Why Bioavailability Matters in Your Nutrition

When it comes to absorbing vitamins and minerals effectively, bioavailability is key. The better a nutrient's bioavailability, the more efficiently your body can utilise it for cellular protection, immune support, and energy production.

In this article, we'll explore what bioavailability means and how to identify foods and supplements that offer high bioavailability.

What Is Bioavailability?

Bioavailability refers to how much of a nutrient (or compound) your body can actually absorb and use—usually measured by how much enters your bloodstream. It could refer to an active ingredient in a medication, or a specific nutrient from food or a supplement.

The general rule: the higher the bioavailability, the greater the benefit for your body.

A number of factors influence nutrient bioavailability—most notably, how your metabolism processes them. This includes digestion, absorption in the gut, and the transformations that occur via enzymes and organs. But your diet and lifestyle also play a role in how effectively nutrients are absorbed.

Why Is Bioavailability Important?

You could be consuming plenty of nutrients—but if they don’t make it into your bloodstream, they won’t do much good. That’s why the bioavailability of the nutrients in your food or supplements is essential.

It’s not just about getting the right amount of a nutrient—it’s about whether your body can use it. If it can’t, you risk developing a deficiency over time, even if your intake appears sufficient.

Macronutrients like protein, fat and carbohydrates generally have very high bioavailability in healthy individuals—over 90% is typically absorbed in the gut. But micronutrients like vitamins and minerals are a different story. Their bioavailability can vary widely, depending on a range of factors.

Factors Affecting the Bioavailability of Vitamins

In addition to metabolic processes (which we can’t control), several other factors determine how bioavailable nutrients in food or supplements are. These include:

• The nutrient’s biochemical properties
• The composition of the food it’s consumed with—also known as the “food matrix”—particularly the presence of substances that enhance or inhibit absorption

The Biochemical Form Determines Bioavailability

Whether a nutrient can be digested, absorbed in the gut, and used effectively by the body depends largely on its biochemical structure. Why? Because your body works on a kind of lock-and-key principle.

That means a reaction can only take place if a nutrient fits the target site exactly. The challenge: many vitamins and minerals exist in multiple chemical forms—and even small differences in structure can affect whether your body can actually use them. Depending on the form, bioavailability may be higher or lower.

Take vitamin B12, for example. It’s actually a group of compounds with similar structures—but different levels of bioavailability.

The most efficiently absorbed forms are the naturally occurring ones: methylcobalamin, adenosylcobalamin and hydroxycobalamin. Cyanocobalamin, by contrast, is a synthetic form. While your body can convert and use it, it’s less effective.

That’s why supplements should ideally contain the active forms—especially if you're relying on them to meet your needs. Other forms like hydroxo-, aquo- or nitrocobalamin are essentially unusable by the body and have poor bioavailability.

Another example is vitamin E. Of the many forms, alpha-tocopherol has the highest efficacy. Beta- and gamma-tocopherol offer only around 15–30% of that effectiveness. Delta-tocopherol is largely inactive in the human body.

The Impact of the Food Matrix on Bioavailability

The combination of nutrients you consume also plays a role in bioavailability—whether from food or supplements. Nutrients can interact with each other, and other food components like fibre, acids or phytonutrients can either help or hinder absorption.

For example, absorption may be reduced when multiple nutrients compete for the same absorption pathway in the gut. Or when food components bind to minerals and block their uptake—these are called “chelating agents.”

A common case: phytic acid, found in legumes and grains, binds to iron and reduces its absorption. Tannins in red wine, black tea or coffee can have a similar effect. That’s why it’s best to wait a while after taking iron before drinking coffee. On the flip side, vitamin C enhances iron absorption. And techniques like soaking, fermenting or sprouting grains and legumes can help reduce the impact of phytic acid.

Other examples of supportive combinations include the fat-soluble vitamins A, D, E and K—which are better absorbed when consumed with some dietary fat.

In short: nutrient bioavailability plays a major role in how well your body is nourished and supported. While natural whole foods often contain nutrients in bioavailable forms—and a balanced diet usually covers your bases—certain eating styles (like vegetarian or vegan diets) may limit your intake of some nutrients. That’s where supplements can help. But only if their ingredients are in the right form—and highly bioavailable.

How Bioavailable Are the Nutrients in AG1?

Great question—and one we ask ourselves, too. That’s why we put AG1 to the test in clinical research. We wanted to know exactly how well the nutrients in AG1 are absorbed by the body.

In a recent clinical study, we measured how well the nutrients in AG1 were absorbed. Participants consumed either AG1 or a placebo. Blood samples were taken at multiple time points over eight hours after each drink.

This allowed us to track how quickly nutrients entered the bloodstream—and how long levels stayed elevated.