Prospective study of dietary energy density and weight gain in women

BACKGROUND: Little is known about the long-term effects of dietary energy density (ED) on weight gain. OBJECTIVE: The objective was to assess the long-term relation between changes in dietary ED and age-related weight gain. DESIGN: We conducted a prospective study of 50 026 women (x +/- SD age: 36.5 +/- 4.6 y) in the Nurses' Health Study II followed from 1991 to 1999. Dietary ED and body weight were ascertained in 1991, 1995, and 1999. Total dietary ED was calculated by dividing each subject's daily energy intake (kcal) by the reported weight (g) of all foods consumed. RESULTS: Dietary ED was positively correlated with saturated fat (r = 0.16), trans fat (r = 0.15), and the glycemic index (r = 0.16), but was inversely correlated with vegetable protein (r = -0.30), vegetables (r = -0.27), and fruit (r = -0.17). ED was not significantly correlated with total fat intake as a percentage of energy (r = 0.08). Women who increased their dietary ED during follow-up the most (5th quintile) had a significantly greater multivariate-adjusted weight gain than did those who decreased their dietary ED (1st quintile) (8-y time period: 6.42 kg compared with 4.57 kg; P for trend < 0.001). However, the amount of weight change over time varied considerably according to the ED values of individual foods and beverages. CONCLUSION: A high dietary ED reflects a dietary pattern higher in saturated and trans fats and refined carbohydrates. Increases in dietary ED were associated with greater weight gain among middle-aged women during 8 y of follow-up. However, public health recommendations cannot be made simply on the basis of ED values of individual foods and beverages.     

Physical activity, protein intake, and appendicular skeletal muscle mass in older men.

BACKGROUND: Aging is associated with physical inactivity, low energy intake, and loss of skeletal muscle mass. It is not clear whether regular physical activity and adequate dietary protein intake can attenuate the loss of skeletal muscle mass. OBJECTIVE: We hypothesized that the maintenance of physical activity and dietary protein intake would attenuate the age-related decline in total appendicular skeletal muscle mass. DESIGN: Total appendicular skeletal muscle mass was determined by dual-energy X-ray absorptiometry in 44 healthy, older white men aged 49-85 y. Physical activity level was determined by using a uniaxial accelerometer over a 9-d period. Dietary protein intake was estimated from a 3-d food record. RESULTS: Aging was inversely associated with total appendicular skeletal muscle mass in older men (r = -0.43; slope: -0. 119 +/- 0.039 kg/y; P < 0.01). An effect of age on appendicular skeletal muscle mass persisted after standing height and physical activity were controlled for (r = -0.34; slope: -0.120 +/- 0.052 kg/y; P = 0.03). Furthermore, an effect of age on appendicular skeletal muscle mass persisted after standing height and dietary protein intake per kilogram body mass was controlled for (r = -0.41; slope: -0.127 +/- 0.045 kg/y; P < 0.01). CONCLUSIONS: Maintaining regular physical activity and adequate protein intake may not offset the age-related loss of appendicular skeletal muscle mass in older men. Prospective studies are needed to confirm these results and to determine whether anabolic physical activity (eg, strength training) can attenuate the age-related loss of muscle mass in the elderly.     

Dietary calcium is associated with body mass index and body fat in American Indians

American Indians have a high prevalence of obesity. Evidence supports a relationship between increased dietary calcium intake and lower body weight. This study was conducted to investigate the association between dietary calcium intake, BMI, and percentage of body fat (PBF) in American Indians (ages 47-79 y) in the Strong Heart Study (SHS) (2nd exam, 1992-1995). SHS data were compared with data for the general U.S. adult population from the NHANES III (1988-1994). BMI was calculated as kg/m(2). PBF was estimated by bioelectrical impedance using an equation based on total body water. The clinical examination included measures of blood chemistry. Dietary data were collected using a 24-h dietary recall. Calcium intake was significantly lower in SHS participants than in age-matched NHANES III participants. Mean calcium intake in the SHS was 680 mg/d (range: 103-4574 mg/d) for men and 610 mg/d (range: 71-4093 mg/d) for women (P < 0.001). After adjustment for potential confounders, BMI and PBF were lower by 0.80 kg/m(2) (95% CI: -1.53 to -0.08, P = 0.046) and 1.28% (95% CI: -2.10 to -0.47, P = 0.011) in SHS participants with higher (> or = 873 mg/d in the 5th quintile) vs. lower calcium intake (<313 mg/d in the 1st quintile). No relation between calcium intake and BMI or PBF was observed in NHANES III participants. Our data may be used to develop nutritional interventions aimed at weight control in culturally appropriate clinical trials.     

Dairy products do not lead to alterations in body weight or fat mass in young women in a 1-y intervention

BACKGROUND: Previous results suggested that increased intake of dairy calcium is associated with reduced weight and fat mass. OBJECTIVE: The purpose of this study was to determine whether long-term increases in consumption of dairy calcium alter body weight and fat mass in young, healthy women. DESIGN: We used a randomized, 1-y intervention for dairy calcium. Subjects were 155 young (aged 18-30 y), healthy, normal-weight women with intake of dietary calcium < 800 mg/d and energy intake 相似文献   

Fat mass gain is lower in calcium-supplemented than in unsupplemented preschool children with low dietary calcium intakes

BACKGROUND: Dietary calcium may play a role in the stimulation of lipolysis and the inhibition of lipogenesis, thereby reducing body fat. OBJECTIVE: The aim was to determine whether an association existed between change in percentage body fat (%BF) or fat mass and calcium intake in children aged 3-5 y. DESIGN: A secondary analysis of a 1-y randomized calcium and activity trial in 178 children was conducted. Three-day diet records and 48-h accelerometer readings were obtained at 0, 6, and 12 mo. Body composition was measured by dual-energy X-ray absorptiometry at 0 and 12 mo. RESULTS: The decrease in %BF was less in girls (-0.6 +/- 2.8%) than in boys (-1.5 +/- 2.6%; P = 0.03) and correlated with age (r = 0.19, P = 0.01) and maternal body mass index (r = 0.19, P = 0.02). Changes in fat mass were not significantly different by activity group or between children randomly assigned to receive calcium or placebo (0.5 +/- 0.9 and 0.6 +/- 0.8 kg, respectively; P = 0.32). Similar findings were observed for the change in %BF. No correlations between %BF and fat mass changes and dietary calcium (r = -0.01, P = 0.9 and r = -0.05, P = 0.5) or total (dietary + supplement) calcium intake (r = -0.02, P = 0.8 and r = -0.06, P = 0.4) were observed. Among children in the lowest tertile of dietary calcium (<821 mg/d), fat mass gain was lower in the calcium group (0.3 +/- 0.5 kg) than in the placebo group (0.8 +/- 1.1 kg) (P = 0.04) but was not correlated with mean total calcium intake (r = -0.20). CONCLUSION: These findings support a weak relation between changes in fat mass gain and calcium intake in preschool children, who typically consume below recommended amounts of dietary calcium.     

The effect of dietary supplements on the nPCR in stable hemodialysis patients.

OBJECTIVE: To investigate whether (1) dietary supplements raise the normalized protein catabolic rate (nPCR) and/or further improve the nutritional status of stable hemodialysis patients who have both a low nPCR and a low dietary protein intake, <1.2 g/kg body weight/day; and if (2) protein intake measured by nPCR reflects protein intake measured by estimated food diaries in stable patients. DESIGN: Prospective experimental study with a single intervention group. SETTING: Hospital outpatient hemodialysis unit. SUBJECTS: Seventeen stable chronic hemodialysis patients (10 men, 7 women) were studied over 8 months. INTERVENTION: Subjects with both a low nPCR and dietary protein intake <1.2 g/kg body weight/day received dietary supplements for the first 2 months. Measurements to assess protein intake and nutritional status were taken at baseline and repeated at the end of 2 months, and at 6 months postintervention. MAIN OUTCOME MEASURE: nPCR, dietary protein intake using 7-day estimated food diaries, serum urea, serum albumin, serum creatinine, serum bicarbonate, dialysis adequacy (Kt/V), and body mass index (BMI). RESULTS: Dietary supplements significantly increased both the nPCR and the total protein intake at 2 months (1.21 +/- 0.26, 1.10 +/- 0.12, respectively) compared with baseline (0.95 +/- 0.18, 0.75 +/- 0.19, respectively) and 8 months (0.99 +/- 0.12, 0.78 +/- 0.21, respectively), P <.0001, respectively. There was no change in the nutritional status of the subjects. There was a significant difference between the nPCR and the dietary protein intake at baseline, P <.004; at 2 months, P <.047; and at 8 months, P <.001. CONCLUSION: Dietary supplements can significantly increase the nPCR and dietary protein intake in stable hemodialysis patients with a low nPCR and dietary protein intake. Because a low nPCR is associated with a high morbidity and mortality rate, it may be prudent to supplement such patients. The use of the nPCR to quantify dietary protein intake in stable hemodialysis patients should be used with caution.     

Digitally Supported Dietary Protein Counseling Changes Dietary Protein Intake,Sources, and Distribution in Community-Dwelling Older Adults

Digitally supported dietary counselling may be helpful in increasing the protein intake in combined exercise and nutritional interventions in community-dwelling older adults. To study the effect of this approach, 212 older adults (72.2 ± 6.3 years) were randomised in three groups: control, exercise, or exercise plus dietary counselling. The dietary counselling during the 6-month intervention was a blended approach of face-to-face contacts and videoconferencing, and it was discontinued for a 6-month follow-up. Dietary protein intake, sources, product groups, resulting amino acid intake, and intake per eating occasion were assessed by a 3-day dietary record. The dietary counselling group was able to increase the protein intake by 32% at 6 months, and the intake remained 16% increased at 12 months. Protein intake mainly consisted of animal protein sources: dairy products, followed by fish and meat. This resulted in significantly more intake of essential amino acids, including leucine. The protein intake was distributed evenly over the day, resulting in more meals that reached the protein and leucine targets. Digitally supported dietary counselling was effective in increasing protein intake both per meal and per day in a lifestyle intervention in community-dwelling older adults. This was predominantly achieved by consuming more animal protein sources, particularly dairy products, and especially during breakfast and lunch.     

Inadequate dietary protein increases hunger and desire to eat in younger and older men

Many older people experience changes in appetite and consume marginal or inadequate dietary protein. This study was designed to examine the appetitive responses to habitual protein intakes that span the range of adequacy in younger and older men. Twenty-two men (12 younger, aged 21-43 y and 10 older, aged 63-79 y) completed, in random order, three 18-d trials that involved consumption of individualized, isoenergetic menus providing 1.00, 0.75, and 0.50 g protein . kg BW(-1). d(-1), which were 125% (trial P125), 94% (trial P94), and 63% (trial P63) of the Recommended Dietary Allowance for protein. Near the end of each trial, the subjects recorded appetitive sensations hourly throughout one day using a visual analogue scale. Independent of age, ratings of hunger were lower for P125 (1.3 +/- 0.5 cm) than P94 (1.8 +/- 0.8 cm) and P63 (1.8 +/- 0.6 cm) (P = 0.037), and desire to eat was lower during the P125 trial (1.4 +/- 0.5 cm), compared with the P63 trial (2.1 +/- 0.7 cm) (P = 0.003), and P94 (1.8 +/- 0.7 cm) was not different when compared with P63 and P125. Protein intake did not influence fullness. These results show that younger and older men who consume inadequate protein experience appetite changes that may promote increased food intake.     

Longitudinal changes in BMI in older adults are associated with meat consumption differentially, by type of meat consumed

Hypotheses regarding the role of meat consumption in body weight modulation are contradictory. Prospective studies on an association between meat consumption and BMI change are limited. We assessed the association between meat consumption and change in BMI over time in 3902 men and women aged 55-69 y from the Netherlands Cohort Study. Dietary intake was estimated at baseline using a FFQ. BMI was ascertained through baseline self-reported height (1986) and weight (1986, 1992, and 2000). Analyses were based on sex-specific categories of daily total fresh meat, red meat, beef, pork, minced meat, chicken, processed meat, and fish consumption at baseline. Linear mixed effect modeling adjusted for confounders was used to assess longitudinal associations. Significant cross-sectional differences in BMI between quintiles of total meat intake were observed (P-trend < 0.01; both sexes). No association between total fresh meat consumption and prospective BMI change was observed in men (BMI change highest vs. lowest quintile after 14 y: -0.06 kg/m2; P = 0.75) and women (BMI change: 0.26 kg/m2; P = 0.20). Men with the highest intake of beef experienced a significantly lower increase in BMI after 6 and 14 y than those with the lowest intake (BMI change after 14 y 0.60 kg/m2). After 14 y, a significantly higher increase in BMI was associated with higher intakes of pork in women (BMI change highest vs. lowest quintile: 0.47 kg/m2) and chicken in both sexes (BMI change highest vs. lowest category in both men and women: 0.36 kg/m2). The results remained similar when stratifying on median baseline BMI, and age-stratified analyses yielded mixed results. Differential BMI change effects were observed for several subtypes of meat. However, total meat consumption, or factors directly related to total meat intake, was not strongly associated with weight change during the 14-y prospective follow-up in this elderly population.     

Zinc intakes and plasma concentrations in men with osteoporosis: the Rancho Bernardo Study

BACKGROUND: Low zinc intakes and reduced blood zinc concentrations have been reported to be associated with osteoporosis in women. OBJECTIVE: The objective was to examine the independent association between dietary zinc and plasma zinc and the association of each with bone mineral density (BMD) and 4-y bone loss in community-dwelling older men. DESIGN: Of the original Rancho Bernardo Study subjects, 396 men (age: 45-92 y) completed BMD measurements at baseline in 1988-1992 and 4 y later. Osteoporosis was defined as a BMD > or = 2.5 SDs below the mean for young women (a T-score < or = -2.5). At baseline, dietary intake data were collected by using a standard food-frequency questionnaire, and plasma zinc concentrations were measured by using inductively coupled plasma spectroscopy. RESULTS: The mean dietary zinc intake was 11.2 mg, and the mean plasma zinc concentration was 12.7 micromol/L. Plasma zinc was correlated with total zinc intake (diet plus supplements). Dietary zinc intake and plasma zinc concentrations were lower in men with osteoporosis at the hip and spine than in men without osteoporosis at those locations. BMDs for the hip, spine, and distal wrist were significantly lower in men in the lowest plasma zinc quartile (<11.3 micromol/L) than in men with higher plasma zinc concentrations. The association between plasma zinc and BMD was cross-sectional, longitudinal, and independent of age or body mass index. However, plasma zinc did not predict bone loss during the 4-y interval. CONCLUSION: Dietary zinc intake and plasma zinc each have a positive association with BMD in men.     

Magnesium intake and plasma concentrations of markers of systemic inflammation and endothelial dysfunction in women

BACKGROUND: Relations between magnesium intake and systemic inflammation and endothelial dysfunction are not well established. OBJECTIVE: The aim of the present study was to examine whether and to what extent magnesium intake is related to inflammatory and endothelial markers. DESIGN: We conducted a cross-sectional study of 657 women from the Nurses' Health Study cohort who were aged 43-69 y and free of cardiovascular disease, cancer, and diabetes mellitus when blood was drawn in 1989 and 1990. Plasma concentrations of C-reactive protein (CRP), interleukin 6 (IL-6), soluble tumor necrosis factor alpha receptor 2 (sTNF-R2), E-selectin, soluble intercellular adhesion molecule 1 (sICAM-1), and soluble vascular cell adhesion molecule 1 (sVCAM-1) were measured. Estimates from 2 semiquantitative food-frequency questionnaires, administered in 1986 and 1990, were averaged to assess dietary intakes. RESULTS: In age-adjusted linear regression analyses, magnesium intake was inversely associated with plasma concentrations of CRP (P for linear trend = 0.003), E-selectin (P = 0.001), and sICAM-1 (P = 0.03). After further adjustment for physical activity, smoking status, alcohol use, postmenopausal hormone use, and body mass index, dietary magnesium intake remained inversely associated with CRP and E-selectin. Multivariate-adjusted geometric means for women in the highest quintile of dietary magnesium intake were 24% lower for CRP (1.70 +/- 0.18 compared with 1.30 +/- 0.10 mg/dL; P for trend = 0.03) and 14% lower for E-selectin (48.5 +/- 1.84 compared with 41.9 +/- 1.58 ng/mL; P for trend = 0.01) than those for women in the lowest quintile. CONCLUSION: Magnesium intake from diet is modestly and inversely associated with some but not all markers of systematic inflammation and endothelial dysfunction in apparently healthy women.     

A short-term,high-fat diet up-regulates lipid metabolism and gene expression in human skeletal muscle

BACKGROUND: Dietary fatty acids may be important in regulating gene expression. However, little is known about the effect of changes in dietary fatty acids on gene regulation in human skeletal muscle. OBJECTIVE: The objective was to determine the effect of altered dietary fat intake on the expression of genes encoding proteins necessary for fatty acid transport and beta-oxidation in skeletal muscle. DESIGN: Fourteen well-trained male cyclists and triathletes with a mean (+/- SE) age of 26.9 +/- 1.7 y, weight of 73.7 +/- 1.7 kg, and peak oxygen uptake of 67.0 +/- 1.3 mL x kg(-1) x min(-1) consumed either a high-fat diet (HFat: > 65% of energy as lipids) or an isoenergetic high-carbohydrate diet (HCho: 70-75% of energy as carbohydrate) for 5 d in a crossover design. On day 1 (baseline) and again after 5 d of dietary intervention, resting muscle and blood samples were taken. Muscle samples were analyzed for gene expression [fatty acid translocase (FAT/CD36), plasma membrane fatty acid binding protein (FABPpm), carnitine palmitoyltransferase I (CPT I), beta-hydroxyacyl-CoA dehydrogenase (beta-HAD), and uncoupling protein 3 (UCP3)] and concentrations of the proteins FAT/CD36 and FABPpm. RESULTS: The gene expression of FAT/CD36 and beta -HAD and the gene abundance of FAT/CD36 were greater after the HFat than after the HCho diet (P < 0.05). Messenger RNA expression of FABPpm, CPT I, and UCP-3 did not change significantly with either diet. CONCLUSIONS: A rapid and marked capacity for changes in dietary fatty acid availability to modulate the expression of mRNA-encoding proteins is necessary for fatty acid transport and oxidative metabolism. This finding is evidence of nutrient-gene interactions in human skeletal muscle.     

Fructose, glycemic load, and quantity and quality of carbohydrate in relation to plasma C-peptide concentrations in US women

BACKGROUND: Circulating C-peptide concentrations are associated with insulin resistance and the development of type 2 diabetes. However, associations between fructose and the quantity and quality of total carbohydrate intake in relation to C-peptide concentrations have not been adequately examined. OBJECTIVE: We assessed the association of dietary fructose, glycemic load, and carbohydrate intake with fasting C-peptide concentrations. DESIGN: Plasma C-peptide concentrations were measured in a cross-sectional setting in 1999 healthy women from the Nurses' Health Study I and II. Dietary fructose, glycemic load, and carbohydrate intake were assessed with the use of semiquantitative food-frequency questionnaires. RESULTS: After multivariate adjustment, subjects in the highest quintile of energy-adjusted fructose intake had 13.9% higher C-peptide concentrations (P for trend = 0.01) than did subjects in the lowest quintile. Similarly, in the multivariate model, subjects in the highest quintile of glycemic load had 14.1% (P for trend = 0.09) and 16.1% (P for trend = 0.04) higher C-peptide concentrations than did subjects in the lowest quintile after further adjustment for total fat or carbohydrate intake, respectively. In contrast, subjects with high intakes of cereal fiber had 15.6% lower (P for trend = 0.03) C-peptide concentrations after control for other covariates. CONCLUSIONS: Our results suggest that high intakes of fructose and high glycemic foods are associated with higher C-peptide concentrations, whereas consumption of carbohydrates high in fiber, such as whole-grain foods, is associated with lower C-peptide concentrations. Furthermore, our study suggests that these nutrients play divergent roles in the development of insulin resistance and type 2 diabetes.     

Predictors of optical density of lutein and zeaxanthin in retinas of older women in the Carotenoids in Age-Related Eye Disease Study, an ancillary study of the Women's Health Initiative

BACKGROUND: Lifestyle, diet, and physical and health predictors of xanthophyll carotenoids in the retina are poorly understood. OBJECTIVE: We aimed to investigate the predictors of the density of lutein and zeaxanthin in the macula of the retina. DESIGN: Macular pigment optical density (MPOD) was measured by heterochromatic flicker photometry. Relations to dietary lutein and zeaxanthin and to other predictors were measured in 1698 women aged 53-86 y. The women were members of observational study cohorts of the Women's Health Initiative at Iowa City, IA, Madison, WI, or Portland, OR, and participated in the Carotenoids in Age-Related Eye Disease Study (2001-2004). RESULTS: MPOD at 0.5 degrees from the foveal center was 30% higher in women in the highest quintile for lutein and zeaxanthin intake [x (+/-SD): 0.40 +/- 0.21] than in women in the lowest quintile (0.31 +/- 0.21) and 20% higher after adjustment for other predictors. Dietary intake of lutein, zeaxanthin, fiber, and polyunsaturated fatty acids (% of energy) together explained 3% of the variability in MPOD. Higher waist circumference and diabetes, which are related to lower MPOD, together with study site explained an additional 5% of variation. The total explained variability increased to 12% when lutein and zexanthin concentrations obtained from the serum, which were collected 4-7 y earlier, were added to the model. CONCLUSIONS: MPOD is directly related to dietary intake of lutein and zeaxanthin but even more strongly to serum concentrations, which may reflect unmeasured physical and medical factors that influence the uptake, distribution, and utilization of lutein and zeaxanthin. Higher abdominal body fat and diabetes are related to lower MPOD. Unknown predictors of retinal carotenoids remain.     

Dietary protein and the risk of cholecystectomy in a cohort of US women: the Nurses' Health Study

In animals, vegetable protein can inhibit gallstone formation. Epidemiologic studies of dietary protein in relation to gallstone disease are sparse, and the effects of dietary protein of different origins are not clear. The authors aimed to examine the relation between dietary protein intake and risk of cholecystectomy among participants in the Nurses' Health Study, a cohort study of US women in 11 states. During 20 years of follow-up (1980-2000), the authors documented 7,831 cases of cholecystectomy. After adjustment for age, other known or suspected risk factors, and specific fats in a multivariate model, the relative risk of cholecystectomy for women in the highest quintile of dietary total protein intake compared with women in the lowest quintile was 1.00 (95% confidence interval (CI): 0.93, 1.08; p for trend = 0.46). When extreme quintiles were compared, the relative risk for animal protein intake was 1.07 (95% CI: 0.98, 1.15; p for trend = 0.08), whereas the relative risk for vegetable protein intake was 0.79 (95% CI: 0.71, 0.88; p for trend < 0.0001), with a significant dose-response relation. Additional mutual adjustment between animal and vegetable proteins did not materially alter the risks. These results suggest that increased consumption of vegetable protein in the context of an energy-balanced diet can reduce the risk of cholecystectomy in women.     

Lower serum albumin concentration and change in muscle mass: the Health, Aging and Body Composition Study

BACKGROUND: Low albumin concentrations in older persons increase the risk of poor health outcomes, including functional decline. OBJECTIVE: The aim of the study was to investigate the association between serum albumin concentration and skeletal muscle loss (sarcopenia) in old age. DESIGN: Serum albumin concentration was measured in 1882 black and white men and women aged 70-79 y participating in the Health, Aging and Body Composition Study. Five-year changes in appendicular skeletal muscle mass (ASMM), total-body fat-free mass (FFM), and trunk lean mass (TLM) were measured by using dual-energy X-ray absorptiometry. Confounders included health and lifestyle factors, which are markers of inflammation and protein intake. RESULTS: A low albumin concentration (< 38 g/L) was observed in 21.2% of the study participants. After adjustment for confounders, the mean (+/-SE) change in ASMM was -82 +/- 26 g per 3-g/L lower albumin concentration (P = 0.002). This association remained after persons with a low albumin concentration (< 38 g/L) were excluded. The decline in ASMM in subjects with low albumin concentrations was almost 30% higher (-930 +/- 56 g) than that in those with albumin concentrations > or = 42 g/L (-718 +/- 38 g; P < 0.01). The association between albumin and change in ASMM remained after additional adjustment for weight change. A weak association was observed for FFM, whereas no association was observed for TLM, which suggests a specific role of albumin in skeletal muscle change. CONCLUSIONS: Lower albumin concentrations, even above the clinical cutoff of 38 g/L, are associated with future loss of ASMM in older persons. Low albumin concentration may be a risk factor for sarcopenia.     

Long-term protein intake and dietary potential renal acid load are associated with bone modeling and remodeling at the proximal radius in healthy children

BACKGROUND: Protein and alkalizing minerals are increasingly described as playing a major role in influencing bone status, not only in the elderly but also in children and adolescents. OBJECTIVE: We examined whether the long-term dietary protein intake and diet net acid load are associated with bone status in children. DESIGN: In a prospective study design in 229 healthy children and adolescents aged 6-18 y, long-term dietary intakes were calculated from 3-d weighed dietary records that were collected yearly over the 4-y period before a one-time bone analysis. Dietary acid load was characterized as potential renal acid load (PRAL) by using an algorithm including dietary protein, phosphorus, magnesium, and potassium. Proximal forearm bone variables were measured by peripheral quantitative computed tomography. RESULTS: After adjustment for age, sex, and energy intake and control for forearm muscularity, BMI, growth velocity, and pubertal development, we observed that long-term dietary protein intake was significantly positively associated with periosteal circumference (P < 0.01), which reflected bone modeling, and with cortical area (P < 0.001), bone mineral content (P < 0.01), and polar strength strain index (P < 0.0001), which reflected a combination of modeling and remodeling. Children with a higher dietary PRAL had significantly less cortical area (P < 0.05) and bone mineral content (P < 0.01). Long-term calcium intake had no significant effect on any bone variable. CONCLUSIONS: Long-term dietary protein intake appears to act anabolically on diaphyseal bone strength during growth, and this may be negated, at least partly, if dietary PRAL is high, ie, if the intake of alkalizing minerals is low.     

Associations of dietary protein intake on subsequent decline in muscle mass and physical functions over four years in ambulant older Chinese people

Objective

To examine the association of dietary protein intake with 4-year change in physical performance measures and muscle mass in Chinese community-dwelling older people aged 65 and older in Hong Kong.

Design

Prospective cohort study design.

Setting

Hong Kong, People’s of Republic of China.

Participants

There were 2,726 (1411 male, 1315 female) community-dwelling older people aged 65 and older.

Measurements

Baseline total, animal and vegetable protein intakes were collected using a validated food frequency questionnaire. Relative protein intake expressed as g/kg body weight was calculated and divided into quartiles for data analysis. Baseline and 4-year physical performance measures (normal and narrow 6-meters walking speed and step length in a 6-meters walk) were measured and 4-year change in appendicular skeletal muscle mass (ASM) from baseline was assessed by dual-energy X-ray absorptiometry. Univariate analysis identified age and sex as significant factors associated with change in physical performance measures or ASM, thus adjustments for these factors were made for subsequent analysis of covariance.

Results

Median relative total protein intake was 1.3 g/kg body weight in men and 1.1 g/kg body weight in women. After adjustment for age and sex, relative total protein intake and animal protein intake were not associated with change in physical performance measures and ASM. In contrast, participants in the highest quartile (>0.72 g/kg body weight) of relative vegetable protein intake lost significantly less ASM over 4-year than those in the lowest quartile of relative vegetable protein intake (<=0.40 g/kg body weight) (adjusted mean ± SE: 0.270 ± 0.029 vs. 0.349 ± 0.030 kg, ptrend=0.025). There was no association between relative vegetable protein intake and change in physical performance measures.

Conclusions

Higher protein intake from vegetable source was associated with reduced muscle loss in Chinese community-dwelling older people in Hong Kong whereas no association between total and animal protein intake and subsequent decline in muscle mass or physical performance measures was observed in this sample.     

Relation of dietary glycemic index, glycemic load, added sugar intake, or fiber intake to the development of body composition between ages 2 and 7 y

BACKGROUND: Observational studies in adults suggest that a diet with a high glycemic index (GI) or glycemic load (GL), a high intake of sugary foods, or a low fiber intake may increase the risk of overweight. OBJECTIVES: We aimed to examine prospectively whether dietary GI, GL, added sugar intake, or fiber intake between age 2 and 7 y are associated with the development of body composition. If so, we aimed to ascertain whether these associations are modified by meal frequency. DESIGN: Linear mixed-effect regression analyses were performed in 380 participants of the DOrtmund Nutrition and Anthropometric Longitudinally Designed (DONALD) Study for whom 4-6 weighed 3-d dietary records and anthropometric data were obtained between ages 2 and 7 y. RESULTS: Changes in dietary GI, GL, or added sugar intake between ages 2 and 7 y were not associated with concurrent changes in percentage body fat (%BF, as estimated from skinfold thicknesses) or body mass index SD scores. An increase in fiber intake was related to a concurrent decrease in %BF between ages 2 and 7 y only in children who consumed <6 meals/d as toddlers (beta +/- SE from fully adjusted model: -0.26 +/- 0.09%BF per 1-SD increase in fiber intake, P = 0.005), whereas children with a higher meal frequency had no concurrent change (0.07 +/- 0.07%BF per 1-SD increase in fiber intake, P = 0.3). CONCLUSIONS: Dietary GI, GL, or added sugar intake between ages 2 and 7 y does not appear to influence the development of body composition. Potential benefits associated with increasing fiber intake throughout childhood may be limited to toddlers with a lower meal frequency.     

Dietary fiber intake and retinal vascular caliber in the Atherosclerosis Risk in Communities Study

BACKGROUND: Dietary fiber appears to decrease the risk of cardiovascular morbidity and mortality. Microvascular abnormalities can be observed by retinal examination and contribute to the pathogenesis of various cardiovascular diseases. The impact of dietary fiber on the retinal microvasculature is not known. OBJECTIVE: We aimed to examine the association between dietary fiber intake and retinal vascular caliber. DESIGN: At the third visit (1993-1995) of the Atherosclerosis Risk in Communities (ARIC) Study, a population-based cohort of adults in 4 US communities, the retinal vascular caliber of 10,659 participants was measured and summarized from digital retinal photographs. Usual dietary intake during the same period was assessed with a 66-item food-frequency questionnaire. RESULTS: After control for potential confounders including hypertension, diabetes, lipids, demographic factors, cigarette smoking, total energy intake, micronutrients intake, and other cardiovascular disease risk factors, higher intake of fiber from all sources and from cereal were significantly associated with wider retinal arteriolar caliber and narrower venular caliber. Participants in the highest quintile of fiber intake from all sources had a 1.05-microm larger arteriolar caliber (P for trend = 0.012) and a 1.11-microm smaller venular caliber (P for trend = 0.029). CONCLUSIONS: Dietary fiber was related to wider retinal arteriolar caliber and narrower venular caliber, which are associated with a lower risk of cardiovascular disease. These data add to the growing evidence of the benefits of fiber intake on various aspects of cardiovascular pathogenesis.