Dietary Changes in Older Americans From 1977 to 1996: Implications for Dietary Quality
Shirley A. Gerrior
More attention is being paid to the nutritional status and nutrition-related health needs of older Americans, as well as to the relationship between nutrition and the ,development of older Americans’ many chronic diseases. Older people are a rapidly growing segment of the U.S. population. In 1996, 12 percent of the U.S. population was over age 65; in 1900, 4 percent of the population was over age 65 (18,19). By 2050 the older population will more than double, with most of the growth occurring between 2010 and 2030 when members of the baby-boom generation enter their elderly years (18). Among older Americans, women outnumber men by 6 million (18.9 versus 12.9 million) because of a higher death rate among older men (18,19). It is therefore important to examine the dietary quality of Americans over age 65 and to evaluate changes in their food and nutrient intakes over time. A better understanding of the dietary quality and food and nutrient intakes of elderly Americans will help identify those at nutritional risk and those whose nutritional status may be improved by preventive nutritional interventions. Accordingly, policymakers and nutrition professionals will need to target food and nutrition programs for elders, establish policies related to food fortification, and develop nutrition- and health-related strategies that help elders better meet the nutritional challenges associated with aging.
The importance of proper nutrition throughout the life cycle is key in determining quality of life. Proper nutrition helps to diminish health problems and physiological decline associated with poor diets and poor health habits over a lifetime. And in the later years, good nutrition helps to maintain a more healthful lifestyle and one with greater independence. An increasing percentage of elderly people, as they age, face chronic, limiting illnesses or conditions such as arthritis, poor dentition, reduced gastrointestinal functioning, diabetes, osteoporosis, senile dementia, and depression. These conditions may result in an overall decrease in their intake of food energy and essential nutrients. These conditions will, as well, impair an older person’s ability to purchase and prepare nutritious foods, the result of which may be dependency on others for help performing daily activities (6,11).
In general, data on food intake from national dietary surveys (2,14), as well as others (4,12), suggest that older Americans consumed less food than required to meet recommendations for food energy and nutrients. Many older Americans, including the presumably healthy, have reported nutrient intakes below the recommendation for food energy, vitamin E, vitamin B6, calcium, magnesium, and zinc (14). These low intakes, however, may be a problem of the survey methods used, that is, underreporting of the foods consumed.
Recent findings from the Third National Health and Nutrition Examination Survey (NHANES III) indicate that 18 percent of the men and 28 percent of the women underreported their energy intakes (2). Underreporting of energy intake was highest in women and persons who were older, overweight, or trying to lose weight.
Also, intakes of vitamins, minerals, fiber, and macronutrients were significantly lower and, in general, paralleled energy intakes. Although underreporting of food quantities and food energy has been observed among the elderly, it is not a unique problem of this segment of the population.
Despite underreporting by the elderly, they may actually eat less as they age because of a number of factors, including a decline in physical activity and a decrease in appetite. Also, surveys show that energy intakes are consistently low for the elderly (2,3,12,14,15), suggesting a real decline in food and nutrient intakes with age. This contrasts with a higher mean energy intake by the general population that is seen in the more recent surveys where additional probes were used for purposes of enhancing recall (2,15). Thus despite the limitation of survey respondents underreporting food quantifies and food energy, dietary survey data are useful when assessing the dietary quality and food and nutrient intakes of the elderly, and the data provide important information on the nutritional status of the elderly.
This study examines the dietary quality of Americans over age 65 and evaluates changes in their food and nutrient intakes from 1977-78 to 1994-96. Nutrient intakes and consumption of major food groups and subgroups from 1977-96 are examined in terms of current dietary guidance. By increasing our knowledge of the dietary behaviors of older people and observing changes in these behaviors over time, we can more effectively evaluate nutrition education efforts and determine future directions for nutrition intervention, the goal of which is to improve the quality of life for this segment of the population.
Methods
Data Source
Data for this study were from the USDA’ s Nationwide Food Consumption Survey of 1977-78 (NFCS 77-78) (16,17) and the 1989-91 and 1994-96 Continuing Survey of Food Intakes by Individuals (CSFII) (14,15). The NFCS 77-78 included individuals selected from stratified-area probability samples of noninstitutionalized households in the 48 conterminous States. For the NFCS 77-78 four waves were conducted, one for each season, and each on a different sample of participants (8,9). Individual dietary data for 3 consecutive days were obtained through a mix of a 24-hour recall and 2-day food records.
The CSFII for 1989-91 and 1994-96 comprise a nationally representative sample of noninstitutionalized persons residing in the United States for each year of the 3-year data sets. For the 1989-91 CSFII, the USDA used a 1-day recall and a 2-day dietary record to collect food intake data for 3 consecutive days (14). The 1989-91 CSFII included an all-income and a low-income sample, which were combined through sample weights. For the 1994-96 CSFII, USDA collected 2 nonconsecutive days of dietary data for individuals of all ages.
The data were collected between January 1994 and January 1997; in-person interviews were used to collect the 24-hour recalls. Only the first day of dietary intake data was used because day-1 data (for each of the surveys used) were collected using the 24-hour recall method. Methods of data collection used on subsequent days were not as comparable. Research has indicated that food intake data based on 1-day dietary intakes provide reliable intakes by groups of people (1). Thus, to best examine changes over time from surveys with different numbers of days of dietary information, this study compared estimates of food and nutrient intake among the surveys based on only the first day’s data collected for each individual.
The data were collected from selected individuals in each household. The method for collecting the 24-hour recall was modified from previous surveys to improve the collection of dietary intake data and included more questions that probed the respondents’ recollection (15).
Sample
In this study, older men and older women made up 10 to 12 percent of the U.S. population between 1977 and 1996: men, 4 to 5 percent; women, 6 to 7 percent. The sample selected for analysis consisted of persons older than age 65 who provided a valid 1-day, 24-hour recall of dietary intake. For each of the three surveys, the USDA developed sample weights to adjust for survey response and for other vagaries of sample selection. Use of weighted data provides results that are more characteristic and generalizable to the U.S. population.
Nutrient Analysis
This study examined food energy, 15 nutrients, and dietary components. Nutrient data were not available in the NFCS 77-78 for saturated fat, cholesterol, folate, vitamin E, zinc, dietary fiber, and sodium. The nutritive value of the foods the elderly said they consumed was calculated using the USDA’s Nutrient Data Bank and survey databases for 1977-78, 1989-91, and 199496. Average nutrient intakes for 1 day were computed for these three periods.
Nutrient intakes as a percentage of the 1989 Recommended Energy Allowance (REA) or Recommended Dietary Allowances (RDA) were used in this study.
They were derived by dividing an individual’s intake by the REA or RDA for the appropriate age/gender group.
Food Analysis
Ten major food groups (used by USDA) and 27 food items that reflect the total diet were analyzed (table 1). For the CSFII surveys, USDA has developed a Food Grouping System for separating mixtures into their component parts (14). However, in this study, for purposes of comparability between the NFCS and CSFII, food mixtures were not separated into individual ingredients. For example, grain and meat mixtures were placed into a grain or meat mixture category based on the primary ingredient (e.g., a macaroni and cheese mixture was assigned to the grain mixture group; the macaroni was not assigned to the grain group, and the cheese was not assigned to the milk group). Average intake in grams for each of the food groups and subgroups was calculated from 1-day recall for 1977-78 and 1994-96.
Table 1. Percentage change in average intake (grams per day), 1977-78 to 1994-96, for Americans over age 65
NFCS 1977-78 NFCS 1977-78
Men Women
Sample size 1,514 2,167
Grams
Total meat 223 155
Red meat 82 51
Luncheon meats 21 11
Poultry 27 24
Fish 10 9
Mixtures 67 46
Total milk and milk products 253 216
Total fluid milk 210 157
Whole milk 109 75
Reduced-fat milks 53 51
Cheese 14 17
Milk desserts 24 20
Eggs 39 21
Legumes, nuts, and seeds 28 16
Total grains 232 182
Breads and rolls 65 49
Other baked goods 65 45
Cereals and pasta 67 55
Grain snacks 3 3
Mixtures 31 31
Total vegetables 248 219
White potatoes 72 57
Tomatoes 29 29
Dark-green vegetables 11 12
Deep-yellow vegetables 12 15
Other vegetables 123 106
Total fruits 169 177
Citrus 66 74
Other fruits 103 103
Fats and oils 15 12
Table fats 9 6
Salad dressing 6 4
Sugars and sweets 30 20
Nonalcoholic beverages 617 571
Coffee 443 374
Tea 117 141
Carbonated soft drinks 41 41
Fruit drinks 16 17
CSFII 1994-96 CSFII 1994-96
Men Women
Sample size 1,101 1,026
Grams
Total meat 204 151
Red meat 39 24
Luncheon meats 21 13
Poultry 22 22
Fish 15 12
Mixtures 102 77
Total milk and milk products 260 211
Total fluid milk 185 148
Whole milk 43 29
Reduced-fat milks 93 70
Cheese 15 13
Milk desserts 37 28
Eggs 21 15
Legumes, nuts, and seeds 42 26
Total grains 301 232
Breads and rolls 61 48
Other baked goods 48 35
Cereals and pasta 102 71
Grain snacks 8 6
Mixtures 64 57
Total vegetables 252 210
White potatoes 66 47
Tomatoes 35 30
Dark-green vegetables 16 18
Deep-yellow vegetables 15 11
Other vegetables 120 104
Total fruits 214 195
Citrus 79 78
Other fruits 130 113
Fats and oils 17 14
Table fats 7 5
Salad dressing 9 9
Sugars and sweets 23 18
Nonalcoholic beverages 717 629
Coffee 419 344
Tea 131 147
Carbonated soft drinks 121 93
Fruit drinks 44 39
Men Women
Sample size
Percent change
Total meat -9 -3
Red meat -52 -53
Luncheon meats 0 18
Poultry -19 -8
Fish 50 33
Mixtures 52 67
Total milk and milk products 3 -2
Total fluid milk -12 -6
Whole milk -60 -61
Reduced-fat milks 65 37
Cheese 8 -24
Milk desserts 54 40
Eggs -46 -29
Legumes, nuts, and seeds 50 63
Total grains 30 27
Breads and rolls 6 -2
Other baked goods -26 -22
Cereals and pasta 52 29
Grain snacks 167 100
Mixtures 106 84
Total vegetables 2 -4
White potatoes -8 -18
Tomatoes 21 3
Dark-green vegetables 45 50
Deep-yellow vegetables 25 -27
Other vegetables -2 -2
Total fruits 27 10
Citrus 20 6
Other fruits 26 10
Fats and oils 13 17
Table fats -22 -17
Salad dressing 50 125
Sugars and sweets -23 -10
Nonalcoholic beverages 16 10
Coffee -5 -8
Tea 12 4
Carbonated soft drinks 195 127
Fruit drinks 165 129
Note: Food item totals may not equal food group totals because of rounding.
Statistical Analysis
Descriptive statistics were derived using the Statistical Package for the Social Sciences (SPSS) (13). Tests for significance were not performed. The differences in the sampling methods of the surveys and the use of sample weights limit the degree to which the survey data can be compared.
For this article, a “trend” was defined as a “change” in the consumption of a food or in nutrient intake. For a given food group (or food), a trend existed when the mean intakes of the food group or food rose or fell continually from 1977-78 through 1989-91 and to 1994-96. Further analysis with more complex methods (i.e., time trends or time series analysis) may reveal additional information.
Results
Changes in Average Daily Nutrient Intakes, 1977-96
From 1977-96, older men’s average intakes of food energy decreased (1,910 to 1,854 kcal); older women’s intakes remained essentially unchanged (1,401 to 1,407 kcal) (table 2). These intakes are below the 1989 REA for men (2,300 kcal) and women (1,900 kcal) (7). Both older men and women increased their intakes of vitamins A, C, and B6; calcium; iron; phosphorus; and magnesium. They decreased their intake of total fat: men by 20 grams and women by 11 grams. From 1989-96 intakes of dietary fiber increased slightly; intakes of folate, saturated fat, and cholesterol decreased. Also, intakes of zinc and sodium for men were lower in 1994-96 than they were in 1989-91.
Table 2. Mean nutrient intakes by gender for older Americans over age 65, 1977 to 1996
1977(1) 1977(1) 1989-91(2)
Men Women Men
Sample size 1,037 1,726 780
Mean
Food energy (kcal) 1,910 1,401 1,823
Total fat (gm) 88.3 61.6 68.2
Saturated fat (gm) 23.6
Cholesterol (gm) 284
Dietary fiber (gm) 17.5
Vitamin A (IU) 6,338 6,015 8,505
Vitamin C (mg) 87 87 110
Vitamin [B.sub.6] (mg) 1.63 1.3 1.9
Vitamin E (mg) 8.7
Folate ([micro] g) 309
Calcium (mg) 709 555 733
Iron (mg) 12.7 9.4 16.3
Phosphorus (mg) 1,194 897 1,204
Magnesium (mg) 257 202 287
Zinc (mg) 13.0
Sodium (mg) 3,275
1989-91(2) 1994-96(3) 1994-96(3)
Women Men Women
Sample size 1,377 1,101 1,026
Mean
Food energy (kcal) 1,392 1,854 1,407
Total fat (gm) 51.9 68.3 50.2
Saturated fat (gm) 17.6 22.5 15.9
Cholesterol (gm) 194 256 185
Dietary fiber (gm) 13.5 18.6 14.0
Vitamin A (IU) 7,651 8,613 6,464
Vitamin C (mg) 102 107 95
Vitamin [B.sub.6] (mg) 1.5 1.98 1.53
Vitamin E (mg) 7.1 8.9 6.7
Folate ([micro] g) 240 298 222
Calcium (mg) 596 778 587
Iron (mg) 12.0 16.6 12.6
Phosphorus (mg) 927 1,214 940
Magnesium (mg) 224 291 229
Zinc (mg) 8.6 11.0 8.3
Sodium (mg) 2,263 3,179 2,344
(1) Mean retakes per individual in a day, 1 -day data, 1977-78 NFCS.
(2) Mean retakes per individual in a day, 1-day data, 1989-91 CSFII.
(3) Mean retakes per individual in a day, 1 -day data, 1994-96 CSFII.
Average Intakes as a Percentage of Recommendation, 1977-96
Older Americans’ diets failed to meet the 1989 REA for food energy for each of the survey years, with women’s intake less than 75 percent of the REA (table 3). Both older men and women exceeded the recommendation for total fat (107 to 129 percent) and for saturated fat (103 to 118 percent) for all years. However, total fat and saturated fat intakes as a percentage of recommendation declined, an indication that in the past decade some progress was made in achieving the goals for fat intake. Whereas both older men and women met the cholesterol recommendation (300 milligrams or less per day), only older women met the sodium recommendation (2,400 milligrams per day). Older men and women failed to meet the dietary fiber recommendation of 25 grams per day: intakes ranged from 54 to 74 percent of the recommendation. Older men and women also failed to meet 100 percent of the RDA for vitamin B6, vitamin E, calcium, magnesium, and zinc. In 1994-96, calcium and zinc intakes for the elderly women were 75 percent or less of the RDA. Despite these shortfalls, intakes of calcium, vitamin B6, and magnesium were higher in 1994-96 than they were in 1977-78 and contributed to meeting a greater percentage of the recommendation.
Table 3. Average intake as percentage of recommendation by gender for older Americans over age 65, 1977 to 1996
1977(1) 1977(1) 1989-91(2)
Men Women Men
Sample size 1,037 1,726 780
Percent
Food energy(4) 83 74 79
Total fat 129 129 112
Saturated fat 118
Cholesterol 95
Dietary fiber 70
Vitamin A 127 150 170
Vitamin C 144 146 182
Vitamin [B.sub.6] 82 81 96
Vitamin E 87
Folate 154
Calcium 89 69 92
Iron 127 94 163
Phosphorus 149 112 150
Magnesium 73 72 82
Zinc 87
Sodium 136
1989-91(2) 1994-96(3) 1994-96(3)
Women Men Women
Sample size 1,377 1,101 1,026
Percent Percent
Food energy(4) 73 82 74
Total fat 112 111 107
Saturated fat 113 110 103
Cholesterol 65 85 62
Dietary fiber 54 74 56
Vitamin A 191 181 183
Vitamin C 169 172 160
Vitamin [B.sub.6] 93 99 95
Vitamin E 89 88 82
Folate 133 143 128
Calcium 74 96 75
Iron 120 167 125
Phosphorus 116 153 117
Magnesium 80 83 82
Zinc 72 77 70
Sodium 94 132 98
(1) Mean intakes per individual in a day, 1-day data, 1977-78 NFCS.
(2) Mean intakes per individual in a day, 1-day data, 1989-91 CSFII.
(3) Mean intakes per individual in a day, 1-day data, 1994-96 CSFII.
(4) Nutrient recommendations arc based on the 1989 Recommended Dietary Allowances; total fat is [is less than or equal to] 30 percent of total calories; saturated fat is < 10 percent of total calorics. Dietary fiber is based on daily intake of 25 grams: sodium, 2,400 milligrams; and cholesterol, [is less than or equal to] 300 milligrams.
The Percentage of Older Americans With Diets Meeting 100 Percent of the Recommendation, 1977-96
The percentage of older men and older women with intakes of food energy that met 100 percent of the REA was low: 25 and 17 percent, respectively in 1994-96, and it essentially remained the same over the 20-year period (table 4). From 1977-78 to 1994-96, the percentage of older men and women meeting 100 percent of the recommendation for intakes of total fat, vitamin B6, and iron increased notably. In 1989-91 and 1994-96, a higher percentage of older women than older men met 100 percent of the recommendation for nutrients that need to be consumed in moderation: Total fat, saturated fat, cholesterol, and sodium. The percentage of older men and women meeting 100 percent of the recommendation for mineral intake (calcium, magnesium, and zinc) was low throughout the study period.
Table 4. Percentage of older Americans by gender over age 65, with diets meeting 100 percent of the recommendation for intake, 1977 to 1996
1977(1) 1977(1) 1989-91(2) 1989-91(2)
Men Women Men Women
Sample size 1,037 1,726 780 1,377
Percent
Food energy(4) 26 16 21 13
Total fat 13 18 36 39
Saturated fat 40 43
Cholesterol 62 83
Dietary fiber 20 6
Vitamin A 40 46 49 51
Vitamin C 57 58 64 67
Vitamin B(6) 26 27 37 36
Vitamin E 23 26
Folate 62 58
Calcium 27 17 36 21
Iron 65 37 69 51
Phosphorus 80 55 77 58
Magnesium 17 19 25 23
Zinc 21 19
Sodium 30 61
1994-96(3) 1994-96(3)
Men Women
Sample size 1,101 1,026
Percent
Food energy(4) 25 17
Total fat 37 43
Saturated fat 43 50
Cholesterol 67 80
Dietary fiber 20 11
Vitamin A 50 51
Vitamin C 62 61
Vitamin B(6) 42 38
Vitamin E 27 28
Folate 60 57
Calcium 40 22
Iron 76 56
Phosphorus 80 62
Magnesium 28 27
Zinc 20 17
Sodium 33 55
(1) Mean retakes per individual in a day, 1-day data, 1977-78 NFCS.
(2) Mean intakes per individual in a day, 1-day data, 1989-91 CSFII.
(3) Mean intakes per individual in a day, 1-day data, 1994-96 CSFII.
(4) Nutrient recommendations are based on the 1989 Recommended Dietary Allowances; total fat is [is less than or equal to] 30 percent of total calories; saturated fat is < 10 percent of total calories. Dietary fiber is based on daily intake of 25 grams: sodium, 2,400 milligrams; and cholesterol, [is less than or equal to] 300 milligrams.
Changes in Average Intake (in grams per day) from 1977-96
Total meat products. In 1994-96 older Americans ate less total meat and 50 percent ate less red meat (beef and pork) than they did in 1977-78 (table 1). Not expected was the decrease during this period in poultry consumption by older Americans (19 percent less for men and 8 percent less for women). The average intake of fish and meat mixtures, however, increased substantially. Because meat mixtures may include appreciable amounts of red meat or poultry, actual consumption of these discrete foods may be higher than the individual food items indicate.
Total milk products. A noticeable shift from whole milk to reduced-fat milks occurred between 1977-78 and 1994-96, with the elderly drinking 60 percent less whole milk and 37 to 65 percent more reduced-fat milks. Despite this shift in milk types during this period, both older men and women consumed less fluid milk overall.
Eggs; legumes, nuts, and seeds. From 1977-78 to 1994-96, egg consumption decreased for both elderly men and women–more so for the men than for the women: -46 versus -29 percent. This is in contrast to the increased consumption of legumes, nuts, and seeds: 50 percent for men and 63 percent for women.
Total grains. Older men and women ate more grain products, especially grain mixtures and snacks (i.e., pizzas and pretzels), in 1994-96 compared with 1977-78. They also ate more cereals and pastas, with the change in men’s intake double that of women’s: 52 versus 29 percent.
Total vegetables and total fruits. Total vegetable intake between 1977 and 1996, on average, remained relatively constant for elderly Americans–they ate less white potatoes but more tomatoes and deep-green vegetables. Older men and women consumed about 50 percent more dark-green vegetables and older men about one-fourth more deep-yellow vegetables and one-fifth more tomatoes. Also, older men and women ate more total fruit, with their intake of both citrus and noncitrus fruits higher in 1994-96 than in 1977-78.
Fats and oils. Elderly Americans ate slightly more fats and oils in 1994-96 than they did in 1977-78, with a shift from table fat to salad dressings. For both men and women, their use of table fats (margarine and butter) in 1994-96 was about one-fourth less than their use in 1977-78.
Nonalcoholic beverages. While older Americans ate less sugar and sweets in 1994-96 than they did in 1977-78, their consumption of carbonated soft drinks and fruit drinks increased appreciably, counterbalancing the positive effects of consuming less sugar and sweets.
Discussion and Conclusions
Older Americans appear to be moving towards dietary guidance and closer to the 1995 Dietary Guidelines for Americans by incorporating nutrition education messages into healthful eating behaviors. From 1977-78 to 1994-96, older Americans made considerable changes in their diets. In 1994-96, their consumption of red meat, eggs, and sugars and sweets was lower than it was in 1977-78. Their consumption of legumes, total grains, and fruits was higher in 1994-96 than it was in 1977-78. This selection of food provided less fat, saturated fat, cholesterol, zinc, and sodium to their diet and more vitamins A and C, folate, dietary fiber, calcium, and other bone-related nutrients.
Despite these dietary changes, average intakes of food energy, dietary fiber, vitamins B6 and E, calcium, magnesium, and zinc were lower than recommendations. In particular, low calcium intakes are a concern for both older men and women, especially in terms of bone health. The declining use of fluid milk products, coupled with the increasing use of soft drinks and fruit drinks is a troubling trend. The consumption of soft drinks and fruit drinks is likely to displace more nutritious foods (e.g., milk products and fruits) from the diet and negatively affect diet quality.
Also, low intakes of dietary fiber and zinc require attention. While the intake of dietary fiber may be due to the low food energy intakes of this sample, these intakes are considerably below intakes expected of individuals consuming the recommended servings of fruits, vegetables, and whole-grain foods, based on the Food Guide Pyramid.
Older Americans have included more of these foods in their diets over the past 10 years. They, however, must continue to make more appropriate food choices and work harder to meet nutrient recommendations by increasing the number of servings of fruits, vegetables, and whole grains consumed, as well as by increasing their servings of milk and meat products. For example, including plenty of fortified cereal foods in the daily diet may counterbalance the loss of zinc from red meat and may also make important contributions to their intakes of magnesium and folate–thereby improving dietary quality. Overall, the low intake of food energy may prevent the older American from achieving the balance of foods needed for optimal diet quality, as indicated by the many nutrients below the recommendation.
In addition, the older Americans’ marginal and low dietary intakes of many minerals and vitamins are a concern. Older Americans may be at risk for micronutrient deficiencies not only from low dietary intakes but also from other non-food factors, such as the ability to buy and prepare food, the presence of disease, or limited income. While the marginal and low dietary intakes of some nutrients (vitamin E, calcium, magnesium, and zinc) in this study are suggestive of clinical deficiencies, such a risk has not been confirmed by biochemical or clinical markers. However, studies using biochemical markers provide some evidence regarding the link between low dietary intake and biochemical status.
The Boston Nutritional Status Survey of the Elderly and related work (10,12) suggest that older people, even in a relatively well-off and generally well-nourished population, may not be getting as much vitamins as they need. For example, plasma levels of pyridoxal phosphate and other measures of vitamin B6 status have been shown to decline with age. Erythrocyte activity (ETK-AC), a biochemical marker of thiamin, has shown a significant relationship between thiamin intake and blood levels. Using this marker, the researchers in the Boston study (12) categorized 5 percent of the study population as deficient, but the study noted that a correlation is more likely to exist between ETK-AC value and supplemental thiamin than between ETK-AC and dietary thiamin. Also, intake of riboflavin has been shown to have a significant effect on the erythrocyte glutathione reductase activity[1] coefficient (EGR-AC) in the population regardless of gender–with a deficiency noted in 5 to 16 percent of elderly people in technologically advanced countries (10).
For folate, the concentration of folate in erythrocytes is considered a better indicator of folate stores in the tissue. Serum levels accurately reflect recent dietary intake. Currently, the level of homocysteine is linked to a person’s folate status, with serum homocysteine levels correlated closely with folate intakes less than 400 [micro]g per day.
As with vitamins, the dietary intake of minerals also has shown a correlation with biochemical markers. Phosphorus intakes relate closely to blood phosphorus levels as does dietary iron and its storage to plasma ferritin levels levels (12). The requirements for calcium in terms of bone mineral loss over time have been linked to the biochemical marker, 25-hydroxy vitamin D–the levels of which are lower in older persons than in younger persons (10).
An older person’s risk for inadequate dietary intake is well established. The results presented from this study emphasize the fact that the quality of older Americans’ diet continues to need improvement. Nutrition intervention strategies need to be developed that improve nutrient intake for the older American. These strategies should emphasize the total diet and overall diet quality; they should help reduce the risk of chronic diseases associated with poor eating patterns. A diet needs to be low in fat and saturated fat and contain foods that provide adequate amounts of essential minerals, vitamins, and dietary fiber. For older people, efforts should be targeted to increase their intakes of food energy, dietary fiber, vitamin E, folate, calcium, magnesium, and zinc.
Limitations of Study
This study has two major limitations in terms of the implications presented: (1) the survey data and (2) the use of the RDA versus the Dietary Reference Intake (DRI) for assessment of dietary quality.
Survey data. The survey design and nutrient databases, underreporting by survey respondents, and the use of 24-hour recall data are included in this limitation. The use of different surveys and nutrient databases may make the data of the earlier years less comparable to the data of later years, especially in terms of the intake of fat and cholesterol and possibly folate. The nutrient data for the later surveys reflect improved data as well as changes in the nutrient content of foods that are attributable to new varieties and species, to new fortification levels, and to changes in the practices of the food industry.
Dietary intake was assessed using data from 24-hour recalls. Such data are poor indicators of a given person’s usual diet but are more useful to characterize a group’s intake when the sample size is sufficient (5). When providing dietary information, survey respondents tend to underreport consumption of certain foods, especially those foods high in fat and calories; they also tend to over-report consumption of foods (e.g., fruits) that are high in nutrients. Underreporting has decreased somewhat in more recent surveys (CSFII 94-96 and NHANES III) because more probes and collection methods have been added. Underreporting, however, remains a problem in certain subgroups, primarily women and persons who are older, overweight, or on a diet to lose weight. Additional research is needed to determine the extent of underreporting of foods consumed, food-preparation methods and ingredients, food quantities, and the effect of underreporting on estimates of food and nutrient intakes (2).
RDA vs. DRI. Adopted by the Food and Nutrition Board, Dietary Reference Intakes (DRI) represent the new approach to providing quantitative estimates of nutrient intakes for use in a variety of settings, thus replacing and expanding on the past 50 years of periodic updates and revisions of the RDA. The new DRI differ in amounts and age categories from the 1989 RDA and include three new categories of reference values: Adequate Intake (AI), the Estimated Average Requirement (EAR), and the Tolerable Upper Intake Level (UL).[2]
The design of this study does not allow calculation of the percentage of AI for calcium or calculation of the percentage of RDA for phosphorus, magnesium, folate, or vitamin B6. However, older Americans’ mean intake of these nutrients as a percentage of their DRI differs from their mean intake as a percentage of the 1989 RDA. Compared with the higher calcium AI value (1,200 mg/d for men and women age 51 and older), mean intake for both men and women met a much lower percentage of the DRI than for the 1989 RDA. This is also observed for the mean intakes of magnesium and folate, with a higher DRI magnesium RDA value (420 mg/d for men and 320 mg/d for women age 51 and older) and a higher DRI folate RDA value (400 [micro]g/d for men and women age 51 and older), respectively than for the 1989 RDA. The mean intake of phosphorus met a higher percentage of the DRI (700 mg/d for men and women age 51 and older) than of the 1989 RDA. Also, mean intakes of vitamin B6 met a higher percentage of the DRI (1.7 mg/d [RDA] for men and 1.5 mg/d [RDA] for women) than of the 1989 RDA, with older men and women in 1994-96 exceeding the DRI.
[1] A biochemical marker of riboflavin activity.
[2] The EARs and AIs for the elderly may reflect a greater variability in requirement, especially for nutrient-related energy expenditures (20).
References
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