© 2019 Nestlé Nutrition Institute, Switzerland/S. Karger AG, Basel
Introduction
The first smile, the first step, the first word… We never learn as much as in our earliest childhood, and: What children learn in their first 1,000 days characterizes them for the rest of their lives. This period is a sensitive one for the development of healthy eating habits, and, for this reason, interventions are likely to have a strong impact on health outcomes later during childhood and adulthood. Anyone setting the right course here lays the foundation for a healthy life. Be it growth, the immune system, or mental development, all benefit from a healthy diet.
The early development of taste and food pleasure plays an important role for children and has long-lasting influences on subsequent food preferences and choices [1, 2]. Eating a variety of foods is essential to achieve adequate coverage of macro- and micronutrients. However, children’s vegetable consumption often falls below current recommendations, highlighting the need to identify strategies that promote better acceptance of vegetables [3]. Apart from our innate liking for sweet foods and disliking for very bitter foods, sensory pleasure for foods is mostly acquired through our early eating experiences. Infants have a fine palate and more taste buds than adults when they are born. They have about 10,000 taste buds all around their tongue, including the roof, back, and sides of their mouth [4]. The flavors of what a mother eats while pregnant can reach the fetus and help set up flavor preferences later on [5, 6]. From birth, infants can taste and smell foods, an experience that can take place through human milk as the food eaten by the mother influences the flavor of her milk and, thereby, the child’s preference [7, 8]. Thus, preferences for specific flavors develop early through milk-related flavor exposure or even during pregnancy, allowing an easier acceptance of new flavors and textures. Breastfeeding favors the taste acquisition of a variety of foods [2, 9, 10]. This early experience serves as the foundation for the continuing development of food preferences across the lifespan and is shaped by the interplay of biological, social, and environmental factors.
At weaning, food preferences develop due to repeated exposure to a variety of foods, especially vegetables and fruits [10–13]. The persistence of these early influences seems to be long-lasting [1]. Factors favoring the development of food acceptance at the beginning of complementary feeding include, in particular, the role of early variety, repeated exposure, timing of food introduction, and sensory properties (texture, taste, and flavors).
With increasing age, the influence of a number of factors, such as peers, personal experience, family, and food availability, continue to mold food preferences and eating behaviors. During the 3rd year of life, most children enter a neophobic phase, during which the introduction of new foods becomes difficult [14]. However, habits of eating a variety of vegetables and foods acquired early in weaning appear to attenuate this neophobia [1].
A Spoon of Culture and Tradition
Young infants are far less fussy than the experience might suggest at the dining table. This shows the diversity of the various complementary food traditions around the globe. Eating habits and attitudes towards eating can be considered one of the most important aspects of a culture. Because of different cultural traditions, attitudes, and systems [15], the reasons for introducing complementary food may vary widely. The literature shows large differences in practice across the world in the timing of the onset of complementary feeding, and even within European cultures, practices are surprisingly varied [16].
When parents in Germany think of the first weaning food, they all think first about allergies. Does my child eat the carrot or is it better to start with the low-allergen parsnip? To be on the safe side, there is often a whole week then of parsnip until a new vegetable will be introduced. In the neighboring country France, the mothers are much more courageous. Almost every day there is a new vegetable introduced during weaning, even fish is introduced quite early and regularly [17]. The wider the perspective, the more confusing is the variety of complementary feeding traditions. While worried parents may be looking for the best solution for their child, experts advise one thing above all: relaxation. A baby’s nutritional needs can be met in many different ways. To provide guidance for parents, it makes sense for each country to develop its own recommendations on how children can grow up healthy with available resources, systems, and traditions. Whether it is fermented corn sorghum paste like in Nigeria, millet porridge with sour milk like in Senegal, or Thai rice porridge with bananas: infants can learn to like almost anything as long as their parents set a good example and demonstrate it to them.
Early Development of Sensory Experience
There is considerable evidence from controlled animal and human studies that sensory experiences early in life can influence flavor preferences and food acceptance [7, 18, 19]. This critical period starts with feeding through the umbilical cord during gestation, continues via oral feeding with milk, and then the complementary feeding begins, and the infant discovers a variety of foods and flavors. Humans generally have inborn positive responses to sugar and salt, and negative responses to bitter taste [20]. Genetically determined individual differences also exist and interact with experience to ensure that children are not genetically restricted to a narrow range of foodstuffs [21]. Children are also predisposed to prefer high-energy foods, to reject new foods, and to learn associations between food flavors and the postingestive consequences of eating [22].