A follow-up to a University of Alberta study done in 2016 confirms that pregnant women who eat more fruit during pregnancy may be giving their babies’ cognitive development a boost.
“Our research followed up on results from the original CHILD Cohort Study, which found that fruit consumption in pregnant mothers influences infant measures of cognition up to one year after birth,” said U of A post-doctoral researcher in psychology Claire Scavuzzo, the co-lead author of the study.
“Although the findings from the (original) study were exciting, they could not establish that fruit consumption, rather than other factors, caused the improvements on infant cognition.”
To determine whether fruit was truly the factor influencing infant cognition, the scientists aimed to replicate the findings from the original study.
They found that infant rats born to mothers that had their diets supplemented with fruit juice performed significantly better on tests of memory – consistent with the previous study.
“Our findings replicated what was found in humans and fruit flies. In a controlled, isolated way, we were able to confirm a role for prenatal fruit exposure on the cognitive development of newborns,” explained Scavuzzo.
“We see this as especially valuable information for pregnant mothers, as this offers a non-pharmacological, dietary intervention to boost infant brain development.”
“The idea that nutrition may also impact mental health and cognition has only recently started to gain traction,” said co-lead author Rachel Ward-Flanagan.
“People want to be able give their kids the best possible start in life, and from our findings, it seems that a diet enriched with fruit is a possible way to do so.”
A Ph.D. student studying under the supervision of Clayton Dickson, Ward-Flanagan embarked on the followup study with Scavuzzo in collaboration with pediatrics professors Francois Bolduc and Piushkumar Mandhane.
Dickson, Scavuzzo, Ward-Flanagan and Bolduc are part of the U of A’s Neuroscience and Mental Health Institute. Bolduc and Mandhane, are both members of the Women and Children’s Health Research Institute, which helped support the original study through funding provided by the Stollery Children’s Hospital Foundation and supporters of the Lois Hole Hospital for Women.
The study, “Prenatal Fruit Juice Exposure Enhances Memory Consolidation in Male Post-weanling Sprague-Dawley Rats,” was published in PLOS ONE.
The first years of life are crucial to a child’s neurodevelopment. Neurodevelopment concerns the acquisition of skills in a variety of developmental domains, including fine and gross motor function, language and social adaptation skills and cognition.
Early neurodevelopment tracks into later in life and is important for later IQ and academic achievement [1,2,3,4]. Genetic, biological and environmental factors such as sex, gestational age, maternal mental health, maternal education and parental socio-economic status are all factors that can influence neurodevelopment [1,5,6].
Nutrition also influences neurodevelopment and adequate diet quality is therefore of utmost importance in the early years in which brain development is at its peak. Infants’ nutrient requirements are high in order to meet the demands of their growth and development.
The World Health Organization (WHO) recommends exclusive breastfeeding for at least 6 months, while the European Society of Paediatric Gastroenterology, Hepatology and Nutrition Committee on Nutrition (ESPGHAN), as well as the Norwegian Health Directorate, recommends the introduction of complementary foods between 4–6 months of age [7,8,9].
Longer duration of breastfeeding has been associated with better cognitive and motor development in preschool children [10,11,12,13,14]. Although several studies have demonstrated an association between breastfeeding and cognitive functioning, results from observational studies are diverse, especially after adjusting for possible confounders such as socioeconomic status and maternal IQ [15,16,17].
Observational studies suggest that several micronutrients, including omega-3 fatty acids, zinc, iron and iodine play important roles in children’s brain development [18]. Since nutrients do not act alone, and individuals consume combinations of food, Nyaradi et al., suggest that public health interventions should focus on the promotion of overall diet quality rather than isolated micronutrients [18].
Healthy dietary patterns in childhood can influence later cognitive and neuropsychological outcomes [19,20]. A recent review found a positive association between healthier foods (wholegrains, fish, fruits and/or vegetables) and executive functioning in children and adolescents, whereas less healthy snack foods, sugar-sweetened beverages and red/processed meats were inversely associated with executive functioning [21].
Smithers et al. found that healthier dietary patterns from 6 to 24 months may have a small but persistent effect on IQ at 8 years [19].
Nyaradi et al. found that a high-quality diet in the early years had a positive effect on academic achievement at ages 10 and 12 [3]. However, to our knowledge, no studies have so far investigated the association between diet and child neurodevelopment measured by standardised screening tools in one-year-olds. With this present study, we aimed to investigate whether breastfeeding and the intake of selected foods and food groups in infancy are associated with higher neurodevelopmental scores as early as at the age of one year.
Discussion
In the present study, we aimed to examine potential associations between frequency of intake of selected foods and neurodevelopment as measured by ASQ total score in a sample of Norwegian one-year-olds.
To our knowledge, there are few, if any, reports on whether and how dietary factors other than breastfeeding are associated with neurodevelopment in children this young. We found that the neurodevelopmental score was not only positively associated with duration of breastfeeding, but also positively associated with the frequency of the children’s intake of fresh fruits, berries and vegetables, and with fish and fish products.
There are few studies comparable to the present study, both including other dietary factors than breastfeeding, and evaluating early diet and neurodevelopment in children as young as one to two years.
We found that breastfeeding duration was associated with higher total neurodevelopmental scores. For this relation, previous results have been conflicting.
Several studies have found similar associations, like the EDEN study of more than 1000 children [11]. They observed a positive association between longer breastfeeding duration and better cognitive and motor development, measured with the ASQ in 2- and 3-years-old children.
Likewise, the Rhea study from Greece and the Mother’s and Children’s environmental Health (MOCEH) study from Korea showed similar results [10,13]. In these two studies, neurodevelopment was assessed by using the Bayley Scales of Infant and Toddler Development.
There is, however, some controversy in this regard, with Holme et al., 2010 and Boutwell et al., 2012 showing no associations and arguing that sociodemographic factors and maternal IQ can explain the association between breastfeeding and neurodevelopment/cognitive development [17,30].
In our study, maternal education was adjusted for. One mechanism that could explain breastmilk’s relation to neurodevelopment is that breastmilk provides the nutrients required for brain development, such as lipids, complex proteins and carbohydrates, as well as vitamins, minerals and other biologically active components [31,32].
In addition, it is suggested that the physical and socioemotional contact between mother and child during breastfeeding can influence neurodevelopment [33].
Beyond breastfeeding, we found that consumption of fish, vegetables and fruit and berries was associated with higher neurodevelopmental scores. This relation was still present after adjusting for the child’s gender, age, parental education and duration of breastfeeding, indicating that these food items could be important contributors to neurodevelopment.
Previous studies have explored relations between early diet and later development and academic achievement. Findings from the Raine cohort showed that diet at one year of age was associated with cognitive outcomes at 10 years of age [2]. Our findings demonstrate that associations between diet and child neurodevelopment can be measurable already in the first years of life.
There may be several mechanisms through which various aspects of a healthy diet are related to neurodevelopment. First, fatty acids in fish, as well as the content of iodine, are important for brain development [18,34,35].
Further, fruits and vegetables provide a broad range of micronutrients that are necessary for brain growth and development. For instance, carotenoids and vitamin C, found in abundance in fruits and vegetables, are presumed to play important roles in brain development and functioning [36,37,38].
Haapala et al. found that intake of red/processed meat was inversely associated with executive functioning in 7-years old children [39]. In our sample, we found a positive association between meat intake and ASQ score.
However, when we removed the intake of liver paste from the variable on meat and meat products, this positive association was no longer present. Liver paste is a popular spread, especially among young children, and most kindergartens in Norway offer liver paste as a spread alternative.
Liver paste has a relatively high iron content, which is important for development, and it is often used as an example of an iron-rich food recommended for children. Further research on this observed association between intake of liver paste and total ASQ score is needed to confirm our findings.
A significant strength of our study concerns generalisability. First, the participants were from 43 different kindergartens from four counties in different parts of Norway. Both large and small, private and public kindergartens were represented from both urban and rural areas, so it is probable that the kindergartens included in our study are representative of Norwegian kindergartens.
Second, we distributed the full version of the ASQ as published, which included pictograms and instructions to attempt every activity with the child. Some earlier studies, using the ASQ as a measure of infant development, have simplified the questionnaire, for instance using it without pictograms, without prompts to try the activity with the child, or using shortened versions with only a few questions or selected domains [40,41,42].
Valla et al. concluded that it seems important to use the correct published version [42]. We also managed to distribute the age-related questionnaire (bimonthly specific) at the relevant age by calculating each child’s age at the day of mailing the questionnaire to the parents.
Third, the study was performed in a country with high breastfeeding rates. Norway is among the countries with the highest breastfeeding rates in the world [43]. In our sample, more than 70 per cent of the children were breastfed (exclusively or partly) at 6 months of age (data not shown).
There are also limitations to our study. First, the sample of participating parents was rather homogeneous, the majority being highly educated mothers of Norwegian ethnicity, and this may have reduced the generalisability at the individual level.
However, Norwegian women are relatively highly educated, with 58.2% of women in the age of 30 to 34 years being highly educated (university or college) [44]. Other aspects, such as the geographic diversity and the diversity in size and type of kindergartens, may enhance the generalisability.
Second, since the breastfeeding rate in this sample was high with only 15 children never being breastfed, it makes it difficult to draw conclusions regarding the associations between diet and neurodevelopment in those never breastfed.
Our robustness test indicates that there might have been differences between those never and ever breastfed. However, our limited sample size suggests that such associations should be investigated further in a larger sample and in other populations.
Third, we did not have information about the mothers IQ, which is another important determinant of neurodevelopment in children. However, we did adjust for both parents’ educational level, and although education is not the same as IQ, it is likely to represent some of the same potentials for confounding.
Fourth, we did not have the possibility to adjust for energy intake in the models. Higher frequencies of intake could be an indicator of higher food intake in general, for example, due to a healthy appetite, larger body mass and beneficial meal routines, and the observed associations might be due to general good nourishment.
Fifth, the results of the study are based on parents’ self-report, which may have its weaknesses. Self-reported data entail a risk of social desirability bias, both as over- and under-reporting, as well as of recall bias.
There are also limitations regarding the questionnaire used to assess food intake. The questionnaire does not measure absolute food intake, only frequencies of intake. It is possible that high-frequency users consume very small amounts each time, and the opposite that low-frequency users consume larger amounts each time is possible. In our study, the mean frequency of vegetable intake was quite high (approximately three times per day).
This can probably be a correct measure of vegetable frequency during the day, but the amounts eaten of each vegetable do most likely not correspond to three full vegetable portions per day, which is the recommended intake of vegetables.
Data shows that Norwegian children, in general, eat fewer vegetables than is recommended: the average intake in one-year-old children is only half of the recommended intake [45]. Nevertheless, FFQs are frequently used because they are simple, quick and reliable tools compared with other more time-consuming dietary assessment methods [46].
We considered the FFQ suitable for use in our study since we primarily wanted it to measure the vegetable variety and certain types of foods eaten, as well as to rank individuals according to food intake, rather than to measure the amount of food or calories in the children’s diet.
Conclusions
In the present study, we found an association between neurodevelopmental score, measured with the Ages and Stages Questionnaire, and the duration of breastfeeding. As one of the first studies, we also found associations between dietary factors and neurodevelopment in children as young as one year old.
We found strong associations between total ASQ score and the intake of fish, fruits and vegetables in one-year-old children. Our results indicate that a healthy diet is important for neurodevelopment in young children, with measurable effects already at the age of one year. To confirm our findings, we suggest further investigation in larger samples and different populations.
More information: Rachel Ward-Flanagan et al. Prenatal fruit juice exposure enhances memory consolidation in male post-weanling Sprague-Dawley rats, PLOS ONE (2020). DOI: 10.1371/journal.pone.0227938
