Protein Digestion: Enzymes, Absorption, And Ways To Improve ...

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Nutrition

How Is Protein Digested?

Medically reviewed by Katherine Marengo LDN, R.D. — Written by Megan Dix, RN, BSN — Updated on June 20, 2023

Enzymes
Absorption
Improving digestion
Takeaway

Chewing food is the first step of protein breakdown. From there, the protein enters your stomach, small intestine, and bloodstream. You can increase protein absorption through consumption of certain foods.

Protein is one of the most important substances in your body. Your muscles, hair, eyes, organs, and many hormones and enzymes are primarily made out of protein. It also helps to repair and maintain your body tissues.

However, not all protein is created equal, and there are things you can do to help your body use it more efficiently.

Protein is a very large nutrient that’s made up of smaller substances called amino acids. There are 20 amino acids, but your body can only make 11 of them. The other nine are called essential amino acids, and you can only get them through your diet.

High-quality protein sources, such as meat, fish, eggs, and dairy products, contain all nine of the essential amino acids. These are also called whole proteins or complete proteins.

Other protein sources, such as nuts, beans, and seeds, only contain some essential amino acids. However, you can combine some of these protein sources, such as rice and beans, to create a complete protein that contains all nine essential amino acids.

Not sure how much protein you need per day? Here’s how you calculate how much you really need.

The role of enzymes

Protein digestion begins when you first start chewing. There are two enzymes in your saliva called amylase and lipase. They mostly break down carbohydrates and fats.

Once a protein source reaches your stomach, hydrochloric acid and enzymes called proteases break it down into smaller chains of amino acids. Amino acids are joined together by peptides, which are broken by proteases.

From your stomach, these smaller chains of amino acids move into your small intestine. As this happens, your pancreas releases enzymes and a bicarbonate buffer that reduces the acidity of digested food.

This reduction allows more enzymes to work on further breaking down amino acid chains into individual amino acids.

Some common enzymes involved in this phase include:

trypsin
chymotrypsin
carboxypeptidase

How is protein absorbed?

Protein absorption also happens in your small intestine, which contains microvilli. These are small, finger-like structures that increase the absorptive surface area of your small intestine. This allows for maximum absorption of amino acids and other nutrients.

Once they’ve been absorbed, amino acids are released into your bloodstream, which takes them to cells in other parts of your body so they can start repairing tissue and building muscle.

How can I absorb more protein?

The first step in increasing your protein absorption is choosing whole proteins that contain all nine essential amino acids. These include:

meat
fish
eggs
dairy products

If you’re a vegetarian, you can make a complete protein with the following combinations:

Protein combination	Examples
whole grains and legumes	brown rice with lentils or pasta salad with kidney beans
nuts and whole grains	nut butter on whole grain toast
legumes with seeds	hummus, which contains chickpeas and sesame seed paste
vegetables and nuts	green bean almondine
vegetables and whole grains	broccoli and whole grain pasta

It was previously believed that vegetarian proteins must be consumed at the same meal in order for the body to form complete proteins. Now it’s known that the body can pool proteins from various foods throughout the day to form complete proteins when needed.

So for vegetarians, variety is key.

Habits to follow

In addition to choosing the right protein sources, you can also adopt certain habits to help get the most out the food you eat. These include:

eating regularly throughout the day
thoroughly chewing your food
reducing stress
avoiding intense exercise right after a meal
limiting your alcohol consumption
managing any underlying condition that affects digestion, such as diabetes or liver disease
taking probiotics, such as B. coagulans 30, which can improve protein absorption
eating protein throughout the day, rather than all at once
following a regular exercise routine

The bottom line

Protein is a vital nutrient for almost every part of your body. It’s digested in your mouth, stomach, and small intestine before it’s released into your bloodstream as individual amino acids.

You can maximize the nutrients you get from protein sources by eating complete proteins and adopting certain habits, such as chewing thoroughly before swallowing.

If you’re ready for more protein now, add these high-protein foods to your diet!

How we reviewed this article:

SourcesHistoryHealthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical journals and associations. We only use quality, credible sources to ensure content accuracy and integrity. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

Cataldo D, et al. (2015). Protein intake for optimal muscle maintenance.https://www.acsm.org/docs/default-source/files-for-resource-library/protein-intake-for-optimal-muscle-maintenance.pdf
Dangin M, et al. (2002). Influenceof the protein digestion rate on protein turnover in young and elderly subjects.DOI:https://doi.org/10.1093/jn/131.10.3228S
Hermann JR. (2019). Protein and the body.http://pods.dasnr.okstate.edu/docushare/dsweb/Get/Document-2473/T-3163web.pdf
Jager R, et al. (2017). Probiotic bacillus coagulans GBI-30, 6086 improvesprotein absorption and utilization.https://link.springer.com/article/10.1007/s12602-017-9354-y
Pendick D. (2019). How much protein do you need every day?https://www.health.harvard.edu/blog/how-much-protein-do-you-need-every-day-201506188096
Your digestive system and how it works. (2017).https://www.niddk.nih.gov/health-information/digestive-diseases/digestive-system-how-it-works

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Medically reviewed by Katherine Marengo LDN, R.D. — Written by Megan Dix, RN, BSN — Updated on June 20, 2023

Protein Digestion: Enzymes, Absorption, And Ways To Improve ...

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