What's in breast milk?
Scientists have discovered over
200 different vitamins, minerals, proteins, fatty acids, amino acids,
hormones, anti-inflammatory agents, and other
constituents of human breast milk.
These are the “standard” ingredients. What about the “extra” ingredients, the flavors in breast milk that vary with a mother’s diet?
When you’re pregnant, breastfeeding, or bottle-feeding, your child’s attitude towards broccoli might seem like a far-off thing.
But food flavors are transmitted through the placenta and breast, and research suggests that babies can detect them.
Babies often like these “second hand” flavors. One experiment gave breastfeeding moms garlic pills and then measured how long their 3-month old infants suckled at the breast (Mennella and Beauchamp 1991).
Between 1.5 and 3 hours after the women had swallowed the pills, the garlic odor of their breast milk reached a peak and the babies noticed. Compared with babies whose mothers took placebo pills, the “garlic babies” spent more time attached to the breast.
So long before your baby’s first attempts to eat solid food, she has already encountered a variety of flavors.
Do these early flavor experiences make a difference? Experiments suggest that they do.
Prenatal learning of baby food preferences
Food flavors pass through the placenta into the amniotic fluid, which fetuses swallow on a regular basis. Studies suggest that newborns are more accepting of flavors they have encountered during gestation, and the effects might last for months after birth. For more information, see these stories on the newborn senses of smell and taste and the prenatal learning of baby food preferences.
The effects of breast milk on baby food preferences
Research also indicates that baby food preferences are influenced by the flavors found in breast milk.
In one study, Julie Mennella and colleagues asked breastfeeding moms to drink carrot juice every day (Mennella et al 2001). Then, when the infants were ready to eat solid foods, the researchers offered babies a choice between plain cereal and cereal flavored with carrot juice.
When the babies were introduced to carrot-flavored cereal, they made fewer negative facial expressions.
These results suggest that breastfed babies might be learning about--and forming preferences for--all sorts of foods.
In fact, there is some evidence that breastfed (as opposed to formula-fed) babies are more accepting of new foods when they begin eating solids (Sullivan and Birch 1994).
But it’s possible that the effect depends on what foods lactating moms consume on a regular basis.
In a study of moms who had consumed low levels of green beans during the months they were lactating, their babies were no more likely to accept pureed green beans than were formula-fed babies. On the other hand, the breastfeeding moms had eaten lots of fruit during lactation, and their babies were more accepting of peaches than were the babies accustomed to formula (Forestell and Mennella 2007).
Baby formula affects food preferences, too
In an experiment on preschoolers, Djin Gie Liem and Julie Mennella asked kids to taste a variety of juices, each characterized by different levels of sweetness and sourness.
The researchers found that kids who’d consumed sour-tasting, protein hydrolysate formulas as babies preferred higher concentrations of citric acid in their juice (Liem and Mennella 2002). Kids who’d used a different formula were less likely to enjoy sour juice.
A similar study found that kids who had consumed soy-based formulas were more likely to enjoy a bitter-tasting juice (Mennella and Beauchamp 2002).
And other experiments suggest that babies fed hydrolysate formulas are less likely than babies on milk-based formulas to consume pureed broccoli or cauliflower (Mennella et al 2006)
More garlic-flavored breast milk, please.
These studies indicate that early flavor experiences have long-lasting effects on a child’s taste preferences. Indeed, some researchers have suggested that spices transmitted through the placenta and breast milk are partly responsible for our enduring ethnic food preferences.
Does this mean that parents should try to control what flavors their young babies encounter?
It might. Research suggests that preschoolers are more likely to eat fruit if they were breastfed and introduced to fruits early in life (Cooke et al 2004). And kids who like fruits and vegetables are less likely to be overweight (Lakkakula et al 2008).
So maybe it’s a good idea for lactating mothers to eat a variety of fruits and vegetables—not just for their immediate nutrition value, but for the flavor experiences they offer babies. And if you want your child to enjoy the enchiladas or Tandoori chicken served at future family reunions, it makes sense to eat these foods while you’re lactating.
And baby formula? Maybe someday we’ll see new formulations that mimic the flavors in breast milk.
Cooke LJ, Wardle J, Gibson EL, Sapochnik M, Sheiham A, and Lawson M. 2004. Demographic, familial and trait predictors of fruit and vegetable consumption by pre-school children. Public Health Nutr. 7(2):295-302
Forestell CA and Mennella JA. 2007. Early determinants of fruit and vegetable acceptance. Pediatrics 120:1247-1254.
Hausner H, Bredie WLP, Mølgaard C, Petersen MA and Moller P. 2008. Differential transfer of dietary flavour compounds into human breast milk. Physiology and Behavior 95(1-2): 118–124
Lakkakula AP, Zanovec M, Silverman L, Murphy E, and Tuuri G. 2008. Black children with high preferences for fruits and vegetables are at less risk of being at risk of overweight or overweight. J Am Diet Assoc. 108(11):1912-5.
Liem DG and Mennella JA.2002. Sweet and sour preferences during childhood: role of early experiences. Dev Psychobiol. 41(4):388-95.
Mennella JA, Kennedy JM and Beauchamp GK. 2006. Vegetable acceptance by infants: effects of formula flavors. Early Hum Dev. 82(7):463-8.
Mennella JA and Beauchamp GK.2002. Flavor experiences during formula feeding are related to preferences during childhood. Early Hum Dev. 2002 Jul;68(2):71-82.
Mennella JA, Jagnow CP, and Beauchamp GK. 2001. Prenatal and Postnatal Flavor Learning by Human Infants. Pediatrics. 107(6):E88.
Mennella JA and Beauchamp GK. 1991. Maternal diet alters the sensory qualities of human milk and the nursling’s behavior.
Sullivan SA and Birch LL. 1994. Infant Dietary Experience and Acceptance of Solid Foods Pediatrics 93 (2): 271-277.
Content of "Flavors in breast milk" last modified 2009