The role of eating frequency on relative weight in urban school-age children.

BACKGROUND: The role of eating frequency on relative weight in childhood is not well understood. OBJECTIVE: To clarify this relationship by assessing the cross-sectional and prospective relationships of weekday eating frequency with BMI z-score (BMIz) and change in BMIz in a sample of schoolchildren. METHODS: Eating frequency, the average number of reported daily eating occasions, was assessed using two weekday 24-h diet recalls. BMIz was measured at baseline, 6 months and 1 year in 155 urban schoolchildren, ages 9-15 years. Multiple linear regression models were used. RESULTS: Cross-sectional analyses at baseline suggest that BMIz was 0.23 units lower for each additional reported eating occasion (regression coefficient = -0.23; 95% confidence interval [CI]: -0.44, -0.07). From baseline to 6 months, BMIz increased by 0.03 units for each additional reported eating occasion (regression coefficient = 0.03; 95% CI: 0.01, 0.05). This relationship was no longer statistically significant at 1 year (regression coefficient = 0.01; 95% CI: -0.01, 0.03). CONCLUSIONS: The findings suggest that the relationship of eating frequency with BMIz differs from that of change in BMIz. This difference may be due to methodological deficiencies of cross-sectional studies, challenges of dietary assessment or differences in eating patterns among normal and overweight youth. Controlled trials are needed to further clarify this relationship.

Impact of supplementation with bicarbonate on lower-extremity muscle performance in older men and women.

UNLABELLED: This study describes the impact of bicarbonate treatment for 3 months on net acid excretion (NAE), nitrogen excretion, and muscle performance in older men and women. Bicarbonate reduced NAE, and the decrement was associated with a decrease in nitrogen excretion. Treatment also improved muscle power and endurance in the women. INTRODUCTION: Bicarbonate enhances muscle performance during strenuous exercise, but its effect on performance during normal activity in older subjects is unknown. METHODS: In this trial, healthy subjects age 50 and older were randomized to 67.5 mmol of bicarbonate or to no bicarbonate daily for 3 months. Changes in lower-extremity muscle power, endurance, urinary nitrogen, and NAE were compared across treatment groups in the 162 participants included in the analyses. RESULTS: In the men and the women, bicarbonate was well tolerated, and as expected, it significantly decreased NAE. The change in NAE correlated with change in nitrogen excretion in women (r = 0.32, P = 0.002) with a similar trend in men (r = 0.23, P = 0.052). In the women, bicarbonate increased double leg press power at 70% one repetition maximum by 13% (P = 0.003) compared with no bicarbonate and improved other performance measures. Treatment with bicarbonate had no significant effect on muscle performance in the men. CONCLUSIONS: Ingestion of bicarbonate decreased nitrogen excretion and improved muscle performance in healthy postmenopausal women. The bicarbonate-induced decline in NAE was associated with reduced nitrogen excretion in both men and women. These findings suggest that bicarbonate merits further evaluation as a safe, low-cost intervention that may attenuate age-related loss of muscle performance and mass in the elderly.

25-Hydroxyvitamin D, dementia, and cerebrovascular pathology in elders receiving home services.

BACKGROUND: Vitamin D deficiency has potential adverse effects on neurocognitive health and subcortical function. However, no studies have examined the association between vitamin D status, dementia, and cranial MRI indicators of cerebrovascular disease (CVD). METHODS: Cross-sectional investigation of 25-hydroxyvitamin D [25(OH)D], dementia, and MRI measures of CVD in elders receiving home care (aged 65-99 years) from 2003 to 2007. RESULTS: Among 318 participants, the mean age was 73.5 +/- 8.1 years, 231 (72.6%) were women, and 109 (34.3%) were black. 25(OH)D concentrations were deficient (<10 ng/mL) in 14.5% and insufficient (10-20 ng/mL) in 44.3% of participants. There were 76 participants (23.9%) with dementia, 41 of which were classified as probable AD. Mean 25(OH)D concentrations were lower in subjects with dementia (16.8 vs 20.0 ng/mL, p < 0.01). There was a higher prevalence of dementia among participants with 25(OH)D insufficiency (< or =20 ng/mL) (30.5% vs 14.5%, p < 0.01). 25(OH)D deficiency was associated with increased white matter hyperintensity volume (4.9 vs 2.9 mL, p < 0.01), grade (3.0 vs 2.2, p = 0.04), and prevalence of large vessel infarcts (10.1% vs 6.9%, p < 0.01). After adjustment for age, race, sex, body mass index, and education, 25(OH)D insufficiency (< or =20 ng/mL) was associated with more than twice the odds of all-cause dementia (odds ratio [OR] = 2.3, 95% confidence interval [CI] 1.2-4.2), Alzheimer disease (OR = 2.5, 95% CI 1.1-6.1), and stroke (with and without dementia symptoms) (OR = 2.0, 95% CI 1.0-4.0). CONCLUSIONS: Vitamin D insufficiency and deficiency was associated with all-cause dementia, Alzheimer disease, stroke (with and without dementia symptoms), and MRI indicators of cerebrovascular disease. These findings suggest a potential vasculoprotective role of vitamin D.

A simple single serum method to measure fractional calcium absorption using dual stable isotopes.

The dual stable isotope method with a timed 24-h urine collection is the gold standard approach to measure fractional calcium absorption. However, the need to collect urine for 24 h makes this technique time-consuming and laborious. Our study sought to determine whether a dual isotope method using a single serum sample obtained 4 h after administration of the initial isotope provides a useful approach to measure fractional calcium absorption. Following a metabolic diet with a fixed calcium intake of 30 mmol/day for 10 days, nineteen healthy subjects age 54-74 were given a test meal with an oral isotope ((44)Ca) followed 2 h later by an intravenous isotope ((42)Ca). Once the oral isotope was administered, urine was collected for 24 h, and a serum sample was obtained after 4 h. The ratio of the oral to intravenous isotopes was measured in the urine and serum by mass spectroscopy. Fractional calcium absorption was 16.2 ± 7.7% by the 4-h single serum method versus 18.5 ± 7.5% by the 24-h urine method. There was a small mean difference between the urine and serum methods of 2.33% with a confidence interval -3.97 to 8.60%. The two methods showed a strong linear association (r = 0.912, p<0.001). Use of dual stable isotopes with a 4-h single serum method gives fractional calcium absorption values that are 12.5% lower than with the 24-h urine method; however, it rank orders subjects accurately thus making it a useful alternative method in clinical research applications.

Food cravings and energy regulation: the characteristics of craved foods and their relationship with eating behaviors and weight change during 6 months of dietary energy restriction.

OBJECTIVE: To examine characteristics of craved foods in relation to dietary energy restriction (ER) with high (HG) and low glycemic load (LG) diets. DESIGN: Assessments of food cravings before and during a randomized controlled trial of HG and LG diets provided for 6 months. SUBJECTS: Thirty-two healthy, overweight women aged 20-42 years. MEASUREMENTS: Self-reported food cravings and dietary intake, body weight, weight history and measures of eating behaviors. RESULTS: Foods craved at baseline were more than twice as high in energy density as the habitual diet (3.7+/-1.5 vs 1.7+/-0.3 kcal/g; P<0.001), and on average were lower in protein (P<0.001) and fiber (P<0.001) and higher in fat (P=0.002). There were no statistically significant changes in nutritional characteristics of craved foods after 6 months of ER. There was a significant relationship between reported portion size of craved food consumed at baseline and lifetime high body mass index (r=0.49, P=0.005). Additionally, there was a significant association between susceptibility to hunger and craving frequency at baseline, and there were significant relationships between hunger score, craving frequency, strength and percentage of time that cravings are given in to after 6 months of ER. In multiple regression models, subjects who lost a greater percentage of weight craved higher energy-dense foods at month 6 of ER, but also reported giving in to food cravings less frequently (adjusted R (2)=0.31, P=0.009). CONCLUSION: High energy density and fat content, and low protein and fiber contents were identifying characteristics of craved foods. The relationships between craving variables and hunger score suggest that the relative influence of hunger susceptibility on cravings may be important before and especially after ER. Portion size of craved foods and frequency of giving in to food cravings appear to be important areas for focus in lifestyle modification programs for long-term weight loss.

Comparative effects of oral aromatic and branched-chain amino acids on urine calcium excretion in humans.

UNLABELLED: In 30 adults, increasing intake of aromatic amino acids increased calcium excretion and serum IGF-1, but not indices of bone turnover, when compared with similar increases in intake of branched-chain amino acids. The mechanisms involved are not certain but these findings suggest a role for the calcium sensor receptor. INTRODUCTION: In contrast to branched-chain amino acids (BCAAs), aromatic amino acids (AAAs) bind to the calcium sensing receptor (CaR) and thus have an increased potential to affect calcium homeostasis. In this study we compare the effects of increased intake of AAAs versus BCAAs on calcium excretion, serum IGF-1, markers of bone turnover, and 4-hr calcium excretion after an oral calcium load. METHODS: After two weeks on low-protein metabolic diets, 30 healthy subjects were randomized to a fivefold increase in intake of AAAs or BCAAs for two weeks. Changes in calcium excretion and other measures were compared in the two groups. RESULTS: With the increase in amino acid intake, 24-hr calcium excretion (P = 0.027), IGF-1 (P = 0.022), and 4-hr calcium excretion after an oral load (P = 0.023) increased significantly in the AAA relative to the BCAA group. Group changes in turnover markers did not differ significantly. CONCLUSION: In comparison with BCAAs, AAAs promoted calcium excretion. The calciuria does not appear to result from increases in bone resorption and may occur by increasing calcium absorption. The AAAs also increased circulating levels of IGF-1. Collectively these findings raise the possibility that AAAs may selectively influence calcium homeostasis through their interactions with the CaR.

Energy cost of physical activities in 12-y-old girls: MET values and the influence of body weight.

BACKGROUND: Few data exist on the energy cost of specific activities in children. The influence of body weight on the energy cost of activity when expressed as metabolic equivalents (METs) has not been vigorously explored. OBJECTIVE: To provide MET data on five specific activities in 12-y-old girls and to test the hypothesis that measured MET values are independent of body weight. SUBJECTS AND METHODS: In 17 12-y-old girls, resting metabolic rate (RMR) and the energy expended while sitting, standing, walking on a flat treadmill at 3.2 and at 4.8 km/h, and walking on a treadmill at a 10% incline at 4.8 km/h were measured using indirect calorimetry. MET values were calculated by dividing the energy expenditure of an activity by the subject's RMR. The influence of body weight was assessed using simple linear regression. RESULTS: The observed METs were more consistent with published values for similar activities in adults than those offered for children. Body weight was a statistically significant predictor of the MET of all three walking activities, but not the MET of sitting or standing. Body weight explained 25% of the variance in the MET value for walking at 3.2 km/h, 39% for walking at 4.8 km/h, and 63% for walking at a 10% incline at 4.8 km/h. CONCLUSION: METs for the three walking activities were not independent of body weight. The use of average MET values to estimate the energy cost of these three activities would result in an underestimation of their energy cost in heavier girls and an overestimation in lighter girls. These results suggest that the estimation of total energy expenditure from activity diary, recall, and direct observation data using average MET values may be biased by body weight.

Calcium supplement and bone medication use in a US Medicare health maintenance organization.

This study was conducted to determine the prevalence of the use of calcium supplements and of prescription medications to prevent or treat osteoporosis in men and women in a large New England Medicare Health Maintenance Organization (HMO). A two-page diet, medication use and medical history questionnaire was sent to a random sample of 9000 out of 82 985 members and 2932 (32.6%) responded. Over 97% of the participants were Caucasian and 64.7% were female. The mean ages of the men and women were 74.4+/-5.8 and 74.6+/-6.2 years, respectively. Sixty-nine percent of the men and 59% of the women consumed two or fewer servings of dairy foods per day. Calcium supplement use was more prevalent among the women than the men (66.8% vs 24.9%, p<0.001). Men and women with higher dairy food intakes were more likely to take calcium supplements than were those with lower dairy intakes. Prescription bone medications (including bisphosphonates, raloxifene and calcitonin) were used currently by 17.5% of the women and 2.3% of the men ( p<0.001). An additional 16.2% of the women currently took estrogen. Among the women, bone medication use did not change with age but estrogen use declined with increasing age. Among women age 80+ years, 15.6% used bone medications and 4.9% took estrogen. According to a national survey, more than half the US Caucasian female population over age 80 years has bone density low enough to warrant treatment under current guidelines. Based on the results of this survey, many elderly men and women may benefit from increased utilization of calcium supplements and bone-active medications.

Do patients with nonmetastatic non-small cell lung cancer demonstrate altered resting energy expenditure?

BACKGROUND: The cancer cachexia syndrome occurs in patients with non-small cell lung cancer (NSCLC) and includes elevated resting energy expenditure (REE). This increase in REE leads to weight loss, which in turn confers a poor prognosis. This study was undertaken to determine whether the cancer cachexia syndrome occurs in patients with nonmetastatic NSCLC. METHODS: In this case-control study, 18 patients with nonmetastatic NSCLC (stages IA to IIIB) were matched to healthy controls on age (+/- 5 years), gender, and body mass index (+/- 3 kg/m2). Only 4 cancer patients had experienced > 5% weight loss. Cancer patients and controls were compared on the basis of: (1) unadjusted REE, as measured by indirect calorimetry; (2) REE adjusted for lean body mass, as measured by dual x-ray absorptiometry; (3) REE adjusted for body cell mass, as measured by potassium-40 measurement; and (4) REE adjusted for total body water, as measured by tritiated water dilution. RESULTS: We observed no significant difference in unadjusted REE or in REE adjusted for total body water. However, with separate adjustments for lean body mass and body cell mass, cancer patients manifested an increase in REE: mean difference +/- standard error of the mean: 140+/-35 kcal/day (p = 0.001) and 173+/-65 kcal/day (p = 0.032), respectively. Further adjustment for weight loss yielded similarly significant results. CONCLUSIONS: These results suggest that the cancer cachexia syndrome occurs in patients with nonmetastatic NSCLC and raise the question of whether clinical trials that target cancer cachexia should be initiated before weight loss.

An oat-containing hypocaloric diet reduces systolic blood pressure and improves lipid profile beyond effects of weight loss in men and women.

Hypertension, dyslipidemia and overweight contribute substantially to cardiovascular disease risk. One of the most effective methods for improving high blood pressure and lipid profiles is loss of excess weight. Other recommendations for reducing cardiovascular risk include changes in dietary micronutrient, macronutrient and fiber intakes. To better define a diet for reduction in cardiovascular risk, 43 adults (body mass index 26.4 +/- 3.3, range 20.5-33.9 kg/m(2)) participated in an 8-wk study to determine the effects of two diets on weight, blood pressure, lipids and insulin sensitivity. For 2 wk, weight was maintained and all subjects consumed a control diet. For the next 6 wk, subjects consumed one of two hypocaloric diets (maintenance energy minus 4.2 MJ/d): the control diet (n = 21) or a diet containing oats [45 g/(4.2 MJ dietary energy. d), n = 22]. There was no significant difference between groups in changes in weight loss (control -4.0 +/- 1.1 kg, oats -3.9 +/- 1.6 kg, P = 0.8). The oats diet resulted in greater decreases in mean systolic blood pressure (oats -6 +/- 7 mm Hg, control -1 +/- 10 mm Hg, P = 0.026), whereas diastolic blood pressure change did not differ between the two groups (oats -4 +/- 6 mm Hg, control -3 +/- 5 mm Hg, P = 0.8). The oat diet resulted in significantly greater decreases in total cholesterol (oats -0.87 +/- 0.47 mmol/L, control -0.34 +/- 0.5 mmol/L, P = 0.003) and LDL cholesterol (oats -0.6 +/- 0.41 mmol/L, control -0.2 +/- 0.41mmol/L, P = 0.008). In summary, a hypocaloric diet containing oats consumed over 6 wk resulted in greater improvements in systolic blood pressure and lipid profile than did a hypocaloric diet without oats.

The new childhood growth charts.

New childhood growth percentiles have been published recently by the Centers for Disease Control and Prevention, and are designed to replace the widely used 1977 National Center for Heath Statistics percentiles. International definitions for overweight and obesity in childhood, based on the body mass index, also have been published. This review discusses appropriate uses of the new percentile charts and international definitions of overweight.

Elevated plasma F2-isoprostanes in patients on long-term hemodialysis.

BACKGROUND: End-stage renal disease (ESRD) patients on long-term hemodialysis (HD) may be under increased oxidative stress, caused by either HD or renal failure. Plasma F2-isoprostanes have been established as an important indicator of in vivo oxidative stress. METHODS: Plasma esterified F2-isoprostanes were measured in 25 HD patients and 23 controls with normal renal function, employing gas chromatography-mass spectrometry with negative chemical ionization (GC-MS-NCI). C-reactive protein (CRP) was determined concurrently in patients and controls by enzyme-linked immunosorbent assay (ELISA). alpha-Tocopherol, retinol, albumin and creatinine were also determined. RESULTS: The average total esterified F2-isoprostanes in the ESRD patients was 1.62 +/- 0.73 vs. 0.27 +/- 0.10 ng/mL in controls (P < 0.001), with no overlap between patients and controls. Plasma F2-isoprostanes in diabetic ESRD patients were similar to F2-isoprostanes in patients with other causes for renal failure. In a subset of 10 of these ESRD patients evaluated eight months after the initial measurement, plasma-esterified F2-isoprostanes were not altered by an individual dialysis session. Average plasma CRP values were also higher in HD patients (P < 0.02), but some patients had CRP values that were similar to controls. In the HD patients, total plasma F2-isoprostanes and plasma CRP were correlated (r = 0.48, P = 0.015). Plasma alpha-tocopherol did not differ between patients and controls, but plasma retinol was higher in patients (3.15 +/- 1.71 micromol/L) than in controls (1.97 +/- 0.51 micromol/L, P < 0.05). CONCLUSIONS: These results are consistent with the hypothesis that oxidative stress in ESRD patients contributes to increased values of esterified plasma F2-isoprostanes, with concurrent increases in plasma CRP levels in some patients. Impaired clearance of esterified F2-isoprostanes may contribute to the elevated levels in renal failure. Plasma esterified F2-isoprostanes may be a useful indicator to evaluate effectiveness of interventions to decrease oxidative stress and associated inflammation.

Longitudinal muscle strength changes in older adults: influence of muscle mass, physical activity, and health.

The longitudinal changes in isokinetic strength of knee and elbow extensors and flexors, muscle mass, physical activity, and health were examined in 120 subjects initially 46 to 78 years old. Sixty-eight women and 52 men were reexamined after 9.7 +/- 1.1 years. The rates of decline in isokinetic strength averaged 14% per decade for knee extensors and 16% per decade for knee flexors in men and women. Women demonstrated slower rates of decline in elbow extensors and flexors (2% per decade) than men (12% per decade). Older subjects demonstrated a greater rate of decline in strength. In men, longitudinal rates of decline of leg muscle strength were approximately 60% greater than estimates from a cross-sectional analysis in the same population. The change in leg strength was directly related to the change in muscle mass in both men and women, and it was inversely related to the change in medication use in men. Physical activity declined yet was not directly associated with strength changes. Although muscle mass changes influenced the magnitude of the strength changes over time, strength declines in spite of muscle mass maintenance or even gain emphasize the need to explore the contribution of other cellular, neural, or metabolic mediators of strength changes.

Meal palatability, substrate oxidation and blood glucose in young and older men.

We investigated the effects of food palatability on the thermic effect of feeding (TEF), substrate oxidation and circulating glucose and insulin. Healthy young men (23.4+/-1.0, SD, years, n=10) and older men (69.4+/-1.3, years, n=9) were resident in a metabolic unit for two 2-day study periods. On the second day of each period, they consumed in random order either a palatable test meal containing 2.93 MJ or a nonpalatable control meal containing the same foods in identical amounts but blended and freeze-dried into biscuit form. TEF and respiratory quotient (RQ) were measured over 6 h and blood samples were taken for measurement of glucose and insulin. Age group had no effect on TEF, RQ or circulating glucose other than to delay the time of peak TEF (P<0.002 for both meals). There was no significant effect of meal type on TEF, but RQ and circulating glucose were higher following consumption of the palatable meal (P<0.001 for both parameters). These results suggest that over 6 h postprandial, consumption of palatable foods does not increase TEF, but is instead associated with increased glycemic response and increased carbohydrate oxidation. These changes, combined with previous work on the glycemic index, predict an accelerated return of hunger and increased energy intake at subsequent meals following consumption of palatable vs. control foods. Further studies are needed to examine the possible mechanism for this previously suggested "second meal" effect of diet palatability on energy intake.

The effect of gender and body composition method on the apparent decline in lean mass-adjusted resting metabolic rate with age.

BACKGROUND: Declining resting energy expenditure (REE) is a hallmark of normal aging, but the cause of this decline remains controversial. Some, but not all, studies have shown that the decline in REE with age is eliminated after adjustment for fat-free mass (FFM). METHODS: We examined the effect of four body composition methods used to assess FFM (underwater weighing [UWW], bioimpedance analysis [BIA], tritium dilution, and total body potassium [TBK]) on the relationship between REE and age in 30 healthy men and 101 healthy women aged 18 to 87 years. RESULTS: The decline in REE with age was significant in women (-80.3 kJ/d/y, p < .004) but not in men (-46.9 kJ/d/y, p = .328). After adjustment for FFM, the decline in REE with age persisted when FFM was measured by BIA, UWW, or tritium dilution, but no decline was seen when TBK was used to adjust for FFM. In both women and men, fat mass was significantly associated with REE after adjusting for age and FFM. CONCLUSION: It is the decline in cell mass with age, detectable by TBK but not by other methods, rather than any metabolic alteration, that explains the decline in FFM-adjusted REE with age.

Effect of withdrawal of calcium and vitamin D supplements on bone mass in elderly men and women.

BACKGROUND: Supplementation with calcium and vitamin D reduces bone loss and prevents fractures in elderly people, but it is not known whether any lasting benefit remains if the supplements are discontinued. OBJECTIVE: The objective was to determine whether gains in bone mineral density (BMD) induced by calcium and vitamin D supplementation persist after supplement withdrawal. DESIGN: Two-hundred ninety-five healthy, elderly men and women (aged >/=68 y) who had completed a 3-y randomized, placebo-controlled trial of calcium and vitamin D supplementation were followed for an additional 2 y during which no study supplements were given. BMD was measured by dual-energy X-ray absorptiometry, and biochemical variables related to calcium metabolism and bone turnover were measured. RESULTS: In the 128 men, supplement-induced increases in spinal and femoral neck BMD were lost within 2 y of supplement discontinuation, but small benefits in total-body BMD remained. In the 167 women, there were no lasting benefits in total-body BMD or at any bone site. Consistent with the observations on BMD, the bone turnover rates in both men and women (as measured by serum osteocalcin concentrations) returned to their original higher concentrations within the same 2-y period. CONCLUSION: Discontinued calcium and vitamin D supplementation has limited cumulative effect on bone mass in men and women aged >/=68 y.

Assessment of healthcare professionals' knowledge about warfarin-vitamin K drug-nutrient interactions.

OBJECTIVE: Dietary vitamin K can interact with oral anticoagulant drugs and interfere with their therapeutic safety and efficacy. Therefore, knowledge about drug-nutrient interactions involving vitamin K possessed by physicians, pharmacists, dietitians and nurses practicing anticoagulant therapy was assessed. METHODS: Healthcare practitioners were surveyed using a 30-question, 98-item questionnaire on the most common and/or important food interactions with warfarin, drug interactions with warfarin and general drug-nutrient interactions involving vitamin K. The study sample included 160 randomly selected healthcare providers (40 physicians, pharmacists, dietitians and nurses) from 10 hospitals with 200 to 1000 beds from six Massachusetts regions. Random selection was conducted from a pool of selected healthcare providers practicing anticoagulant therapy who counsel patients receiving warfarin. RESULTS: All surveys were completed within three months of the start of the study, and all participants provided usable data for statistical analysis. The mean scores (+/- SD) on the overall test were 72.5+/-9.0 for pharmacists, 62.51+/-10.6 for physicians, 56.9+/-8.8 for dietitians and 50.2+/-9.3 for nurses, with 100 being a perfect score. Pharmacists scored significantly higher in the area of drug interactions (75.9+/-11.3, p<0.05). Dietitians scored higher in the area of food interactions (73.0+/-10.3). No significant differences between physicians and pharmacists were evident on general drug-nutrient interactions. While over 87% of the healthcare professionals correctly identified some common foods containing large amounts of vitamin K, such as broccoli and spinach, fewer than 25% were able to identify others such as pea soup, coleslaw and dill pickles. CONCLUSIONS: Although the healthcare professionals surveyed in this study appear to have demonstrated some proficiency in their respective areas of expertise, they exhibited less knowledge in others. Therefore, additional training and integration of knowledge and expertise about drug-nutrient interactions among healthcare professionals are essential to provide appropriate patient counseling and optimal therapeutic outcomes.

Lack of efficacy of a food-frequency questionnaire in assessing dietary macronutrient intakes in subjects consuming diets of known composition.

BACKGROUND: We compared the validity of a semiquantitative food-frequency questionnaire in assessing intakes of macronutrients (absolute amounts and percentages of energy) by 19 subjects fed natural-food diets of known composition. In small subsets (n = 5 or 6), we also tested 3-d diet records. OBJECTIVE: The objective of this study was to investigate the efficacy of food-frequency questionnaires and diet records in subjects fed natural-food diets of known composition. DESIGN: Each subject consumed 3 different diets for >/=6 wk and self-reported his or her food intake by using a food-frequency questionnaire and a diet record. The diets varied in their chemically analyzed contents of fat (15-35% energy), saturated fat (5-14%), monounsaturated fat (5-14.5%), polyunsaturated fat (2.5-10.5%), carbohydrate (49-68%), and cholesterol (108-348 mg/d). RESULTS: The food-frequency questionnaire significantly underestimated fat, saturated fat, monounsaturated fat, and protein intakes and significantly overestimated carbohydrate intake with the high-fat diet. The percentage of energy from fat was significantly underestimated for the high-fat diet and significantly overestimated for the very-low-fat diet. Estimates from the food-frequency questionnaire differed significantly from actual intakes for fat (absolute and percentage), saturated fat (absolute and percentage), monounsaturated fat (absolute and percentage), and protein (percentage) in the high-fat diet and for polyunsaturated fat (absolute and percentage), saturated fat (percentage), fiber (absolute), and cholesterol (daily absolute; in mg/d) in the lower-fat diet. Estimates from the diet records better agreed with actual intakes than did estimates from the food-frequency questionnaire except for monounsaturated fat (absolute and percentage) in the high-fat diet and polyunsaturated fat (percentage) in the lower-fat diet and the very-low-fat diet. CONCLUSION: Our data indicated that the food-frequency questionnaire did not provide reliable estimates of absolute amounts of dietary fats or cholesterol.

Development of a self-assessment instrument to determine daily intake and variability of dietary vitamin K.

OBJECTIVE: To develop and validate a brief, self-assessment instrument (K-Card) to determine daily variations in dietary vitamin K1 (phylloquinone) intake for use in patients receiving oral warfarin anticoagulant therapy. METHODS: The K-Card was designed to include a checklist of selected common foods and beverages providing > or = 5 microg vitamin K per serving in American diets and items with lower vitamin K content typically consumed in quantities which contribute significantly to total vitamin K intake. The K-Card was validated against records of weighed food intake from thirty-six healthy volunteers, 20 to 40 and 60 to 80 years of age, whose phylloquinone intakes and plasma concentrations had been previously measured by the Metabolic Research Unit, Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA USA. Future use of the K-Card by patients was simulated by a single investigator using 108 one-day weighed food records to estimate phylloquinone intakes. Dietary phylloquinone calculated from the K-Card was compared to the values of phylloquinone intake from the diet records collected on the same days, and to fasting plasma phylloquinone concentrations obtained from the same individuals on the following day. RESULTS: The mean dietary phylloquinone intake (+/- SEM) was 138.8 +/- 15.7 microg for the K-Cards compared to 136.0 +/- 15.8 microg for the diet records (p = 0.067). Bland-Altman limits of agreement between quantities of dietary phylloquinone calculated from the K-Card and values obtained from the weighed food records were +/- 38 microg. CONCLUSION: In this simulation, the K-Card provided an accurate estimate of dietary phylloquinone intake and therefore deserves further testing for use by patients receiving coumarin-based anticoagulant therapy to determine whether variability in dietary patterns contributes to disruptions in anticoagulant drug efficacy and safety.

Bone mineral measurements: a comparison of delayed gamma neutron activation, dual-energy X-ray absorptiometry and direct chemical analysis.

A system in vitro consisting of a femur from a cadaver and soft-tissue equivalent material was used to test the agreement between several techniques for measuring bone mineral. Calcium values measured by delayed gamma neutron activation (DGNA) and bone mineral content (BMC) by Lunar, Hologic and Norland dual-energy X-ray absorptiometers (DXA) were compared with calcium and ash content determined by direct chemical analysis. To assess the effect of soft-tissue thickness on measurements of bone mineral, we had three phantom configurations ranging from 15.0 to 26.0 cm in thickness, achieved by using soft-tissue equivalent overlays. Chemical analysis of the femur gave calcium and ash content values of 61.83 g +/- 0.51 g and 154.120 +/- 0.004 g, respectively. Calcium measured by DGNA did not differ from the ashed amount of calcium at any of the phantom configurations. The BMC measured by DXA was significantly higher, by 3-5%, than the amount determined by chemical analysis for the Lunar densitometer and significantly lower, by 3-6%, for the Norland densitometer (p<0.001-0.024), but only 1% lower (not significant) for the Hologic densitometer. DXA instruments showed a decreasing trend in BMC as the thickness increased from 20.5 to 26.0 cm (p<0.05). However, within the entire thickness range (15.0-26.0 cm), the overall influence of thickness on BMC by DXA was very small. These findings offer insight into the differences in these currently available methods for bone mineral measurement and challenge the comparability of different methods.