4805.0 - National Nutrition Survey: Nutrient Intakes and Physical Measurements, Australia, 1995
ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 17/12/1998
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SUMMARY OF FINDINGS
Tables 1-36 present information for mean and median nutrient intakes. The median is particularly useful for interpreting nutrient intake, as it is unaffected by the extreme values which may be recorded on a single day's intake. As practically everyone consumes some of each nutrient each day, medians have been calculated for all people in the population group being considered. The exception is median alcohol intake, which has been calculated only for alcohol consumers because of the high level of non-consumption. Only 33% of adults consumed alcohol during the day prior to interview. Ratio of energy intake to basal metabolic rate Basal metabolic rate (BMR) is the amount of energy expended at rest over a given period of time. BMR has been predicted for NNS participants aged 10 years and over from their weight, age and sex (see Appendix 4). The ratio of energy intake to basal metabolic rate (EI/BMR) has been included in all tables on mean and median macronutrient intake, to aid data interpretation. Low EI/BMR values may indicate dieting, unusually low consumption or under-reporting of food consumption during the 24-hour reference period. Further information on EI/BMR and its effects on the interpretation of survey data is provided in Appendix 4. AGE AND SEX DIFFERENCES Energy Energy is released from food components containing fat, protein, carbohydrate and alcohol. Across all age groups, males had a higher energy intake than females. Median daily energy intake was 10,380 kJ for men, compared to 7,080 kJ for women. Energy intake increased steadily with age, to a peak of 13,010 kJ for males aged 16-18 years and 8,140 kJ for females aged 16-18 years, and then declined gradually with age. (Table 2.) Macronutrients Males consumed larger amounts of each macronutrient than females for all age groups. In general, intakes increased with age until the second or third decade of life and then decreased:
The patterns in intake of individual macronutrients differed with age and sex. Young children and adolescents consumed slightly more fat than protein, the reverse of the pattern for males aged 19 years and over and females 16 years and over. Similarly, children and adolescents consumed more sugars than starch whereas adults ate more starch than sugars.
Carbohydrates contributed the largest proportion of energy intake for all age groups. It contributed over 50% to the total energy intake of those aged under 19 years, reducing to 45% for adults aged 45-64 years. Fat contributed about one-third to all age groups. Protein contributed about 14% for children under 15 years, increasing to 17% for adults over 45 years. These proportions were similar for both males and females. Adults who consumed alcohol obtained approximately 4-9% of their energy intake from alcohol. (Table 4.) The proportion of total energy provided by saturated fat and sugars decreased with age, and the proportion provided by protein increased with age. The proportion provided by other macronutrients did not differ significantly with age. Vitamins and minerals As with macronutrients, males consumed larger quantities of vitamins and minerals than females. For males, median intakes generally peaked at 16-24 years although for some vitamins and minerals the median intake was higher in older ages (e.g. vitamin C). For females, the highest median intakes for the majority of vitamins and minerals were by women aged 45-64 years. (Table 6.) Vitamin and mineral intakes have also been expressed in relation to energy intake. This provides an indication of the 'richness' of the diet, relative to the total amount of energy consumed. In contrast to actual intake of vitamins and minerals, adult females generally consumed higher amounts per 1,000 kJ of energy than adult males. However, men and women had similar intakes per 1,000 kJ of energy for thiamine, riboflavin and zinc. Females aged 2-15 years also generally consumed similar or larger amounts of vitamins and minerals per 1,000 kJ of energy than males, except for calcium and preformed vitamin A. (Table 8.) People aged 45 years and over usually had the highest vitamin and mineral intakes per 1,000 kJ of energy. However, 2-3 year olds had the highest intakes of calcium and preformed vitamin A per 1,000 kJ of energy, because of their high intake of milk and milk products. Thiamine and riboflavin were relatively stable across age groups. OTHER FACTORS AFFECTING NUTRIENT INTAKE BY ADULTS State and Territory Differences in adult nutrient intake across States and Territories were generally small. Median energy intake was highest in South Australia for men and in the Australian Capital Territory for women. It was lowest in Queensland for men and in Tasmania for women. Women in the Australia Capital Territory consumed larger amounts of most macronutrients than other females. Western Australian men consumed the largest amounts of carbohydrates and South Australian men consumed the largest amounts of fats. (Table 10.)
Geographic region was classified as metropolitan, rural centres, and rural and remote areas. Median nutrient intake by adults varied across geographic areas. (Tables 14 and 16.) Some illustrations include:
Region of birth Nutrient intake for persons aged 19 years and over varied across region of birth and there were marked differences in the composition of nutrient intake for adults born in East Asia and Australia (see the Glossary). Adults born in East Asia consumed much larger amounts of protein, total carbohydrate, starch and cholesterol than other adults. Their ratio of starch to sugars intake was also much higher than other adults. They also consumed smaller amounts of fat, sugars and dietary fibre. Men born in Australia consumed more energy, moisture, fat and sugars than other men. Women born in Australia and the United Kingdom, Ireland and New Zealand consumed more moisture, fat and sugars than other women. (Table 18.) Adults born in East Asia consumed more provitamin A and zinc but less calcium than other adults. Adults born in Australia and the United Kingdom, Ireland and New Zealand generally had the highest intakes of the B vitamins (thiamine, riboflavin, niacin equivalents and folate), calcium and other minerals. (Table 20.) Index of relative socio-economic disadvantage for areas The index of relative socio-economic disadvantage for areas assigns an index to geographic areas based on socio-economic variables such as economic resources, education and occupation. Adults living in the most disadvantaged areas (those in the first quintile) had the lowest median intakes of most nutrients, whereas adults living in the least disadvantaged areas (those in the fifth quintile) generally had the highest intakes. The main exception was alcohol intake, which was actually highest for men and women living in the most disadvantaged areas. (Tables 22 and 24.) Weekday/weekend There was a clear difference between median nutrient intake on weekdays and the weekend. (Tables 26 and 28.) The main differences were:
Season Some features of median nutrient intake for adults by season were:
Body mass index There was a clear relationship between body mass index (BMI) and reported nutrient intake for both sexes. For women, energy and macronutrient intake was highest for those in the underweight range. As BMI increased there was a clear decline in intake, with obese women consuming the lowest amounts. There was the same decline in vitamin and mineral intakes with increasing BMI for women. (Tables 34 and 36). The same general pattern was evident for men. Men with a BMI in the acceptable range reported the largest median intakes of energy and most macronutrients, whereas obese males reported the smallest intakes of energy, saturated fat, cholesterol, total carbohydrate, starch and dietary fibre. Vitamin and mineral intake was also highest in acceptable weight males and lowest in obese males. The exceptions were total vitamin A, calcium and potassium, which were highest in underweight males.
Some overweight and obese people may consume small amounts of nutrients consistent with lower physical activity levels and/or dieting. However, there may also be under-reporting of food consumption. The median EI/BMR ratio in obese men and in overweight and obese women was below that required even for minimal sedentary activity (see Appendix 4). FOOD SOURCES OF NUTRIENTS Information on the main food sources of each nutrient reflects both the amount of food consumed and the level of nutrient found in the food. In the following discussion, the term 'major sources' refers to food groups that contributed about 10% or more to intake of a specific nutrient. The term 'moderate sources' refers to food groups that contributed about 5%-10%. See Appendix 2 for further information about the food groups. At the major food group level, cereals, cereal-based products, milk products and meat were the major contributors to nutrient intake. Other food groups that made major contributions included: fruit products and non-alcoholic beverages to intake of sugars; and fats and oils (e.g. butter, margarine and cooking oils) to intake of fat. However, the contribution varied by nutrient, particularly at the sub-major food group level. (Tables 37-63.) Energy Energy from food provides the 'fuel' for growth, movement, metabolism and physical activity. Approximately half of energy intake came from cereals, cereal-based products and milk products. Regular breads and rolls provided about 10% of energy intake across all ages, as did dairy milk for children aged 2-11 years. Moderate sources of energy included: potatoes for all ages; dairy milk for adolescents and adults; and fruit and vegetable juices and drinks for children and adolescents. (Potatoes include products such as hot chips, mashed potato, potato patties and potato salad, as well as simpler versions of potato.) (Table 37.) Protein Protein supplies amino acids and is also a source of energy. Approximately half of protein intake came from milk products and meat products, and a further 30% came from cereal products and cereal-based products. Major sources of protein intake were: regular breads and rolls; dairy milk for children and adolescent males; and muscle meat for adolescents and adults. Moderate sources of protein intake were: dairy milk for adults and adolescent females; muscle meat for children; and, for all ages, mixed dishes where cereal is the major ingredient, poultry and other feathered game and mixed dishes where beef or veal is the major ingredient. (Table 39.)
Fat provides the most concentrated source of energy in the human diet, is a carrier for fat soluble vitamins and is a source of essential fatty acids. Fat also contributes to the palatability of foods. High intakes of fat, particularly saturated fat, are associated with elevated serum cholesterol, obesity and increased mortality from cardiovascular disease in populations where the level of physical activity is low. Pastries, mixed dishes where cereal is the major ingredient, potatoes, cheese and margarine were all moderate sources of total fat for all ages. (The fat from potatoes comes from fat added during cooking or preparation, e.g. hot chips or mashed potato.) Muscle meat was a moderate source for adults, but its contribution was lower for younger age groups. Dairy milk was a major source for children but only a moderate source for adults. (Table 40.) The contribution from particular foods to fat intake varied according to the type of fat. For example:
Dietary fibre Fibre attracts and absorbs water and helps to prevent constipation. Its effects on health are still incompletely understood but some components have a role in lowering blood cholesterol, while others help in controlling blood glucose and in protecting against the development of a number of intestinal problems. Foods of animal origin do not contain dietary fibre. Approximately 80% of dietary fibre came from cereal products, cereal-based products, fruit and vegetables. The major sources of dietary fibre were: regular breads and rolls for all ages; and potatoes for adolescents. Potatoes contributed a moderate amount to intake by children and adults. Other foods that contributed a moderate amount to dietary fibre intake were pome fruit, single source breakfast cereals, mixed source breakfast cereals and mixed dishes where cereals are the major ingredient. (Table 48.) Vitamin A Vitamin A is a fat soluble vitamin required for cell differentiation, growth and vision. Both preformed vitamin A (retinol) and provitamin A (carotenoids) contribute to the total vitamin A content, which is expressed as retinol equivalents. The major sources of preformed vitamin A were dairy milk and margarine for all ages, and organ meats and offal for adolescents and adults. (The contribution of organ meats and offal reflects its high level of preformed vitamin A, as only 1.6% of adults consumed these foods.) Foods contributing a moderate amount to preformed vitamin A were: cheese for all ages; frozen milk products and mixed source breakfast cereals for children and adolescents; and dairy fats (e.g. butter) for adults. (Table 51.) Carrots and similar root vegetables provided over 40% of provitamin A intake irrespective of age or sex. Other fruiting vegetables were a major source in adolescents and adults and a moderate source in children. Other moderate contributors were fruit and vegetable juices and drinks for children and adolescents, and soup for adults. (Table 52.) Folate Folate is a water soluble B vitamin which plays an essential role in metabolism and in the division of all body cells including those in blood. Survey estimates of folate intake are based on the natural folate content of foods and beverages and do not include additional folate from food and beverages fortified with folate. Cereal products, vegetables and milk products provided approximately 55% of folate intake for all ages. Adults obtained a higher proportion of folate from vegetable products and less from milk products than children and adolescents. Regular breads and rolls provided 12-14% of folate consumed. Moderate sources of folate included potatoes, dairy milk, fruit/vegetable juices and drinks and yeast extracts for all ages. In addition, tea made a moderate contribution to women's folate intake as did beer to men's intake. (Table 56.)
Calcium Calcium is a major component of bones and teeth. Approximately 50-66% of calcium intakes was provided by milk products, with 30-45% from dairy milk, about 10% from cheese and about 5% from frozen milk products. The contribution of most milk products was higher for children aged 2-11 years except for cheese. Regular breads and rolls and mixed cereal dishes also made a moderate contribution. (Table 58.) Iron Iron is essential because of its role in oxygen and electron transport. Animal sources of iron are better absorbed than those from plant food. The presence of vitamin C or animal protein enhances the availability of iron derived from plant foods. Approximately 55% of iron intake was provided by cereal products and meat products, with cereal-based products and vegetable products contributing an additional 20%. Cereal products made a larger contribution to children's iron intake than to adolescents' and adults' intake, and the reverse applied to meat products. (Table 61.) The major sources of iron intake were: regular breads and rolls for all ages; single source breakfast cereals for children and males aged 12-18 years; and mixed source breakfast cereals for all ages. Moderate sources of iron intake for all ages were mixed dishes where cereal is the major ingredient, potatoes, muscle meat and mixed dishes where beef or veal is the major ingredient. In addition, single source breakfast cereals were a moderate source of iron intake for adult males and females aged 12 years and over, as was tea for adults. Zinc Zinc has a major role in protein and carbohydrate metabolism and is needed for many different functions, including growth, sexual maturation and wound healing. The major sources of zinc intake were: dairy milk for children and adolescent males; and muscle meat for adolescents and adults. Dairy milk made a moderate contribution for intake by adults and adolescent females, as did muscle meat for children. Moderate sources of zinc intake for all people aged two years and older were regular breads and rolls, mixed dishes where cereal is the major ingredient and mixed dishes where beef or veal is the major ingredient. (Table 61.)
Tables 1-63 contain information based on a 24-hour recall period. Tables 64-89 contain information adjusted using data for a second 24-hour recall period collected from a small sub-sample of respondents. Information on percentile distributions of nutrient intake, adjusted for within-person variation, provides a better indication of the 'usual' range of intake in the population. Adjustments were made to all nutrients except alcohol. See paragraphs 27-35 of the Explanatory Notes for more information on the adjustments. The percentile distributions of adjusted nutrient intake describe the range of nutrient intake between the 10th and 90th percentiles. The range of intake was widely dispersed for calcium, riboflavin, vitamin C, provitamin A and total vitamin A expressed as retinol equivalents. The intake range was less dispersed for the other nutrients, that is the 10th percentile was up to 50% less than median intake and the 90th percentile was up to 70% more than median intake. The adjusted nutrient intakes are more appropriate than the unadjusted intakes for estimating the likelihood of nutrient inadequacy or excess in the population when the data are based on only a single day's intake for each person. Recommended Dietary Intakes (RDIs) are the levels of essential nutrients considered adequate to meet the nutritional needs of most healthy individuals (NHMRC 1991). They are based on estimates of requirements for age and sex groups and, therefore, apply to group needs. As they incorporate generous factors to allow for variations in metabolism, absorption and individual needs, RDIs exceed the actual nutrient requirements for practically all healthy people. Therefore, they are not synonymous with requirements. See Appendix 3 for the RDIs of the nutrients described in this publication. Issues to be taken into account when comparing population intakes with RDIs include:
PHYSICAL MEASUREMENTS With participants' written consent, the blood pressure (of those aged 16 years and over), height, weight, and waist and hip circumferences were measured by trained interviewers (see paragraphs 16-18 of the Explanatory Notes). Pregnant women were excluded from this component of the survey. Height Males were generally taller than females at all ages. While boys aged under 12 years had a similar mean height to girls in this age group, males aged 12 years and over were much taller than females in every age group. Height increased rapidly during childhood. Average height increased from 96 cm for both girls and boys aged 2-3 years until the age of 19-24 for males (178 cm) and 16-18 years for females ( 164 cm). Average height then decreased with age to 170 cm for men aged 65 years and over and 157 cm for women aged 65 years and over. The decrease in average height with age in adults is largely due to two factors: a general trend over time for new generations to be taller than previous generations; and a loss of height by individual adults as part of the ageing process. (Table 90.) Weight On average, males were heavier than females. Mean weight was approximately the same for boys and girls aged under 12 years but was higher for males than females in all other age groups. This is the same pattern as was evident for height. Average weight was greatest in men and women aged 45-64 years, in contrast with the peak in height for 16-24 year olds. This ongoing weight gain, after maximum height is reached, is possibly due to factors such as exercise and diet. (Table 90.)
Overweight and obesity Indicators of underweight, overweight and obesity vary with age, although all indicators are based on weight in relation to height. For adults, BMI was derived. Adult BMI categories are, however, inappropriate for children and adolescents as both weight and height are age and sex dependent. Consequently, 'weight for height' has been derived for children aged 2-8 years (see the Glossary) and 'BMI for age' has been derived for people aged 9-18 years. Comparisons across all age groups should be made with care because of the different indicators used. Weight for height indicates whether a child is thin/wasted or overweight compared with others of the same sex and height, based on comparison with an international reference population (see Explanatory Notes and Glossary). Over 85% of children aged 2-8 years had a normal weight for height. A very small proportion of children of this age had low weight for height (thinness), and approximately 5% had a high weight for height (overweight). (Table 93.) BMI for age uses age and sex specific BMI cut-offs, based on international reference values (in contrast with the adult categories, for which the cut-offs are the same across all age and sex groups). The majority of people aged 9-18 years had a normal BMI for age (approximately 75%). A small proportion of 9-18 year olds were underweight, and about 23% were overweight or at risk of overweight. (Table 93.) Adults were classified as being underweight, acceptable, overweight or obese using the World Health Organisation's classification of BMI categories (see the Glossary for details). At every age, men were more likely than women to be overweight or obese. The proportion who were overweight or obese increased with age and peaked at 50-54 years for men and 60-64 years for women. Overall, 45% of men and 29% of women were considered to be overweight with a further 18% of both men and women being classified as obese. For people aged 45 years and over, only about 25% of men and 35% of women were within an acceptable weight range for their height. (Table 94.)
Waist and hip Waist and hip circumferences were largest for men and women aged 45 years and over. On average, males aged 12 years and over had larger waists than females, whereas girls and boys aged 2-11 years were similar within each age group. The average waist circumference for persons aged 19 years and over was 94 cm for men, compared to 81 cm for women. In contrast, hip measurements were generally similar for males and females within the same age group. The average hip circumference for persons aged 19 years and over was 102 cm for men and 103 cm for women. (Table 91.) However, height, weight and waist circumference for males were larger than for females from 12 years of age. The waist to hip ratio (WHR) was calculated for people aged 19 years and over. A high WHR is generally indicative of excessive abdominal fat which is associated with an increased risk of cardiovascular disease. The mean WHR was higher for men than women (0.91 compared to 0.79) and it increased with age. WHR greater than 0.9 in men and 0.8 in women is considered to be of concern (Ball et al. 1993). The proportion of people exceeding these thresholds increased with age, with more men (55%) having a high WHR than women (36%). (Table 91.)
Blood pressure was measured for respondents aged 16 years and over, with the exception of pregnant women. On average, systolic and diastolic blood pressures were slightly higher for men than women. Mean systolic blood pressure was relatively similar for people below 45 years of age (111-114 mmHg for women and 122-124 mmHg for men) and then increased with age to an average of 143 mmHg for people aged 65 years and over. Mean diastolic blood pressure increased with age and peaked at an average of 79 mmHg for people aged 45-64 years. (Table 95.) High blood pressure is an important risk factor for coronary heart disease and stroke. People with high blood pressure were classified to a hypertension category based on their systolic and diastolic blood pressure and use of blood pressure medication (see the Glossary for more information). Less than 5% of people aged 16-44 years were hypertensive, compared to 23% of people aged 45-64 years and 48% of people aged 65 years and over. (Table 95.)
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