Breakfast consumption and adiposity among children and adolescents: an updated review of the literature.

BACKGROUND: Breakfast consumption has been associated with reduced risk of overweight and obesity among children, but previous evidence reviews fail to confirm a causal relationship. OBJECTIVES: To review recent literature on breakfast consumption and adiposity among children and discuss potential underlying mechanisms. METHODS: A comprehensive literature search of studies published since the 2010 US National Evidence Library review (January 2010-January 2015) was conducted. RESULTS: Twelve studies met inclusion criteria. All were conducted in industrialized countries: six in Europe, four in the USA, one in China and one in Australia. Ten of the studies used observational longitudinal designs, with follow-up periods ranging from 1 to 27 years (median: 3, mean: 7.4); of these, eight reported inverse associations between breakfast consumption and excess adiposity, while two found no association. The other studies (1 case-control, 1 experimental) each reported a protective effect of breakfast consumption on overweight and obesity among children. CONCLUSIONS: Findings corroborate results from previous reviews, adding support for a possible, protective role for breakfast consumption in preventing excess adiposity during childhood and adolescence. However, drawing a causal conclusion from the collective evidence is curtailed by methodological limitations and inconsistencies, including study design, follow-up duration and frequency, exposure and outcome assessment, as well as limited consideration of confounding, mediating and effect-modifying variables. More rigorous study designs employing valid and standardized measurement of relevant variables are needed.

The relationship between childhood BMI and adult serum cholesterol, LDL, and ankle brachial index.

OBJECTIVE: Effects of childhood overweight may persist into adulthood. We assessed the effect of childhood overweight on cardiovascular disease high risk factor levels in the same participants as adults, after controlling for adult body mass index (BMI) status. DESIGN: A subset of participants in an observational study (Heartwatch) were contacted approximately 26-27 years after initial enrollment to participate in a follow-up study on the long-term effects of childhood overweight. During follow-up, BMI, waist:hip circumference (WHC), blood pressure (BP), serum lipids, and ankle brachial index (ABI) were measured; additional BMI measures throughout childhood were obtained as available from the electronic medical record. Primary outcomes were ABI and serum low density lipoprotein (LDL). SETTING: The 1982 Heartwatch study was conducted with children participants living in Marshfield, Wisconsin; follow-up included original participants who were re-contacted and agreed to be enrolled. PARTICIPANTS: Participants were a stratified random sample of eligible participants in the original 1982 Heartwatch study. Of the original 3106 participants, 647 adult participants completed follow-up exams. RESULTS: Among males with 1982 BMI ≥ 85(th) percentile, adult BMI, WHC, (both P ≤ 0.001), ABI (P = 0.001), total cholesterol (P = 0.01), LDL (P = 0.003) and BP (P < 0.02) were higher in 2008-2009 as compared to males with 1982 BMI < 85(th) percentile. Among females, BMI, BP and WHC (all P < 0.001) were higher in 2008-2009. BMI in 1982 and 2008-2009 were correlated [r = 0.56 (males); 0.58 (females), P < 0.001]. 2008-2009 BMI was more strongly correlated with 2008-2009 measures of ABI (r = 0.16, P = 0.006, males) and high LDL [r = 0.18, P = 0.002 (males); r = 0.11, P = 0.046 (females)]. 1982 BMI was not independently associated with ABI or LDL after adjusting for adult BMI. CONCLUSION: In a cohort studying childhood and adult overweight, childhood BMI was associated with health outcomes relating to cardiovascular disease in adulthood. However, childhood BMI was not independently related to LDL-C or ABI levels in adulthood after accounting for adult BMI. Longitudinal measurements of BMI and other health risk factors were not found to improve accuracy of models for high cardiovascular disease risk factor levels.

Predicted 25-hydroxyvitamin D score and change in fasting plasma glucose in the Framingham offspring study.

Data on the association between vitamin D status and actual change in glycemic measures are limited. We examined the prospective association between a predicted 25-hydroxyvitamin D (25(OH)D) score and change in fasting plasma glucose concentration over a mean follow-up of 7 years, in 2571 men and women (mean age 54 years) without diabetes in the Framingham Offspring Study cohort. After adjustment for age, sex, body mass index and fasting plasma glucose at baseline, higher predicted 25(OH)D score at baseline was associated with a smaller 7-year increase in fasting plasma glucose concentrations (0.23 mmol/l versus 0.35 mmol/l for highest versus lowest tertile of 25(OH)D score, respectively, P-trend=0.002). Vitamin D status may be an important determinant for change in fasting plasma glucose concentration among middle-aged and older adults without diabetes.

The association between sports participation and athletic identity with eating pathology among college-aged males and females.

The current study examined associations among sports participation (SP), athletic identity (AI), weight status, and eating pathology, and whether these relations differed by gender. Data come from male and female first-year college students who participated in the Tufts Longitudinal Health Study (TLHS) between 1999-2007 (N=712). Relations among SP, AI, actual and perceived weight statuses, Eating Disorders Inventory (EDI) subscale scores, and indices of body shape concern and restrictive eating were examined with hierarchical ordinary least squares (OLS) regression. Associations between SP and eating pathology among females were moderated by perceived weight status. By contrast, relations between males' EDI subscales scores and SP were moderated by ethnicity, as well as by actual weight status. Our findings support that sports participation alone neither promotes nor protects against eating pathology among males and females.

Precision of Lunar Achilles+ bone quality measurements: time dependency and multiple machine use in field studies.

Qualitative ultrasound (QUS) is a portable, safe and relatively inexpensive technique used to obtain information on bone mineral quality in adults and children. QUS measures bone stiffness index (SI) through the incorporation of speed of sound (SOS) and broadband ultrasound attenuation (BUA). QUS technology may prove to be extremely useful in field research where more than one machine is used over different periods of time. 13 adults (27.6+/-4.6 years old) were recruited to determine the internal stability of two Lunar Achilles+ QUS machines (Lunar1, Lunar2), as well as the repeatability in bone stiffness measures between the two machines over time. Triplicate measurements of the calcaneus were taken within the same day (n = 258) and at 1 week (n = 120), 6 months (n = 54) and 1 year (n = 18) apart to determine the time-dependent repeatability. Using paired t-tests and separate mixed effects models, there were no differences reported in SI, SOS or BUA values within one machine, or between two machines over these short- and long-term time-frames. These results indicate that QUS machines are internally consistent and different machines may be used over time to provide reliable measurements of changes in bone quality.

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.

Application of bioelectrical impedance analysis to elderly populations.

BACKGROUND: Bioelectrical impedance analysis (BIA) can potentially be used to estimate body composition in large populations studied at multiple sites. However, it is not clear whether age-specific BIA equations are necessary for accurate application of BIA to research on elderly subjects. METHODS: We compared a published equation designed to predict fat-free mass (FFM) that had been derived in a young healthy population (mean age 27 y; mean BMI 23.9 kg/m2), with equations that we developed for the elderly by using data from 455 participants in the Framingham Heart Study (78 Y; 27.3 kg/m2), using dual-energy x-ray absorptiometry (DXA) as a reference technique. The BIA equations were then compared in an independent sample of 283 participants in the New Mexico Aging Process Study (76 y, 25.5 kg/m2), who also underwent BIA and DXA. RESULTS: When the young-population equation was applied to Framingham, it caused an overestimation of FFM in heavier subjects that was eliminated by use of the age-specific equation. However, when the two equations were tested in the New Mexico population, the published equation gave estimates of FFM that were closer to DXA than the Framingham equations did. CONCLUSIONS: The accuracy of a BIA equation depends on the body composition of the population of the population and the validation method rather than on age per se. Application of BIA to elderly populations requires uniform validation procedures in the actual study population, rather than reliance on age-specific equations.

A multi-center comparison of dual energy X-ray absorptiometers: in vivo and in vitro soft tissue measurement.

OBJECTIVE: To assess intra- and inter-site soft tissue variability by dual energy X-ray absorptiometry (DXA). DESIGN: Cross-sectional trial. SETTING: Three medical research institutions. SUBJECTS: Five humans (in vivo) and four phantoms (in vitro), configured from two whole body phantoms with artificial skeletons and thickness overlays. INTERVENTIONS: Duplicate total-body DXA scans were performed on all subjects at each institution within a 15 d period. RESULTS: All intra-site coefficients of variation (CV) were < 0.5% for total tissue mass, but in vitro and in vivo Cvs were 7.2% and 2.3% for fat mass (FM) and 2.5% and 0.9% for lean mass (LM), respectively. Several total-body and regional FM and LM measurements were significantly different between sites (P < 0.05), with percent differences between sites ranging from 2.6-13.3% for FM and from 1.6-13.6% for LM. Site 2 was consistently lower for FM and Site 3 was consistently lower for LM. CONCLUSIONS: These results stress the need for both rigorous and standardized cross-calibration procedures for soft tissue measurement by DXA.

Analysis of body-composition techniques and models for detecting change in soft tissue with strength training.

The purpose of this study was to compare the ability of various body-composition assessment techniques to detect changes in soft tissue in older, weight-stable women (50-70 y of age) completing a 1-y randomized, controlled trial of progressive resistance training. The intervention group (n = 20) performed high-intensity strength-training 2 d/wk with five different exercises; the control group (n = 19) was untreated. Hydrostatic weighing, 24-h urinary creatinine, computed tomography of thigh sections, total body potassium, and tritium dilution techniques were used to measure increases in total fat-free mass (FFM) and the muscle and water components of FFM. A decrease in fat mass (by hydrostatic weighing) was seen in the strength-trained women compared with the control subjects (P - 0.01-0.0001). Anthropometry, bioelectric impedance, dual-energy X-ray absorptiometry, and total body nitrogen and carbon did not measure any significant change in soft tissue. The choice of a body-composition technique is important when designing a study expected to affect soft tissue, because not all techniques available are precise enough to detect small changes.

Calibration of the delayed-gamma neutron activation facility.

The delayed-gamma neutron activation facility at Brookhaven National Laboratory was originally calibrated using an anthropomorphic hollow phantom filled with solutions containing predetermined amounts of Ca. However, 99% of the total Ca in the human body is not homogeneously distributed but contained within the skeleton. Recently, an artificial skeleton was designed, constructed, and placed in a bottle phantom to better represent the Ca distribution in the human body. Neutron activation measurements of an anthropomorphic and a bottle (with no skeleton) phantom demonstrate that the difference in size and shape between the two phantoms changes the total body calcium results by less than 1%. To test the artificial skeleton, two small polyethylene jerry-can phantoms were made, one with a femur from a cadaver and one with an artificial bone in exactly the same geometry. The femur was ashed following the neutron activation measurements for chemical analysis of Ca. Results indicate that the artificial bone closely simulates the real bone in neutron activation analysis and provides accurate calibration for Ca measurements. Therefore, the calibration of the delayed-gamma neutron activation system is now based on the new bottle phantom containing an artificial skeleton. This change has improved the accuracy of measurement for total body calcium. Also, the simple geometry of this phantom and the artificial skeleton allows us to simulate the neutron activation process using a Monte Carlo code, which enables us to calibrate the system for human subjects larger and smaller than the phantoms used as standards.

A multicenter comparison of dual-energy X-ray absorptiometers: in vivo and in vitro measurements of bone mineral content and density.

As part of a multicenter research project, we compared dual-energy X-ray absorptiometry (DXA) instruments at three research centers (sites 1, 2 and 3) to determine both intra- and intersite variability of bone mineral content (BMC), bone mineral density (BMD), and bone area (BA). Scans of the total body and lumbar spine were performed in duplicate on five humans (in vivo), and scans of the total body were performed on two whole body phantoms with artificial skeletons and thickness overlays (in vitro) at all sites over 15 days. The average intrasite variability in two consecutive total body BMD measurements, expressed as a percent difference, was significantly higher in vitro, 1.74 +/- 1.97%, than in vivo, 0.71 +/- 0.38% (p < 0.05). Average intrasite variability of the in vivo lumbar spine BMD was 1.08 +/- 1.12%. The intersite coefficients of variation for all BMD, BMC, and BA measurements were < 2.0%. The total body BMD from site 2 was systematically lower than at sites 1 and 3 both in vivo and in vitro (p < 0.05) with no differences in BMC and BA. Although significant, the total body BMD differences between sites were small (< 1.2%) in vivo compared with in vitro (< 2.6%) and are encouraging for the comparison and pooling of human data from multicenter trials, provided that appropriate standardized cross-calibration and analysis procedures are applied.

Strength improvements with 1 yr of progressive resistance training in older women.

Thirty-nine healthy women (59.5 +/- 0.9 yr) were randomized to either a control group (CON) or a progressive resistance training group (PRT) that trained twice weekly for 12 months. PRT trained at 80% or more (average of 84%) of their most recent one repetition maximum (1RM) on the lateral pull-down (LPD), knee extensor (KE), and double leg press (DLP) apparatus. One RM was measured for each exercise once monthly in PRT and at baseline, midstudy, and end of study in CON. One RM significantly increased in PRT for all muscle groups trained compared to CON (P < 0.0001). Increases of 73.7 +/- 12%, 35.1 +/- 3%, and 77.0 +/- 5%, respectively, for KE, DLP, and LPD in PRT and 12.7% +/- 8%, 3.7% +/- 3%, and 18.4% +/- 4%, respectively, in CON were observed. Approximately 50% of the gains in KE and LPD and 40% in the DLP were seen in the first 3 months of the study. In all three exercises, strength gains in PRT continued over the entire 12-month period. These data indicate that high-intensity strength training results in substantial, continual increases in strength in postmenopausal women for at least 12 months, with the greatest gains seen in the first 3 months of training.

Nutritional practices of elite athletes. Practical recommendations.

The nutritional intake of elite athletes is a critical determinant of their athletic performance and ability to compete both physically and mentally. However, their demanding training and travel schedules in addition to a possible lack of nutritional knowledge may prohibit them from maintaining an optimal dietary intake. Sound scientific data about the nutritional habits of elite athletes are limited and, therefore, it is not clear as to whether elite athletes are following nutritional recommendations and maintaining nutritionally sound diets. This review takes a comprehensive look at 22 recent dietary intake studies, including 50 groups of elite athletes. The time period for food record collection ranged from 3 to 7 days except for 2 studies which collected records for 21 and 22 days. Energy intakes of > 50 kcal/kg/day for male athletes who train for > 90 min/day and 45 to 50 kcal/kg/day for female athletes training for > 90 min/day are recommended. Bodyweight should be monitored frequently as a check on calorie intake. With a sufficient calorie intake (1.2 to 2.0 kg/kg/day) protein supplementation is not necessary. Ingested carbohydrate stored as glycogen serves as the primary fuel for muscle performance. Athletes in training should consume 70% of total calories as carbohydrate. Athletes on low energy diets (< 2200 kcal/day) should have a diet of < 25% fat, and athletes with large energy needs should consume 30% fat in their diet. In general, fat intakes should be reduced and carbohydrate intakes increased. Athletes should also restrict alcohol intake during training and competition periods. Athletes with low calorie intakes should consume foods with high contents of iron, calcium, magnesium, zinc and vitamin B12. Athletes with high calorie intakes should consume foods that are naturally high in or fortified with B-group vitamins. Fluid, electrolyte and energy supplementation is desirable to support circulatory, metabolic and thermoregulatory functions. There is no special food that will help elite athletes perform better; the most important aspect of the diet of elite athletes is that it follows the basic guidelines for healthy eating.