Evaluation of micronutrient intakes of children and adolescents: National Nutrition Survey 1995 and comparison with 1985 data. (Original Research).

Abstract

Objective: To evaluate the vitamin and mineral intakes of two to 18-year-old participants in the National Nutrition Survey 1995 (NNS95) against recommended dietary intakes (RDIs) and a previous national survey (1985) often to 15-year-olds.

Design: Secondary analysis of the NNS95.

Subjects: Nationally representative sample of 3007 two to 18-year-olds surveyed in the NNS95. Main outcome measures: Percentage of subjects in each of five age groups by sex with nutrient intakes <0.7 RDI.

Statistical analysis: Data were adjusted for non-respondents and day-to-day variation using weighting and correction factors respectively, provided by the Australian Bureau of Statistics. Descriptive statistics and Pearson's chi-square tests for comparisons by age and sex and between 1995 and 1985.

Results: Among two to 11-year-olds calcium was the only nutrient for which more than 6% subjects had intakes < 0.7 RDI. In 12 to 18-year-old males more than 10% had intakes of vitamin A and calcium < 0.7 RDI, and in females intakes of these two nutrients plus iron, magnesium, zinc and phosphorus were <0.7 RDI in between 12% and 50% of subjects. Among 12 to 18-year-olds, 5% males and 23% females had three or more nutrient intakes <0.7 RDI. Subjects who had nutrient intakes < 0.7 RDI ate less food but also food of lower nutrient density. The proportions of subjects with intakes < 0.7 RDI were similar to 1985.

Conclusion: Many adolescents, particularly females are at risk of inadequate micronutrient intakes which may put them at risk of disease. Food and nutrient intake of children and adolescents must continue to be monitored in order to guide the development of appropriate health promotion strategies with the potential to reduce future disease burden.

Key words: children, adolescents, vitamins, minerals, recommended dietary intakes, nutrient density

Introduction

The nutritional status of individuals is important throughout life. In children and adolescents poor nutrition may affect growth, intellectual capacity and school achievement and in the longer term lay the foundations for adult disease (1). Diet-related disease places a considerable economic burden on the Australian public (2) and ensuring adequate nutrition in childhood is an important prevention strategy. The abundance and diversity of the Australian food supply means the nutritional needs of the population can be met (3). However, the enormous variety and the increasing proportion of foods of poor nutritional value that are available to the consumer can result in many individuals selecting foods on a daily basis that may not meet their nutrient requirements.

The National Nutrition Survey conducted in 1995 (NNS95) was the first nationally representative sample to include persons from as young as two years of age (4). A summary report from this study states that 'mean nutrient intake from food and beverages was very close to or exceeded the Recommended Dietary Intakes (RDIs) for most vitamins and minerals in all age groups' (5) with a few exceptions, predominantly in adolescents (6). Mean, median and percentile distributions of micronutrient intakes have been published for nine separate age groups from two to 65+ years (7). However, more detailed analyses of age and sex comparisons and the determination of the proportions in each age group who have poor intakes (defined as <0.7 RDI) of one or more nutrients that may increase their risk of nutrition-related disease, have only been published on those aged 65 years and over (8). Data from a previous national survey of ten to 15-year-old school children conducted in 1985 indicated that up to one third of males and hal f of the females had calcium and zinc intakes less than 0.7 RDI and up to one third of females had vitamin A and iron intakes less than 0.7 RDI (9). Comparison with this earlier data enables determination of whether there has been a change in the risk of poor nutrient intake in this vulnerable group.

The aims of this study were to use data from NNS95 to:

1. determine the proportion of Australians aged two to 18 years with nutrient intakes less than 70% of the current national RDIs (5);

2. investigate differences in diet quality, defined as nutrient density, that may have contributed to poor intake; and

3. compare the proportion of ten to 15-year-olds with low intakes with a previous national survey (9).

Methods

Sample selection and measurement

NNS95 was a joint project of the Australian Bureau of Statistics and the Commonwealth Department of Health and Aged Care and data were collected from February 1995 to March 1996. Details of the methods used in NNS95 have been described in a guide (4). Briefly the NNS95 sample was a systematically selected sub-sample of private dwellings of the National Health Survey. This survey was conducted on a multistage area sample of private dwellings and a list sample of non-private dwellings. All eligible members of the selected household were invited to participate. For NNS95 up to two eligible people per household in urban areas and three per household in rural areas were randomly selected from the sub-sample. The response rate for two to 18-year-olds selected from the NHS participants was 67%. All States and Territories, and urban, rural and remote areas were represented. Age was determined as whole year at last birthday. Detailed data, collected between February 1995 and March 1996, on total daily food and beverag e intake, based on a 24-hour recall, is available for 3007 individuals (1535 males, 1472 females) aged two to 18 years. Mean and median intakes of six vitamins (vitamin A, thiamin, riboflavin, niacin, folate, vitamin C) and six minerals (calcium, iron, magnesium, phosphorus, potassium, zinc) by sex and for six age groups (2-3, 4-7, 8-11, 12-15, 16-18 years) have been published (7).

For comparison with 1985 data the subset of 290 males and 233 females aged ten to 15 years that completed diet recalls between May and October was used. The data analysed in this paper were provided by the Australian Bureau of Statistics as a Confidentialised Unit Record File (10). Vitamin and mineral supplements are not included in the present analysis. However, only 13 % of all participants took any form of supplement and those most frequently consumed were vitamin C (8%), multivitamins (3%) and multivitamins with iron (2%). Other forms of supplement were consumed by less than one percent of participants. Total food intake was calculated as the sum of the amount of each of the 21 food groups to which every item of food was assigned and excludes plain drinking water.

Nutrient density was expressed as nutrient intake per 100 g food. This food-based approach (compared with the more usual nutrient per 1000 kJ energy) was taken as this is in keeping with dietary guidelines. When making recommendations for improving intake, messages about nutrient per amount of food have more meaning than expressing nutrient in relation to energy. The main source of nutrient information for consumers (the nutrient information panel) provides data as nutrient per 100 g of food.

The National Dietary Survey of Schoolchildren (aged ten to 15 years):1985 (NDS85) (9) was a subset of the Australian Health and Fitness Surveys (it). This study was conducted by the Australian Council on Health, Physical Education and Recreation from May to October 1985 inclusive, and details of the methods have been described (11). Briefly, a representative sample of seven to 15-year-old Australian children attending school, was selected using a two-stage probability sampling design. Firstly, 109 schools were selected randomly from a list of all primary and secondary schools with ten or more students enrolled in each age and sex category. The probability of selection of each school was proportional to the number of children enrolled at that school. All States and Territories were included and a good geographical distribution was achieved. Secondly, within selected schools 15 students within each age and sex category were sampled from enrolment lists using a systematic selection process. Age of participants in whole years at 30 June 1985 was determined from date of birth. Only those aged ten to 15 years participated in NDS85 which provides detailed food and nutrient intakes based on a 24-hour record from 2624 males and 2586 females (9). The mean, percentile distribution and proportion with intakes <RDI and <0.7 RDI for nine micronutrients have been reported (9). Data used in the present analyses were provided on computer disk by the Social Science Data Archives (12).

Statistical analysis

Statistical analyses were undertaken using SPSS for Windows 10.0 (SPSS Inc, Chicago, SPSS for Windows, version 10.0 2001). Subject weighting factors which adjust for non-respondents were scaled back to the study population size and applied before all analyses. For NNS95 data nutrient adjustment factors (provided by the Australian Bureau of Statistics) were applied to individual nutrient intakes to take account of the within-person variation (13). These adjustment factors were not applied for analyses on food intake as no adjustment for this variable was available, nor for comparison with the NDS85 data as similar factors were not available for the earlier study. Descriptive statistics were used to report the percentage of participants with nutrient intakes below 0.7 RDI and Pearson chi-squared tests were undertaken for sex separately for each age group and for the total sample using P = 0.004 as the level of significance (Bonferroni correction for multiple analyses; n = 12 nutrients). Mann-Whitney independent t-tests were used to determine any differences in the nutrient density of the diet (defined as nutrient intake per 100 g food), energy density of the diet (defined as kJ/g food) and energy intake expressed as Id/kg body weight within each gender and age group. Comparisons between surveys used P = 0.006 (n = 9 nutrients).

Results

1995 cohort: age and sex comparisons (data not shown)

Intakes of all nutrients varied significantly with age (P < 0.001) and in males were greatest in the oldest age group (16 to 18 years) and least in the youngest (two to three years). In females intakes of vitamin A, thiamin and riboflavin were greatest in the eight to 11-year-olds, calcium intake was similar and greatest in two to three and eight to 11-year-olds and for the other nutrients intakes increased from two to three years to 12 to 15 years and remained at a similar level for 16 to 18 years. Within each age group from four years, intakes of almost all nutrients were significantly greater in males than females (P < 0.001), but vitamin A was only greater for 12 to 18-year-old males and vitamin C for 16 to 18-year-old males, whereas vitamin C was greater in females in the four to seven-year age group. In the two to three-year-olds there were only sex differences for five nutrients (thiamin, niacin, magnesium, zinc and phosphorus) for which intake was greater in males (P < 0.001).

Comparison with RDI

Table 1 shows the percentage of males and females with nutrient intakes on the day surveyed, less than 0.7 RDI in each age group. There were significant age differences in the percentage of males with intakes below 0.7 RDI for five of the 12 nutrients, and in the percentage of females with intakes below 0.7 RDI for nine of the 12 nutrients (Table 1). In both sexes subjects aged 12 years and older were more likely to have intakes less than 0.7 RDI than younger subjects. There were no sex differences in the proportion of two to three-year-olds with intakes < 0.7 RDI for any nutrient, and in four to seven and eight to 11-year-olds the only nutrient for which there was a sex difference was calcium with significantly more females than males with low intakes (< 0.7 RDI). Among 12 to 15-year-olds, females were more likely than males to have low intakes of iron, zinc and phosphorus, and in 16 to 18-year-olds, intakes of these three nutrients plus folate, calcium, magnesium and potassium were more likely to be below 0 .7 RDI in females compared with males.

Subjects were classified into three groups according to the number of nutrients for which intake was < 0.7 RDI:0, 1 or 2, and 3 or more (Table 2). There were significant differences between sexes in the percentages in each category (P < 0.001) and within each sex significant age differences (P < 0.001). Nine males and 64 females had low intakes of five or more nutrients and all but three of these were aged 12 years or older. In males if three or more nutrients were low the most common combination included calcium, vitamin A and riboflavin (n = 17). In females the most commonly included nutrients if three or more nutrient intakes were low were calcium, iron and zinc (n = 75) or calcium, vitamin A and zinc (n = 64).

Nutrient density of food

The variation by age and sex in the percentage of subjects with intakes < 0.7 RDI on the day surveyed was investigated further by examining the amount of food eaten and the nutrient density of the food i.e. mg nutrient per 100 g food. The absolute amount of food consumed increased with increasing age and at every age was significantly greater in males compared with females (Table 3) (P < 0.001). There were significant differences according to age in males for nutrient density (mg/100 g food) (P < 0.001) for all nutrients except vitamin C, and in females for all but thiamin, vitamin C and phosphorus (P < 0.004). In both sexes nutrient density was greatest in the eight to 11-year or 12 to 15-year age group and least in two to three and 16 to 18-year-olds for all nutrients except calcium in males and females and riboflavin in females. In these cases nutrient density was greatest in the youngest and least in the oldest subjects. There were few sex differences in nutrient density except in the 12 to 15-year age gr oup in which thiamin, niacin, riboflavin, calcium, iron, zinc and phosphorus densities were greater in males compared with females (P < 0.001) and vitamin C was greater in females. Table 3 shows these data by showing the median and interquartile range for calcium and iron density in each age group by sex.

Specific nutrient density (mg/100 g food), total food intake and total food intake per kg body weight (g/kg) were compared between those participants with intakes greater than or equal to 0.7 RDI and those with intakes below 0.7 RDI for each nutrient by sex and age subgroup. Unadjusted nutrient intakes were used for these analyses by RDI group as adjustment for day-to-day variation in total food intake was not possible. Overall, specific nutrient density, total food intake and food intake per kg body weight were significantly greater in those subjects with intakes [greater than or equal to] 0.7 RDI compared with those with nutrient intakes < 0.7 RDI. Table 4 shows these data in males and females aged 12 to 15 years for four nutrients: vitamin A, calcium, iron and zinc.

Food and nutrient intakes were compared between the three groups determined according to the number of nutrients for which intake was < 0.7 RDI (Table 2) (i.e. 0, 1 or 2, 3 or more). In both males and females and in all age groups both the amount of food per kg body weight and the energy intake per kg body weight decreased with increasing number of nutrient intakes < 0.7 RDI (P < 0.001). The energy density of food (kJ/g) was not significantly different according to the number of nutrient intakes < 0.7 RDI except for eight to 11-year-old females (P = 0.001) and 16 to 18-year-old males (P = 0.03). In eight toll-year-old females energy density was greatest in those who had intakes of one or two nutrients < 0.7 RDI (5.2 kJ/g) and similar in the other two groups (4.6 and 4.7 kJ/g) (P = 0.001), and in 16 to 18-year-old males energy density decreased with increasing number of nutrient intakes < 0.7 RDI (0:4.5; 1 or 2:4.3; [greater than or equal to]3:3.4 kJ/g; P = 0.01).

Comparison with NDS85

The percentages of participants in ND585 and of ten to 15-year-olds in NNS95, from whom intake data were collected between May and October, with intakes < 0.7 RDI for each of the nine nutrients (vitamin A, thiamin, niacin, riboflavin, vitamin C, calcium, iron, magnesium, zinc) were compared. Two age subgroups were considered, ten to 11 years and 12 to 15 years. For the majority of nutrients the percentage of participants with intakes < 0.7 RDI was slightly higher in 1985 for both age groups and sexes but none of the differences was significant at P = 0.006 level except for zinc in 12 to 15-year-old males (1985 30%; 1995 19%).

Discussion

This paper evaluates the vitamin and mineral intakes in a 24-hour period of Australian children and adolescents based on the nationally representative sample of 3000 two to 18-year-olds from the National Nutrition Survey (4) against current Australian RDIs (5). The results suggest that micronutrient intakes are of greater concern in adolescents than young children, and in females compared with males. In two to 11-year-olds the only nutrient for which more than 6% of participants had intakes < 0.7 RDI was calcium (up to 22% of females). In 12 to 18-year-old males intakes of vitamin A and riboflavin were low in 15% and 6% respectively, in addition to calcium (21%). In females between 6% and 41% had low intakes of riboflavin, phosphorus, magnesium, iron, calcium and zinc. The greater proportion of females and older subjects with low intakes is reflected in the greater proportion in these groups of those with multiple low intakes.

The high percentage with low calcium intakes from the age of four years is a major concern for long-term bone health. Adequate calcium intake is vital in the adolescent years to maximise peak bone mass (14). In addition it is unlikely that calcium intake will be increased in later years if dairy products are not a regular component of the diet in younger life, thus further increasing the risk of osteoporosis. Estimates of vitamin A intake include the carotenoids which have an important anti-oxidant role. Those with low vitamin A intakes are likely to have a low carotenoid intake which may increase the risk of developing a range of diseases (14). As a result of the low iron intake many adolescent girls are at increased risk of iron deficiency anaemia and possible impaired immune function, and delayed wound healing as a result of poor zinc intake (14).

The observed sex differences in the percentages with low nutrient intakes generally reflect differences in overall quantity of food eaten i.e. males eat more than females, and as the sex differences in RDI are small, males are more likely to meet the recommended intakes. Recommended dietary intakes increase with age and it might be expected that increased food intake would ensure nutrient recommendations are met provided the nutrient density of the food is constant over age. However, nutrient density of food (mg nutrient/100 g food) varies with age and tends to be least in the oldest subjects (16 to 18 years) and thus for this age group nutrient density contributes to the variation in the proportion of subjects meeting RDIs. Similarly, within each age and sex group, subjects who have nutrient intakes [greater than or equal to] 0.7 RDI have overall greater food intake and that food has a greater specific nutrient density compared with subjects with intakes < 0.7 RDI. The differences in food choices that result in these differences in nutrient density require further exploration which is beyond the scope of this paper. However, we previously reported that less than 50% of two to 18-year-olds met the recommendation for fruit intake and only one third met the vegetable intake recommendation suggesting variation in intake of these two food groups may account for some of the variation in nutrient density of overall food intake (15).

The relative importance of overall food intake and nutrient density to nutrient intake varies according to the nutrient in question and the age of the subjects. For example in 12 to 15-year-old females most nutrient densities (mg/100 g food) were less than for males but this was not the case in 16 to 18-year-olds in whom there were no sex differences. Nutrient densities were calculated using unadjusted nutrient and food intakes and do not take account of day-to-day variation in food choice but the 24-hour recall is a valid method for estimating usual intake of a group including nutrient density. These results highlight the importance of nutrient dense food for those with small appetites and/or lower energy (and therefore food) requirements. This is emphasised by the observation that food intake decreased with increasing number of nutrient intakes < 0.7 RDI. Selection of nutrient fortified foods are a potential way for those with overall low food intakes to increase their nutrient intake e.g. breakfast cereals fortified with B vitamins and iron, and calcium-fortified milk.

It is difficult to make direct comparisons with nutrition studies from other countries as few have evaluated intake in relation to proportions of subjects falling below a recommended intake or a fraction of that, instead most express mean intake as a proportion of recommended intake. This figure indicates whether the mean intake is above or below the recommended intake but does not give any indication of the proportion of subjects with intakes that may place them at risk of nutrient inadequacy. However, certain trends can be deduced from published results of intake studies from the US (16,17) and a wide range of countries in Europe (18-20). Overall, results from these studies indicate that mean nutrient intakes in children are greater than recommended intakes. Adolescent males have higher nutrient intakes than females and mean intake is less likely to be below the recommended intake in males. Older females (16 to 18 years) tend to have lower intakes than those 15 years and younger but the reverse is the case for males. The nutrients for which mean intake was often less than a recommended intake were calcium, iron, zinc and vitamin A. Adolescent females were frequently cited as at risk of calcium and iron deficiency due to their low intake. The results presented in this paper indicate that micronutrient intakes of Australian adolescents put them at similar risk of nutrient inadequacy as their US and European counterparts.

The present analyses do not include supplements but it is unlikely that these would address the poor intakes described. Only 13% of participants took any form of supplement on the day prior to survey and the most common supplement was vitamin C which was taken by 8% of participants. All other supplements were consumed by less than 4% of participants.

The only significant difference between 1985 and 1995 in the proportions of participants with nutrient intakes < 0.7 RDI was for zinc in 12 to 15-year-old males. The smaller proportion with a low intake in 1995 suggests that meat intake in this group may be higher in 1995 but investigation of actual foods eaten is required to confirm this.

Every dietary assessment study has its limitations. The 24-hour recall is a valid method for estimating usual intake of groups but not individuals, as long as the individuals sampled are representative of the relevant population group (21). In NNS95 non-response bias is accounted for by the use of survey weighting factors. In order to standardise procedures and reduce bias all interviewers were dietitians and received extensive additional training (4). Application of nutrient adjustment factors in part account for day-to-day variation but individual adjusted values do not represent usual intake values for individuals (13). Thus NNS95 is considered to provide a nationally representative sample and should provide a generalised estimate of average nutrient intake.

Caution must be exercised when comparing data from 1985 and 1995. The 1985 survey used a 24-hour record (not recall), and had a different sampling frame (school-based not community-based). The different time frame (covered May to October only, not a full year) was accounted for by only including from the 1995 survey those subjects from whom data was collected between May and October. As adjustment factors for day-to-day variation were unavailable for NDS85 unadjusted nutrient intakes from NNS95 were used for comparison. This results in over-estimation of proportions below 0.7 RDI but provides a valid comparison between the two surveys. Differences in food composition tables used for the two surveys may also affect estimates of nutrient intakes, in particular vitamin A for which intake was underestimated in 1985 (22). Thus there may have been an actual increase in the proportion with low intakes of vitamin A from 1985 to 1995. This is supported by the decline from 1985 to 1995 in the proportion who consumed f ruit and vegetables on the day surveyed (16). It appears that the diet quality in terms of nutrient adequacy of ten to 15-year-olds has changed very little between 1985 and 1995 and that substantial numbers of adolescents potentially have inadequate intakes of one or more nutrients, in particular calcium and vitamin A, and also iron and zinc in females. An additional consideration is the increased energy intake that occurred between 1985 and 1995 (23) which suggests that diet quality has declined in terms of nutrient density (mg per MJ energy).

In addition to the methodological issues the limitations of the current RDI values must also be considered. The basis for each RDI varies from nutrient to nutrient--some are based on preventing deficiency while others are based on maintaining a particular pool size. Consequently using < 0.7 RDI as the criterion to evaluate adequacy of nutrient intake has a different meaning for each nutrient. In general 0.7 RDI will equate to the estimated average requirement for each nutrient. However, the safety margins that have been applied to each nutrient recommendation range from 120% to 200% of the estimated average requirement (5). Thus establishing adequacy of individuals' dietary and nutrient intakes is difficult to determine based on the RDI. Alternative measures of micronutrient status such as blood analyses are required to accurately assess an individual as having an inadequate nutrient intake. No blood samples were taken for such analyses in NNS95.

The importance of nutrition for health and in disease prevention has long been recognised in Australia (24,25) but specific dietary guidelines for children and adolescents were not endorsed until 1994 (27). There was too short a time frame between release of these guidelines and the NNS95 to expect an improvement in nutrient intake as a result of this health promotion strategy. This highlights the importance of continued monitoring of the food and nutrient intake of children and adolescents in order to identify those nutrients for which a high proportion of individuals has potentially inadequate intakes. Such information will allow development of appropriate health promotion strategies with the potential to reduce future disease burden.

Table 1

The percentage of males and females with vitamin and mineral intakes <
0.7 Recommended Dietary Intake (RDI)(5)by age

                                                         n
                                                    age (years)
                                   2-3    4-7          8-11

                          male     183    367           364
                          female   174    346           348
Nutrient
vitamin A (retinol        male     2.6    3.2           5.8
 equivalents) ([micro]g)  female   0.6    0.5           4.5

thiamin (mg)              male       0     0             0
                          female     0     0             0

niacin (mg)               male       0     0             0
                          female     0     0             0

riboflavin (mg)           male       0     0             0
                          female     0     0             0

folate ([micro]g)         male       0     0             0
                          female     0     0            0.4

vitamin C (mg)            male       0     0             0
                          female     0     0             0

calcium (mg)              male     4.8    12.3          6.0
                          female   1.3    22.4 (c)     21.2 (c)

iron (d)(mg)              male     4.4    0.2            0
                          female  11.0    2.8           1.2

magnesium (mg)            male       0     0            0.2
                          female     0     0            0.8

zinc (mg)                 male       0     0            0.4
                          female     0     0            1.5

potassium (c) (mg)        male       0    0.9           0.7
                          female     0     0            0.8

phosphorus (mg)           male       0    0.3            0
                          female     0     0            0.4

                                                 p (a)

                           12-15      16-18

                            362        268
                            342        254
Nutrient
vitamin A (retinol          15.2       15.7     <0.001
 equivalents) ([micro]g)    18.6       22.8     <0.001

thiamin (mg)                 0         1.2       0.01
                             0          0         na

niacin (mg)                  0          0       na (b)
                             0          0         na

riboflavin (mg)             5.4        7.8      <0.001
                            2.0       11.9      <0.001

folate ([micro]g)           1.0         0        0.01
                            4.4        4.3 (c)  <0.001

vitamin C (mg)               0          0       na (b)
                             0          0       na (b)

calcium (mg)                29.9       9.2      <0.001
                            22.5      31.7 (c)  <0.001

iron (d)(mg)                4.1        2.6      <0.001
                           21.7 (c)   24.2 (c)  <0.001

magnesium (mg)              3.3        7.4      <0.001
                            7.8       19.5 (c)  <0.001

zinc (mg)                    0          0         ns
                           43.4 (c)   39.0 (c)  <0.001

potassium (c) (mg)           0          0         ns
                            1.0        5.0 (c)  <0.001

phosphorus (mg)             0.8        1.2       0.16
                           13.6 (c)   10.2 (c)  <0.001

(a)Pearson chi-square for differences between ages in percentage with
intake < 0.7 RDI (df = 4); significant if P < 0.004

(b)not applicable

(c)Pearson chi-square for differences between sexes in percentage with
intake < 0.7 RDI (df = 1); significant if P < 0.004

(d)mid-point RDI range

(e)lower bound of RDI range

Table 2

The proportion of subjects with 0, 1 or 2, and 3 or more nutrient
intakes < 0.7 RDI by sex and age

                         age (years)

           2-3       4-7       8-11      12-15      16-18

                                %

Males

n           183       367       364       361        268
0          91.5      87.1      88.7      64.8       76.3
1 or 2      8.5      12.0      10.9      28.4       20.5
3 or more   0.0       0.9       0.4       6.4        2.0

Females

n           174       346       348       342        254
0          89.0      75.9      78.2      46.7       43.4
1 or 2     10.7      23.9      20.5      32.1       30.8
3 or more   0.3       0.2       1.3      21.2       25.9

Table 3

Median (interquartile range) for total weight of food consumed (g) and
calcium and iron density (mg/100 g food) by age and gender

age (years)              2-3                   4-7

grams food        m (a)  1604 (b) (1310-1907)  1663 (b) (1314-2012)
                  f (a)  1368 (1113-1782)      1456 (1184-1820)

calcium           m (a)  50.3 (34.7-71.4)      47.2 (36.6-61.6)
density (c)
                  f (a)  53.1 (38.8-69.8)      44.9 (31.6-57.9)

iron density (c)  m (a)  0.44 (0.34-0.63)      0.59 (0.46-0.76)
                  f (a)  0.51 (0.39-065)       0.57 (0.45-0.72)

age (years)       8-11                  12-15

grams food        1863 (b) (1471-2251)  2218 (b) (1710-2800)
                  1640 (1267-2051)      1840 (1399-2247)

calcium           44.4 (32.9-65.6)      47.4 (b) (32.3-57.6)
density (c)
                  46.2 (31.4-64.2)      40.4 (27.8-54.5)

iron density (c)  065 (0.49-0.83)       0.67 (b) (0.51-0.87)
                  0.59 (0.47-0.78)      0.57 (0.45-0.72)

age (years)       16-18

grams food        2789 (b) (2099-3820)
                  1991 (1377-2392)

calcium           39.7 (28.1-56.1)
density (c)
                  36.5 (26.2-54.8)

iron density (c)  0.56 (0.42-0.79)
                  0.54 (0.40-0.73)

(a)significant difference according to age (P < 0.001)

(b)significantly greater in males compared with females p < 0.001

(c)mg/100 g food

Table 4

Median (interquartile range) for specific nutrient density (/100 g
food), total food intake (kg) and total food intake per kg body weight
(g/kg) for males and females aged 12 to 15 years with nutrient intakes
0.7 RDI and < 0.7 RDI

                                    n               specific
                                                    nutrient
                                                density

                          [greater            /g food)(a)
                           than or             [greater than
                          equal to]            or equal to]
RDI                          0.7     < 0.7          0.7

Males

vitamin A (b) ([micro]g)     286      76        46 (35-69)
calcium (mg)                 215      146       54 (47-65)
iron (mg)                    315      46       0.7 (0.6-0.9)
zinc (mg)                    279      82       0.6 (0.4-0.7)

Females

vitamin A (b) ([micro]g)     228      113       54 (39-74)
calcium (mg)                 181      161       50 (41-66)
iron (mg)                    231      111      0.6 (0.5-0.8)
zinc (mg)                    169      172      0.5 (0.5-0.7)

                             specific             food intake (kg)
                             nutrient
                              density                   (a)
                            /g food)(a)

                                         [greater than
                                         or equal to]
RDI                           < 0.7           0.7           < 0.7

Males

vitamin A (b) ([micro]g)   20 (14-28)    2.4 (2.0-3.0)  1.6 (1.2-2.1)
calcium (mg)               31 (23-43)    2.5 (2.0-3.1)  1.7 (1.3-2.4)
iron (mg)                 0.4 (0.4-0.5)  2.4 (1.8-3.0)  1.5 (1.2-2.0)
zinc (mg)                 0.4 (0.3-5.8)  2.5 (2.0-3.0)  1.5 (1.2-2.1)

Females

vitamin A (b) ([micro]g)   23 (15-31)    1.9 (1.6-2.4)  1.5 (1.1-2.0)
calcium (mg)               28 (20-38)    2.0 (1.7-2.4)  1.5 (1.1-2.0)
iron (mg)                 0.5 (0.3-0.5)  2.0 (1.7-2.4)  1.3 (1.0-1.8)
zinc (mg)                 0.4 (0.3-0.5)  2.1 (1.7-2.5)  1.5 (1.1-1.9)

                                food intake/kg
                                  body weight
                                  (g/kg) (a)

                          [greater than
                          or equal to]
RDI                            0.7         < 0.7

Males

vitamin A (b) ([micro]g)   43 (33-57)    31 (20-41)
calcium (mg)               46 (36-59)    33 (23-46)
iron (mg)                  43 (32-55)    30 (20-42)
zinc (mg)                  44 (34-58)    30 (21-41)

Females

vitamin A (b) ([micro]g)   37 (28-46)    26 (20-37)
calcium (mg)               39 (30-47)    28 (19-38)
iron (mg)                  38 (29-46)    24 (18-34)
zinc (mg)                  39 (32-48)    27 (20-36)

(a)Mann-Whitney independent t-test for differences between individuals
with specific nutrient intakes 0.7 RDI compared with those with intakes
< 0.7 RDI, P < 0.001

(b)retinol equivalent

References

(1.) Tomkins A. Vitamin and mineral nutrition for the health and development of the children of Europe. Public Health Nutr 2001;4:9l-9.

(2.) Crowley 5, Antioch K, Carter R, Waters AM, Conway L, Mathers M. The cost of diet-related disease in Australia. Canberra: Australian Institute of Health and Welfare; 1992.

(3.) Australian Bureau of Statistics. Apparent consumption of foodstuffs and nutrients Australia 1986-7. Canberra: Australian Bureau of Statistics Catalogue No. 4306.0; 1988.

(4.) McLennan W, Podger A. National Nutrition Survey User's Guide 1995. Canberra: Australian Bureau of Statistics Catalogue No. 4801.0; 1998.

(5.) Truswell AS. Truswell AS, editor. Recommended nutrient intakes: Australian papers. Sydney: Australian Professional Publications; 1990.

(6.) McLennan W, Podger A. National Nutrition Survey. Selected Highlights. Canberra: Australian Bureau of Statistics Catalogue No. 4802.0; 1997.

(7.) McLennan W, Podger A. National Nutrition Survey. Nutrient Intakes and Physical Measurements. Canberra: Australian Bureau of Statistics Catalogue No. 4805.0; 1998.

(8.) Bannerman E, Magarey AM, Daniels LA. Evaluation of micronutrient intake of older Australians: the National Nutrition Survey--1995. J Nutr Health Aging 2001;5:1-4.

(9.) Department of Community Services and Health. National Dietary Survey of Schoolchildren (aged 10-15 years): 1985 No. 2 Nutrient intakes. Canberra: Australian Government Publishing Service; 1989.

(10.) Australian Bureau of Statistics. 1995 National Nutrition Survey (NNS) Confidentialised Unit Record File (CURF). Canberra: Commonwealth of Australia; 1999.

(11.) Pyke JE. Australian Health and Fitness Survey 1985. Adelaide: The Australian Council for Health, Physical Education and Recreation Inc; 1987.

(12.) Department of Health. Social Science Data Archives. National Dietary Survey of Schoolchildren, Australia, 1985. Canberra: Australian National University; 1993.

(13.) Rutishauser IHE. Getting it right: how to use the data from the 1995 National Nutrition Survey. Canberra: Commonwealth of Australia; 2000.

(14.) National Health and Medical Research Council. Dietary guidelines for children and adolescents. Infant feeding guidelines. Draft 2001. Canberra: NHMRC; 2001.

(15.) Magarey AM, Daniels LA, Smith A. Fruit and vegetable intakes of young Australians aged 2 to 18 years: An evaluation of the 1995 National Nutrition Survey data. Aust N Z J Public Health 2001;25:155-61.

(16.) Cavadini C, Siega-Riz AM, Popkin BM. US adolescent food intake trends from 1965 to 1996. Arch Dis Child 2000;83:18-24.

(17.) Devaney BL, Gordon AR, Burghardt JA. Dietary intake of students. Am J Clin Nutr 1995;61:205S-12S.

(18.) Amorim Cruz JA. Dietary habits and nutritional status in adolescents over Europe-Southern Europe. Eur J Clin Nutr 2000;54:29S-35S.

(19.) Samuelson G, Bratteby L-E, Enghardt H, Hedgren M. Food habits and energy and nutrient intake in Swedish adolescents approaching the year 2000. Acta Paediatr Scand 1996;85:1-20.

(20.) Rolland-Cachera MF, Bellisle F, Deheeger M. Nutritional status and food intake in adolescents living in Western Europe. Eur J Clin Nutr 2000;54:41S-6S.

(21.) Margetts B, Nelson M. Design concepts in nutritional epidemiology, second edition. Oxford: Oxford University Press; 1997.

(22.) Baghurst K, Record S, Leppard P. Red meat consumption in Australia: intakes, nutrient contribution and changes over time. Aust J Nutr Diet 2000;57(4 Suppl):3S-36S.

(23.) Cook T, Rutishauser I, Seelig M. Comparable data on food and nutrient intake and physical measurements from the 1983, 1985 and 1995 national nutrition surveys. Australian Food and Nutrition Monitoring Unit. Canberra: Commonwealth Department of Health and Aged Care; 2001.

(24.) National Health and Medical Research Council. Dietary guidelines for Australians. Canberra: Australian Government Publishing Service; 1992.

(25.) Nutbeam D, Wise M, Bauman A, Harris E, Leeder S. Report prepared for the Commonwealth Department of Health Housing and Community Services. Goals and targets for Australia's health in the year 2000 and beyond. Canberra: Australian Government Publishing Service; 1993.

(26.) National Health and Medical Research Council. Dietary guidelines for children and adolescents. Canberra: Australian Government Publishing Service; 1995.

Nutrition Unit, School of Medicine, Flinders University of South Australia, Adelaide

A.M. Magarey, BSc(Hons), DipNutrDiet, PhD, APD, NHMRC Postdoctoral Research Fellow

E.Bannerman, BSc(Hons) Dietetics, PhD, Lecturer 

Correspondence: A. Magarcy, Nutrition Unit, School of Medicine, Flinders University of South Australia, Bedford Park SA 5042. Email: anthea.magarey@ flinders.edu.au