the inflammatory bowel diseases ( ibds ) are chronic illnesses affecting the gastrointestinal tract : they predominantly comprise crohn 's disease ( cd ) and ulcerative colitis ( uc ) . although cd and uc share some features , they have distinctive endoscopic and histological characteristics and disease patterns . furthermore , the clinical manifestations and outcomes of these two conditions vary . at present , there are no specific medical cures for cd and uc : current therapies aim to control the disease and prevent adverse outcomes . although ibd is uncommon in the first decade of life , presentation in infancy is well recognized . ibd is more common in the second decade , particularly in adolescence [ 2 , 3 ] . there are clear demonstrations of increasing incidence of ibd around the world over the last decades , with increased rates also noted in areas with previous very low rates [ 38 ] . the changing incidence of ibd has also been noted in paediatric populations , with particular increases in cd [ 9 , 10 ] . a history of weight loss or poor weight gain is commonly recorded at the time of diagnosis with ibd in children and adolescents . poor linear growth may also be evident at the initial assessment , leading to growth failure in some . impaired nutrition may lead onto short- and long - term consequences that include delayed puberty , micronutrient deficiencies , impaired adult height , and bone disease . regular monitoring and detailed attention to nutritional support remains a central facet of the management of children and adolescents with ibd . this paper will focus on the impact of ibd upon the nutritional state of children and adolescents and will highlight recent advances in this area . numerous cohort studies have demonstrated weight loss or poor weight gains at the time of initial diagnosis of ibd . reports indicate that most children with cd have a history of weight loss or absent weight gains prior to diagnosis . in a cohort of 386 canadian children diagnosed with cd over a ten - year period , 80% had a history of weight loss . a retrospective chart review of a cohort of 61 children diagnosed with cd at sydney children 's hospital , sydney , australia showed that 51% had a history of weight loss at the time of diagnosis . in a prospective uk study of 379 paediatric cd patients , 58% had weight loss at diagnosis and 27% had weight weight loss tends to be seen less commonly in children with uc  up to 31% of 172 children in the same uk cohort had a history of weight loss at diagnosis . maintaining appropriate weight gain also continues to be an ongoing issue after diagnosis . in a cohort of 41 children with longstanding cd recruited to assess dietary intakes and nutrition , the 18 children with active cd had lower mean z scores for weight , height , and bmi than the 23 children currently in remission . the reasons for altered weight gains are likely multifactorial , with decreased caloric intake being the most common [ 1419 ] . poor intake may be the consequence of the anorexic effects of proinflammatory mediators , such as interleukin-1 or tumour necrosis factor ( tnf)- [ 20 , 21 ] or result from early satiety , pain , or nausea . pain associated with eating , leading to poor tolerance of foods , and the fear of diarrhoea following meals are additional reported reasons for reduced intake . small bowel involvement may lead to disaccharide intolerance resulting in shorter gut transit times , pain , and exacerbation of diarrhoea . malabsorption of food components and the diversion of calories to sites of gut inflammation may be further contributing factors leading to impaired growth . in addition to presentation with loss of body weight or poor weight gains , children also commonly have altered patterns of linear growth . decreased height velocity was noted in up to 88% of a group of 50 children at the time of diagnosis with cd  a number of these children had impaired linear growth prior to the onset of gut symptoms . impaired linear growth tends to be more pronounced in boys than girls  this is principally related to the male pubertal growth spurt occurring later and lasting longer . furthermore , the limited duration of puberty limits the time before impaired linear growth becomes irreversible [ 23 , 24 ] . cd is commonly associated with impaired linear growth either at diagnosis or as a long - term outcome [ 2229 ] . some earlier studies reported that despite growth retardation occurring during teenage years , many of these patients eventually achieved heights within the normal range for the general population [ 30 , 31 ] ; however , the genetic component of linear growth was not considered in these studies . markowitz et al .   retrospectively assessed the growth patterns of 48 adults with ibd ( 38 with cd and 10 with uc : 73% male ) who had previously been diagnosed during childhood . these investigators used two height prediction methods and employed the american national centre for health statistics growth charts : 31% of this group were found to have permanently impaired linear growth . in their study of 132 children and young adults aged between 525 years , sentongo and colleagues   argued that height adjusted for genetic potential was a more powerful way of assessing height status in children with cd . in these children , the z scores based on adjusted heights were significantly lower than z scores based on measured heights . again , males in this group were most severely affected , with the average adjusted height for age z score one standard deviation less than expected . lee et al .   recently undertook a prospective assessment of height in 295 children with cd and uc who had been diagnosed between 2002 and 2008 in boston , usa . twenty - two percent of these children ( 90% of whom had cd ) had linear growth impairment ( height for age z - score of 1.64 or less ) documented on one or more measurements from the time of diagnosis . the final mean adult height z score in this cohort was 0.39.the main predictors of final adult height in this cohort were found to be lower parental height and the patient 's lowest height z score . a recent british study also assessed the final adult height of a group of 23 individuals who had been diagnosed with cd prior to their 16th birthday . this group had a final adult height z score of 0.29 : very similar to that observed in the north american study . the mean final height of these patients was 2.4  cm less than the parental or target height ( range of 20.0 to + 9.0  cm ) . twenty percent of the group had a final adult height greater than 8.0  cm below their target height . jejunal disease and the length of symptoms prior to diagnosis ( diagnostic delay ) were predictive factors of final adult height in this cohort . in this cohort , exposure to corticosteroids , surgical intervention , and parental height jejunal disease location has previously been suggested to be associated with linear growth impairment [ 32 , 33 ] . a danish population - based assessment of growth in children with ibd highlights the differential effects of cd and uc upon growth . forty - four children with cd were included in this study , along with 50 with uc and four with ibd unclassified ( ibdu ) . the children with uc had similar height and bmi scores for age to control data . in contrast , the children with cd had height for age z score of 0.77 : also they were shorter than the children with uc ( p = .005 ) . fifty percent of the children with cd had a height less than the 25th centile for age . elegant studies in rodent models show that approximately 40% of growth impairment is consequent to the effects of inflammatory proteins , especially il-6 [ 38 , 39 ] . further , tnf- and il-6 both independently suppress levels of insulin - like growth factor ( igf)-1 , a critical mediator of the local actions of growth hormone . male gender , age at diagnosis , disease location , disease severity , and treatment modality may also all affect final height acquisition . severity of disease ( defined by various measures such as steroid requirements , use of immunosuppressives , and cumulative period of hospitalisation ) was correlated with impaired weight and height gains in a cohort of israeli children . interestingly , the presence of the nod2 genotype was not associated with impaired weight or linear growth , despite associations between ileal location and mutations in this gene . a recent report highlighted the importance of genetic influences upon linear growth in children with ibd . in a cross - sectional study , 951 subjects , comprising 317 cd patient - parent trios , linear growth impairment in the children with cd was associated with a polymorphism in the dymeclin gene dym ( odds ratio 3.2 ) . delayed puberty is also frequently observed in children with ibd , especially those with cd [ 43 , 44 ] . in one cohort of children diagnosed with cd prior to the onset of puberty , menarche was noted to occur at or later than 16 years of age in almost three - quarters of the girls . delayed pubertal development is more common in children who have never achieved remission or who have had repeated disease relapses , emphasizing the interactions between disease control and growth in children . although the most concern in regard to the nutritional impact of ibd in children is towards under nutrition , some children with ibd may be overweight ( bmi > 85% ) and/or obese ( bmi > 95% ) . in a cohort of 166 children with newly diagnosed ibd from wisconsin , usa , 12.1% of those with cd and 17.6% of those with uc were overweight / obese .   in a group of 1598 american children with known ibd overweight / obesity in this multicentre cohort was associated with african - american ethnicity and medicaid insurance status . in addition , a prior surgical intervention was linked with overweight / obese status in the children with cd , suggesting that the presence of over nutrition may be associated with a more severe disease course . corticosteroids , for example , can lead to numerous side effects , including nutritional consequences . increased appetite and fluid retention are commonly seen after commencement of steroids . consequently , apparent improvements in weight during a course of corticosteroids may reflect fluid retention and not an improvement in the underlying nutritional status . steroids also lead to enhanced bone resorption and decreased new bone formation , adversely affecting bone health [ 48 , 49 ] . further , daily corticosteroid therapy can suppress igf-1 activity , contributing to inhibition of linear growth and impaired final height . sulphasalazine may lead to folate malabsorption ; however , daily folate supplementation does not appear necessary . folate supplementation is required , however , when methotrexate is used to avoid folate deficiency due to the inhibition of the conversion of folate to the active moiety tetrahydrofolate . cholestyramine , when required for bile - salt diarrhea , may impede absorption of vitamin b12 . in contrast , some interventions , such as exclusive enteral nutrition ( een ) and biological therapies , have numerous positive nutritional effects . een is a specific nutritional therapy that involves the administration of a liquid formula as sole nutritional intake ( with exclusion of normal diet ) for up to 8 weeks . this therapy is efficacious in active cd , with remission rates similar to those seen with corticosteroids . een leads to positive improvements in weight and linear growth , normalization of igf-1 levels , and stabilization of bone turnover . een is also associated with improved vitamin d status compared to children treated with corticosteroids .   biological therapies in children with cd examined the growth patterns of 32 children treated with infliximab ( 28 responders ) for severe cd . these children had improved height velocity , and height centile increases after infliximab , with timing prior to early puberty being important . .   found that improvements in linear growth after infliximab can be independent of pubertal status and reduction in corticosteroids . these effects of infliximab in children with cd may be due to improved inflammation with mucosal healing or due to direct effects upon growth hormone and igf-1 signaling . in a recent report , cromb et al . demonstrated that the height z scores of a group of 41 french children responding to infliximab improved from 0.57  1.18 to 0.25  0.99 ( p = .04 ) over the period of followup . in contrast , those children not responding to this drug had no catch up growth . given the frequency and patterns of disturbed growth in children with ibd ( and especially those with cd ) , the management of such children must include a clear and constant focus upon growth and nutrition . resumption of normal growth patterns should be seen as an element of the success of therapy . baseline assessment of nutritional status at the time of diagnosis should include detailed standard anthropometry , along with clear documentation of preceding growth patterns and familial growth patterns ( especially parental heights ) . furthermore , close monitoring of growth during followup must be considered a mandatory part of the multidisciplinary care of children and adolescents with ibd . there is now plentiful evidence demonstrating the significant impact of ibd upon growth and nutrition in children . recent studies have helped to demonstrate the importance of nutritional , inflammatory , and genetic factors in growth outcomes . consequently , a key aspect of the ongoing management of children and adolescents with ibd should be the close and constant attention to growth .
the inflammatory bowel diseases ( ibds ) are chronic inflammatory processes affecting the gastrointestinal tract . 
 when diagnosed in childhood and adolescence , ibd almost always impacts adversely upon the nutritional state of the patient . weight loss and impaired linear growth 
 may be present at diagnosis or subsequently . 
 further potential nutritional consequences in childhood ibd include malnutrition , anaemia , osteopaenia , and delayed puberty . 
 understanding the nutritional aspects of ibd is paramount in growing children , especially those entering and advancing through puberty . 
 this paper focuses upon the nutritional impacts of ibd in children and adolescents .