Marks Daily Apple
Serving up health and fitness insights (daily, of course) with a side of irreverence.
18 Apr

Should You Chew Your Child’s Food?

By now, you’ve probably seen the Alicia Silverstone pre-mastication video. It’s totally safe for work (maybe not for lunch, but your mileage may vary), but some viewers will find it a bit unsettling: Silverstone feeds her baby pre-chewed food directly from her mouth, just like a bird. I found it pretty fascinating and not at all upsetting. Before you recoil in disgust and/or horror, think about how people weaned babies before Magic Bullets, Vitamixes, Gerber baby food, and even mortar and pestles hit the scene. That’s right – they chewed their food for them. In a paper entitled “Premastication: the second arm of infant and young child feeding for health and survival,” Gretel Pelto speculates that pre-mastication was likely common practice among pre-agricultural groups and confirms that it continues today across every continent (PDF).

As to why this practice arose in humans but not other mammals, it’s the neoteny. Humans are born completely helpless, and remain so for several years (some would suggest “decades”). Newborn babies have no teeth and don’t even develop a decent set until about a year or later. This isn’t an issue at first, since they have access to plenty of delicious, nutritious breastmilk that goes down smooth. But because breastmilk is fairly low in iron (albeit a highly bioavailable form designed specially for infants), once kids run out of their pregnancy iron stores, they need a more reliable source of the mineral in addition to the milk. Nowadays, kids get iron-fortified rice cereal or baby vitamins or something silly like that, but before all that stuff, kids needed to eat iron-rich foods when the iron supply dwindled. What’s simpler and more effective for a hard-working hunter-gatherer who needs to feed her child some adult, iron-rich food – chopping up and crushing a strip of venison liver on a wooden plank with stone knives, or chewing it up and transferring it directly to the kid’s waiting mouth?

Okay, so there’s historical and evolutionary precedent for it, but is there any reason to chew your kid’s food today rather than whip out the food processor? Are there any extra upsides?

Free Mechanical Digestion

Since babies are rather limited in the tooth department, they can’t chew their food effectively, which is how most animals – humans included – mechanically digest their food. That’s why “baby food” is pureed; it’s a more socially acceptable (and financially lucrative) way of pre-chewing their food for them. And since the greater surface area of mechanically digested food bits exposes more of them to enzymatic action, pre-chewed food is more easily digested by babies (and adults).

Chewing your kid’s food is definitely cheaper than buying baby food, and it’s more time-efficient than making it in a blender or food processor.

Oral Enzymatic Pre-Digestion

Infants are born equipped with the enzymatic machinery to handle the simple sugars, animal fats, and animal protein in breast milk. They are not ready to digest a whole lot of other things, particularly dietary starch (which is often “baby’s first food” regardless). In humans who have it, salivary amylase predigests starch during the chewing process, initiating the conversion of starch into more easily assimilable carbohydrate derivatives like maltose (a disaccharide of two glucose units) and dextrin (a polysaccharide). Infants don’t come equipped with much salivary amylase right out of the box, so when a parent who wields the full array of salivary enzymes pre-masticates their food, the infant digests the food better. To get an idea of what kind of enzymatic digestion this pre-mastication is providing, let’s check the numbers:

In adults, salivary amylase (which predigests starch) is present in concentrations of 70-300 U/ml. Infants are born with “negligible” amounts, attain “appreciable levels” by 3 months, and reach 85% of adult salivary amylase levels by five months (PDF). Since Alicia Silverstone feeds her kid a vegan diet, presumably rich in fruits and starches, pre-mastication is a sound tactic.

There’s also lingual lipase, which breaks down long-chain triglycerides into glycerides and free fatty acids. Infants have lingual lipase at birth, but they have very little gastric (gut) lipase. Since babies absorb far less dietary fat than adults (65-80% versus more than 95%), a little extra lingual lipase activity provided by the pre-masticating parent combined with the kid’s lingual lipase could improve absorption rates. Hey, maybe that’s what’s causing infant obesity – a wave of pre-mastication sweeping the nation!

Unless you’re drooling into your Vitamix, the parent who pre-masticates may be giving her kid a digestive advantage.

Transplantation of “Good” Oral Bacteria

Over 700 species of oral bacteria have been identified from human mouths, and the oral microbiome of any given individual may house from 30 to more than 100 different species. While oral bacteria can trigger the development of dental caries and periodontal disease, it’s not all “bad.”  For example, many strains of oral bacteria taken from healthy children actually provide protection against harmful oral pathogens and are being developed as oral probiotics. Other strains have been shown to directly influence the immune response in gum tissues, as well as protect the host from oral pathogen-induced apoptosis and inflammation.

I wasn’t able to pull up any explicit references to pre-mastication as a transplantation method for “good” bacteria, but there is evidence that mouth to mouth contact between mother/father and offspring can transfer pathogenic cavity-causing bacteria to the child. If the “bad” can be transferred, why not the “good”?

Development of the Immune System

Saliva contains the very same antibodies found in breastmilk, like immunoglobulin A, immunoglobulin G, and immunoglobulin M. These help establish the budding immune system and provide passive resistance to pathogens, including bacterial infections and viral infections. There’s very little research on the impact of saliva-borne immunoglobulins on infant health, but we do know that breastmilk-borne immunoglobulins are crucial to the development of an infant’s immune system, so it seems likely that pre-mastication is also helpful (especially since both breastmilk and pre-chewed food enter a child through the same orifice).

Perhaps it’s even a way for non-breastfeeding mothers to give their child a leg up.

Are there any downsides?

Transfer of “Bad” Oral Bacteria

As I just mentioned, a parent with dental disease caused by bacteria could transfer the same bacteria to their child by pre-chewing his food. If the bacteria takes hold early enough, it could be difficult to dislodge it. The same could just as easily be said for the early transfer of good bacteria, though, so it’s impossible to say who “wins.”

It all depends on the oral health of the pre-masticator.

Transfer of Saliva-Borne Disease

Transfer of saliva-borne diseases is a possibility. Those include hepatitis G, herpes, TT-virus (which is widespread and seems pretty harmless), hepatitis B (although the hepatitises are present in low amounts in saliva), and there’s mixed evidence that pre-mastication can and has transferred HIV from caregiver to child, although that probably requires an open sore or wound in the mouth.

Again, it depends on the health of the caregiver.

Pre-mastication appears to be a valid, viable way for Ma (or Pa) to deliver food to a baby’s maw. There are some impressive potential health benefits, it might save money, and it could even bolster immunity. The potential downsides, however, must be considered. Overall, I don’t think it’s necessary for parents, and the social pariahism you’re likely to face may not be worth the trouble, but I certainly find it intriguing.

How about you, folks? Would you – or have you already – pre-chew your kid’s food?

You want comments? We got comments:

Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

  1. My sons nursed for the first year. They did not like cereal. My La-leche league teacher told me to feed them meat. So I did. I had a baby food grinder. I would have done whatever it took. Even prechewing if I had to. Our second son would eat 4 pieces of roasted chicken at 18 months for dinner. I was amazed at his appetite for meat early on.

    lynn wrote on May 1st, 2012
  2. We decided to freeze and grate grass-fed chicken liver as our now 9 year old daughter’s first food. She loved it and the pastured egg yolks! For young parents on this leg of their life journey, I recommend Nina Plank’s Real Food for Mother and Baby. (pre-mastication not required!)

    Ivana Kadija wrote on May 7th, 2012
  3. Can I just say that the risk of dental caries may not be very high because the main bacteria species implicated in initiating a carious lesion in a tooth is Streptococcus mutans. They aren’t found in mouths without teeth, and what is more, don’t colonise the mouth until aroud 18 months to 2 years, during a ‘window of infectivity’. This may be due to a tailing off or loss of protective factors in breastmilk. (I’m not sure how this stands for artificially fed infants.) Of course, there are other bacteria implicated in the carious process, but again I’m not sure how important they may be in this context.

    April Whitlock wrote on May 14th, 2012
  4. My 10-month-old was not interested in the joys of eating. I tried store-bought purees. I tried mashing up yams and rice with breast milk. I tried finger foods to give him control. He showed minimal interest. Yogurt was the only hit for weeks. We’d sneak fruits and veggies into it. But he was passionately interested in anything we ate. One night I looked at my plate – it was all great, organic, simple food. I gave him some out of my mouth without even thinking about it. It was an IMMEDIATE hit. He couldn’t get enough. In the back of my mind I wondered if it was gross, but it seemed so incredibly natural. Some genetic mom part of my brain knew what it was doing. Since that night, he has loved eating and will now feed himself. I still pre-masticate (amazing to know there’s a term for this) some things, but he’s well on his way to becoming an independent eater. Pre-chewing makes a million times more sense than using our Magic Bullet every meal. Thanks for providing some beneficial science!

    Jade wrote on August 16th, 2012
  5. I think this idea has plenty of merit. At least it’s just chewing the food, unlike wolves who throw up partly digested meat to feed their young.

    Rosalie wrote on November 12th, 2012
  6. Yes I’ve done it, when your baby’s hungry and you’re eating and there’s no way to get baby food, it’s just the logical thing to do, I don’t even think about it. I don’t do the mouth to mouth thing, I usually spit it onto a finger and put it in his mouth. Quite often baby prefers to eat off my finger than his spoon. I just go with it, it’s natural he likes the skin contact. It’t not like they do this forever, so I enjoy it while it lasts.

    Krish wrote on March 27th, 2013
  7. Pre-mastication of food for babies really isn’t such a crazy or even new concept at all. When I was a baby in China my grandfather was the one who chewed up food for me and fed it to me directly from his mouth. In China this practice is quite a traditional approach for many families and normal, especially considering that many people there (and from other cultures too I’m sure) do not buy commercial baby food for their infants as is now the norm for many families in the US. Providing babies with whole-foods pre-masticated has benefits that far outweigh buying processed packaged baby foods, and healthy babies around the world have been brought up on pre-chewed foods.

    CYS wrote on April 14th, 2013
  8. My mom chewed certain foods then fed them to me because i refused to chew them myself, but when i think about it as an adult it makes me want to vomit

    Taurus wrote on July 15th, 2013
  9. I have a few extremely early memories of my infancy. In one I am sitting in a high-chair and my Japanese mother is chewing peanuts and putting them in my mouth with her hand . As gross as it sounds now, I remember liking it :)

    Robin H wrote on October 25th, 2013
  10. Wow I am really late on this comment but wanted to share. I didn’t know anything about the Alicia Silverstone thing. I was just looking up on the web more info about pre-masticating food for babies. The thought popped into my head one day when I realized my baby opens his mouth every time I go in to kiss his lips like he is expecting something. Then it got me thinking about the people who say that saliva cures pink eye because of all the beneficial bacteria in saliva. If ever you get pink eye, rub some saliva in it or have someone spit in your eye if you trust them. Anyway, I think it would be good for you child, if you have a good diet and mouth hygiene. Lots of animals do it for their young. I’m not saying regurgitation, that just is yucky, but I think chewing is fine.

    Xmom101 wrote on March 8th, 2015
  11. I chewed up my 6-10 month olds meats. I did it before I even knew there was a name for it. I am a ‘crunchy’ but also ‘normal’ mother, and I’m proud of being a pre-masticator!

    Amanda Templeman wrote on June 24th, 2015
  12. Does anybody read this anymore? I noticed my 3 month old has been making an “o” face a lot when you look at him (no not from Office Space). Recently I noticed that he made that face when I went to kiss his nose. Out of curiosity, I stuck my open mouth next to his and he did it again and stuck his tongue out like he was ready to take in food (or at least that’s what I thought). I understand 3 months might be too early for solids, or even pre-chewed solids. But I’m curious for those who have done it for a baby of around 6 months, how much did you chew (i.e. what was the consistency like in YOUR mouth)? And how much from each bite? My concern is choking more than anything.

    AR wrote on February 24th, 2016

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