dietary amino acids in the living organism may be largely dependent on the luminal digestion process.

Analysis of bound amino acids in the plasma of fed rats : a new preparation procedure

Abstract Oligopeptides have been proposed as an important form of transport of amino acids in circulation, but current preparation and analysis methods do not allow detection of peptides in plasma samples. In order to measure the concentration and composition of bound amino acids in comparison with those under free form in plasma, blood samples were collected in portal vein and aorta of rats fed a 20% rapeseed protein diet. Samples were deproteinized with sulfosalicylic acid, and centrifuged in 3000 molecular weight cut-off filters. Analyses were performed by ion-exchange chromatography before and after hydrolysis of filtrates in 6N HCl, to assess by difference the amount of bound amino acids in plasma. Hydrolyzed samples from portal vein and aorta contained, respectively, 8.2% and 10.3% more total amino acids than nonhydrolyzed samples ( P

Nutritional strategies to prevent hypoglycemia at exercise in diabetic adolescents.

UNLABELLED Studies on nutritional strategies to prevent exercise-induced hypoglycemia in adolescents with type 1 diabetes are scarce. OBJECTIVE This study aimed to compare the effect of two food strategies on blood glucose (BG) during and after 60 min of moderate-intensity exercise. METHODS Subjects performed exercise 120 min after breakfast in three conditions: 1) standardized breakfast + preexercise placebo beverage (PL), 2) standardized breakfast + preexercise CHO beverage (8 mg of CHO·kg of body weight·min of exercise; CHO), or 3) protein-supplemented breakfast (8 mg of protein·kg of body weight·min of exercise added to the standardized breakfast) + preexercise placebo beverage (PROT). As soon as BG falls <4 mmol·L or symptomatic hypoglycemia occurred during exercise, the session was stopped and CHO tablets were provided to correct hypoglycemia. RESULTS Ten subjects (age = 14.0 ± 1.5 yr) participated in all conditions. BG decreased by 6.0 ± 1.9, 1.0 ± 3.1, and 4.6 ± 1.9 mmol·L in PL, CHO, and PROT conditions, respectively (P < 0.05). The proportion of subjects reaching hypoglycemic values or sensations of hypoglycemia was significantly different between conditions with 4/10, 1/10, and 0/10 in the PL, CHO, and PROT conditions (P < 0.05). CONCLUSIONS The preexercise CHO beverage induced the least dramatic BG decrease during exercise. The PROT breakfast induced an overall similar BG drop compared to PL, a larger BG drop compared to CHO, but a similar rate of hypoglycemia compared to CHO. Our results suggest that taking CHO supplement before unplanned exercise is still the best strategy to prevent exercise-induced hypoglycemia in an adolescent population. However, a protein supplement strategy may also have some benefits in limiting the rate of hypoglycemia during and immediately after exercise.

Relationship between amino acid intestinal effluent in rat and in vitro protein digestion products

Abstract Amino acid absorption as measured by proto-aortic differences was studied in rats given 10% protein diets ad libitum. Free plasma amino acid (PAA) levels were determined in portal and aortic blood sampled at 2200 h (low intestinal absorption time), 0400 h were beef, casein, rapeseed, soybean and gluten. These proteins were also submitted to an in vitro digestion process by which free amino acids and low molecular weight peptides (digestion products) were collected as they were released after pepsin and pancreat in hydrolysis. Even though most essential amino acids (EAA) were preferentially hydrolysed during the 6-h digestion, the pattern of release was different for each protein. Essential PAA of intestinal effluent (porto-aortic difference) were compared with both in vitro digestion products and protein EAA. In most instances, correspondence between EAA patterns and digestion products was higher. Correlations were rather low for beef and casein (r=0.70), but higher with rapeseed and particularly with soybean and gluten (r=0.92 between PAA of 2200 h intestinal effluent and peptide fraction of in vitro digestion products for soybean, and r=0.93 between 0700 h intestinal effluent and peptide fraction for gluten). It can thus be stated that compared to protein amino acid composition, in vitro digestion products appear to be better predictors of amino acid bioavailability.

Validation of an FFQ to assess dietary protein intake in type 2 diabetic subjects attending primary health-care services in Mali

OBJECTIVE To validate a 53-item quantitative FFQ (QFFQ) for the assessment of dietary protein intake in type 2 diabetic outpatients in Bamako, Mali. DESIGN Consumption of protein-containing foods over the week preceding the interview was measured with a 7d QFFQ and compared with intakes measured with 48-h recalls. SETTING Centre National de Lutte contre le Diabète. SUBJECTS Seventeen male and forty female adults with type 2 diabetes. RESULTS Correlation between protein intakes estimated using the QFFQ and 48h recalls was 0.63 (P < 0.0001). There was no significant difference between the two methods concerning the total protein daily intakes and intakes per kilogram of body weight. The QFFQ indicated that foods of animal origin were a lesser source of protein. Animal protein intake did not differ between men and women but sources did. In men, the main sources were beef (54 % of total animal protein), fish (15 %) and milk powder (8 %). In women, the principal sources were fish (28 %), beef (20 %) and birds (13 %). In contrast, plant protein intake was significantly higher in men than in women (P = 0.01), but the same plant foods contributed in similar proportions for both genders, rice being by far the greatest source (47 % of plant protein in men, 53 % in women). CONCLUSION The QFFQ developed in this study is a valid tool to evaluate dietary protein intakes in Malian diabetic subjects. While the total protein intakes were low in both men and women, differences in choices and amounts of protein food sources were shown.

Independent effects of protein and fibre sources on glucose and cholesterol metabolism in the rat

Abstract Casein and soy protein were used in combination with wheat bran and oat bran in four balanced diets to verify the effects of protein and fibre sources on various parameters of glucose and cholesterol metabolism in the rat. Fifteen animals were fed each diet for two weeks, under a dephased light/dark cycle. On day 15, blood samples were collected in the portal vein and abdominal aorta and liver was excised in fasted (09:00 h) and fed rats(12:00 h and 16:00 h) from each group. The animals fed casein had significantly higher total plasma cholesterol levels at all sampling times, higher HDL-cholesterol values at 12:00 h and higher hepatic cholesterol concentrations at 12:00 h and 16:00 h, as compared to those fed soy protein. Systemic glycemia at 09:00 h and 12:00 h and insulin levels at 12:00 h were also highest in casein fed groups. As regards fibre sources, wheat bran feeding induced lower portal and systemic glycemia at 12:00 than did oat bran feeding. Oat bran diet groups had the lowest HDL-cholesterol levels and the highest hepatic cholesterol concentrations at 09:00 h. No interaction between dietary protein source and fibre source was evidenced by ANOVA on any of the parameters tested. Thus, these nutrients fed simultaneously seem to exert independent and mostly distinct effects on glucose and cholesterol metabolism.

Development of a Malian food exchange system based on local foods and dishes for the assessment of nutrient and food intake in type 2 diabetic subjects

Abstract Objective: To develop exchange lists for the assessment of food and nutrient intakes for people with diabetes in Mali. Design: Based on North American exchange lists, a Malian food exchange system was developed using food composition tables for Mali. Dietary intakes were assessed by two 48-hour dietary recalls. Daily numbers of exchanges were determined for the whole sample and for each gender. Energy and macronutrient intakes obtained by a software-based nutritional analysis of the dietary recalls were compared with the average energy and nutrient values calculated with the exchange lists. Setting: Centre National de Lutte contre le Diabète. Subjects: Seventeen male and 40 female adults with type 2 diabetes. Results: The analysis of food recalls using the Malian exchange system showed that subjects consumed the following numbers of exchanges per day: 2.6 ± 1.5 meat and substitutes, 0.5 ± 0.8 legumes, 0.7 ± 1.2 milk, 8.0 ± 4.1 fat, 8.3 ± 3.0 starch, 1.5 ± 0.9 vegetables, 0.2 ± 0.5 fruit, and 0.0 ± 0.2 sugar-added foods, totalling 1 854 ± 648 kcal, 260 ± 92 g carbohydrate, 56 ± 23 g protein and 63 ± 31 g fat. These results concerning energy and macronutrients did not differ significantly from those obtained from the nutritional analysis of food recalls with software using data from the Food Composition Table for Mali. Compared to women, men consumed significantly larger numbers of exchanges of meat and substitutes, fat, starch, and fruit. No significant differences were found for the intakes of legumes, milk, vegetables and sugar-added foods. Conclusions: This study allowed the development of Malian food exchange lists and demonstrated their usefulness for the description of the dietary pattern and energy and macronutrient intakes of male and female Malian type 2 diabetic patients.

Seasonal vitamin D intake in Quebec preschoolers.

As a number of seasonal factors affect cutaneous synthesis of vitamin D, especially in young children, our objective was to verify if winter and summer vitamin D intakes in Quebec preschoolers reach the adequate intake of 5 µg/day. A three-month retrospective food frequency questionnaire and a 24-hour food recall were used with parents of 98 children (mean age 56 months) in summer and of 72 of these children (mean age 65 months) in winter. To ensure completeness of data, vitamin D content of foods not covered in the Canadian Nutrient File was taken from other sources. According to the food frequency questionnaire, total vitamin D intakes were 9.7 ± 4.3 g/day in summer and 11.6 ± 4.8 g/day in winter. Only 10% of children in summer and 7% in winter had an intake below 5 µg/day. The 24-hour food recall vitamin D intake estimate was lower (summer 7.0 ± 3.8 µg/day, winter 7.2 ± 4.2 µg/day). This difference could be partly due to a discrepancy in the estimation of multivitamin supplement intake. However, accord...As a number of seasonal factors affect cutaneous synthesis of vitamin D, especially in young children, our objective was to verify if winter and summer vitamin D intakes in Quebec preschoolers reach the adequate intake of 5 µg/day. A three-month retrospective food frequency questionnaire and a 24-hour food recall were used with parents of 98 children (mean age 56 months) in summer and of 72 of these children (mean age 65 months) in winter. To ensure completeness of data, vitamin D content of foods not covered in the Canadian Nutrient File was taken from other sources. According to the food frequency questionnaire, total vitamin D intakes were 9.7 ± 4.3 g/day in summer and 11.6 ± 4.8 g/day in winter. Only 10% of children in summer and 7% in winter had an intake below 5 µg/day. The 24-hour food recall vitamin D intake estimate was lower (summer 7.0 ± 3.8 µg/day, winter 7.2 ± 4.2 µg/day). This difference could be partly due to a discrepancy in the estimation of multivitamin supplement intake. However, accord...As a number of seasonal factors affect cutaneous synthesis of vitamin D, especially in young children, our objective was to verify if winter and summer vitamin D intakes in Quebec preschoolers reach the adequate intake of 5 microg/day. A three-month retrospective food frequency questionnaire and a 24-hour food recall were used with parents of 98 children (mean age 56 months) in summer and of 72 of these children (mean age 65 months) in winter. To ensure completeness of data, vitamin D content of foods not covered in the Canadian Nutrient File was taken from other sources. According to the food frequency questionnaire, total vitamin D intakes were 9.7 +/- 4.3 microg/day in summer and 11.6 +/- 4.8 microg/day in winter. Only 10% of children in summer and 7% in winter had an intake below 5 microg/day. The 24-hour food recall vitamin D intake estimate was lower (summer 7.0 +/- 3.8 microg/day, winter 7.2 +/- 4.2 microg/day). This difference could be partly due to a discrepancy in the estimation of multivitamin supplement intake. However, according to both estimates, vitamin D intakes appeared generally adequate in this sample of Quebec preschoolers.