An unborn baby begins ingesting amniotic fluid at around 12 weeks and a powerful sense of smell starts developing by 28 weeks. Based on this prenatal development process, it is worth determining whether or not babies can learn about flavors and odors even before they are born. This is called prenatal flavor running or flavor learning in utero.
Prenatal Flavor Learning In Unborn Human Infants: Do Pregnancy Foods Influence Flavor Perception And Food Preference
Several studies have explored the possibility of influencing flavor perception and food preference of unborn human infants. Researchers J. A. Mennella, C. P. Jagnow, and G. K. Beauchamp hypothesized that pregnant women can shape the palate of their unborn children through their food choices because flavors from their diet are transmitted to amniotic fluid and swallowed by their fetuses.
The researchers tested the aforesaid hypothesis through a study that involved recruiting 46 pregnant women and grouping them into three. The first group was asked to drink carrot juice during their pregnancy and stop after their babies are born. The second group was asked to drink water during pregnancy and begin drinking carrot juice after their babies are born. The third control group was asked to avoid carrot juice before and after their pregnancy.
After these women gave birth, the researchers tested the flavor preferences of the involved infants more than five months post-pregnancy. They gave the babies two kinds of cereals, their first experience with solid foods: plain and carrot-flavored.
The feeding experience was recorded through videos. Results revealed that babies from the first group or more appropriately, the prenatally-exposed babies exhibited fewer negative expressions while eating the carrot-flavor cereal compared with plain cereal. A nine-point rating scale fulfilled by the mothers also showed that babies exposed to carrots while in the womb were perceived as enjoying the carrot-flavored cereal more compared with the plain cereal.
Nevertheless, the study has supported earlier animal studies about prenatal flavor learning and it further established the fact that unborn babies acquire food and taste preferences through their intrauterine environment and prenatal exposures to flavorings initially ingested by their pregnant mothers and transmitted to the amniotic fluid.
Implications Of Influencing Food Perception and Preference During Pregnancy: Sociocultural Relevance and Healthcare Significance
The study also has several implications. Mennella, Jagnow, and Beauchamp mentioned that the very early flavor experiences that transpire during prenatal development may provide the foundation for cultural and ethnic differences in cuisines.
Apart from sociocultural relevance, the study and other similar undertakings suggest a possible workaround for preventing diet-related diseases in the future. Researchers Kimberly K. Tout and Lisa Wetzel-Effinger suggested that the concept of prenatal flavor learning could be used to motivate women to eat healthy food. This learned flavor preference persists in infancy and even into childhood and adulthood.
Because of the long-term effect of the intrauterine environment and prenatal exposures, pregnant women and healthcare practitioners could take advantage of this developmental stage to promote healthy eating habits and future-proof children from obesity and diabetes. Simply put, the obesity pandemic and prevalence of diabetes can be controlled and prevented by starting with pregnant women.
Pregnant women can essentially shape the food preferences of their children. However, this prenatal flavor learning process can also have negative impacts. Researchers P. Abate et al. demonstrated that rodents who were prenatally exposed to alcohol are more attracted to alcohol-tainted water after they were born. Furthermore, the newborn rodents were more attracted to the smell of alcohol than the smell of their own amniotic fluid.
The study of Abate et al. could not be replicated in human subjects for obvious ethical and practical reasons. However, their review also suggested that babies born to women who drank moderate amounts of alcoholic beverages during pregnancy have more pleasurable reactions to the smell of alcohol. Note that Abate et al. also reviewed several epidemiological studies that linked prenatal or fetal alcohol exposure and alcoholism in later life. These studies controlled for genetics and postnatal environmental factors.
Another animal study by S. A. Bayol, S. K. Farrington, and N. C. Stickland revealed that rats that were prenatally exposed to high-fat and high-sugar diets are more at risk for obesity and diabetes due to an exacerbated taste preference for high-fat and high-sugar diet. The study of Z. Y. Ong and B. S. Muhlhausler support this finding through their separate study that showed that feeding pregnant rats junk foods had altered the reward system in the brain of their offspring. These prenatally-exposed rats need to eat more high-fat and high-sugar food to get a sense of “high” or “rush” and make eating pleasurable.
Prenatal flavor learning can essentially put unborn children at risk of developing bad habits and poor eating habits later in life. Nevertheless, this same phenomenon or prenatal development process can also be used to the full advantage of pregnant women and healthcare practitioners. As mentioned, by incorporating healthy eating habits during pregnancy, mothers and their healthcare partners can shape the taste and food preferences of their children and in a wider perspective, the future or upcoming generation.
FURTHER READINGS AND REFERENCES
- Abate, P., Pueta, M., Spear, N. E., and Molina, J. C. 2008. “Fetal Learning About Ethanol and Later Ethanol Responsiveness: Evidence Against ‘Safe’ Amounts of Prenatal Exposure.” Experimental Biology and Medicine. 233(2): 139-154. DOI: 3181/0703-mr-69
- Bayol, S. A., Farrington, S. J., and Stickland, N. C. 2007. “A Maternal ‘Junk Food’ Diet in Pregnancy and Lactation Promotes an Exacerbated Taste for ‘Junk Food’ and a Greater Propensity for Obesity in Rat Offspring. British Journal of Nutrition. 98(4). DOI: 10.1017/s0007114507812037
- Mennella, J. A., Jagnow, C. P., and Beauchamp, G. K. 2001. “Prenatal and Postnatal Flavor Learning by Human Infants.” Pediatrics. 107(6): e88. DOI: 1542/peds.107.6.e88
- Ong, Z. Y. and Muhlhausler, B. S. 2011. “Maternal ‘Junk‐Food’ Feeding of Rat Dams Alters Food Choices and Development of the Mesolimbic Reward Pathway in the Offspring.” The FASEB Journal. 25(7): 2167-2179. DOI: 1096/fj.10-178392
- Trout, K. K. and Wetzel-Effinger, L. 2011. “Flavor Learning In Utero and Its Implications for Future Obesity and Diabetes.” Current Diabetes Reports. DOI: 1007/s11892-011-0237-4
