Food Additives and Contaminants, 2002, Vol. 19, No. 10, 969 ±973
Estimation of iron, copper, zinc and manganese intake from duplicate diets provided by hospitals in Poland, 1993±96 K. A. Skibniewska* University of Warmia and Mazury in Olsztyn, Institute of Commodities Science and Food Quality Evaluation, Pl. Cieszynski 1, 10-957 Olsztyn, Poland
(Received 10 January 2001; revised 23 November 2001; accepted 29 November 2001)
Daily intakes of iron (Fe), copper (Cu), zinc (Zn) and manganese (Mn) from whole-day food rations composed by dieticians and collected in hospital canteens in Krakow, Lodz, Olsztyn and Poznan, Poland, in the winters of 1993/94, 1995 and 1996, were determined by atomic absorption spectrometry. The average intake of ¡ Fe, 14 mg day 1 , was satisfactory for both women and men; 13 mg Zn ful®lled the safe level for women (taken as the recommended minimum level to meet the needs of 97.5% of the population) but it was too low for men, and 1.3 mg Cu corresponde d to 65±72% of the safe level set for this microelement in Poland. There is no recommended level set in Poland for Mn, but compared with recommended levels in Germany and the USA, the determined daily Mn intake equal to 3.7 mg should be su cient. Statistical analysis con®rmed higher amounts of Zn and Mn in diets collected in Krakow, higher Cu content in diets from 1996, and lower Mn content in food collected in 1995. Keywords : food, intake, iron, copper, zinc, manganese
Introduction Of several approaches to determine the daily intake of food nutrients, the analysis of single-day duplicate food portions is the most troublesome and expensive, but it brings the most adequate data on individual consumption. The aim was to determine the daily * e-mail: [email protected]
intake of iron (Fe), copper (Cu), zinc (Zn) and manganese (Mn) using single-day food portions made up by professional dieticians working in hospital canteens in di erent regions of Poland. The dieticians were charged with planning the menus to secure adequate intake of all the nutrients.
Material and methods
Complete meals were collected over 3 consecutive days in canteens of city hospitals in Krakow, Lodz, Olsztyn and Poznan in the winters of 1993/94, 1995 and 1996. Olsztyn is a town in north-eastern Poland, an area called the `green lungs of Poland’ because of its relatively clean environment. The other three towns are in ecologically threatened regions in Central or South Poland. One sample comprised a duplicate of the diet for one person per day. The menus were designed by hospital dieticians for patients without special nutritional requirements. The energy content of the meals averaged 3001 § 521.6 kcal as calculated from menus based on Programme FOOD 2.0 (Polish database of nutrient content in food). Every sample was chopped and homogenized using an MPW-324 homogenizer (Mechanika Precyzyjna, Warsaw, Poland). Then, 30-g samples of the rations were ashed in quartz crucibles at 450°C; the ash was dissolved in 25 cm3 1 m nitric acid, Suprapure for AAS. Reagent blanks were prepared parallel to every batch of samples. Before analysis, the samples were diluted with deionized water. The analysis of microelements was performed in the Central Analytical Laboratory at the University of Warmia and Mazury in Olsztyn, which permanently takes part in national and European interlaboratory tests. Flame atomic absorption spectrometry using a Unicam 939 AA apparatus provided with a data station and background correction was used. The method of
Food Additives and Contaminant s ISSN 0265±203X print/ISSN 1464±5122 online # 2002 Taylor & Francis Ltd http://www.tandf.co.uk/journals DOI: 10.1080/0265203021015193 0
K. A. Skibniewska
Results of the analysis of reference materials. (mg g
Material Lyophilized bovine muscle BcR No. 184 Lyophilized bovine liver BcR No. 185
Fe dry mass)
Certi®ed Determined 79 § 2
76 § 3
214 § 5
220 § 4
Cu dry mass)
Zn dry mass)
Determined Certi®ed Determined
2.36 § 0.06
2.28 § 0.07
166 § 3
158 § 3.5
189 § 4
182 § 5
142 § 3
147 § 3
standard addition was employed. The limits of detection determined as the smallest amount detectable at ¡ 95% probability were: Fe, 0.04 mg g 1 ; Cu, 0.02 ¡1 ¡1 ¡ mg g ; Zn, 0.01 mg g and Mn, 0.025 mg g 1 . The method of analysis was veri®ed with certi®ed reference materials: lyophilized bovine muscle BCR No. 184 and Lyophilized bovine liver BCR No. 185. Analysis of variance (test F) for one- and two-factor experiments was employed for statistical elaboration of the results (table 1).
Results and discussion
The average intake of Fe (table 2) amounted to 14 mg/person/day and was near the recommended safe level for women in Poland (14±17 mg). No relationship was found between the Fe content of foods and either the place or time of diet collection. The results for Fe were surprisingly good probably because menus were planned by professionals who tried to ensure the balance of nutrients. Most Polish and foreign authors (Rafalski et al. 1991, Rutkowska et al. 1991a, Drabowicz et al. 1992, Maruszewska et al. 1992, Loewik et al. 1994, Urieta et al. 1996, Ilow and Regulska-Ilow 1996, Berry et al. 1997, Ysart et al. 1999) found inadequate levels of this element in human diet. According to Ziemlanski (1994), in highly developed countries a common consequence of incorrect nutrition or irrational slimming was anaemia. In Poland, anaemia is the most widespread de®ciency disease (Rafalski and Switoniak 1991). A controversy exists on how to increase Fe daily intake with food. Although animal liver is rich in Fe, the high content of heavy metals and other toxins, cholesterol, etc.
Mn dry mass) Determined
0.334 § 0.028 0.326 § 0.016 9.3 § 0.3
8.96 § 0.4
makes its usefulness as a food product doubtful. Thus, bread forti®cation with Fe salts to elevate Fe daily intake should be carefully examined because some cereal components, especially phytates, can bind elements, including Fe (Fairweather-Tait 1992, Idouraine et al. 1996). The present study showed that a carefully planned diet can provide an adequate source of Fe in the diet. The mean daily intake of Cu was 1.3 mg/person/day and corresponded to 65±52% of its Polish safe level. There was no dependence between Cu intake and the town of diet collection, but daily intake of this element was signi®cantly higher (p ˆ 0:05) in 1996. Every year the results of the micronutrients determination were sent back to the dieticians who participated in the study. This procedure helped correct the Cu content in the third year of the study. A wide range of Cu content in the diets (0.5±4.1) suggested that it should be possible to improve the menu in order to elevate Cu consumption in food. An average of 13 mg Zn (8±19) was determined, which was adequate for women but insu cient for men; the ¡safe levels for Zn in Poland¡amount to 10 mg/day 1 for women and 14 mg/day 1 for men. Signi®cantly higher amounts of the element were found in the diets from Krakow (p ˆ 0:05). Drinking water or cooking pots made of metal coated with Zn could be another source of elevated levels of Zn in diets. Many Polish and foreign authors reported various levels of Cu and Zn food de®ciency (Ellen et al. 1990, Rutkowska et al. 1991b, Buss and Rose 1992, Swerts et al. 1993, Cauwenbergh et al. 1995, Urieta et al. 1996, Berry et al. 1997, Ysart et al. 1999). Recent data obtained by Szajkowski (1996) revealed a dramatically low daily intake of these trace elements with diet by seven groups of Wielkopolska Region inhabitants, which was close to half their safe levels. Moreover,
Duplicate diets in Polish hospitals, 1993±96
Table 2. Daily intake of the trace elements (average § SD) with the hospital diets in dependence on town and year of diet collection.
Town Krakow (n ˆ 9) Lodz (n ˆ 9) Olsztyn (n ˆ 9) Poznan (n ˆ 9) Year 1993/94 (n ˆ 12) 1995 (n ˆ 12) 1996 (n ˆ 12) Minimum Maximum Average Polish safe level Average % of Polish safe level Signi®cant di erences:
p ˆ 0:05;
14 § 1 14 § 6 17 § 8 12 § 3
1.7 § 0.6 1.1 § 0.2 1.2 § 0.7 1.2 § 0.3
15 § 2 b 11 § 0 a;b 13 § 1 b § 11 0
6.4 § 3.9 B 3.4 § 1.8 B 2.9 § 1.9 B § 2.2 0.7
15 § 7 11 § 3 18 § 3 7 36 14 14±17 women 11 men ¹100 women >100 men
1.1 § 0.5 b 1.0 § 0.3 a § 1.7 0.5 0.5 4.1 1.3 2.0±2.5
13 § 2 13 § 2 12 § 1 8 19 13 10 women 14 men >100 women 92 men
4.7 § 2.3 B 1.5 § 0.4 A § 5.0 3.0 0.9 11.0 3.7 not set
Mn (mg) A
p ˆ 0:01.
diets of manual workers and white-collar female workers contained only 25% of the recommended Cu content. In addition, Rutkowska et al. (1994) found 30% of Cu and 60±68% of Zn RDA in reconstructed diets. The author’s study (Skibniewska 2000) on bioelement content in whole-day food rations of university students (winter 1997/98) and adults (winter 1998/99) collected by a duplicate-portion method con®rmed the frequent presence of Cu at one-third and Zn at one-half of the safe level. Szajkowski (1996) pointed out that a very low intake of Cu was responsible for an inappropriat e Zn:Cu ratio diet, even in the situation of Zn de®ciency. The Zn:Cu ratio would equal about 6; in the present study, it is approximately twice as high, thus increasing the risk of cardiovascula r diseases, abnormalities in bone mineralization and anaemia in women. The diets were found to contribute an average of 3.7 mg/person/day of Mn, but in a wide range from 0.9 to 11.0 mg. Signi®cantly higher daily intake of Mn was observed in the diet from Krakow (p ˆ 0:01). In addition, the year of sampling in¯uenced the Mn intake: in the diets collected in winter 1995, the Mn contents were signi®cantly lower (p ˆ 0:01). Similar data on Mn were reported by other authors (Ellen et al. 1990, Rutkowska 1991b, 1994, Buss and Rose 1992).
The Polish norms (Ziemlanski et al. 1994) do not provide any guidelines for Mn. Referring to the recommendations of the German Nutrition Society, Sadowska (1993) proposed RDA for Mn at 2.0± 5.0 mg; the US norms are similar (Pennington and Wilson 1990). Although there is no recommended daily allowance level set in Poland, in comparison with RDAs from Germany and the USA, the determined daily Mn intakes with food in Poland should be su cient, although considerable di erences are found among individual diets depending on the time and place of sampling.
The average intake of Fe was near the recommended safe level for women in Poland (14±17 mg). No relationship between Fe content in food and the place or time of diet collection was found. The mean daily intake of Cu corresponded to 65±52% of the recommended Polish safe level. There was no dependence of Cu intake on the town of diet collection, but daily intake of this element was signi®cantly higher (p ˆ 0:05) in 1996. A wide range of Cu content in the diets (0.5±4.1) suggested that it should be easy to
K. A. Skibniewska
correct the menu in order to improve Cu consumption in food. Zn daily intake with the diets was adequate for women but insu cient for men. Signi®cantly higher amounts of the element were found in the diets from Krakow. Mn daily intake averaged 3.7 mg with a wide range from 0.9 to 11.0 mg/person/day. Signi®cantly higher daily Mn intake was observed in the diet from Krakow (p ˆ 0:01). In the food samples collected in winter 1995, the Mn contents were signi®cantly lower (p ˆ 0:01). Although there is no recommended daily allowance level set in Poland, in comparison with RDAs from Germany and the USA, the determined daily Mn intakes with food in Poland should be su cient. All the diets were designed by professional dieticians who received feedback on the results of the analysis every year. However, this did not prevent errors in balancing the trace elements in the diets. Insu cient knowledge of the nutrient content in food products and poor composition of meals could be the reasons for the dietary imbalance. Another frequent error was the wide use of highly processed food, with decreased amounts of minerals. The initial preparation of food products and cooking could cause a loss in the food nutrient content. One also has to remember, however, that because of the economic situation of hospitals in Poland, the low monetary levels earmarked for catering make it di cult to implement proper nutrition principles.
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