Fruit Consumption in Pregnancy Tied to Kids' Cognitive Outcomes

Nancy A. Melville

June 06, 2016

Fruit consumption during pregnancy is linked to improvements in infant learning ― and not just in humans but also in Drosophila, or fruit flies. Drosophila is known for its importance as a model of learning and memory, an intriguing fact that suggests that the new findings are valid.

"It was a surprise to see an association between fruit and neurodevelopment [as well as] how strong the association was," coauthor Piushkumar Mandhane, MD, associate professor in the Department of Pediatrics at the University of Alberta, in Edmonton, Alberta, Canada, told Medscape Medical News.

"We couldn't find any prior studies that have looked at gestational fruit consumption and infant development."

The article was published online April 22 in EBioMedicine.

Significant Association

The study included 688 participants in the Canadian Healthy Infant Longitudinal Development (CHILD) study, a birth cohort of term and near-term infants who entered the study while their mothers were pregnant. Data on prenatal and postnatal fruit intake were available for a subcohort in the study.

Analysis of the data showed a significant association between increased daily fruit intake during pregnancy and increased 1-year cognitive and adaptive development in infants, as assessed by the Bayley Scale of Infant Development (population standardized mean of 100 points, with a standard deviation of 15) in univariate and multivariate analyses.

After controlling for variables that included maternal education, gestational age, socioeconomic status, maternal vitamin supplementation, and other factors, each daily serving of fruit consumed during pregnancy was associated with a 2.38 increase in cognitive development at age 1 year (P < .05), the authors report.

Fruit intake was categorized as being more than or less than seven servings a day; consumption of seven or more servings of fruit per day was associated with a 5.10-point increase in cognitive development (P < .05).

About two thirds of the women in the study consumed fewer than 3.5 servings of fruit per day. The largest proportion, 26%, consumed fewer than 1.5 servings per day.

A sensitivity analysis found no association between cognitive or adaptive development at age 1 year and the mother's healthy eating index score, total calorie count, total dietary fiber consumption, and total omega 3 fatty acid intake.

The authors found no association with breastfeeding duration and cognitive development at 1 year of age.

Dr Mandhane noted that many mothers in the study breastfed for a mean duration, 7.8 months.

"The limited variation in breastfeeding may be one reason why we didn't show an influence of breastfeeding on cognitive development," he said. "On the flip side, the limited variation may have allowed us to uncover other factors (eg, gestational fruit) that may also be important for childhood development."

Specific Nutrients

The association between fruit intake and infant neurocognition was strongest among children born earlier in gestation, closer to a gestational age of 34.3 weeks (P = .06).

In analyzing the role of specific nutrients, a link was found regarding lycopene, a nutrient most commonly found in tomatoes but which is also found in watermelon and papaya. The authors observed a 0.14-point increase in cognitive development for each 1-mg increase in lycopene consumed per day during pregnancy (P = .05).

Those findings are interesting in light of previous research that showed that lycopene deficiency is associated with preterm labor and intrauterine growth restriction. However, Dr Mandhane cautioned against drawing too many conclusions.

"I don't think the lycopene association necessarily suggests that lycopene alone is the important nutrient. I think lycopene represents a marker for a particular dietary pattern that includes more lycopene-high foods, such as tomato, foods that include tomato sauce, or fresh fruit, such as guava or watermelon. I would not go out and consume more lycopene based on this finding. A balanced diet is going to be the best, safest strategy."

Because Drosophila species share 85% of genes involved in human brain function, fruit flies are considered an important model for human memory and cognition. The researchers therefore sought to determine whether similar results would be seen in the insects.

"Because the finding was so new and because of the risk of confounding, we looked to validate our findings in the fruit fly model. We found similar results: "parent" fruit flies supplemented with fruit juice had offspring with improved cognitive development," said Dr Mandhane.

The results showed 30% higher learning performance, as reflected in index scores, in Drosophila whose parents' diets had been supplemented with 30% fruit juice prenatally (P < .05) compared with Drosophila whose parents were fed a standard diet (predictive index, 65.0; standard error, 3.4), the authors reported.

Importantly, no association was observed between the postnatal consumption of fruit and the offsprings' cognitive development, either in humans or Drosophila.

The fruit fly data further led the researchers to speculate on a mechanistic role of the cyclic adenylate monophosphate (cAMP) pathway, which was among the first pathways linked to learning and memory in Drosophila. Fruit-associated cognitive enhancement was blocked in Drosophila rutabaga mutants in which there was a reduction in the level of Ca2+-calmodulin- dependent adenylyl cyclase.

"The cAMP pathway has been implicated in physiological and pathological learning, but cognitive enhancement in healthy individuals has not been previously observed," the authors write.

"In Drosophila, cAMP signaling during development is required for fine-tuning mushroom-body output neurons, a key component of learning and memory," they add.

Boost Fruit Consumption

Although the investigators encourage healthy diets for women during pregnancy, the study showed no particular association between a generally healthy diet and infant cognition.

"The 'healthiness' of the diet was not significantly associated with the infant's cognitive development when we included fruit consumption in the model. That being said, I should stress that the best approach for the overall health of the child is a balanced diet that includes fruit, but not so much that foods rich in protein are excluded," said Dr Mandhane.

The US Department of Agriculture and US Department of Health and Human Services each recommends 2 cups (3 to 4 servings) of fruit per day for active women, with one cup consisting of either 1 cup of raw or cooked fruit, 1 cup (8 oz) of 100% fruit juice, or a small whole fruit.

Although the authors note that their results support the increased consumption of fruit (6 to 7 servings; 3 cups) for pregnant women, Dr Mandhane noted that more research is needed, particularly with regard to the risk for gestational diabetes and maternal weight.

"I would like to see other studies replicate our findings before making major changes to our recommendations for fruit intake during pregnancy," he said.

"We don't know about disadvantages that may be associated with increased fruit consumption, such as gestational diabetes and increased maternal weight gain during pregnancy. Both are associated with poorer outcomes for infants."

Interpret With Caution

Extensive research points to a host of factors in gestational nutrition that have the potential to influence cognitive and brain development outcomes in children. The strongest evidence points to folate and omega-3 fatty acids. Little has been published regarding fruit, said Anett Nyaradi, PhD, of the Telethon Institute for Child Health Research, the University of Western Australia, in West Perth. Dr Nyaradi has written a review on the role of nutrition in children's neurocognitive development.

"There are studies that linked maternal micronutrients, such as B12, folate, zinc, iron, and iodine level, to children's cognitive development," Dr Nyaradi told Medscape Medical News.

"However, regarding whole-food consumption, as far as I know, only fish consumption during pregnancy was linked to higher cognitive development in children.

"Therefore, this study is a significant addition to the current literature.

"Fruit consumption represents a marker for healthy eating behavior more generally. Therefore, I am not surprised to see the results."

Potential limitations of the study include the fact that it may be difficult to measure infant fruit consumption at 6 months, a time during which infants are often being breastfed but are also being introduced to other foods.

"Therefore, I would be cautious to interpret this as there being no association between postnatal fruit consumption and cognitive development. In addition, children's current diet at age 1 may influence their cognition, so it would have been appropriate to adjust for it as well."

The authors and Dr Nyaradi report no relevant financial relationships.

EBioMedicine. Published online April 22, 2016. Full text

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