The influence of dietary vitamin A supplementation on vitamin A and insulin levels in sedentary or physically trained rats

Male rats of Wistar strain (n = 48) were fed a vitamin A deficient diet for 3 days of adaptation period and then a 10 day experimental period to reduce slightly the body stores of this vitamin. Half of the animals were subjected to physical training and/or oral vitamin A supplementation. Four different doses of supplementation were used--0, 7.5, 15 and 60 microg/d/rat, which is equivalent to 0, 25, 50 and 200 IU of vitamin A, respectively. Animals from the defined groups ran on a treadmill with a rate of 2.0 m/s for 15 minutes per day for 10 days. After overnight fasting, the rats were sacrificed, and insulin in blood serum and hepatic retinol concentrations were estimated. Daily feed intake and daily body gains were similar in groups of sedentary and physically trained rats. A moderate level of oral vitamin A supplementation (the highest supplemented dose was about 6 x the above recommended NRC level) did not cause any changes in these zootechnical parameters. Oral Vitamin A supplementation resulted in an increase in retinol concentration in the liver (F = 15.2, p < 0.001), but without significant difference between trained and untrained animals. Physical training of rats caused a statistically significant decrease of insulin concentration in blood serum (1.53 +/- 0.18 vs. 1.73 +/- 0.20). This difference was highly significant (F = 11.1, p < 0.001). Vitamin A supplementation was found not to influence the concentration of this hormone, which is responsible for energy metabolism regulation in the body. Based on estimated parameters, the necessity of vitamin A excessive use in physically trained subjects was not proven.

[Frequency of intake and energy value of breakfast for students from selected primary schools in Warsaw]

Energy value and frequency breakfast intake in Warsaw primary schools were estimated in a group of 330 children aged 7-15 years. The research was carried out in autumn 1998 year. The nutrition mode was assessed by questionnaire interviews and of 24-hour recall [4] and computer programme "Zywienie". The size of the consumed portion was determined with an album containing colour photographs of products and dishes of different size [14]. Food consumption quality was estimated using test of Bielińska modified by Kulesza et al. [8]. Frequency breakfast intake decreased at older schoolchildren. Breakfast milk and products, vegetables and fruits intake was too low; intake of fat sweets and beverages like "coca-cola" was too high. Breakfast energy value was too low compared with recommended dietary allowances.

[The evaluation of nitrates and nitrites food intake among Polish households in 1991-1995]

The studies on nitrates and nitrites food intakes in year 1991-1995 were carried out in four types of households i.e. works, worker-farmers, farmers, pensioners and retired persons and from 1993 in self-employed households and families maintaining themselves on non-income sources; altogether and with regard to the number of persons in family. Using household budget data and literature concerning nitrates and nitrites contents in food products, mean and maximum food intakes of these compounds were calculated and compared to acceptable daily intake (ADI) taking into consideration main sources of them. The obtained results indicated that the mean nitrate and nitrite food intakes did not exceed ADI but maximum intakes of one were several times higher than ADI. Nitrate and nitrite food intakes depended on type of household being highest at farmers, pensioners and the number of persons in family. Six persons families took nearly half less than did one-person one. There were no differences in main food sources of nitrates and nitrites for all types of households and number of person in families. Vegetables and their products supplied 94-98% of nitrates whereas meat products supplied 98% of nitrites.

[Effect of nutrition education on nutrition behaviors of investigated students' group]

The aim of the study was evaluation if nutrition education effect on food consumption in students. The group of 110 students, 50% from Faculty of Human Nutrition & Home Economics and other from Horticulture Faculty was investigated. Food consumption quality was estimated using 24 hours recall method and modified by Kulesza test of Bielińska. It has been shown, that nutrition education did not significantly effect on food consumption of students.

[Evaluation of food consumption and nutritional status of children at preschool and school age based on the literature in 1980-1995]

The study includes a survey of literature reports from the last 15 years on the consumption of food and nutritional status of preschool and school children. The nutritional status of preschool and school children suggested many shortcomings independent of social class and nutrition type (individual, mass nutrition). Generally, the nutrition of town children was better than that of rural children, and signs of deficiency of certain vitamins and mineral components were found in a lowe per cent of the former children. The food rations of the studied children contained too low consumption of milk and dairy products, vegetables and fruit, with high intake of fats, meat and its products, sugar and sweets. The daily food rations contained low amounts of calcium, vitamins A, B and C, with excess of phosphorus and fats. The nutrition of school children depended on year season, social class and education of parents. The most frequent faults included inappropriate timetable of meals, their poor quality, inadequate number and monotony. No such data could be obtained with respect to preschool children. The nutritional status of preschool and school children gives rise to objections, especially in the case of rural areas. There is a need to evolve and introduce a standardized study method for the assessment of nutrition and nutritional status of preschool and school children and continuous monitoring in this respect.

[The in vitro effect of ascorbic acid on sodium nitrite intoxication]

The in vitro effect of ascorbic acid on the content of sodium nitrite in relation to pH and time of incubation and also effect of sodium nitrite on the total content of vitamin C as a sum of both reduced and oxidized forms was demonstrated. Ascorbic acid in respective quantities of 60 mg, 120 mg, 180 mg and sodium nitrite in quantity of 12 mg were added to the in vitro simulated stomach content at pH 1.5, 2.5, 3.5. The control samples were tested without addition of ascorbic acid. The Griess method for determination of nitrite and the Tillmans method with Pijanowski's modification were used for the determination of vitamin C. It was found that the choice of lower pH significantly decreased the level of nitrite in the control samples produced the disappearance of nitrite increased depending on the quantity of ascorbic acid added to the sample and on pH. The total content of vitamin C did not change after adding of sodium nitrite to the samples. The performed studies suggested a positive effect of ascorbic acid decreasing of the nitrite level.

[Evaluation of beta-carotene bioavailability from selected vegetables grown by conventional and ecologic methods]

The availability of beta-carotene was studied from carrots and sorrel grown by conventional and ecological methods. The vegetables were bought in the market and in a shop with ecological food, and they had Ekoland atests. The bioavailability was determined by the hepatic test. No significant effect of growing method of the studied vegetables on beta-carotene bioavailability was found.

[Evaluation of nitrate, nitrite and total protein content in selected vegetables cultivated conventionally and ecologically]

Nitrates, nitrites and total protein content in selected vegetables from conventional and ecological farms were estimated. The beetroots, carrots, potatoes available on market or special shops in January, May and March were evaluated. The content of nitrates and nitrites was determined by colorimetric method with Griess reagent after previous reduction of nitrates to nitrites by metallic cadmium. Total protein content was determined by Kjel-Foss Automatic 16210 analyser working on the basis of classical Kjeldahl method. The higher content of nitrates was found in vegetables from conventional farms. Amounts of nitrates in both groups of vegetables did not exceed allowed limits. Levels of nitrites in ecological and conventional vegetables were similar-above 0.5 mg NaNO2/kg (except conventional potatoes from January). Slightly more content of protein was recorded in conventional vegetables.