Food intake measurements: is there a "gold standard"?
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Adult↗
Biomedical subjects
W Mertz
Publications and source records attributed to W Mertz.
What are people really eating? The relation between energy intake derived from estimated diet records and intake determined to maintain body weight.
Two hundred sixty-six free-living human volunteers, 21-64 y old, were trained by dietitians to record daily their food intake for at least 7 d. Subsequently, they were fed diets of conventional foods adjusted in amounts to maintain their body weight for greater than or equal to 45 d. Comparing their estimated energy intake with the intake determined to maintain weight yielded mean differences of 2365 and 1792 kJ (565 and 428 kcal) in men and women, respectively, representing an underreporting of 18%. Twenty-two individuals (8%) overestimated and 29 (11%) were accurate to within 419 kJ (100 kcal) of their maintenance requirement. The remaining 215 individuals (81%) reported their habitual intake at 2930 +/- 1586 kJ (700 +/- 379 kcal) below that subsequently determined as their maintenance requirement. These findings suggest caution in the interpretation of food-consumption data.
Adult↗
The role of trace elements in the aging process.
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Aged↗
Sources of variation in energy intake by men and women as determined from one year's daily dietary records.
Data from a year-long study conducted by the US Department of Agriculture's Beltsville Human Nutrition Research Center were used to identify sources of variation in daily energy intakes. A specific hypothesis was that an inverse relationship exists between past body weight and future energy intake whereas a direct relationship exists between past energy intake and future weight. Daily energy intakes of 29 male (n = 13) and female (n = 16) adult subjects were related through linear-regression analysis to sex (+ for males), age (-), height (+), weight (- for past and present measurements, + for future measurement), data collection method (- for duplicate plate), day of week (+ for Friday and Saturday), and month (+ for May, July, August, December, and January). These relationships were statistically significant (p less than 0.05). The results confirmed the hypothesis and were in general agreement with previously published studies that used larger samples but fewer days of data.
Adult↗
Acceptability of a 7-day higher-carbohydrate, lower-fat menu: the Beltsville Diet study.
For 13 weeks, 20 men (aged 23 to 56), 19 premenopausal (aged 21 to 48), and 14 postmenopausal women (aged 49 to 65) consumed a 7-day rotation menu conforming to dietary recommendations of several research and health organizations. The diets were designed to make minimal changes in the standard American diet by the use of well-accepted normal foods. The average daily composition of the diet was 50% carbohydrate (complex 35%, simple 15%), 35% fat (P:S 0.7), and 15% protein; it contained 100 mg cholesterol, 1 gm sodium, and 14.5 gm neutral detergent fiber per 1,000 kcal. The acceptability of the menus was examined through questionnaires administered after the experimental diet period. Subjects rated the menus and individual foods and made recommendations for improvement of the menus. Most subjects (33 of 41 responding) rated the menu better than or almost as good as their usual diet. Few (9) were ever hungry during the 13-week period. During the study, a number of biochemical parameters were measured; the measurements indicated beneficial results. Blood pressure, cholesterol levels, and glucose responses were all improved after consumption of the menu. The results indicate that with minimal changes in the normal U.S. diet, acceptable menus that have beneficial effects on risk factors for heart disease and diabetes can be developed.
Adult↗
Long-term consumption of beef extended with soy protein by men, women and children: I. Study design, nutrient intakes, and serum zinc levels.
The effect of long-term consumption, under practical conditions, of beef extended with soy protein on serum zinc levels of men, women and children was studied. Fifty-two families were randomly assigned to consume for 180 days 1 of 7 beef products: all beef, beef extended with either soy isolate, soy concentrate or soy flour (20% reconstituted soy product, 80% beef), or beef extended with each of the 3 soy products fortified with 60 mg Fe and 25 mg Zn/100 g protein. The beef product was consumed by the subjects as their principal source of protein for 1 meal a day (children 1-8 yrs) or 1-2 meals a day (11 per week) for adult men and women. A control group consumed their usual self-selected diet. Diet records (4-day) of all foods and beverages consumed by the subjects were obtained pre-study and 63 +/- 7 and 126 +/- 7 days for calculation of nutrient intakes. No deleterious effects were found on the serum zinc levels when subjects consumed beef extended with soy protein for 180 days.
Adolescent↗
Long-term consumption of beef extended with soy protein by men, women and children: II. Effects on iron status.
The iron status of men, women and children consuming beef extended with soy protein was evaluated by measuring serum ferritin and clinical parameters of iron status during a six-month study. Fifty-two families (245 participants) were randomly assigned to consume, for 180 days, 1 of 7 beef products: all beef, beef extended with either soy isolate, soy concentrate or soy flour (20% reconstituted soy product, 80% beef), or beef extended with each of the three soy products fortified with 60 mg Fe and 25 mg Zn/100 g protein. The beef product was consumed by the subjects as their principal source of protein for 1 meal a day (children 1-18 yr) or 1-2 meals a day (11 per week; adult men and women). A control group consumed their usual self-selected diets. No evidence was found that consumption of beef extended with soy protein deleteriously affected the iron status of men, women or children. Consumption of beef extended with soy protein, at the levels used in this study, by military men and women and by school lunch participants would not appear to impose a risk in these population groups.
Adolescent↗
Long-term consumption of beef extended with soy protein by children, women and men: III. Iron absorption by adult men.
Forty-nine ostensibly healthy men consumed either patties of all-beef or beef extended with soy-isolate, -concentrate or -flour as the principal protein source in 1 to 2 meals daily for 180 days. Iron status was monitored by absorption of radioiron from a reference dose of ferrous ascorbate and by serum ferritin concentration. In addition, nonheme iron absorption from a test meal of the respective beef pattie consumed for the 180 days was estimated by the extrinsic tag procedure. There was no detrimental effect on iron stores as indexed by reference ferrous ascorbate absorption or serum ferritin concentration. Absorption of nonheme iron from the test meals was low except for individuals having indices of low iron stores. When adjusted for the effect of level of iron stores the relative absorption of nonheme iron from soy-isolate and -flour containing meals was greater than from the all-beef meal, indicating marked differences in the effect on iron absorption by different soy products. Consumption of soy-extended beef should have no detrimental effect on iron status of adult men if consumed in mixed diets at the level used in this study.
Adolescent↗
Use and misuse of balance studies.
Balance studies are inadequate tools to determine human requirements for minerals and trace elements. At best, they estimate the amount of an element in a specified diet that maintains the existing pool size of the test subject. The relevance of pool size to health remains to be established by different and independent means.
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Number of days of food intake records required to estimate individual and group nutrient intakes with defined confidence.
The number of days of food intake data needed to estimate the intake of 29 male (n = 13) and female (n = 16) adult subjects, individually and as a group, was determined for food energy and 18 nutrients. The food intake records were collected in a year-long study conducted by the U.S. Department of Agriculture's Beltsville Human Nutrition Research Center. Each individual's average intake of nutrients and standard deviation over the year were assumed to reflect his or her "usual" intake and day-to-day variability. Confidence intervals (P less than 0.05) for each individual's usual intake were constructed, and from these the number of days of dietary records needed for estimated individual and group intake to be within 10% of usual intake was calculated. The results indicated that the number of days of food intake records needed to predict the usual nutrient intake of an individual varied substantially among individuals for the same nutrient and within individuals for different nutrients; e.g., food energy required the fewest days (averaging 31) and vitamin A the most (averaging 433). This was considerably higher than the number of days needed to estimate mean nutrient intake for this group, which ranged from 3 for food energy to 41 for vitamin A. Fewer days would be needed for larger groups.
Adult↗
Effects of sugars on indices of glucose tolerance in humans.
Ten men and nine women were studied to determine whether replacement of utilizable complex carbohydrate by sugars (mono- and disaccharides) in a high-fiber, low-saturated fat diet would affect indices of glucose tolerance. Diets differed in that the 50% of calories derived from carbohydrate was either 35% complex and 15% sugars (low-sugar) on 15% complex and 35% sugars (high-sugar). Summation of glucose responses 30-180 min following an oral glucose tolerance test was significantly higher in men, but not women, after they consumed the high-sugar diet. Corresponding insulin responses were significantly higher in men consuming the high-sugar compared to the low-sugar diet. Insulin binding was significantly lower during the base line period and after the high-sugar diet compared to the low-sugar diet. Results indicate that sugars adversely affect indices of glucose tolerance when they replace complex carbohydrates even in a high-fiber, low-saturated fat diet.
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Modification of the United States' diet to effect changes in blood lipids and lipoprotein distribution.
Twenty men, 19 premenopausal and 14 postmenopausal women consumed a diet for 13 weeks that supplied 35% of the calories from fat, 50% from carbohydrate, and 15% from protein. The diet was low in cholesterol, saturated fat, and salt, and high in complex carbohydrate and fiber. The 7-day menu was composed of common well-accepted foods prepared in a simple attractive manner. Plasma total cholesterol, LDL cholesterol, and VLDL cholesterol were reduced, but triglyceride levels were not different than after self-selected diets. When 20% of the complex carbohydrate was replaced by simple carbohydrate and other diet components remained optimal, triglyceride and VLDL cholesterol levels increased in men and premenopausal women and total cholesterol increased in premenopausal women. These results suggest that beneficial effects on the blood lipids and lipoprotein distribution of men and women may be obtained by minimal modification of a typical U.S. diet.
Adult↗
Indices of copper status in humans consuming a typical American diet containing either fructose or starch.
Twenty-four male subjects originally participated in a study to determine the effects of feeding diets comparatively low in copper (1.03 mg/day/2850 kcal) and containing either 20% fructose or starch on indices of copper status. During the course of feeding the diets for 11 wk, four of the subjects exhibited heart-related abnormalities and were removed from the study. Fructose ingestion had no effect on serum ceruloplasmin activity or serum copper concentration but did significantly reduce cuprozinc superoxide dismutase (SOD) activity of erythrocytes as compared to starch. Repletion of the subjects with 3 mg copper/day for 3 wk significantly increased SOD levels in subjects previously fed fructose but not starch. Apparent copper balance was significantly greater when the subjects consumed the fructose as compared to the starch diet. These results suggest that the type of dietary carbohydrate fed can differentially affect indices of copper status in humans.
Adult↗
Sodium and potassium intake and balance in adults consuming self-selected diets.
Twenty eight adults, 12 men and 16 women, participated in a 1-yr study designed to assess daily nutrient intake accurately. All subjects lived at home, consumed self-chosen diets, and maintained a detailed daily dietary record throughout the year. During four 7-day balance studies, one in each season of the year, meals, beverages, urine, and feces were analyzed for sodium and potassium content by atomic absorption spectrometry. Total intakes averaged 3.4 g/day for sodium and 2.8 g/day for potassium. The Na:K ratio for all diets analyzed averaged 1.3. Nutrient densities of sodium and potassium were 1.8 and 1.5 g/1000 kcal, respectively. Apparent absorptions of sodium and potassium were 98 and 85%, respectively, and did not change significantly over the wide range of intakes. Average urinary excretions of sodium and potassium were 86 and 77% of total intake, respectively. Mean metabolic balances were positive for sodium, +0.47 g/day, and potassium, +0.28 g/day. The data of this study provide useful information concerning the dietary intakes, excretions, and balances of sodium and potassium for adults based on analytic determination.
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Rationale and design of the Beltsville one-year dietary intake study.
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Adult↗
Evaluation of long-term dietary intakes of adults consuming self-selected diets.
Mean daily intakes of calories and 19 nutrients were calculated for 13 males and 16 females, ages 20 to 53 yr, who kept daily diet records for 1 yr. Mean daily caloric and 19 selected nutrient intakes of the subjects met or exceeded the 1980 recommended dietary allowances except for iron and calcium for females. Males had higher intakes than females for all nutrients studied except crude fiber, vitamin A, and vitamin C. However, nutrient density values were comparable for both sexes, except that the females had higher nutrient density values for vitamin A than did the males. The younger subjects had higher intakes of calories and saturated fat than the older ones. The younger males had higher intakes of total fat, saturated fat, and oleic acid than the older males. The consistency of reporting food intakes examined by applying a systematic sampling method designed for this study did not vary considerably when diet records kept over a long period of time were evaluated by four methods.
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Effect of making duplicate food collections on nutrient intakes calculated from diet records.
In a 1-yr study in which food intakes were recorded daily, subjects were asked to make duplicate food collections for 1 wk during each of the four seasons. Mean calculated energy intake of the 29 subjects was 12.9% less during the food collection periods than the mean for the entire year (which included collection periods). There were also significant reductions in the reported intake of all nutrients during the collection periods. Protein, vitamin A, saturated fat, and cholesterol intakes were decreased to the greatest extent. The actual decrease in energy intake was greater for the males than for the females, but the percentage was the same (12.9%). The younger group of subjects (less than or equal to 35) decreased energy intake 16.8% and the older group (greater than 35) 8.8%. Comparison of intakes during collection periods with intakes the week before and the week after showed that 28 of the 29 subjects decreased their energy intake from 1.1 to 32.3%. These data suggest that intakes of subjects during food collection periods do not represent their habitual levels of intake reported throughout the year.
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