Why do we eat? Aside from the obvious answer—to sustain life functions and grow—food is more than just nutrients, and eating is for more than just health. Eating is a source of pleasure. The rise in the brain’s serotonin level that results from eating chocolate makes us happy. Thus, eating is a complex behavior aimed to satisfy our physical hunger and our psychological desires. However, the two needs sometimes conflict.
Most people know what's good for them in terms of nutrition. They are also aware of the consequence of an unbalanced diet. But often, this is where their awareness stops. When I was a child I had a dog. She knew she was not allowed to cross the street, but she did it anyway because she couldn't resist the cat that was eyeing her from the other side. One day, she was hit by a car. I give this example to show how knowledge of what is right and wrong is a prerequisite for general behavior and intentional healthy eating, but so often, it has no affect on the choices we make.
What makes people tick—or in this case, lick? Our food choices are set during the course of our lives. They can be divided into three interrelated groups:
- Factors related to food: taste and texture. Most of us are born with a tendency to like sweets and the creamy texture of fats. Several factors affect the choices we make as we grow, such as: hunger and satiety mechanisms; past experiences with foods and the consequences of eating them, for example, the good feeling generated by serotonin or, adversely, nausea after eating certain foods; repeated exposure to different foods and the resulting familiarity with them; and learning to accept new foods. Our food preferences also change with age to embrace more complex tastes, such as bitterness. Most of our inborn physiological mechanisms stem from times when certain foods were scarce, such as carbohydrates, and high-fat nutrition was considered safe and healthy. Not today!
- The individual making these choices: perceptions, beliefs, knowledge, personal meaning and values, social and cultural norms, and family and peer networks.
- External physical and social environmental influences: food availability; social structure; cultural practices; economic factors, such as price, income and time; and the information environment, including media and advertising.
Can any of the above explain my daughter's marked desire for salad, of all things? Sweet, it is not! And why would different members of one family get hooked on three very different food items? This rules out the environmental factor. And while my taste buds have changed since childhood, with a marked shift toward onions, it was not at the expense of strawberries.
Our food choices are set during the course of our lives. That's true, yet when does this life begin?
My mom admittedly devoured nothing but strawberry pies when she was pregnant with me. During the last month of my pregnancy with my grape-loving child, I had to consume buckets of the sweet juice when testing for her viability—and did she get a kick out if it! I can also explain the salad: it was all I could eat during the last months of my pregnancy with you-know-who.
In fact, this kind of craving is backed by scientific evidence. As described above, more than one factor is responsible for our food choices. Children are not born with a preference for French fries over spinach and certainly not salad over sweet chocolate. Eating is a behavior that develops through exposure and repetition, beginning in the uterus. A study by Menella et al in 2001 became the first experimental evidence that showed how prenatal food experiences in humans influence postnatal responses to that type of food and nutrition. In other words, your mom's cravings during pregnancy may be your food birthmark or ID. Infants who were exposed to carrots prenatally through their mothers' food intake were perceived as enjoying carrot-flavored cereal more than plain cereal. But how can that be? As far as I recall, strawberries don't make their way, mouth-to-fetus, in one piece.
Experimental studies have shown that the amniotic sac, the environment in which the human fetus lives, changes based on the mother’s food choices, as dietary flavors are transmitted to the amniotic fluid and swallowed by the fetus. This means the fetus perceives the sense of the food it absorbs, and its experiences with flavors lead to increased enjoyment and preference for these flavors at birth and during weaning.
Consequently, the types of food eaten by women during pregnancy and, hence, the flavor principles of their culture may be experienced by their infants long before they are first exposed to solid foods. Infants will experience some of the same flavors in breast milk, a liquid that, like amniotic fluid, has the flavors of the foods, spices and beverages consumed by their mothers. This prenatal and early postnatal experience highlights the importance of a varied diet for pregnant and lactating women.
Food for thought! (No pun intended.) Consider this another reason why we should maintain a healthy diet during pregnancy. It's much easier than chasing your toddler down the hallway with a spoonful of veggies.
Are there any examples in your life that you'd like to share?
1. Contento, IR. Nutrition Education, Linking Research, Theory and Practice. 2007; 28-45. Jones and Bartlett publishers.
2. Mennella, JA, Jagnow, CP, and Beauchamp, GK. “Prenatal and Postnatal Flavor Learning by Human Infants.” Pediatrics. 2001, June ; 107(6): E88.
3. Mennella, JA. “Development of Food Preferences: Lessons Learned from
Longitudinal and Experimental Studies.” Food Qual Prefer. 2006, October; 17(7-8): 635–637.
4. Mennella, JA, Johnson A, Beauchamp GK. “Garlic ingestion by pregnant women alters the odor of amniotic fluid.” Chemical Senses. 1995; 20:207–209.