IGF-I and IGFBP-3 concentrations at 2 years: associations with anthropometry and milk consumption in an Indian cohort

Optimizing Growth: The Case for Iodine

Iodine is an essential micronutrient and component of thyroid hormone. An adequate dietary iodine intake is critical to maintain and promote normal growth and development, especially during vulnerable life stages such as pregnancy and early infancy. The role of iodine in cognitive development is supported by numerous interventional and observational studies, and when iodine intake is too low, somatic growth is also impaired. This can be clearly seen in cases of untreated congenital hypothyroidism related to severe iodine deficiency, which is characterized, in part, by a short stature. Nevertheless, the impact of a less severe iodine deficiency on growth, whether in utero or postnatal, is unclear. Robust studies examining the relationship between iodine and growth are rarely feasible, including the aspect of examining the effect of a single micronutrient on a process that is reliant on multiple nutrients for optimal success. Conversely, excessive iodine intake can affect thyroid function and the secretion of optimal thyroid hormone levels; however, whether this affects growth has not been examined. This narrative review outlines the mechanisms by which iodine contributes to the growth process from conception onwards, supported by evidence from human studies. It emphasizes the need for adequate iodine public health policies and their robust monitoring and surveillance, to ensure coverage for all population groups, particularly those at life stages vulnerable for growth. Finally, it summarizes the other micronutrients important to consider alongside iodine when seeking to assess the impact of iodine on somatic growth.

Diet and Nutrients Intakes during Infancy and Childhood in Relation to Early Puberty: A Systematic Review and Meta-Analysis

The onset of puberty has become earlier over the decades, and nutrients and diet are related to the timing of puberty onset. Hence, we aimed to investigate the association between diet or nutrients in infancy, childhood and early puberty. PubMed, Embase, and Cochrane library were searched systematically up to 15 April 2022. The pooled relative risks (RRs) or regression coefficients (beta) were estimated using the random-effect model or fixed-effect model according to the heterogeneity between studies. Twenty-two articles on diet or nutrients in childhood and six about breastfeeding in infancy were included. The prolonged breastfeeding duration in infancy could reduce the risk of early menarche (beta 0.31, 95% CI: 0.01, 0.60, p = 0.045). The high intake of yogurt was associated with a 35% reduction in the risk of earlier menarche (RR 0.65, 95% CI: 0.47, 0.89, p = 0.008). Girls with severe food insecurity experienced later menarche (RR 0.81, 95% CI: 0.67, 0.98, p = 0.027). Conversely, due to the high intake of protein, the risk of early menarche increased by 8% (RR 1.08, 95% CI: 1.01, 1.16, p = 0.016). High intake of yogurt, longer duration of breastfeeding, and food insecurity decreased the possibility of earlier menarche, while high intake of protein increased that risk. As a modifiable factor, diet and nutrients in infancy and childhood provide new insights into the future prevention of early puberty.

The effect of milk and rapeseed protein on growth factors in 7-8 year-old healthy children - A randomized controlled trial

OBJECTIVE

Milk protein may stimulate linear growth through insulin-like growth factor-1 (IGF-1). However, the effect of plant proteins on growth factors is largely unknown. This study assesses the effect of combinations of milk and rapeseed protein versus milk protein alone on growth factors in children.

DESIGN

An exploratory 3-armed randomized, double-blind, controlled trial was conducted in 129 healthy 7-8 year-old Danish children. Children received 35 g milk and rapeseed protein (ratio 54:46 or 30:70) or 35 g milk protein per day for 4 weeks. The primary outcome was difference in IGF-1 changes between intervention groups after 4 weeks. Secondary outcomes included changes in IGF-1 after 1 week and changes in insulin-like growth factor binding protein-3 (IGFBP-3), IGF-1/IGFBP-3, insulin, height, weight and body composition after 1 and 4 weeks. Results were analysed by multiple linear mixed-effect models.

RESULTS

There were no differences in changes of plasma IGF-1, insulin-like growth factor binding protein-3 (IGFBP-3), IGF-1/IGFBP-3 ratio or insulin between groups after 1 or 4 weeks based on 89 complete cases (P > 0.10). IGF-1 increased by 13.7 (95% CI 9.7;17.7) ng/mL and 18.0 (14.0;22.0) ng/mL from baseline to week 1 and 4, respectively, a 16% increase during the intervention. Similarly, insulin increased by 31% (14; 50) and 33% (16; 53) from baseline to week 1 and 4. Fat-free mass index (FFMI) increments were higher with milk alone than rapeseed blends (P < 0.05), coinciding with a trend towards a lower height increment. Body mass index increased within all groups (P < 0.05), mainly due to an increase in FFMI (P < 0.01).

CONCLUSION

There were no differences in changes of growth factors between the combinations of milk and rapeseed protein and milk protein alone in healthy, well-nourished children with a habitual intake of milk. Within groups, growth factors increased considerably. Future studies are needed to investigate how intakes of plant and animal proteins affect childhood growth.

Evolution of Lactase Persistence: Turbo-Charging Adaptation in Growth Under the Selective Pressure of Maternal Mortality?

The emergence of the capacity to digest milk in some populations represents a landmark in human evolution, linking genetic change with a component of niche construction, namely dairying. Alleles promoting continued activity of the enzyme lactase through the life-course (lactase persistence) evolved in several global regions within the last 7,000 years. In some European regions, these alleles underwent rapid selection and must have profoundly affected fertility or mortality. Elsewhere, alleles spread more locally. However, the functional benefits underlying the rapid spread of lactase persistence remain unclear. Here, we set out the hypothesis that lactase persistence promoted skeletal growth, thereby offering a generic rapid solution to childbirth complications arising from exposure to ecological change, or to new environments through migration. Since reduced maternal growth and greater neonatal size both increase the risk of obstructed labour, any ecological exposure impacting these traits may increase maternal mortality risk. Over many generations, maternal skeletal dimensions could adapt to new ecological conditions through genetic change. However, this adaptive strategy would fail if ecological change was rapid, including through migration into new niches. We propose that the combination of consuming milk and lactase persistence could have reduced maternal mortality by promoting growth of the pelvis after weaning, while high calcium intake would reduce risk of pelvic deformities. Our conceptual framework provides locally relevant hypotheses to explain selection for lactase persistence in different global regions. For any given diet and individual genotype, the combination of lactase persistence and milk consumption would divert more energy to skeletal growth, either increasing pelvic dimensions or buffering them from worsening ecological conditions. The emergence of lactase persistence among dairying populations could have helped early European farmers adapt rapidly to northern latitudes, East African pastoralists adapt to sudden climate shifts to drier environments, and Near Eastern populations counteract secular declines in height associated with early agriculture. In each case, we assume that lactase persistence accelerated the timescale over which maternal skeletal dimensions could change, thus promoting both maternal and offspring survival. Where lactase persistence did not emerge, birth weight was constrained at lower levels, and this contributes to contemporary variability in diabetes risk.

Correlates of serum IGF-1 in young children with moderate acute malnutrition: a cross-sectional study in Burkina Faso

BACKGROUND

Serum insulin-like growth factor 1 (sIGF-1) is an important growth factor in childhood. However, studies on sIGF-1 among children from low-income countries are few, and the role of body composition is unknown.

OBJECTIVES

To assess the associations of anthropometry, body composition, inflammation, and breastfeeding with sIGF-1 among children with moderate acute malnutrition (MAM).

METHODS

A cross-sectional study based on admission data from 6- to 23-mo-old children with MAM participating in a nutrition intervention trial (Treatfood) in Burkina Faso. Linear regression analysis was used to identify correlates of sIGF-1.

RESULTS

Among 1546 children, the median (IQR) sIGF-1 was 12 (8.2-18.3) ng/mL. sIGF-1 was highest at 6 mo, with a nadir ∼10-11 mo, and higher in girls than boys. Length-for-age z score (LAZ), weight-for-length z score (WLZ), and midupper arm circumference were positively associated with sIGF-1 (P ≤ 0.001). Fat-free mass (FFM) was also positively associated, as sIGF-1 increased 1.5 (95% CI: 0.5, 2.5) ng/mL for each 1-kg increase in FFM. However, the association disappeared after adjustment for height. Elevated serum C-reactive protein and α1-acid glycoprotein were negatively associated with sIGF-1 (P ≤ 0.001), as was fever (P < 0.001) but not a positive malaria test per se (P = 0.15). Children never breastfed had lower sIGF-1 (-5.1; 95% CI: -9.8, -0.3).

CONCLUSIONS

LAZ and WLZ were positively and inflammation negatively associated with sIGF-1. As all children were moderately malnourished and many had inflammation, this probably explains the very low median sIGF-1. The association of FFM with sIGF-1 was fully explained by height. There was a marked age pattern, with a nadir in late infancy, confirming findings from smaller studies from well-nourished populations. There is a need for prospective studies to disentangle the role of sIGF-1 in growth and health. This trial was registered at https://www.isrctn.com as ISRCTN42569496.

Milk and dairy consumption is positively associated with height in adolescents: results from the Israeli National Youth Health and Nutrition Survey

PURPOSE

Milk consumption is associated with increased height primarily in early childhood. However, in adolescents, data are scarce with inconsistent results. Since height is a proxy for overall health and well-being, this study evaluated the association of dairy intake with height in adolescents.

METHODS

Students in 7th-12th grades, participating in the 2015-2016 Israeli Health and Nutrition Youth Survey, a school-based cross-sectional study, completed self-administered questionnaires, including a semi-quantitative food frequency questionnaire (n = 3529, 48% males, 15.2 ± 1.6 years). Anthropometric measurements were also performed. Dairy servings were calculated as the calcium equivalent of 1 cup of milk, and consumption was divided into four categories from very low (< 1 serving/day) to high (3 + servings/day). BMI- and Height-for-age z scores (HAZs) were calculated according to WHO growth standard; relatively short stature (RSS) was defined as HAZ < - 0.7 SD (< 25th percentile). Multivariable linear and logistic regression analyses were performed to evaluate the association of dairy intake with HAZ and prevalence of RSS, respectively.

RESULTS

Median consumption of dairy products was 2 servings/day, 1.4 from unsweetened products (milk, cheese and yogurt). Controlling for age, sex, BMI-z-score and socioeconomic status, each increment of unsweetened dairy intake was associated with on average 0.04 higher HAZ (equivalent to 0.3-0.4 cm, p < 0.05), and with reduced risk for RSS: OR 0.90, 95%CI: 0.84, 0.97, p < 0.01. No such associations were found with sweetened dairy products.

CONCLUSION

Consumption of unsweetened dairy products (3-4 servings/day) appears to contribute to achieving growth potential in adolescents. Intervention studies are necessary to determine the causal relationship between dairy intake and linear growth.

Protein Intake, IGF-1 Concentrations, and Growth in the Second Year of Life in Children Receiving Growing Up Milk - Lite (GUMLi) or Cow's Milk (CM) Intervention

The relationship of protein intake with insulin-like growth factor 1 (IGF-1) concentrations in well-nourished children during the second year of life is poorly understood. The aim of this study was to explore the effect of a reduced-protein Growing Up Milk Lite (GUMLi) or unfortified cow's milk (CM) on protein intake, growth, and plasma IGF-1 at 2 y. An exploratory analysis of a sub-sample of Auckland-based children (n = 79) in the GUMLi trial (a double-blind, randomised control trial, N = 160) completed in Auckland and Brisbane (2015-2017) was conducted. One-year old children were randomised to receive a reduced-protein GUMLi (1.7 g protein/100 mL) or a non-fortified CM (3.1 g protein/100 mL) for 12 months. Blood sampling and anthropometric measurements were made at 1 and 2 y. Diet was assessed using a validated food frequency questionnaire. Total protein intake (g/d) from all cow's milk sources was 4.6 g (95% CI: -6.7, -2.4; p < 0.005) lower in the GUMLi group after 12 months of the intervention, with a significant group-by-time interaction (p = 0.005). Length-for-age (LAZ) and weight-for-length (WLZ) z-scores did not differ between groups, however, mean body fat % (BF%) was 3.2% (95%CI: -6.2, -0.3; p = 0.032) lower in the GUMLi group at 2 y. There was no difference between the intervention groups in relation to IGF-1 and IGF-BP3 (p = 0.894 and 0.698, respectively), with no group-by-sex interaction. After combining the groups, IGF-1 concentration at 2 y was positively correlated with parameters of growth (all p < 0.05), total cow's milk intake (p = 0.032) after adjusting for sex, breastfeeding status, and gestation. Randomisation to a reduced protein GUMLi resulted in small reduction in %BF and lower total protein intakes but had no effect on growth. Plasma IGF-1 concentrations were independently associated with total protein intake from cow's milk at 2 y, highlighting a potential area of the diet to target when designing future protein-related nutrition interventions. Clinical Trial Registration: Australian New Zealand Clinical Trials Registry number: ACTRN12614000918628. Date registered: 27/08/2014.

Interactions between Growth of Muscle and Stature: Mechanisms Involved and Their Nutritional Sensitivity to Dietary Protein: The Protein-Stat Revisited

Childhood growth and its sensitivity to dietary protein is reviewed within a Protein-Stat model of growth regulation. The coordination of growth of muscle and stature is a combination of genetic programming, and of two-way mechanical interactions involving the mechanotransduction of muscle growth through stretching by bone length growth, the core Protein-Stat feature, and the strengthening of bone through muscle contraction via the mechanostat. Thus, growth in bone length is the initiating event and this is always observed. Endocrine and cellular mechanisms of growth in stature are reviewed in terms of the growth hormone-insulin like growth factor-1 (GH-IGF-1) and thyroid axes and the sex hormones, which together mediate endochondral ossification in the growth plate and bone lengthening. Cellular mechanisms of muscle growth during development are then reviewed identifying (a) the difficulties posed by the need to maintain its ultrastructure during myofibre hypertrophy within the extracellular matrix and the concept of muscle as concentric "bags" allowing growth to be conceived as bag enlargement and filling, (b) the cellular and molecular mechanisms involved in the mechanotransduction of satellite and mesenchymal stromal cells, to enable both connective tissue remodelling and provision of new myonuclei to aid myofibre hypertrophy and (c) the implications of myofibre hypertrophy for protein turnover within the myonuclear domain. Experimental data from rodent and avian animal models illustrate likely changes in DNA domain size and protein turnover during developmental and stretch-induced muscle growth and between different muscle fibre types. Growth of muscle in male rats during adulthood suggests that "bag enlargement" is achieved mainly through the action of mesenchymal stromal cells. Current understanding of the nutritional regulation of protein deposition in muscle, deriving from experimental studies in animals and human adults, is reviewed, identifying regulation by amino acids, insulin and myofibre volume changes acting to increase both ribosomal capacity and efficiency of muscle protein synthesis via the mechanistic target of rapamycin complex 1 (mTORC1) and the phenomenon of a "bag-full" inhibitory signal has been identified in human skeletal muscle. The final section deals with the nutritional sensitivity of growth of muscle and stature to dietary protein in children. Growth in length/height as a function of dietary protein intake is described in the context of the breastfed child as the normative growth model, and the "Early Protein Hypothesis" linking high protein intakes in infancy to later adiposity. The extensive paediatric studies on serum IGF-1 and child growth are reviewed but their clinical relevance is of limited value for understanding growth regulation; a role in energy metabolism and homeostasis, acting with insulin to mediate adiposity, is probably more important. Information on the influence of dietary protein on muscle mass per se as opposed to lean body mass is limited but suggests that increased protein intake in children is unable to promote muscle growth in excess of that linked to genotypic growth in length/height. One possible exception is milk protein intake, which cohort and cross-cultural studies suggest can increase height and associated muscle growth, although such effects have yet to be demonstrated by randomised controlled trials.

Nutrition and growth in children

The well-balanced nourishment during "the first 1000 days," the period between conception (day 18) and the age of two years, is quite important for two main reasons. Firstly, the nutritive requirement is high due to the rapid physiological growth and functional development. Then, this period is characterized by extreme susceptibility to external stimuli such as inadequate maternal and infant nutritional status which they can interfere with the different stages of the development process leading to short and long-term consequences for health. Linear growth and brain development are particularly impaired from not sufficient nutrition. In consideration of the irreversible damage of malnutrition, especially on developing brain, an adequate nutrition during the first 1000 days of life is paramount. The aim of this review was to overview the latest scientific evidences on the relationship between nutrition and growth, focusing on nutritional requirements during the first 1000 days, and the impact of inadequate nutrition on brain development and linear growth.

Circulating Insulin-Like Growth Factor-1 Is Positively Associated with Growth and Cognition in 6- to 9-Year-Old Schoolchildren from Ghana

BACKGROUND

Milk intake stimulates linear growth and improves cognition in children from low-income countries. These effects may be mediated through insulin-like growth factor-1 (IGF-1).

OBJECTIVE

The objective was to assess the effect of milk supplement on circulating IGF-1 and to assess IGF-1 as a correlate of growth and cognition in children.

METHODS

Secondary data on blood spot IGF-1 from a randomized, double-blind, controlled trial in 6-9-y-old children from rural Ghana were analyzed. Intervention groups received porridge with non-energy-balanced supplements: 8.8 g milk protein/d, 100 kcal/d (Milk8); 4.4 g milk and 4.4 g rice protein/d, 100 kcal/d (Milk/rice); 4.4 g milk protein/d, 48 kcal/d (Milk4); or a control (no protein, 10 kcal/d). IGF-1, length, body composition, and Cambridge Neuropsychological Test Automated Battery (CANTAB) were measured at 3.5 or 8.5 mo. Linear regressions were used to assess the effect of milk interventions on IGF-1 and IGF-1 as a correlate of growth and cognition.

RESULTS

The increase in IGF-1 was 15.3 (95% CI: 3.3, 27.3) ng/mL higher in children receiving Milk8 compared with the control. The IGF-1 increases in the isonitrogenous, isoenergetic Milk/rice or the Milk4 groups were not different from the control (P ≥ 0.49). The increase in IGF-1 was associated with improvements in 4 out of 5 CANTAB domains. The strongest associations included reductions in "mean correct latency" from Pattern Recognition Memory and "pre-extradimensional (pre-ED) shift errors" from Intra/Extradimensional Set Shift (P ≤ 0.005). In addition, change in IGF-1 was positively associated with changes in height, weight, and fat-free mass (P ≤ 0.001).

CONCLUSIONS

Intake of skimmed milk powder corresponding to one, but not half a glass of milk on school days stimulates IGF-1 in 6-9-y-old Ghanian children. IGF-1 seems to mediate the effect of milk intake on growth and cognition. The association between IGF-1 and cognition in relation to milk intake is novel and opens possibilities for dietary interventions to improve cognition.

DHEAS and Human Development: An Evolutionary Perspective

Adrenarche, the post-natal rise of DHEA and DHEAS, is unique to humans and the African Apes. Recent findings have linked DHEA in humans to the development of the left dorsolateral prefrontal cortex (LDPFC) between the ages of 4-8 years and the right temporoparietal junction (rTPJ) from 7 to 12 years of age. Given the association of the LDLPFC with the 5-to-8 transition and the rTPJ with mentalizing during middle childhood DHEA may have played an important role in the evolution of the human brain. I argue that increasing protein in the diet over the course of human evolution not only increased levels of DHEAS, but linked meat consumption with brain development during the important 5- to-8 transition. Consumption of animal protein has been associated with IGF-1, implicated in the development of the adrenal zona reticularis (ZR), the site of DHEAS production. In humans and chimps, the zona reticularis emerges at 3-4 years, along with the onset of DHEA/S production. For chimps this coincides with weaning and peak synaptogenesis. Among humans, weaning is completed around 2 ½ years, while synaptogenesis peaks around 5 years. Thus, in chimpanzees, early cortical maturation is tied to the mother; in humans it may be associated with post-weaning provisioning by others. I call for further research on adrenarche among the African apes as a critical comparison to humans. I also suggest research in subsistence populations to establish the role of nutrition and energetics in the timing of adrenarche and the onset of middle childhood.