Fast Digesting and Absorbing Protein

fast digesting protein

Fast absorbing protein is a protein that is easily digested and absorbed by the body rapidly, usually within 60 to 90 minutes. Fast acting protein has become popular with athletes and bodybuilders because of its benefits of rapidly raising the blood levels of amino acids. Having amino acids levels rise quickly is beneficial as it allows you to fuel your working muscles with the amino acids they need to function optimally and recover and grow.

Fast acting protein and bodybuilding 

Bodybuilders and athletes consume protein supplements right before they start working out. According to fitness experts, the body breaks down this fast absorbing protein. It ensures that you have the amino acids necessary to workout at peak levels and can recover and grow. You may see bodybuilders drinking whey protein shakes after working out. It’s because whey protein contains a significant amount of high-quality protein that gets absorbed by their bodies quickly. When you consider eating foods with a high protein percentage, you should also check their absorption rate. 

Fast absorbing protein foods usually get digested within a couple of hours. On the other hand, slow absorbing proteins may take more than four hours. 

How do protein digestion and absorption work?

In your stomach, pepsin, an enzyme that breaks down peptide bonds keeping protein molecules bound together, starts to convert proteins into amino acids.[1]

Polypeptides, or chains of amino acids linked together, are what is left after the bonds are fully dissolved. Your small intestine further digests these polypeptides after they reach your gastrointestinal tract.[2]

The polypeptides are then broken down further into their single amino acid components in the small intestine.[3]

What is a fast digesting protein?

As the name suggests, these proteins get digested in your body quickly, and peak amino acid concentrations are reached in the blood within between 60 to 90 minutes.[4] This absorption rate means your body breaks down and utilizes the protein faster. This speed helps get the needed amino acids to the muscle so the body can start the anabolic process of protein synthesis. Muscle protein synthesis is a process where the protein repairs damaged muscles after an intense workout session. This repairing is what creates muscle growth.

A study was done by researchers at the University of Birmingham on people who consumed fast absorbing whey protein pre-workout, and another group of people who consumed it post-workout showed that the fast-acting whey protein, when taken before working out, had a greater positive benefit on muscle growth and protein synthesis.[5] The study pointed out that muscle protein synthesis was the highest right before the participants started an intense workout session. The study showed benefits from consuming fast absorbing protein like whey post-workout, but the effect was not as strong as consuming it before your workout.

What is the fastest absorbing protein?

Whey protein isolate is the fastest absorbing protein, with pea protein isolate a very close second. Whey has an absorption rate of approximately 90 percent, and pea protein has an absorption rate of 89 percent.[6] These two proteins get absorbed in 60 to 90 minutes. Whey concentrate is third with an absorption rate of 2 to 3 hours, followed by soy, casein and egg proteins, all with similar rates of 3 to 4 hours.

A general rule is the more refined the protein source is, the quicker it will be absorbed by the body. So protein isolates such as whey protein isolate etc., are the fastest absorbing proteins.

Whole or unrefined protein foods such as eggs, meat or plant proteins will be longer in terms of absorption because they contain other things such as fibre, fat, etc. These other items within the food can slow down digestion and absorption.

What factors affect protein digestion?

The main factor that affects the rate of protein absorption is

  • high levels of insoluble fiber
  • high concentrations of antinutritional factors

Antinutritional factors are things found within the protein food source that negatively impact the absorption of the protein. They can include Mustard and rapeseed protein products containing glycosinolates; lentil protein products containing trypsin inhibitors and hemagglutinins; cereal products containing phytates; cottonseed protein products containing gossypol.

Protein and amino acid digestibility can be substantially reduced by trypsin inhibitors found in kidneys and soybeans, and other grain legumes. Research on pigs shows a reduction of up to 50 percent protein absorption.[7]

high levels of tannins can negatively affect the absorption rate by as much as 23 percent, as demonstrated in rats.[8]

phytates found in legumes and cereals reduce amino acid and protein digestibility by 10 percent.[9]

Summary of fast acting protein

Consuming fast absorbing protein foods can significantly affect how your muscles react during and after a workout. When taken before a workout, fast acting protein can quickly raise the amino acid levels in your blood. This elevated amino acid level can help provide your working muscles with the amino acids they need to fuel your workouts. When taken after a workout, fast-absorbing proteins can help get crucial muscle-building amino acids to the muscles quickly.
Every athlete and bodybuilder looking for optimal performance, recovery and muscle growth should be using fast-absorbing proteins as part of their supplement regimen. These proteins offer tremendous benefits, especially when used pre and post-workout.

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Please always consult with your doctor regarding health and medical information. The information found within this article is not intended to be taken as medical or health advice.