INTRODUCTION

The initial phases of life are of extreme importance for human development, which suffer influences of nutritional factors and metabolic determinants for a healthy growth and development. These habits acquired resonate until adulthood and cause implications on health status^{1 2}.

In this context, breastfeeding is considered as the wisest natural strategy of protection, bond and child nutrition. It is a valuable intervention for the reduction of morbidity/mortality, contributing to the prevention of intestinal diseases, respiratory, allergic and metabolic diseases².

In spite of the efforts and scientific evidence demonstrating the dominance of human milk at the expense of other foods, the prevalence rates of breastfeeding, especially exclusive breastfeeding, are still unsatisfactory, if compared to the recommendations of the World Health Organization (WHO)^{2 3}. In 2009, a survey conducted by the department of programmatic actions says that the median of exclusive breastfeeding in Brazilian capitals, was 1.8 months and 11.2 months, breastfeeding and a prevalence rate for exclusive breastfeeding (EBF) of 36.6%, since it may indicate the early food introduction (EFI)^{4 5}.

The introduction of other foods in the diet of infants is a critical phase by the high susceptibility to lead the child to the nutritional deficit and the development of infectious diseases and food allergies⁶.

The first and most frequent food started early to the baby’s diet are the preparations of cow milk^{7 8}, which bring to the fore the scenario of food allergies, in particular, the allergy to cow’s milk protein (ACMP).

The ACMP is defined as an adverse immune response to antigens present in cow’s milk, their signs and symptoms usually present themselves in the first year of life, after weaning and/or after their first exposure⁹.

The ACMP has been widely commented upon in recent times. Its prevalence rate has doubled in the last century and had an increase of approximately 20% in the last decade. Some studies bring a prevalence of 2 to 5% among infants younger than 1 year, but the rates of sub diagnosis are still high, reaching 15%^{10 11}.

The differential diagnosis for other pathologies is important, due to the specificity of symptoms, which can present with abdominal cramps, vomiting, diarrhea, skin rashes and respiratory impairment^{10 11}.

In this context, it is understood the need for activities that encourage breastfeeding, timely, as a measure of health promotion and disease prevention. In this way, the Ministry of Health (MOH) launches hand strategies to promote, protect and support breastfeeding^{12 13}. The creation of the Breastfeeding Friendly Basic Health Unit, with the release of “10 Steps to Successful Breastfeeding”, as well as the Network Breastfeeds Brazil, both deployed in Primary Care (PC), confirm the importance of the stimulus to the practice in this scenario, with an increase in the prevalence of EBF in the studied population^{12 13}.

In the presence of these initial considerations presented, emerged the following guiding question: What are the causes listed in national and international scientific articles about the early complementary feeding and the risk of allergies? Thus, this study aims to analyze the publications about the question of introducing early feeding and the risk of developing food allergies.

MATERIALS AND METHODS

It is an integrative literature review, which is a methodological resource subsidized by evidence-based practice (EBP), which enables and facilitates the critical evaluation and the applicability of scientific studies, in the practice of care to the patient/client/user¹⁴.

For the development of this review, it was used as a parameter the steps referred to by Mendes, Silveira and Galvão¹⁵, began with the elaboration of the guiding question of this study, in sequence, the search of literature in the main data bases for national and international health, subsequently became the collection of data, the critical reading of the material caught, evaluation, categorization of content and finally, the analysis and understanding of the selected studies.

The search of the material was performed online in large databases, such as the Latin American and Caribbean Literature in Health Sciences (Lilacs), US National Library of Medicine, National Institutes of Health (Pubmed) and Science Direct, at the portal of the Coordination of Improvement Higher Education Staff (Capes) and on the Virtual Health Library (VHL).

For the selection of the sample, we used the following inclusion criteria: articles online, available in their entirety, published in Portuguese, English and Spanish, in the period between 2008 and 2017 and that beheld the chosen subject to be studied. There were excluded: review of the literature, theses, dissertations, letters to the reader and editorials.

The data were collected during the month of January 2018. As a research strategy we used the descriptors in Health Sciences (DeCS): “breastfeeding”, “hypersensitivity to milk”, “infant nutrition”, in order to associate the 3 descriptors and their possible combinations, in Portuguese and English, by the union of the Boolean operator “AND”. As a result, we found 50 articles in total, of which 11 comprised the sample.

To facilitate the collection of data, it has been using a previously validated instrument, directed to Integrative reviews(12), whereas the items: Identification: The title of the article, authors, year of publication, language, country of publication and the publication; Methodological Characteristics of the study: publication type and goals, added the information: the context of the study. These items were grouped in the software Microsoft Office Excel 2010. The data obtained were organized in tables and in thematic categories and interpreted based on scientific literature.

The articles were classified into 4 categories: “Breast milk: protective effect against allergies and stimulating growth factor”; the second: “The feeding practice and the development of allergies”; the third: “The influence of habits in the cow’s milk protein allergy” and the fourth entitled: “Perinatal factors associated with cow’s milk protein allergy”.

RESULTS

The sample for this study was composed by 11 articles from the last 10 years; being 2010 and 2015 with a higher prevalence of publications about the theme investigated, making up 27.27% of the sample.

About the scientific sources, the Latin American and Caribbean Literature in Health Sciences (Lilacs) and the Library BVS, apprehended 27.27% of the “n” of the sample.

With respect to the languages, 72.72% were written in English, marking of the prevalence of English language and the low representativeness of studies published in the Portuguese. As the country of realization of researches, these varied in China, Chile, Denmark, UK, USA, Japan, India and Israel, all of them contributed an article for percentage of 9.09% and Brazil with 18.18%.

The professional category that most published on the theme were doctors, with 81.81%, followed by nutritionists. Pointing out the lack of studies of other professional classes, the example of nursing, so this group and necessary in direct assistance to breastfeeding and its particularities.

Another point to be considered is the context, the absolute majority (100%) of them is from hospital studies, and there is no occurrence, in this study, of research conducted in primary health care.

What concerns to the design methodology of research, highlighted the prospective cohort and cross-sectional studies with 36.36%.

As to the objectives proposed by the publications, 02 articles composed the Category I: “Breast milk: protective effect against allergies and stimulating factor of growth”, 4 the Category II: “The feeding practice and the development of allergies”, 4 The Category III: “The influence of habits in the cow’s milk protein allergy” and only 1 Category IV: “Perinatal factors associated with cow’s milk protein allergy”, presented in the following schedules:

Schedule 1. Distribution of Category I items, according to the authors, title and objective of the publications. 

Schedule 2. Distribution of articles of Category II, according to the authors, title and objective of the publications. 

Schedule 3. Distribution of articles of Category III, according to the authors, title and objective of the publications. 

Schedule 4. Distribution of articles of Category IV, according to the authors, title and objective of the publications. 

DISCUSSION

On the “Breast milk: protective effect against allergies and stimulating growth factor”, the publications listed corroborate on the numerous benefits of breastfeeding in the prevention of diseases, in the various stages of the infants’ life, especially those that occur concomitantly with allergic symptoms^{16 17}.

The risk to develop allergic symptoms, such as eczema is portrayed in a study which specifies that children on exclusive breastfeeding until the sixth month of life have a lower risk of developing this symptomatology, in comparison with the partially breastfed infants, which has a higher risk for rashes¹⁷.

The protective factor against allergies is explained by the fact that breast milk is rich in varied compounds such: factors of humoral immunity and biologically active molecules that assist in the development and maturity of the baby¹⁸.

Another finding of human milk, in which concerns its ability to provide organic factors of ascension, is in the presence regulatory T cells, involved in maintaining the balance of the intestinal microbiota and cytokines/growth factors, which contribute to promote the maturation of the intestinal mucosa, impairing the penetration of pathogens¹⁷.

This assumption is reinforced by assigning a large part of this importance the presence of long-chain polyunsaturated fatty acids, which act in the production of defense cells (T37) in the infant’s body¹⁹.

About the growth of children who were breastfed exclusively grow faster compared with those who have predominant breastfeeding and consumed infant formula. However those who use exclusively the infant formulas have the lowest rates of growth, demonstrating that there is a direct influence between the feeding practices and the growth factor of children in the first and second month of life^20).

Based on these facts, it is possible to identify the importance of incentive to exclusive breastfeeding until the sixth month of life in preterm and term. Its properties of health protection and disease prevention, are strongly based and ratified, attentive to the need for greater investment in policies for the promotion of breastfeeding.

When dealing with the “Feeding Practice and the development of allergies”, submitted articles emphasize on the erroneous feeding practices and the consequences for health.

It is known that breastfeeding should be kept until the 6 months of life. Later, other foods should be introduced gradually, complementing the breastfeeding and diet of infants².

The early introduction of foods other than human milk, in feeding the infant, before the stage of maturation of the organism brings harmful consequences to their health, to the detriment of a reduced ingestion of protective factors present in human milk^{6 8}.

These erroneous eating practices increase the risk for development of acute and chronic diseases such as: diarrhea, food allergies, with involvement of the plural of systems and metabolic diseases. These findings were reported by the majority of articles in this category^{6 8}and are also identified, in a survey conducted in 2013, on the question of early weaning, which brings that 41.2% of infants in their sample, developed some chronic pathology, at the expense of food error²¹.

The authors argue that the damages are intensified from the age and type of food inserted, as ratifies a study conducted in the United Kingdom⁸found that babies exposed to solid food between 12 and 16 weeks developed food allergies⁸, while a cross-sectional study identified that 1/3 and 1/4 of the children participating in the research, received fruit juice and porridge, fruit or soup for 4 months, respectively, making association of increased risk for cardiovascular diseases and obesity and complementary feeding before 6 months of life⁶.

Another important point to be highlighted in the context of introducing early food, is the interruption of breastfeeding. Low levels of prevalence of breastfeeding were found in studies of this category, as for example, a study with a sample of 1,176 children, only 15% were being exclusively breastfed at 4 months of age and 34% received breast milk predominantly, by completing 6 months old and only 5% were on exclusive breastfeeding, while 13% were classified in predominant breastfeeding⁶.

In that heart to early weaning, some reasons reported by the mothers as justification were: the low milk production (16.7%) and the refusal of the child (8.4%). In the same study, mothers brought to the feeding practices adopted by them, were based in the first place, their own experience or their family (67.6%) and only then in professional guidelines⁷. Concordant scenario was seen in the study participants in 2013 that in addition to these two justifications, mothers add not have nipple favorable to breastfeeding²¹.

Even in the face of difficulties faced by mothers, it is notorious that human milk provides the necessary nutrients to the full development of the baby, including their oral tolerance, due to the presence of factors immunomodulators, reflecting on an important protective effect against allergies. In this way, keeping breastfeeding simultaneously the introduction of solid food and cow milk at an opportune moment, has been confirmed as a strategy beneficial to development⁸. These are guidelines that health professionals can use to enrich the dialog with the caregivers.

Thus it is revealed that the low prevalence of breastfeeding, the early introduction of cow milk and solids to babies’ diets, coupled with the revelation that mothers do not follow the guidelines professionals as the main orientation when will start the introduction of food will result in a greater exposure of these children the total diseases and allergies, including food. Realizes the need to strengthen the links between health professionals and families with the aim of providing greater confidence in the guidelines about the importance of exclusive breastfeeding and the correct start of introduction of food, in actions and education services for health promotion and disease prevention.

It is noteworthy that, as there is the early introduction of food or milk different from human can result in nutritional and immunological risk to the health of the baby. When this milk is derived from cow’s milk, an allergy commonly presented is the allergy to cow’s milk protein- APLV (in Portuguese), the authors bring different perspectives on: “The influence of habits in the cow’s milk protein allergy”.

Research carried out in cities of Ukraine, says that the premature insertion of cow's milk proteins in the feeding infants, can cause hypersensitivity reactions and allergies. Even identified that 11% of children in the sample were exposed to cow's milk proteins during the first year of life, as main food or supplement, with an average age for introduction between 1.7 and 7.9 months of age¹¹.

With increasing prevalence rates of 17.04% in group 1 (children who do not come into contact with the cow’s milk proteins during the first and second year of age), 49.2% for the second group (children receiving cow milk during the first year of life) and 51.52% for the group 3 (children that fed cow’s milk in the first and second year of life, the authors confirm the association between the use of cow milk and food allergic reactions, for example APLV, as well as atopic diseases and rashes^{11 22}.

Starting in against two other studies^{23 24}, bring another point of view regarding the introduction of cow’s milk protein, in the diet of the baby. A prospective cohort study one of the authors assess the levels of IgA in human milk, in the light of the withdrawal of cow’s milk proteins in the diet of the mother²²and the other, discusses the risk factors for the development of APLV, mediated by IgE, using the introduction of protein in the diet of infants, as evaluative method²⁴.

To evaluate the actions of milk protein, mothers were separated into three groups, the first with the exception of cow’s milk protein in the first 3 months of lactation, the second group, withdrew the protein from the diet of breastfeeding, with more than 3 months of breastfeeding and the third group, made no restriction of maternal diet²³.

Of the 37 mothers who initiated the limitation in the first 3 months of breastfeeding, 16 babies had immediate, delayed APLV 16 and only 5 had no APLV. Already in the 49 mothers who established the elimination with more than 3 months of lactation, 27 infants had APLV of immediate and delayed type 15, only 7 were not diagnosed with the allergy²³.

Among the 59 mothers participating in the study, which does not have any restriction in the diet, none of the infants presented APLV, demonstrating in this way, the non-respect of the introduction of protein in the diet with the development of allergy²³.

Given that reiterates the idea advocated by the authors that added the low prevalence of allergies in breastfed children without dietary restriction of the mother, the levels of IgA and IgG are lower in the milk of lactating women who have restriction, when compared to mothers who did not do it, with a p value of p = 0.019 and 0.047, respectively²³.

The premise is explained by the authors, using the hypothesis that reduced rates are given by the lack of antigenic stimulation during breastfeeding, considering its occurrence is common in the presence of allergenic foods in the diet of the mother, due to suspicion of food allergy in infants²¹. Suggesting that the exposure of breastfeeding, cow’s milk in the first months of life, may represent a window of opportunity for the induction of oral tolerance^{23 24}.

The difficulty in finding can be related to the symptoms of food hypersensitivity are often unspecific, they present themselves as 63% of their sample of gastroesophageal reflux (GER) and 49%, colic. The symptoms begin around 1.5 and 2 months of age, time which coincides with the beginning of the use of infant formula based on cow’s milk¹⁰.

In the suspicion of hypersensitivity to milk, it is important to investigate the history of atopy and in first-degree relatives, food allergies, in view of the genetic predisposition to this condition¹⁰.It is also important, emphasizing the relevance of detailing the age of onset of symptoms, time between ingestion and manifestation of reactions, quantity of food consumed, type of physical manifestations and duration of symptomatic²⁵.

To assist in the confirmation or discard of APLV, launches the hand of some resources, and the oral provocation test (TPO) is designed as a main reference¹⁰. Despite this, there is controversy in the use of other complementary tests, such as test of specific IgE and skin prick test, which does not confirm the diagnosis of APLV, because of their low predictive value²⁵.

Another important difficulty in establishing the correct diagnosis is the high cost for the realization of the TPO and alternatively a publication of 2010 used the response to the exclusion diet only and then TPO, in the study. Identifying that 14% and 26% of participants, achieved significant response for diagnostic confirmation, respectively¹⁰.

As reported above, studies of this category of analysis are still not so well represented in the academy, in quantitative terms, demonstrating that it is still necessary to greater dedication on the theme, which has scientific relevance, making it possible to establish relationships and associations to base the decision of therapeutic decisions. Faced with this situation, the correct diagnosis of food allergies is fundamental in the therapeutic driving of infant and family, avoiding unnecessary behaviors that can bring harm to your health and family context.

Before the relevance of the theme of APLV, it is worth mentioning that there are “perinatal factors associated with cow’s milk protein allergy”.

The use of antimicrobial agents is one of these factors and has a relationship with the prematurity, the type of delivery, the low prevalence of breastfeeding and the development of APLV²⁴. Some associations were identified by determining the increase in risk to APLV: like the fact that the mother has done antibiotic therapy in the last trimester of pregnancy, increasing the risk of children develop the APLV. The author explains that the risk exists, due to the occurrence changes in intestinal microbiota of the mother-baby, changing the immune response, reducing the levels of cytokines that promote intestinal tolerance to such allergens²⁶.

Another relationship established is around the time duration of breastfeeding, in which it was observed that the group of APLV had an average duration of 2.2 months, versus the 5.9 months of breastfeeding in the control group²⁶. Another study recognizes that there are significantly different values for the duration of breastfeeding in infants of eutocic birth and cesarean, with average time of 11.11 months, and 5.79 months, respectively. Bringing to the fore the reflection on the association between type of birth and duration of breastfeeding, which constitutes a risk factor for the development of allergy, due to less contact with immunological factors present in human milk²⁷.

The type of birth by cesarean section was also proposed as one of the risk factors for food allergies²⁴. The relationship between the type of birth and development of allergies, especially food, was cited in a study where 12 children born from cesarean labor presented allergies and only 2 born from eutocic childbirth developed some type of allergic reaction²⁷.

In this way, it is understood that there is the influence of perinatal factors for the development of allergies, in particular APLV and with the results of the publications in this category, again it is perceived breastfeeding as the single source of nutrients necessary for growth and full development of the infant. Highlights the importance of the correct diagnosis of food allergies, in order to avoid harmful conduct, as well as a burden to the health system and/family responsible for the cost of the treatment.

CONCLUSION

To ensure an adequate nutrition of the babies, encouraging breastfeeding and the correct introduction of complementary feeding, with the aim of ensuring a healthy growth and development and avoid food allergies and/or related to cow’s milk protein, it is necessary to follow the rules and parameters of organs such as the health authorities in the national and international context.

It is worrying that there is not any study in the sample conducted in Primary Health Care, what reforms of the need to develop more studies in this level of attention, as well as promoting closer links between health professionals and families, so that it is held the incentive to exclusive breastfeeding until six months of life and adequate complementary feeding.

Given the above, it becomes necessary the expenditure and dedication of more studies with respect to risk factors for food allergies, in particular, cow’s milk protein allergy and the important maintenance of breastfeeding, faced with the risk of food allergic reactions.

It is still necessary a greater encouragement to public policies for the promotion of breastfeeding, including in pathological situations, in view of the wide range of benefits of the same.