What is bioavailability?
The short answer
Bioavailability is the share of a dose that actually reaches your bloodstream in a usable form. Two products with the same amount on the label can deliver very different amounts to the body, depending on the form of the ingredient and how it is made.
Choose your depth
Bioavailability is the share of a dose that actually reaches your bloodstream in a usable form. Two products with the same amount on the label can deliver very different amounts to the body, depending on the form of the ingredient and how it is made.
Choose Detailed for the fuller picture, or Scientific for mechanisms and study data.
When you swallow a tablet, it has to dissolve, cross the gut wall and survive processing by the liver before it reaches the rest of the body. At each step some is lost.
Why form matters
- Curcumin on its own is poorly absorbed. Pairing it with piperine improves this.
- Benfotiamine is a fat-soluble form of vitamin B1 that is absorbed far better than ordinary thiamine.
- L-methylfolate is the active form of folate, ready for the body to use.
- Calcitriol is the active form of vitamin D.
Why it matters to you
When comparing products, the form and formulation can matter as much as the number of milligrams on the label.
Absolute oral bioavailability (F) is the dose-normalised area under the plasma concentration-time curve after oral administration relative to intravenous administration. Determinants include solubility, permeability (the Biopharmaceutics Classification System), first-pass metabolism, efflux transporters and formulation technology.
What we know
- Form and formulation strongly affect absorption.
What remains uncertain
- How absorption differences translate to outcomes for many ingredients.
Related ingredients
Sources
Last updated 15 October 2026.
This is educational content and does not replace advice from a qualified doctor. If you have symptoms or take medicines, please speak to your doctor before making changes.
