Could a “Breastfeeding Diet” Help Kids Eat More Vegetables?

A new study suggests that healthier food choices may start with learned tastes — from breast milk.

Convincing children to eat the recommended servings of fruits and vegetables is a perennially difficult task, but new research suggests that new mothers may be able to make the task a little easier — by altering their own diet.

A study published this year in the Journal of Dairy Science suggests that the diet consumed by a lactating mother impacts the taste of her produced breast milk. In the study, mothers maintained a food diary and performed a self-assessment of their own milk, using controlled vocabulary. Mothers rated their milk on odor, taste, and mouthfeel.

The study found correlations between levels of differently flavored foods consumed by the mothers, and the tastes measured in their produced milk:

• Consuming more carbohydrates increased milk sweetness.
• Consumption of glutamic acid (found in meat, poultry, eggs, and dairy products) increased the umami flavor (richness/savoriness) of the produced milk.
• Consumption of bitter foods, such as vegetables, increased bitterness in fore milk (milk produced at the start of feeding), but not hind milk (milk produced at the end of feeding).

This study provides one link in the chain, connecting the mother’s diet to the taste of her produced milk. A second study, from May of 2017, provides the second link, demonstrating that when mothers consumed a vegetable (carrots, in the case of the study) during breastfeeding, the infant showed a preference for carrot consumption after weaning (switching to solid foods).

How much of dietary preference is learned from early life experiences or passed down from a parent?

The Need for Vegetables at an Early Age

One of the top disease-linked risk factors today, especially in Western cultures, is an underconsumption of fruits and vegetables. Recent statistics suggest that the vast majority of toddlers, three out of every four children, do not consume a single vegetable in a day!

Instead, most children follow an innate preference for sugary and salty foods. A 2010 peer-reviewed study found that the top sources of calories for children between the ages of 2–18 were pizza, grain-based desserts such as cookies, cake, and brownies, and sugary sodas. Among children between the ages of 2 and 3, the top calorie sources were whole milk, fruit-based beverages (which lack much of the fiber and nutritional content found in whole fruits), pasta, and grain-based desserts.

Consumption of vegetables is important for several reasons. Along with being an excellent source of many vitamins and minerals, vegetables are less calorically dense, reducing the number of “empty calories” that a child consumes. They also serve as one of the main sources of dietary fiber, which may help children maintain a healthy gut environment.

Of course, the “yuck” factor that most children express when confronted with a strange vegetable is familiar to any parent. This quality, known as neophobia, is considered by researchers to be an adaptive strategy to help young children avoid potentially poisonous foods. By sticking with what is familiar and safe, young children may avoid sources of illness.

Overcoming the Fear of Novel Tastes

When does a baby’s taste preference shift from novel discovery of new tastes, to the rejection of unfamiliar flavors? Evidence suggests that this shift occurs at approximately two years old. Babies are more accepting of novel flavors, especially if that flavor is repeated. By the time the child reaches 2–5 years old, however, novel flavors are rejected.

All babies, regardless of what they’re fed, appear to have an innate preference for sweet foods, and to a lesser extent, a preference for salty foods. We’re all born with a love of sugar — after all, it contains lots of useful calories in an easy-to-access form. Similarly, we crave salt for its role in regulating our water balance (although most Westerners consume far more salt than is necessary for health, and it’s dangerous to give babies salty foods, as their kidneys are not yet fully developed and can’t handle the salt).

The other strong preference shown by babies, however, is for familiarity — the more often an infant is exposed to a food, the more likely they are to enjoy consuming it in the future. This “reinforcement learning” effect has been repeatedly demonstrated, but it only lasts for a limited time. During the first couple years of a baby’s life, they will try new foods and express a preference for food they’ve tasted before. But by ages 3–4, dietary patterns are “locked in” and remain consistent for most of childhood.

Breastfeeding Can Introduce Bitter Taste Familiarity

If, as research suggests, food that the mother consumes influences the taste of her produced breast milk, this may add yet another item to the long list of reasons why breastfeeding is recommended for all infants. Unlike other benefits of breastfeeding, however, this benefit depends on the mother to consume the right products — if the mother isn’t eating vegetables, bitter flavors may not be passed on to the infant, and the benefit won’t be realized.

This new research also further emphasizes the complexity of breast milk, and the need for further research into ensuring that all human infants receive optimal nutrition during the first years of life. Breast milk is far more complex than formula, containing antibodies, appetite-regulating hormones, prebiotics and probiotics, complex proteins and fatty acids, and more.

Not all women, however, are able to breastfeed their infant. Research into the effects and mechanisms by which breast milk improves the health and future diet of the infant are also important to the makers of formula. They will hopefully lead to improvements that help all babies, regardless of their initial milk source, become more accepting of novel, healthier flavors.

Encouraging a better, more vegetable-rich diet in children may start from the moment that an infant is born. Soon, a “maternal diet” may include foods for the mother that bring dietary preference benefits to the baby.

Sam Westreich holds his PhD in genetics, focusing on methods for studying the gut-associated microbiome. He currently works at a bioinformatics-focused startup in Silicon Valley.

Follow on Twitter at @swestreich.