A very brief overview of digestion.
A well-functioning digestive system is the foundation of overall health. By understanding and supporting these natural processes, we can ensure that our bodies get the nutrients they need to thrive.
Digestion: the basics
Digestion is the process by which food is broken down into smaller, simpler molecules that the body can absorb and use for energy, growth, and repair. This transformation happens through two primary processes:
1. Mechanical digestion, involving physical actions like chewing and the rhythmic movements of the digestive tract.
2. Chemical digestion, where enzymes break down complex food molecules into smaller, absorbable ones.
Digestion is an intricate system involving multiple organs and stages, all designed to ensure the body extracts as many nutrients as possible. Here’s how digestion works, step by step:
1st phase: the mouth and chewing
Digestion begins in the mouth, where food is chewed (masticated) and mixed with saliva. Saliva plays a crucial role, containing:
• Amylase: This enzyme begins breaking down starch into simpler sugars, such as maltose. Around one-third of dietary starch is broken down at this stage.
• Mucus: Lubricates food to make it easier to swallow.
• Bicarbonate (HCO3): Provides the ideal pH environment for amylase to work effectively.
• Water and electrolytes: Moisten food, preparing it for further digestion.
The importance of chewing cannot be overstated. Studies show that thorough chewing increases nutrient absorption and reduces the strain on other parts of the digestive system. A good guideline is to chew each bite 20–30 times to ensure proper breakdown and mixing with saliva.
2nd phase: the stomach and pepsin enzyme
Once swallowed, the chewed food (bolus) moves down the esophagus into the stomach through rhythmic muscle contractions known as peristalsis. In the stomach:
• Hydrochloric acid (HCl): Creates a highly acidic environment (pH 1.5–3.5) that kills most harmful microorganisms and activates the enzyme pepsin.
• Pepsin: Breaks proteins into smaller peptides and amino acids. This is the first major step in protein digestion.
• Peristalsis: Mixes food with gastric juices, transforming it into a semi-liquid substance called chyme.
Some nutrients, such as water, simple sugars, and alcohol, are absorbed directly in the stomach.
Incorporating herbal bitters, such as dandelion greens, rocket, and watercress, is a tradition in many cultures. It is believed to stimulate the production of digestive enzymes and bile. Research suggests that these compounds prime the stomach for efficient digestion. A few drops of Swedish Bitters under the tongue or bitter greens at the start of a meal are effective ways to activate the digestive system.
3rd phase: the small intestine and digestive juices
The partially digested chyme is gradually released into the small intestine through the pyloric sphincter. This is where the majority of digestion and nutrient absorption occurs.
• Pancreatic enzymes: The pancreas releases enzymes such as amylase (for carbohydrates), proteases like trypsin (for proteins), and lipase (for fats), which further break down food molecules.
• Bile: Produced by the liver and stored in the gallbladder emulsifies fats, making them easier for enzymes to digest.
• Absorption: Approximately 95% of nutrients, including vitamins, minerals, amino acids, fatty acids, and glucose, are absorbed into the bloodstream through the small intestine’s villi and microvilli, which increase surface area for maximum absorption.
Research highlights the importance of maintaining a healthy gut lining to optimize nutrient absorption. A diet rich in fiber supports this function. Probiotics and prebiotics may also help.
4th phase: the colon and the microbiota
The remaining digested food enters the large intestine (colon), where the final stages of digestion take place:
• Water and electrolyte absorption: Excess water, along with minerals such as sodium and potassium, is absorbed into the bloodstream.
• Gut microbiota: Trillions of microorganisms in the colon help break down any remaining undigested food. These microbes produce beneficial compounds like short-chain fatty acids (SCFAs), which support gut health, reduce inflammation, and even influence immune function.
• Vitamins: Gut bacteria synthesize essential vitamins, such as biotin and vitamin K, which are absorbed here.
Waste products of digestion are then compacted into stool and eliminated through the rectum and anus.
An imbalance in gut bacteria, known as dysbiosis, can be linked to a range of conditions, from digestive issues like irritable bowel syndrome to broader health concerns like obesity and depression. Eating a diverse, fiber-rich diet supports a healthy microbiome.
Key takeaways for optimal digestion
• Chew thoroughly: This simple habit significantly aids digestion and nutrient absorption.
• Eat mindfully: Avoid rushing through meals; eating in a calm environment improves digestion.
• Stay hydrated: Water plays a critical role in digestion at every stage.
• Support gut health: Include probiotic and prebiotic-rich foods to nurture your microbiome.
• Incorporate bitters: They may stimulate digestive enzymes and bile production.