Bioavailability: the word everyone uses without really explaining it

“High bioavailability.”

It has become the nutritional equivalent of “high performance”.

It sounds technical, and therefore reassuring. Very quickly, it becomes: “this form is better absorbed, so it works better”.

There are a few missing steps between the two.

Swallowed does not mean available

Before an ingredient can be used by the body, it often has to be released from its matrix, dissolve, cross the intestine, sometimes undergo first-pass metabolism, and then be distributed.

Each step can reduce or alter the amount that actually reaches the circulation or the site of action.

Three terms that are often mixed up

How is it measured?

A dose is administered and the concentration of the substance, or a relevant marker, is often followed in the blood over time.

Three values appear frequently:

A formulation can therefore produce a higher peak, arrive faster or create greater total exposure.

These are real pharmacokinetic differences.

But none of them yet tells you that your skin, sleep or fatigue will change more.

Omega-3 illustrates the role of form rather well

In a trial of 72 volunteers, different forms of EPA + DHA produced different exposures. Re-esterified triglycerides were better absorbed than ethyl esters under the conditions studied.

But other protocols produce less clear-cut results.

The meal, especially its fat content, can itself change absorption.

“Twice as bioavailable” is therefore never a complete sentence without the comparator and conditions of intake.

CoQ10 shows why formulation can matter as much as the molecule

CoQ10 is lipophilic and its oral delivery is challenging.

A 2020 crossover trial in older adults compared several formulations and found substantial differences in blood concentrations.

Two capsules containing the same amount of CoQ10 can therefore expose the body differently.

Very interesting for a formulator.

Still not proof that the formulation with the best AUC will produce the best clinical result.

Magnesium reminds us to look at the right measure

Citrate, oxide, bisglycinate and other forms do not have the same solubility.

Several trials have observed higher bioavailability for citrate than oxide.

But blood magnesium is tightly regulated and represents only a very small fraction of total magnesium in the body.

Depending on the question, researchers may therefore look at serum, urine, retention or several parameters.

Bioavailability also depends on how you measure it.

A better-absorbed form can still provide less

Take a deliberately simple example.

Form A is absorbed at 50% and provides 300 mg.

Form B is absorbed at 75% but provides only 50 mg.

Form B is proportionally better absorbed. Yet the absolute amount available can still be lower.

That is why form and dose should always be read together.

And at Eclo?

In Ressource™, we use TRAACS® magnesium bisglycinate from Albion® Minerals. We chose it for its form and supplier quality, but the product provides 56.25 mg of elemental magnesium, or 15% of the NRV.

We do not turn a study at a different dose into evidence for the finished product.

In Régénère™, CoQ10 is also part of a wider architecture. Again, the bioavailability of another CoQ10 formulation does not become evidence of Régénère™’s clinical efficacy.

Five questions when you see “more bioavailable”

Bioavailability tells you about the journey. Efficacy tells you what changes at the end of that journey.