Amino Acid Absorption: Stomach Enzymes or Small Intestine's Villi?

By now, you've probably come across many nootropic brands promoting all sorts of release profiles—immediate release, time release, delayed release, and so on—each touting the effectiveness of a particular method for absorbing certain nutrients.

However, these discussions often focus on vitamins, minerals, and a range of herbal extracts—including some 'miracle plants' most of us have never heard about—and tend to overlook a crucial group of nutrients that may significantly impact our cognitive health: amino acids.

This one topic—where amino acids are best absorbed—doesn't seem to get enough attention. Given all the potential benefits amino acids can have for your brain, we think it's a pretty important piece of information, wouldn't you agree?

Question is: stomach or small intestine?

Breaking down proteins into amino acids and absorbing them mainly happens in the stomach and small intestine. Each part plays a distinct role due to its unique environment.

To kick things off, let’s give you a visual of what we’re talking about.

Now let’s break it down: starting with the 'absorption' in the stomach.

Here, what happens to amino acids is not that much different from, let's say, vitamins or minerals. The stomach's primary role in amino acid absorption is still the same: the initial protein breakdown.

The stomach's environment is highly acidic, with a pH of around 1.5 to 3.5. This acidic setting is important for activating pepsin, an enzyme that starts the process of breaking protein molecules into smaller pieces, including some amino acids.¹

However, the stomach doesn't absorb a significant amount of amino acids. Its acidic environment mainly prepares the proteins for further digestion and absorption down the line.

In the stomach, proteins are introduced to a highly acidic environment with a pH of about 1.5 to 3.5.

This acidity serves a purpose—it activates pepsin, a specialized enzyme.

Pepsin is important for slicing protein molecules into smaller chains or peptides, effectively beginning the process of protein digestion. But pepsin doesn't work alone; it's supported by Hydrochloric Acid and a group of enzymes called proteases.²

Hydrochloric Acid unfolds the protein structures, making them more accessible for enzymatic action. Proteases then take the stage, targeting the peptides—chains of amino acids linked together—and breaking them into smaller segments.

This initial breakdown is significant but doesn't go all the way to freeing individual amino acids.

Instead, the stomach's acidic milieu primarily sets the stage for the proteins, now reduced to smaller peptide chains, to be further digested and absorbed in the small intestine.

The small intestine is where the magic happens for amino acid absorption.

Unlike the stomach's harsh, acidic environment, the small intestine offers a more welcoming space for nutrients with its slightly alkaline pH level, ranging from 5.5 to 6.5.

This shift to a milder environment is thanks to bile and pancreatic secretions that neutralize stomach acids, setting the stage for the most efficient phase of digestion.¹

Why does this matter?

Well, the small intestine's walls are covered with villi and microvilli—think of them as tiny "nutrient-catching fingers".

These structures greatly expand the intestine's surface area, making it a super-efficient nutrient absorber. Enzymes come into play here, breaking down what's left of the protein chains from our diet into individual amino acids or small peptides.

These are then easily absorbed into the bloodstream, ready for our bodies to use for everything from repairing tissue to making enzymes and hormones.^*3

It's not just about what's in your favorite nootropic; how it's delivered to your body is what (really) matters.*

From our POV, quality in nootropics isn’t just about the nutrient quality and manufacturing process (Don't get us wrong, those are two aspects we put a lot of emphasis on). But a well-thought-out release profile can significantly enhance the effectiveness of amino-acid-based nootropics.*

Ultimately, it's all about making the most of your favorite nootropic. One that leverages the right release profile can better align with your body's natural digestive rhythms, ensuring that amino acids are not only delivered to the right place but also at the right time.*