Infant digestive system development

Proper nutrition is crucial in supporting healthy growth and development during the first 1,000 days of life as the digestive system develops. 

The first 1,000 days of life is a period of rapid growth and development, including a baby’s digestive tract and brain, as they continue to develop outside the womb. During this time, the digestive system is still developing as certain enzymes, the microbiome, and motility mature. 

See ‘How nutritional changes can impact digestive comfort and support gut health’ to find out more.

Enzyme development

Decreased activity of protein enzymes can result in difficulty to digest proteins.^1,2 For example, protein enzymes like enterokinase, chymotrypsin, and carboxypeptidase do not reach maturity until 2 years of age.^3,4 Similarly, lactase enzyme activity can be lower at birth, which can reduce the ability to break down lactose.^5,6

Motility development

Motility of the GI tract, or peristalsis, also continues to mature during the first year of life.⁷ Additionally, the lower esophageal sphincter, which controls the flow of food from the esophagus to the stomach, does not function in a mature way during infancy and can allow stomach contents to flow back into the esophagus.^8,9

Microbiome development

The gut microbiome, which consists of microorganisms that live in the digestive tract, also plays a significant role in digestion and nutrient absorption.¹⁰ Although the colonization of these microorganisms starts in the womb, the microbial makeup gradually shifts and reaches adult-like composition around 3 years of age.¹⁰