Dietary intake of older Victorians

Transcription

1 Dietary intake of older Victorians Catherine A. McCarty, Mukesh B. Nanjan and Hugh R. Taylor Abstract Objectives: To describe the nutrient intake of Victorians aged 44 years and older and to compare this intake with recommended levels. Design: Cluster stratified sampling was employed to enable recruitment of subjects by household census. Subjects were recruited and attended baseline examinations from 1992 to 1994 and were followed-up five years later. Dietary data were collected at follow-up using a four-page self-administered food frequency questionnaire. Subjects: 3271 adults aged 40 years and older who were permanent Australian residents and lived in Victoria between 1992 and were alive for the five-year follow-up. Setting: Data were collected from participants of the Melbourne Visual Impairment Project. Main outcome measures: Dietary intake of vitamins A, B complex, C and E, and iron, calcium and zinc. Statistical analysis: χ 2 analysis for categorical data and student s t-test for continuous data. Results: Of the 3040 participants eligible to return for follow-up examinations, 2594 (85%) participated, 51 (2%) had moved interstate or overseas, 83 (3%) could not be located, and 312 (10%) refused to participate. The mean age of the participants examined at follow-up was 62.5 years (SD ± 10.9; range, ) and 1421 (55%) were female. Nutrients for which more than half the population consumed less than the daily RDI included: vitamin A, vitamin E, calcium, magnesium, iron (women of child-bearing age only) and zinc. Intake of anti-oxidant supplements had very little influence on the percentage of participants who consumed less than the RDI. Ten per cent or fewer of the population had average daily intakes less than the RDI for the following nutrients: vitamin C, niacin, iron (all except younger females), and sodium. Sixty-nine per cent of the population had average daily fat intakes greater than the recommended limit of 30% of energy intake, while the mean saturated fat intake was greater than 12% for all ages. Discussion: In conclusion, these population-based data have identified a number of nutrients for which the usual intake does not meet RDIs or national guidelines. Public health campaigns are warranted to increase the consumption of low fat foods high in calcium, iron, and anti-oxidants, and to decrease the daily intake of saturated fat. (Nutr Diet 2002;59:12 17) Key words: nutrient intake, adults, anti-oxidants Introduction - and gender-specific recommended dietary intakes (RDIs) have been produced and published by the National Health and Medical Research Council (1). They are set at levels that exceed the nutrient requirements for almost all healthy persons because they incorporate factors to accommodate variations in absorption and metabolism. The RDIs are updated periodically to reflect current scientific knowledge about nutrient intake and health and disease relationships. To assist people in food selection to meet the RDIs, and to promote health and prevent disease, the National Health and Medical Research Council has released dietary guidelines (2,3). Periodic surveys of dietary intake have been undertaken in Australia (4 8). Large differences in dietary intake by gender and ethnicity have been observed (9 12). The purpose of this study was to quantify the dietary intake of Victorians aged 44 years and older and to compare their nutrient intake with RDIs. Methods The Melbourne Visual Impairment Project was a population-based epidemiologic study of eye disease (13). Random cluster sampling was employed to identify nine pairs of census collector districts within the Melbourne statistical division from which to recruit all permanent residents aged 40 years and older. A household census was employed to identify and recruit eligible residents. Eighty-three per cent of eligible residents (n = 3271) attended the baseline examinations, which were conducted from 1992 to 1994 (14). This cohort was shown to be representative of the Melbourne and Australian population aged 40 years and older (14). Five-year follow-up examinations of the surviving members of the cohort were conducted from 1997 to The protocol was approved by the Human Research and Ethics Committee of the Royal Victorian Eye and Ear Hospital. At the initial household census, basic demographic information was collected from each participant including age, gender, country of birth, language spoken at home, education, and use of eye care services. At locally established test sites, participants underwent a standardised clinical eye examination and health interview that included questions on the use of medications and dietary anti-oxidant supplements. In relation to dietary antioxidant supplement use, people were asked to provide the name, frequency and duration of use for every supplement that they had ever taken on a regular basis (i.e. at least once per week for at least one month). Nutrient constituents of all products were obtained from supplement labels or from the manufacturers. The amount of the following The Melbourne Visual Impairment Project was funded in parts by grants from the National Health and Medical Research Council, the Victorian Health Promotion Foundation, the Ansell Ophthalmology Foundation, the estate of the late Dorothy Edols, the Jack Brockhoff Foundation, the Eye Ear Nose and Throat Research Institute, the Appel Family Bequest and the Hugh Williamson Foundation. Dr McCarty was the recipient of the Wagstaff Fellowship in Ophthalmology from the Royal Victorian Eye and Ear Hospital. Centre for Eye Research Australia, University of Melbourne C.A. McCarty, PhD, MPH, RD, formerly, Associate Professor (currently Senior Research Scientist, Marshfield Medical Research and Education Foundation, Marshfield, WI, USA) M.B. Nanjan, PhD, Research Fellow H.R. Taylor, MD, FRACO, Ringland Anderson Professor Correspondence: C. McCarty, Marshfield Medical Research and Education Foundation, Marshfield Clinic, 1000 N. Oak Avenue (ML2), Marshfield, WI 54449, USA. mccartyc@mmrf.mfldclin.edu 12 Nutrition & Dietetics (2002) 59:1

2 anti-oxidants in each product was recorded: vitamin A, β- carotene, vitamin C, vitamin E and zinc. Details about the use of dietary supplements other than these anti-oxidants was neither collected nor coded. Questions concerning the use of anti-oxidant supplements were repeated at the follow-up. Modified home examinations were offered for homebound residents. Interpreters were offered for anyone who did not speak English as their first language. One field team member spoke Greek and one field team member spoke Italian. At follow-up the participants were asked to complete a four-page, self-administered food frequency questionnaire that was developed by researchers at the Anti-Cancer Council of Victoria (15). These questionnaires were available in Greek and Italian as well as English. The completed questionnaires were checked to ensure that all questions were answered, and were then sent to the Anti-Cancer Council of Victoria for nutrient analysis. Daily intake of the following nutrients was quantified: total energy, protein, total carbohydrate, complex carbohydrate, simple carbohydrate, total fat, saturated fat, polyunsaturated fat, mono-unsaturated fat, cholesterol, alcohol, fibre, vitamin A, thiamin, riboflavin, vitamin C, vitamin E, niacin, folate, calcium, iron, potassium, magnesium, phosphorous, zinc and sodium. The percentage of energy from protein, fat, saturated fat, polyunsaturated fat and carbohydrate was calculated. Participants were also asked about their intake of supplemental anti-oxidants including vitamin A, vitamin C, vitamin E and zinc because antioxidants have been shown to be associated with a reduced risk of cataract (16) and age-related maculopathy (17). The percentage of participants with dietary intakes less than the RDI (1) were calculated. This percentage was recalculated with the addition of the supplementary intake. Interview data were entered directly into a Paradox data entry program (Borland International, Scotts Valley, California) with in-built consistency checks. Demographic data were entered twice and verified. Data were analysed with the SAS statistical package (SAS Institute, Cary, North Carolina, SAS, version 6.10, 1999) Data were stratified by age and gender (44 to 64 years old and > 64 years old for males, and 44 to 54 years old and > 54 years old for females) to allow comparison with the RDIs. Analyses were also stratified by the major non-australian-born ethnic groups represented in the cohort Greek-born and Italian-born. Chi-squared analyses were used for categorical data and independent student s t-tests were used for continuous data. A P < 0.05 was considered statistically significant. Results Two hundred and thirty-one (7.1%) of the original 3271 participants died before the five-year follow-up examination. Of the remaining 3040 participants eligible to return for follow-up examinations, 2594 (85%) did participate, 51 (2%) had moved interstate or overseas, 83 (3%) could not be located, and 312 (10%) refused to participate. Reasons for refusal were provided by 222 of the 312 refusals and included the following: not interested (33.8%), other or multiple answers (17.1%), too busy (12.2%), unhappy with drops from the previous examination (9.0%), illness (8.1%), personal (6.3%), apprehension (6.3%), disagree with the study (4.5%), and language (2.7%). The mean age of the participants examined at follow-up was 62.5 years (SD ± 10.9; range, ) and 1421 (55%) were female. The percentage of participants who reported taking any vitamin or mineral supplement was 20.3 (433/2133). Females were significantly more likely to report use of supplements (23.9% versus 16.2%, χ 2, 1df = 19.4, P < 0.001). The percentage of participants who took various anti-oxidant supplements varied by age and gender (Figure 1). For all age groups, females were more likely to use supplements than males. Younger males and females were more likely to use anti-oxidant supplements, with the exception of vitamin A supplementation in females. Vitamin C was the most commonly used anti-oxidant, with 15.6% of the entire cohort reporting its use. The mean daily dietary intake of these four anti-oxidants was not significantly different between the users and non-users of the various anti-oxidants (data not shown). The dietary intake of vitamins and minerals and percentage of participants with intakes less than the RDI are presented in Tables 1a and 1b, stratified by age and gender. Nutrients for which more than half the population consumed less than the daily RDI included: vitamin A, vitamin E, calcium, magnesium, iron (women of childbearing age only) and zinc. Intake of anti-oxidant supplements did not change significantly the percentage of participants who consumed less than the RDI. Ten per cent or fewer of the population had average daily intakes less than the RDI for vitamin C, niacin, iron (all except younger females) and sodium. The percentage of participants who consumed less then the RDI daily for various nutrients was evaluated separately for the two ethnic groups with sufficient numbers to allow relatively precise stratified analyses, i.e. Greek-born and Italian-born (Table 2). The nutrients that were consumed at an average level less than the RDI by 50% or more of the population were: vitamin A, riboflavin (younger Greek males), vitamin E, folate (older Italians), calcium, iron (Italian women of child-bearing age), potassium (older Italian men), magnesium, phosphorous (all Italian women and older Italian men), and zinc. Again, anti-oxidant supplement intake did not improve significantly the percentage of people consuming less than the RDI for those anti-oxidants. The mean and range of daily intake of macronutrients in the population are summarised in Table 3. The mean Figure 1. Percentage Percentage of participants who took anti-oxidant supplements by age and gender Vitamin A Vitamin C Vitamin E Zinc Males Males >64 Females Females > Nutrition & Dietetics (2002) 59:1 13

3 percentage of energy derived from the various sources, as calculated in the lower section of Table 3, was nearly identical between the genders and age groups. The percentage of men with greater than 8% of their energy intake from saturated fats was 92.6%, compared with 87.3% for women (χ 2, 1df = 17.4, P < 0.001). Eight per cent of men and 9% of women had daily alcohol intakes that exceeded the guidelines from the National Health and Medical Research Council (i.e. no more than 40 g for men and no more than 20 g for women) (2). Discussion These data provide population-based information about the nutrient intake profile of a random sample of Melbourne residents aged 44 years and older. They indicate a number of nutrients for which a public health campaign is warranted to encourage increased intake to promote health and prevent disease. The only sub-group of the population that should be specifically targeted separately is women, due to their low iron intake relative to the RDI. These die- Table 1a., median and range of average daily intake of vitamins by age and gender Males Females Vitamin Vitamin A (µg) (diet Vitamin A (µg) (incl Vitamin E (mg) (diet Vitamin E (mg) (incl Vitamin C (mg) (diet Vitamin C (mg) (incl (years) Median RDI (1) (years) Median RDI (1) > > > > > > > > > > > > Thiamin (mg) > > Riboflavin (mg) > > Niacin (mg equivalent) > > Folate (µg) > > Table 1b., median and range of average daily intake of minerals by age and gender Males Females Mineral (years) Median RDI (1) (years) Median RDI (1) Calcium (mg) > > Phosphorus (mg) > > Magnesium (mg) > > Iron (mg) > > Zinc (mg) (diet Zinc (mg) (incl > > > > Potassium (mg) > > Sodium (mg) > > Nutrition & Dietetics (2002) 59:1

4 tary data could provide baseline information to assess the impact of any public health campaigns implemented. The strengths of this study include the cluster sampling and relatively high response rate that resulted in a study sample that has been shown to be representative of the Melbourne statistical division and Australia in general (14). The relatively large number of Italian-born and Greek-born participants allowed us to provide precise estimates of dietary intakes in these two subgroups of the population. The weakness of this study is that detailed information about nutrient supplement intake was only available for selected anti-oxidants, and not for all possible nutrients. Also, differential mortality by nutritional status could have affected the estimates of population dietary intakes in this follow-up study. The National Health and Medical Research Council has specific guidelines related to calcium intake, Eat foods containing calcium (2) for all Australians and specifically for older Australians, Include foods high in calcium (3). As estimated from food consumption data from 1985 to 1991, calcium was consistently the least available nutrient in Australia (7). Data collected in elderly Table 2. Percentage of Greek-born and Italian-born participants who had dietary intakes less than the recommended dietary intake (1), by age and gender Males (a) Females (b) Vitamins and minerals group (years) Greek-born Italian-born group (years) Greek-born Italian-born Vitamin A (diet > > Vitamin A (including > > Thiamin > > Riboflavin > > Vitamin C (diet > > Vitamin C (including > > Vitamin E (diet > > Vitamin E (including > > Niacin (mg equivalents) > > Folate > > Calcium > > Iron > > Potassium > > Magnesium > > Phosphorus > > Zinc (diet > > Zinc (including > > Sodium > > (a) Numbers of men in each group: 49 Greek men aged 44 to 64 years old, 24 Greek men aged >64 years old, 55 Italian men aged 44 to 64 years old, 49 Italian men aged >64 years old. (b) Number of women in each group: 21 Greek women aged 44 to 54 years old, 65 Greek women aged >54 years old, 25 Italian women aged 44 to 54 years old, 75 Italian women aged >54 years old. Nutrition & Dietetics (2002) 59:1 15

5 South Australians (5) in the 1980s and in a Victorian survey (4) in 1985 and 1990 revealed that more than half of the population had intakes of calcium less than the RDI. Data from the national food consumption survey (18) and the national nutrition survey (19) reveal that calcium has consistently been shown to be consumed at a level less than the RDI and that this figure has not changed significantly over time. Our data, collected from 1997 to 1999, confirmed that calcium continues to be a problem nutrient, with the majority of adults failing to meet the daily RDI. Similar to the previous Victorian survey (4), we found that more women than men have diets deficient in calcium and that the older age groups are more deficient in calcium intakes than the younger age groups. The percentage of women aged 54 years or older in our study who had daily calcium intakes less than the RDI (82%) was considerably higher than the percentage of women aged 60 years or older reported in the 1985 (75%) and 1990 (50%) Victorian nutrition surveys with deficient calcium intakes. The subgroup of our study population with the lowest intake of calcium in relation to the RDI was Italian women. These findings highlight the need to educate the public to increase their intake of low-fat foods high in calcium to decrease their risk of osteoporosis (2). This is especially important as the number of elderly persons is increasing (20) and bone density decreases with age (2), thus predisposing people to osteoporosis. In addition to dairy foods as a generally well known source of calcium, tinned salmon, sardines and shellfish are also good sources (21). A nutrient of particular concern to women of childbearing age is iron. The National Health and Medical Research Council has a specific guideline for Australians that reads, Eat foods containing iron (2). In our study, the majority of women aged 44 to 64 years did not consume the RDI for iron. Again, this was higher than was reported in the 1985 and 1990 Victorian Nutrition Surveys (4) and could indicate that dietary iron intake has decreased in the past decade, perhaps as people eat less meat in an attempt to decrease their total fat intake. Foods high in iron include red meats, silver beet and spinach (20). The dietary intakes of anti-oxidant vitamin A, vitamin E and zinc were all identified in the current study to be deficient in the majority of adults. Similar to a study of Victorians conducted in 1985, we found no consistent relationship between the intake of these anti-oxidants and age (9). It has been suggested that low anti-oxidant intake may be related to cancer (9), cataract (16) and age-related macular degeneration (17). Low fat food sources of many of these anti-oxidants include apricots, mangoes, rock melon, cabbage, carrot, capsicum, pumpkin, spinach, sweet potato and silver beet (21). Nuts and seeds are good sources of vitamin E in addition to oils. For all of these deficient nutrients, the difference between the mean intake in the population and the RDI for that nutrient is the equivalent of one serving of food high in that particular vitamin or mineral. For example, a 100 g edible portion of raw spinach contains 53 mg of calcium, 390 µg of retinol (vitamin A) equivalents, 68 mg of magnesium, and 3.2 mg of iron (21). This one food could Table 3. average daily intake of macronutrients by age and gender Males Females Macronutrient years, n = 615 >64 years, n = years, n = 367 >54 years, n = 903 Energy (kcal) Protein (g) Carbohydrate (g) Complex carbohydrate (g) Simple carbohydrate (g) Total fat (g) Saturated fatty acids (g) Polyunsaturated fatty acids (g) Mono-unsaturated fatty acids (g) Cholesterol (g) Alcohol (g) Fibre (g) Percentage of energy as Protein Fat Saturated fatty acids Polyunsaturated fatty acids Total carbohydrate Sugars Starches Nutrition & Dietetics (2002) 59:1

6 supply sufficient amounts of nearly all of the nutrients that are deficient in the diets of Victorians. The addition of oil and vinegar dressing would supply the necessary vitamin E to meet all of the deficient needs. The National Health and Medical Research Council advises that Australians should Eat a diet low in fat and, in particular, low in saturated fat (2) and that older Australians should Eat a diet low in saturated fat (3) because of epidemiologic evidence linking high fat intake with cancer and heart disease. The National Heart Foundation recommends that trans fatty acids and saturated fatty acids together should contribute no more than 8% of total energy intake (22). In the current study, the mean intake of saturated fatty acids was 12%, well above recommendations, and the vast majority of the population had intakes exceeding recommendations. However, the data do support a trend towards a decrease in percentage of total energy from saturated fat as was observed between the 1985 and 1990 Victorian nutrition surveys for both genders and all ages (6). For both males and females, the calculated saturated fat intake was about 1% less in the current study than was calculated in 1990, which was approximately 1% less than was calculated in The Victorian data mirror the overall national trends for fat consumption that have been documented in the national food consumption survey (18) and the national nutrition survey (19). It appears that public health programs to decrease fat intake are resulting in positive dietary changes and should continue to be supported. The National Health and Medical Research Council recommends to Australians that, If you drink alcohol, limit your intake because excess alcohol intake is associated with increased morbidity and mortality (2,3). Slightly less than 10% of the population had average daily alcohol intakes that exceed recommendations (no more than 40 g or approximately four standard drinks per day for men and no more than 20 g or approximately two standard drinks per day for women). In conclusion, these population-based data for older Australians have identified a number of nutrients for which the usual intake does not meet RDIs or national guidelines. Public health campaigns are warranted to increase the consumption of low fat foods that are high in calcium, iron, and anti-oxidants, and to decrease the daily intake of saturated fat. Public health messages to encourage increased intake of fresh green leafy vegetables, low fat meat and low fat dairy products would assist the community in meeting the RDIs and guidelines that are currently not met. Improved nutritional intake could decrease nutrition-related morbidity and mortality. References 1. National Health and Medical Research Council. 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