The digestion of meat

There are horror stories about how difficult it is to digest meat and how it rots in the intestines for weeks. This is pure nonsense and probably another one of the food and pill industries' propaganda campaigns, to lure you away from the healthiest food on the planet.

They want to lure you into Big Foods and Big Pharma, into the addictive and disease-causing factory food, and into all the pills you need after eating it.

How does digestion take place?

Digestion is a fascinating and complex process that starts in the mouth. When we chew our food, it is broken down into smaller pieces, and saliva from the salivary glands mixes with it. Saliva contains the enzyme amylase, which starts the breakdown of starch into simpler sugars.

This process makes food easier to swallow and prepares it for further digestion. After food is swallowed, it is transported through the esophagus by peristalsis, a series of wave-like muscle contractions, before reaching the stomach.

In the stomach, food encounters gastric juice, which contains hydrochloric acid and the enzyme pepsin. The hydrochloric acid breaks down connective tissue in meat and eliminates potentially harmful microorganisms, while pepsin begins to break down proteins into smaller peptides.

Fat is broken down to a small extent in the stomach, but food is mixed well with gastric juice into a viscous mixture called chyme.

This is common to all carnivores; the acidic stomach.

How quickly does meat decompose?

Meat and fat leave the stomach relatively quickly, usually within 4–6 hours, depending on the composition of the meal, while plant fiber remains undigested and continues further in the digestive system.

As food enters the small intestine, bile from the gallbladder and digestive enzymes from the pancreas are added. Bile emulsifies fat, while the enzyme lipase breaks it down into fatty acids and glycerol, which are quickly absorbed through the intestinal walls.

Carbohydrates are further broken down into simple sugars such as glucose and fructose, and proteins are cleaved into individual amino acids by proteases such as trypsin and chymotrypsin.

The nutrients from meat and fat are absorbed efficiently in the small intestine, usually within a few hours of leaving the stomach.

The small intestine is also the only place where fatty acids are absorbed into the body. Although short-chain fatty acids are produced in the large intestine through fermentation of plant fibers, these remain in the large intestine and are used locally.

They do not contribute to the body's overall nutrient absorption, and there is no mechanism to carry these fatty acids back up to the small intestine for absorption.

How does the body use plant foods?

Plants contain complex carbohydrates such as cellulose and fiber, which the human body cannot break down because we lack the enzyme cellulase.

Such materials pass through the digestive system undigested, reaching the large intestine, where our bacteria ferment some of it.

The fermentation produces short-chain fatty acids and gases as byproducts, but the energy we can extract from this process is minimal compared to animals that have specialized digestive systems to utilize cellulose.

How long does plant food stay in the system?

Plant fibers can remain in the colon for up to 24–48 hours before being excreted as part of the stool.

Should you experience constipation, which is common if you eat a lot of plant fiber (large volume takes up a lot of space), plants can remain in the colon longer, causing pain, gas, and discomfort. They can also to do harm, and create chronic inflammation.

In other words, it is plants that rot in the intestines, not meat.

Two different operating systems

An interesting way to understand the difference between plant and animal nutrients is to think of them as two different operating systems. Plants and animals operate at different biological levels, and the nutrients in plants are often "encrypted" in a form that the human body must convert before they can be used.

For example, vitamin A is found in plants only as a precursor, beta-carotene, which must be converted to the actual vitamin retinol before the body can use it. This process can be inefficient, and many people have genetic variations that reduce the ability to perform this conversion.

Proteins from plants are also often incomplete, as they lack one or more essential amino acids, and the ratio between the various amino acids is also wrong for us.

Meat, on the other hand, contains all the essential building blocks we need, in abundant amounts, and the nutrients are already in a form that is compatible with the human body.

Meat stands out as a nutritional powerhouse because it is highly bioavailable and easy to digest. The amino acids in animal protein are absorbed quickly and efficiently, and the fat-soluble vitamins A, D, E and K are in forms that the body can use immediately.

In addition, it does not contain meat antinutrients, such as phytates and lectins, which are commonly found in plants and can inhibit the absorption of minerals such as iron, zinc and calcium. This makes meat a more direct source of energy and essential nutrients compared to plants.

From an evolutionary perspective, meat has been an essential part of the human diet. Unlike herbivores, who have developed specialized, massive digestive systems to extract energy from cellulose, humans have evolved to utilize nutrients from animal sources quickly and efficiently. The digestive process is therefore an elegant reflection of how we have adapted biologically to access the nutrients that are most available and useful to us.

From the first chew to the last trip to the toilet, digestion is an impressive process that shows how the body utilizes the energy and nutrients of food.

What is clear is that the nutrients from meat require far less conversion, are easier to break down, and easier to absorb, and are thus easier for the body to use directly.

Human digestion of cellulose and plant material

Percentage of cellulose digested in humans

Bioavailability and digestibility of meat

Protein digestibility in meat

MORE SOURCES

Photo: Shutterstock license

Anyone can comment by logging in with their Facebook or Google accounts.. Norwegian Carnivory is not health care. You must seek medical attention for medical problems.

Written 2025 © Norwegian Carnivory