Determinants of body composition in breastfed infants using bioimpedance spectroscopy and ultrasound skinfolds—methods comparison

Abstract

Background: Accurate, noninvasive, and inexpensive methods are required to measure infant body composition. Ultrasound (US) and bioimpedance spectroscopy (BIS) have been validated in adults and introduced in pediatric populations. The aim of this study was to evaluate the performance of both methods in determining percentage fat mass (%FM) in breastfed infants. Methods: %FM of 2, 5, 9, and 12 mo-old healthy, breastfed term infants (n = 58) was calculated using BIS-derived total body water equations and skinfold equations then compared with reference models. Skinfolds were measured with US at two and four sites (biceps, suprailiac and/or triceps, and subscapular). results: %FM differed widely within and between methods, with the degree of variation affected by infant age/sex. Not a single method/equation was consistent with the distributions of appropriate reference values for all age/sex groups. Moderate number of matches with references values (13-24 out of 36) was seen for both types of equations. High number of matches (25-36) was seen for US skinfold-based equations. %FM values calculated from US and BIS were not significantly different (P = 0.35). conclusion: Both BIS and US are practical for predicting %FM in infants. BIS calculations are highly dependent upon an appropriate set of validated age-matched equations. Body composition (BC) in early life plays an important role in the programming of long-term health outcomes including obesity, type II diabetes, and cardiovascular disease (1). The majority of large studies reporting an association of infant development with disease later in life use anthropometric measurements or BMI to monitor growth that provide limited indices of adiposity as they fail to reflect body shape, fat distribution, and density.The number of techniques available to assess infant BC is increasing. These measures have better accuracy than anthropometric measurements, but may be either time consuming, expensive, and invasive, expose infants to low levels of radiation (dual-energy X-ray absorptiometry and computed tomography), require the infant to be restrained (magnetic resonance imaging) or have weight restriction (air displacement plethysmography).Bioelectrical impedance spectroscopy (BIS) is noninvasive and often used to estimate BC due to its ease of application and low cost. BIS measures the electrical impedance, or opposition to flow through the body tissues of a small harmless electric current. The measured impedance, corrected for the reactive component, known as electrical resistance is inversely and quantitatively related to the volume of conductive compartment which can be used to calculate total body water (TBW) and estimate fat-free mass (FFM) and fat mass (FM) (2). BIS provides reliable estimates of TBW in adults and equations have been developed for children and infants (3,4). While in very young infants (<5 mo) BIS is associated with poorer predictive performance that could be due to the higher conductivity of the infant's adipose tissue with its increased vascularizat...

Ensuring breastfeeding-supportive legislation

“…In this issue of Pediatric Research, Julvez et al report on lower rates of autistic traits and improved cognitive function in breastfed infants in early childhood (2). Gridneva and colleagues, also in this issue, reinforce the beneficial effects of breastfeeding on adiposity, a risk factor for later obesity (3).…”

“…the national Healthy People 2020 benchmarks have been observed over time (1). Two articles in this issue add to the well-known benefits of breastfeeding (2,3). Interestingly, there appears to be substantial overlap between states whose breastfeeding rates are lower than Healthy People 2020 goals with those who chose not to accept the federally-funded Medicaid Expansion as part of the Affordable Care Act (ACA).…”

Bioelectrical Impedance Analysis—An Easy Tool for Quantifying Body Composition in Infancy?

“…However, it is unclear how the resistivity coefficients used in these modelling equations change as an infant grows [26], therefore the inclusion of population-specific adjustments is thought to increase accuracy at the individual level [27]. Despite this, to date, bioelectrical impedance spectroscopy has seldom been used to assess body composition in infancy [28][29][30][31]. Indeed, recent studies frequently rely on older previously published single-frequency bioimpedance predictive equations, for example those by Kushner et al [32], to inform prediction of body composition among their participants [33,34].…”

“…When cross-validated with Lingwood et al's [29] cohort, the predictive equations performed similarly only when the infants were age-matched. Likewise, Gridneva et al [31] found that the performance of bioelectrical impedance equations was strongly influenced by whether there was an appropriate age-match for their population of infants. It should be noted that both Tint et al [30] and Gridneva et al [31] used resistance at 50 kHz, as is standard with single frequency bioimpedance devices.…”

“…Likewise, Gridneva et al [31] found that the performance of bioelectrical impedance equations was strongly influenced by whether there was an appropriate age-match for their population of infants. It should be noted that both Tint et al [30] and Gridneva et al [31] used resistance at 50 kHz, as is standard with single frequency bioimpedance devices. Lingwood et al [29], however, found better prediction of fat-free mass when using other impedance values, for example, impedance at the characteristic frequency (Zc) and resistance at zero frequency (R 0 ).…”