Several readers have emailed me to ask about babies’ ability to digest starch. Here’s one:
“I have noticed you recommending cereals for babies several times. I am sure that you are aware that many people look at feeding a baby grains before the age of one or even two as if you have offered your child strychnine. One of the reasons cited is that they supposedly do not have amylase to digest grains before that time. I have often wondered what exactly is happening to the cereal if it is not being digested, but the only statement I could find is something about it “rotting” in the gut.
I would love to get information from a scientific point of view on this topic. Everything I have been able to find thus far has been very biased towards one point of view or another. Either “cereal is the perfect first food. Easy to digest and enriched with iron” from the infant cereal companies or “Cereal is junk. No infant should ever eat grains. It is not natural or traditional and they can’t digest it” from online parenting sites.
I need a little clarity and common sense.”
I love the skepticism in Hope’s email, and I can also empathize with her frustration about how difficult it is to find good information about a seemingly simple question: Can babies digest starch? If you search for the answer to this question online, you will run into dire warnings of the dangers of giving starch to babies. But these sites might set off your woo detector – as they should. So, after receiving multiple emails about this question as well as seeing it mentioned in discussions on the Science of Mom Facebook page, I figured it was time to put some evidence-based information about babies and starch digestion on the Internet.
Researching this question has given me an excuse to read some classic nutrition physiology papers harkening back to the 1960’s and 1970’s, and it’s brought back memories of years in the lab, exploring nutrient digestion and metabolism. And starch digestion in infancy, it turns out, is a really neat story.
Let’s start with some basics about carbohydrate digestion.
What is starch? How is it digested?
Starch is a type of complex carbohydrate. Made from lots of glucose molecules bonded together in long, branching chains, it is a plant’s way of storing glucose – product of photosynthesis and source of energy – in a stable form. We find starch in grains, root vegetables, winter squashes, beans, and some fruits, like bananas. Starch is an important storage depot for the plant, and it also makes for tasty staple foods for cultures around the world.
A chain of 3 glucose molecules, like a tiny section of starch.
Glucose is the major fuel for the cells of the body. When we eat starch, we have to break the bonds in those chains of glucose molecules, liberating them to be absorbed from the small intestine into our blood. Starch digestion begins in the mouth, where salivary amylase starts chopping up those large glucose chains. When this partially digested starch gets to the small intestine, amylase made and secreted by the pancreas jumps in to do more bond-breaking and is responsible for most of starch digestion in adults. A suite of enzymes produced by the cells lining the small intestine, including sucrase, isomaltase, maltase, and glucoamylase, work on the remaining short chains, finishing up the job and making glucose available for absorption.
Starch Digestion in Infants
Infants go through some incredible nutritional transitions in the first months of life. Prior to birth, their growth and development is fueled almost entirely by glucose from mom, absorbed across the placenta. After birth, they have to abruptly transition to an exclusive milk diet, which is high in fat and lactose, still a relatively simple sugar. As they start solid foods, babies have to adapt to a much more complex and varied diet. Around the world, starch is a major source of energy in the diets of children and adults alike. But when infants are first introduced to starchy foods – often in the form of cereals and porridges – starch is a novel nutrient to their digestive tract. They need to turn it into glucose, but are they equipped to do this? Continue reading