Early feeding patterns among Mexican babies: findings from the 2012 National Health and Nutrition Survey and implications for health and obesity prevention

This is the first study to our knowledge that describes, in detail, the transitions in food consumption patterns of a nationally-representative sample of infants and young children from birth up to age 4 years living in Mexico. Our findings provide a comprehensive picture of the changes in food consumption habits in the first few years of life and identify the magnitude of feeding and dietary issues including low breastfeeding rates, early introduction of cow’s milk, early introduction of complementary foods, especially low consumption of iron-rich foods, low consumption of fruits and vegetables, and early and excessive consumption of sweets, especially sugar-sweetened beverages.

In this national sample, we see concerning percentages of children with conditions of undernutrition, especially stunting, and excess body weight and with caretakers who are predominantly single with limited education and incomes. As mentioned previously, Mexico is undergoing a nutrition transition characterized by declining rates of undernutrition in past decades and increasing rates of obesity in all age groups. It has been suggested that Mexico may be experiencing an advanced stage of the nutrition transition due to lower than expected prevalences of the coexistence of the conditions at the household and individual levels, particularly overweight/obesity with anemia and stunting in school-aged children [3]. Yet, the presence of the double burden at national, household and individual levels is an onorous public health concern and comprises a complex interplay of social, economic and political factors. The feeding practices and food consumption patterns of the infants and young children observed in our study are probably influenced by a range of environmental and behavioral factors that are likely shared by both conditions of undernutrition and obesity. These factors may include, but are not limited to, the mother’s cultural beliefs, perceptions, knowledge, social support networks, and educational level, as well as household income, and socioeconomic resources [30, 44–49], which we describe in more detail in the context of our findings.

Breastfeeding is recognized as the ideal feeding choice for infants to achieve and maintain optimal health [15, 18], to reduce risk of morbidity and mortality [50] and to protect against overweight/obesity [51, 52]. Breastfeeding has been associated with desirable feeding practices such as delaying introduction of solid foods [53] and less frequent offering of inappropriate high-sugar, high-fat foods [54]. Early exposure to flavor compounds from breast milk may modify future flavor and food acceptance [55], and thus duration of breastfeeding may positively shape children’s food preferences and food variety [56]. The WHO recommends exclusive breastfeeding up to age 6 months followed by the introduction of appropriate complementary foods and continuing as long as mutually beneficial for the mother and child [15, 16]. Breastfeeding exclusively for 6 months is a desirable goal [15, 17, 18, 42], yet partial breastfeeding and breastfeeding for shorter periods of time are valued feeding choices [42].

Whereas breastfeeding is recognized as the ideal feeding choice [57], the rates in Mexico, especially those for exclusive breastfeeding, continue to decline. A recent study using data from the NHNS 2012 reported a marked deterioration of exclusive breastfeeding in Mexican infants under age 6 months from 22.3 % to 14.5 % between 2006 and 2012 [34]. Our study further shows that the rate of exclusive breastfeeding peaks at 15 % in the first three months of life, plummets to 4 % in ages 4–5.9 months and declines further to ~1 % in ages 6–8.9 months. These declining rates are considerably lower than those of any breastfeeding from 78 % down to 62 % and 55 % in the same age groups. The overall decline in exclusive breastfeeding could, in part, be related to the early introduction of other beverages such as water (prevalence of 20 % and 45 % of infants ages 0–3.9 months and 4–5.9 months, respectively; data not shown), and sugar-sweetened tea/coffee as well as complementary foods among some infants. Additional factors affecting breastfeeding practices could be related to changes in perceptions due to the migration from rural areas where breastfeeding is considered to be more ‘natural’ to urban cities where life is faster and there is a perception of a non-breastfeeding culture, i.e., breastfeeding is getting lost as fewer women see other women breastfeeding, which may explain their embarrassment to breastfeed in public [46]. Moreover, the findings on breastfeeding could be a response to the Mexican Ministry of Health’s recommendation for breastfeeding initiated prior to the NHNS 2012 data collection period, which was to exclusively breastfeed from birth until age 4 to 6 months [58], and was subsequently changed to age 0 to 6 months in 2012 [17].

The overall drop in breastfeeding rates in our study is consistent with the pattern of decreasing percentages of infants who received breast milk. While infant formula use was high in early infancy, consumption also decreased over the first year of life as cow’s milk, considered an inappropriate milk for children under age 1 year [16, 17, 19], was fed to increasing percentages of infants. Communication of the guideline to delay feeding cow’s milk to infants is important, since some Mexican mothers think that if whole cow’s milks are fortified, they can be given to babies under 1 year [46]. Early feeding of cow’s milk is associated with an increased risk of developing iron-deficiency anemia (IDA) [59], a concern especially in Mexico, where IDA is a prevalent (23 %) public health problem in young children ages 1 to 4 years [60] at all socioeconomic levels [61] and given the potential serious and irreversible consequences of IDA on physical and cognitive development and long term health of children [62].

The timely introduction of complementary foods is essential to fulfill the nutritional and developmental needs of a child and to facilitate the rapid transition from consuming milks to foods consumed by the family. Both early (younger than 6 months) and late (older than 6 months) complementary feeding can have undesirable health outcomes [63]. Evidence suggests that early feeding of complementary foods puts infants at a higher risk for microbial infections, [51] and excess weight gain later in life [25–27]. Late feeding of complementary foods and/or reliance on poor quality foods increases an infant’s risk of malnutrition, poor growth, and micronutrient deficiencies [64] and is a major cause of preventable mortality in young children [50]. National surveys in Mexico have shown the coexistence of early and late complementary feeding patterns [35]. Complementary feeding begins as early as age 3 to 5 months among some Mexican infants [34], and up to 92 % of Mexican infants are fed complementary foods before age 6 months [35]. Yet, WHO indicators for measuring dietary diversity or late complementary feeding practices have shown improvement after age 6 months in Mexico [34, 35].

Our data confirm that from age 6 months many infants consumed a wide variety of complementary foods, and also show the magnitude of the alarming early feeding patterns before age 6 months. Moreover, we examine, in detail at the national level, the specific types of foods and beverages consumed by infants before age 6 months, which has been reported with varying degrees in other studies [11, 12, 14, 49]. This early feeding pattern is consistent with the drop in exclusive breastfeeding after age 3 months described previously, and may be related to the perception of insufficient milk as a common reason for discontinuing breastfeeding [45], and to common beliefs that maternal milk is insufficient to satisfy baby’s energy and nutritional needs and that early feeding of solids is seen as an accomplishment or indicator of infant maturity [44, 48].

Whereas delaying the introduction of complementary foods may be appropriate for younger infants, few infants in the second half of infancy, especially those 6–8.9 months of age, were fed iron-rich foods, a consumption pattern consistent with those observed by others, including the low rates of consumption of iron-rich foods and iron-fortified foods of only 54–56 % [30, 34, 35] and inadequate iron intakes among Mexican infants ages 6–11.9 months [65]. Thus, the low prevalence of iron-fortified infant cereals and meats is a concern given the high risk of inadequate iron intake among this age group and depending on whether older infants are fed breast milk or iron-fortified infant formula. Feeding iron-fortified complementary foods such as fortified infant cereals can be an effective strategy to prevent iron-deficiency in infants [16, 19, 66]. Pureed meats, especially beef, are recommended as a source of the highly bioavailable form of heme iron, and provide a developmentally-appropriate form for infants after age 6 months [19].

Daily consumption of a wide variety of fruits and vegetables is the foundation for a healthy diet. Thus, it is astounding that ~50 % of children ages 6–47.9 months consumed no fruit and ~80 % consumed no vegetables both as distinct food items in a day. This low consumption may be related to the widespread lack of fruit and vegetable consumption among Mexicans of all ages [36, 37]. Additional factors to consider are that a child’s food preferences may guide what foods the mother offers [44], and that household income and food cost/availability affect what specific foods [30, 44] as well as the variety of foods [44] that the family and thus the young child consumes. Soups, stews, and broths which often contain vegetables were among the most frequently consumed foods among children of all ages in our study. Thus, consumption rates of vegetables as well as fruits would likely be higher if their contributions from sources in other food groups, like mixed dishes, were considered. Mixed dishes contributed 39 % of total vegetable intake among U.S. children ages 2 to 5 years [67]. Yet, most two- to three-year-olds still underconsume vegetables relative to U.S. dietary recommendations [68]. The apparent preference for fruit in Mexican children under age 4 years has also been reported in US [11–14] and Mexican [36] children. In contrast, a higher vegetable intake was observed in Mexican children with adequate body mass index (BMI) compared to those who were obese [36], which is consistent with other studies [31, 32]. In our study, larger percentages of children consumed fruit than 100 % fruit juice, which is in line with recommendations to encourage consumption of whole fruit rather than juice and to limit fruit juice intake [16, 19].

The greatest cause for concern is the early introduction and sharp increase in the consumption of low-nutrient, energy-dense sweets, sweetened beverages, and salty snack foods. Our data show that these foods comprise the most frequently consumed food group (other than milks) by the age of 9 months, and by the age of 2 years the vast majority of children consumed one or more types of sweets/sweetened beverages on a given day. This pattern may, in part, reflect cultural beliefs that some of these types of foods are satiating, i.e. ‘stick to the stomach’ or acceptable as occasional treats or comfort foods [44]. It is sobering to see in our study that between the ages of 9–11.9 months, more children consumed any type of sweet (75 %) in a day than consumed a distinct portion of fruit (54 %) or vegetable (25 %), a consumption pattern reported by the age of 2 years in U.S. children [13]. The pattern is also consistent with an increase in snacking among Mexican children ages 2 to 5 years between 1988 and 2012 during which calories from snacking (% of total energy) increased from 12 to 20 % [69]. Early complementary feeding may be a risk factor for consumption of non-carbonated sweetened drinks and high-fat snacks (30]. Consumption of sugar-sweetened beverages has been positively associated with overweight and adiposity in infants [30] and toddlers, as well as preschool children [28, 29]. Data from our study and other studies [11, 12, 14, 30, 49] confirm that even very young infants are consuming sweets and sugar-sweetened beverages.

We acknowledge that our study has limitations and strengths. The NHNS 2012 is a cross-sectional, observational study of proxy-reported data, which may be subject to measurement error. This could be due, in part, to respondent burden for recalling the food and beverages that were fed to their young child. Additionally, the sample size in some of the age groups (e.g. n = 75 ages 4–5.9 months) could also be a limitation in achieving unbiased prevalence estimates. We used a single 24HDR, which may not reflect usual intake, but the dietary data are based on valid methods (e.g. trained interviewers conducting interviews on both weekday and weekend days, use of an automated 5-step multi-pass method) for estimating food intake of population groups. The 24HDR is accepted as the most thorough, comprehensive, and complete dietary intake instrument that exists to date [70, 71], but there may be methodological concerns related to dietary intake data collection in countries undergoing rapid nutrition transitions that were not considered [72].

Nevertheless, the NHNS 2012 provides the most comprehensive dietary intake data for the Mexican population. A major strength of our study is the use of specific age categories and food groups to describe, in detail, the transitions in food consumption patterns of a nationally representative sample of Mexican infants and young children from birth up to age 4 years. The dietary data also provide baseline population-based food consumption patterns to evaluate public health programs and policies changed or initiated after data collection in May 2012, such as the 10 % excise tax on sugar-sweetened beverages in 2014.

Our study has implications for future research. Differences in breastfeeding practices, timing of complementary feeding, consumption of vegetables, fruits, high-fat snacks and juices were found among three cities in different regions of Mexico [30]. This warrants further studies examining differences in feeding practices and food consumption patterns across subpopulations of infants and young children such as socioeconomic groups, and urban versus rural locations or geographical regions of Mexico. There is also a need to understand the factors that influence the way Mexican mothers feed their children and the barriers for adopting improved feeding practices.