Early-life nutritional exposures are significant determinants of the development and futurehealth of all organ systems. The dramatic rise in infant immune diseases, most notablyallergy, indicates the specific vulnerability of the immune system to early environmentalchanges. Dietary changes are at the center of the emerging epigenetic paradigms thatunderpin the rise in many modern inflammatory and metabolic diseases.

Infant food and weaning practices are highly debated with lots of unanswered questions.It is becoming more apparent that early-life feeding may have an effect on the long-termhealth of humans, particularly for noncommunicable diseases such as obesity and allergicdiseases. It is important to understand how environmental influences in early life can affectthe development of the immune system and metabolic profiling. In terms of nutritionand diet, one should consider the role of the total/whole diet, as well as particular nutrientsin the development of noncommunicable diseases.

Food allergy is a common disease. In recent years, recommendations for the preventionof food allergy have been shifted from avoidance strategies to active oral tolerance induction.Due to evidence from observational studies, it has been suggested that sensitizationoccurs via the skin especially in children with atopic dermatitis due to skin barrier defects,whereas early oral introduction of the allergenic food(s) will promote tolerance. The currentevidence does not justify recommendations about either withholding or encouragingexposure to potentially allergenic food(s) after 4 months once weaning has commenced,irrespective of atopic heredity.

Food allergy is an important and increasing public health problem worldwide, affectingpredominantly infants and young children. There is an urgent need to develop effectivetreatment strategies to restore oral tolerance in food-allergic individuals.

Factors operating in the preconception and prenatal periods, such as maternal obesity,excessive gestational weight gain and gestational diabetes, predict a substantial fractionof childhood obesity as well as lifelong adverse health consequences in the mother. Theseperiods may lend themselves to successful intervention to reduce such risk factors becauseparents may be especially willing to change behavior if it confers health advantagesto their children

It is now widely recognized that the environment in early life can have important effects onhuman growth and development, including the ‘programming’ of far-reaching effects onthe risk of developing common metabolic and other noncommunicable diseases in later life.We have shown that greater childhood adiposity is associated with higher maternal adiposity,low maternal vitamin D status, excessive gestational weight gain and short duration ofbreast-feeding; maternal dietary patterns in pregnancy and vitamin D status have beenlinked with childhood bone mineral content and muscle function.

There is growing evidence of long-term effects of early dietary intervention in infancy onlater obesity risk. Many studies showed reduced risk of obesity with breastfeeding in infancy,which could be related to the reduced protein intake with human milk comparedto infant formula. In a randomized controlled trial (Childhood Obesity Project), we wereable to show that infant formula with reduced protein content results in lower BMI bothat 2 and 6 years. These effects seem to be mediated mainly by branched-chain amino acidswhich stimulate the insulin-like growth factor (IGF)-1 axis and insulin release.

Breastfeeding induces a different metabolic and endocrine response than feeding conventionalinfant formula, and it has also been associated with slower weight gain and reduceddisease risk in later life. The underlying programming mechanisms remain to beexplored. Breastfeeding has been reported to induce lower levels of insulin, insulin-likegrowth factor-1 and some amino acids (AAs) than formula feeding. In the Childhood ObesityProject (CHOP), infants fed a conventional protein-rich formula had a higher BMIat 2 and 6 years than those fed a protein-reduced formula. At 6 months, higher proteinintakes induced increased plasma concentrations of branched-chain AAs (BCAAs) andtheir oxidation products, short-chain acylcarnitines. With increasing BCAA levels, theseshort-chain acylcarnitines increased proportionally only until a break point was reached,after which BCAAs seemed to escape their degradation. The resulting marked elevationin BCAA levels with high-protein (HP) intakes appears to contribute to increased insulinlevels and to affect β-oxidation of fatty acids. The ratios of long-chain acylcarnitines to freecarnitine decreased in infants who received a HP formula, which indicates a reduced initiationof β-oxidation. We conclude that HP intakes inducing high BCAA plasma levels mayinhibit fat oxidation and thereby enhance body fat deposition and adiposity.

Worldwide, 38% of women are now overweight (BMI 25–30) or obese (BMI ≥ 30). There isincreasing evidence that maternal obesity can result in unfavorable (epigenetic) pre- andpostnatal programming of important genes of the offspring. Infants of overweight mothersshow faster weight gain during infancy, which is associated with higher risk of obesityduring childhood and adult life.

Nutrition and growth during early infancy influence later health and development, butmost research has focused on the period of milk feeding, and the possibility that thetiming, content or method of complementary feeding (CF) might have similar later effectshas received less attention. Such effects are plausible, given that the CF period isone of rapid growth and development when infants are susceptible to nutrient deficienciesand excesses, and during which there are marked changes in diet with exposure tomany new foods, tastes and feeding experiences.

Because infants are totally dependent upon parents (or other caregivers) for care and sustenance,parents’ feeding practices are a key feature of the family environments in whichinfants and young children learn about food and eating. Feeding practices include notonly what the child is fed, but also the how, when, why and how much of feeding. Extensiveevidence indicates that parenting behavior influences a variety of child outcomes, includingcognitive and socioemotional development, as well as the development of self-regulatoryskills.

Our ability to perceive the broad range of flavors imparted by foods involves the assimilationof multiple chemosensory sensations: primarily those of taste and olfaction. Due totheir adaptive value, these chemosensory systems are functional before birth and continueto mature throughout childhood. As a result, children live in their own flavor world,preferring foods that are high in sugar and salt over those that are sour and bitter tasting,such as fruits and vegetables.

Guidelines for healthy infant feeding provide advice on breastfeeding and complementaryfeeding. The Avon Longitudinal Study of Parents and Children (ALSPAC) derived dietarypatterns in comparison to infant feeding guidelines and by using principal componentsanalysis (PCA). The ALSPAC cohort was recruited during pregnancy.

Obesity has reached epidemic proportions and research into its prevention is increasinglyfocusing on the earliest stages of life. Avidity of appetite has been linked to a higherrisk of obesity, but studies in infancy were scarce. The Gemini twin cohort was establishedto investigate genetic and environmental determinants of weight trajectories in earlychildhood with a focus on appetite and the home environment.