December 26th, 2022
"Humans are the only mammals who feed our young special complementary foods before weaning and we are the only primates that wean our young before they can forage independently. There appears to be a sensitive period in the first several months of life when infants readily accept a wide variety of tastes and this period overlaps with a critical window for oral tolerance. As a result, infants should be exposed to a wide variety of flavors while mother is pregnant, while mother is nursing and beginning at an early age. There also appears to be a sensitive period between 4 and 9 months when infants are most receptive to different food textures.
There remains debate about when it is best to begin introducing solid foods into an infant's diet however, the available evidence suggests that provided the water and food supply are free of contamination, and the infant is provided adequate nutrition, there are no clear contraindications to feeding infants complementary foods at any age. There is emerging evidence that introduction of solid foods into an infant's diet by 4 months may increase their willingness to eat a variety of fruits and vegetables later in life, decrease their risk of having feeding problems later in life, and decrease their risk of developing food allergies, and the early introduction of solid foods into an infant's diet does not appear to increase their risk of obesity later in childhood." (Borowitz S. 2021)
Food Introductions - How should we do it?
When infants begin to transition to eating solid foods, there are differing theories on how to progress through this process. I tend to always think anthropologically here. What would humans have done for 100s of years before the advent of gerber, processed puffs, etc.. Food is meant to be provided to a child by his mother and father in a whole foods form initially that was broken down by the parent mechanically by chewing, cooking or crushing it. First foods allowed for many human benefits. Mothers could wean off of breast milk earlier allowing for more procreation which was a major species benefit. The massive energy needs of the brain, roughly 30% of ingested calories, could be supplemented to allow mom a break from giving up so much energy every day or to help her get out to procure food more easily. These realities lead to survival advantages for mom and babe leading me to believe that they were baked into our DNA.
How does this historical reality translate to today?
Children will always prefer sweet to bitter, i.e. fruits to vegetables. Children also tend to cluster food preferences to that which the mother was exposed to during pregnancy. This is a problem in modern society as we have far too many foods that hijack this taste preference reality and lead to poor choices for mom and child over time. Sweet foods also were evolutionarily safe and energy rich. Bitter could be a poison and often not energy dense. Thus, it is not surprising that children left to their own devices will consume energy rich processed and sweet foods.
"There appears to be a sensitive period during the first several months of life when infants are most receptive to a wide diversity of flavors, and what they taste during this sensitive period can influence their taste preferences later in life. Most infants <4 months of age readily drink formulas that contain hydrolyzed casein which are extremely bitter, however beyond 6 months, infants who have never been exposed to these formulas refuse to drink them. Moreover, infants fed hydrolysate formulas in the first several months of life are more willing to eat savory, sour or bitter foods than are infants fed standard milk-based formulas and as compared to children who were never fed a hydrolysate formula, 5 year old children who were fed a hydrolysate formula during infancy more readily eat foods with sour or bitter tastes or aromas." Repeating the exposure to a food also has a major influence on acceptance over time. "In one study, mothers of seven month old infants were asked to identify a vegetable their infant disliked and were instructed to offer that vegetable on alternate days for 16 days, and to offer a well-liked vegetable, typically something sweet like carrots, sweet potatoes or squash, on the other days. On the first day, infants ate substantially less of the disliked vegetable than the well-liked vegetable however by the eighth repetition, the intake of the liked and unliked vegetables were identical."(Borowitz S. 2021) Other studies noted that children offered diverse foods in the first year of life tolerated a wider palate of foods in the later age ranges.
Aside from taste, is there really a sensitive period of time whereby the type of solid introduced has a downstream affect on texture choice later on? The answer appears to be yes. Babies, infants and toddlers tend to prefer smooth food textures over lumpy or chunky but this reality if unchallenged can cause downstream issues. According to Dr. Borowitz, most fruits and vegetables have complex textures which require the infant to use their tongues to move the food around their mouths in preparation for swallow. The infant's ability to use their tongues to manipulate food in their mouth appears to be more dependent upon their experiences with textured food than on any particular developmental stage. Research shows that they are more willing to eat and enjoy chopped or chunky foods by 1 year of age, are more likely to eat a variety of fruits and vegetables at 7 years, and are less likely to suffer from feeding problems during childhood if they are offered different textures often while beginning to eat solids in any form . On the other hand, children who are not introduced to varying textured solids until after a year are more likely to develop oral defensiveness and refuse more highly textured foods which is a constant problem in our clinic these days. (Borowitz S. 2021)
Ideas for feeding:
Babies should be able top open their mouths when they see food coming and move it in and around with their tongue. They should move their head to the side when they don't want anymore. They should be able sit upright in a chair or self sustained position to feed safely. Use whole and real foods in all varieties in a safe texture that is not a choking hazard. Avoiding starting with sweet foods that will make bitter foods like vegetables harder to accept. Start between 4 and 6 months of age.
Researcher Lisa Daniels and her colleagues advise parents to follow these guidelines (2015):
• Always test the foods yourself before you give them to your baby. Make sure foods are soft enough “to mash with the tongue on the roof of the mouth (or are large enough that small pieces don’t break off when sucked or chewed, e.g., strips of meat).”
• Don’t offer foods that “form a crumb in the mouth.”
• Make sure your baby is always sitting upright during the meal — not leaning back.
• Don’t leave your baby unattended. An adult should monitor the baby at all times during the meal.
• Don’t try to put finger foods in your baby’s mouth. “Never put whole foods into the infant’s mouth – the infant must do this at their own pace and under their own control.” (Dewar G. 2019)
Do not use fat free, sugar free or anything free in the beginning. Use real food in real non choke-able forms. Avoid adding salt or sugar to any foods. Do not start with starchy rice cereal. Instead try steel cut oatmeal. No raw meats, fish or honey because of pathogenic disease risks post consumption.