What is bioavailability? And why is it so important in supplements?

If you’ve ever bought a supplement, you’ve probably looked mostly at the amount of a particular ingredient on the label. But the question is: How much of that is actually absorbed by your body? That’s what bioavailability is all about. In this blog, we take a technically-based look at what bioavailability means, why it is essential in dietary supplements, and what factors improve or hinder this absorption.

What is bioavailability?

Bioavailability is the percentage of an ingested substance that enters the systemic circulation (bloodstream) unchanged. This parameter is a fundamental measure in pharmacokinetics, often expressed as the ratio of area under the curve (AUC) of oral versus intravenous administration (US FDA Guidance for Industry, 2014).

A high-dose supplement by itself says nothing about efficacy if its bioavailability is low. For example, curcumin, a polyphenol derived from turmeric, has been extensively studied for its biological potential, but has exceptionally low oral availability. This is due to poor water solubility, rapid metabolism in the liver (first-pass effect) and limited permeability through the intestinal epithelium. According to a study by Prasad et al. (2014, Molecular Nutrition & Food Research, IF >6), free curcumin is barely measurable in plasma after oral intake.

Not for nothing that we improve the bioavailability of curcumin, by offering it liposomally. Curious? Learn more about how we make curcumin highly absorbable with our liposomal curcumin capsules.

From ingestion to action: ingestion in steps

The path from supplement to cellular action passes through several biological barriers:

1. Stomach: pH-sensitive substances can be deactivated or broken down by stomach acid and enzymes.
2. Small intestine: Here absorption occurs via transport proteins or passive diffusion. Poor solubility hinders absorption.
3. Liver (first-pass metabolism): Many substances are largely metabolized before they circulate systemically.
4. Bloodstream and cellular uptake: Only free, intact molecules can diffuse through cell membranes or be taken up via endocytosis.

Thus, for true effectiveness, it is not only the intake that matters, but more importantly the extent to which a substance arrives at the right place in active form.

Technological solutions: liposomes and micelles

To increase bioavailability, pharmaceutical delivery systems such as liposomes, nanoemulsions or micellar complexes are used. Liposomes are spherical structures composed of phospholipids, similar to cell membranes. They can encapsulate hydrophilic or lipophilic substances, protect against stomach acid and fuse with cell membranes for efficient delivery. Want to know when liposomes really make sense as a delivery system? Then read our in-depth blog on liposomes.

A study by Schiborr et al. (2014, Molecular Nutrition & Food Research) shows that liposomal curcumin provides a 5- to 10-fold increase in AUC compared to standard curcumin preparations. Similarly, nanoformulations of astaxanthin demonstrate increased plasma levels after oral ingestion (Fang et al., 2017, Drug Delivery).

Pharmacokinetic parameters

Important measures of bioavailability are:

• Cmax: maximum plasma concentration
• Tmax: time until Cmax is reached
• AUC (Area Under the Curve): total exposure to the active substance over time
• T1/2 (half-life): time period in which half the substance has been eliminated

High Cmax and AUC are desirable in supplements, if within safe margins. An extended half-life (e.g., by liposomal administration) contributes to more stable bioavailability.

Omega-3: indirect facilitator of uptake

A lesser-known aspect of bioavailability is the role of cell membrane composition. Omega-3 fatty acids such as EPA and DHA increase the fluidity of cell membranes, which promotes nutrient absorption at the cellular level. Too much omega-6 leads to stiffer membranes, which actually hinders this absorption.

Although this effect is indirect, it does affect how efficiently other nutrients can be absorbed into the cell. In addition, EPA and DHA are essential fatty acids for the heart, for example: “EPA and DHA contribute to normal heart function at a daily intake of 250 mg” (EFSA Journal, 2012). This claim highlights their broader physiological value beyond intake promotion. Thus, restoring a proper omega-3 status not only brings numerous health benefits, but in doing so can also enhance the effectiveness of other supplements, by improving bioavailability within the cell.

How to choose a supplement with high bioavailability?

• Formulation method: look for liposomal, micellar or nanoemulsion preparations.
• Clinically substantiated: See if human studies are available on Cmax or AUC.
• Transparency in dosing: Pay attention not only to milligrams, but also to uptake data.

On health claims and our limits as a brand

Although many of our ingredients have been extensively researched, due to European legislation we are not allowed to mention on this website all the health benefits shown by scientific studies.

Would you like to know more about our products or formulas? We are happy to think along with you without any obligation. Call us at (+31) (0)70 345-0290.

Conclusion

Bioavailability is the determining factor in the efficacy of supplements. It determines how much of a substance actually becomes actively available in the body. Thanks to technological innovations such as liposomes, and with the support of a healthy fatty acid balance (such as a good omega-3 status), we can significantly improve this availability.

Want to use supplements designed with maximum absorption power? Then check out our selection of liposomal formulas and high-quality omega-3 products.

About the author: Jesse

What I value most about my job is that every day I can contribute to promoting products that I fully support. The science and quality behind our nutritional supplements motivate me to make sure as many people as possible get to know them.

I feel at home in a team with a clear vision, that takes responsibility and has a passion for health and wellness. I have a BSc. in Health Sciences from the University of Twente and an MSc. from Maastricht University. With this background, I combine science with communication and focus on transparent, and factual explanations of our product development. No empty claims, but sharing knowledge, and building a relationship based on trust and expertise.

Sources consulted

• Prasad S, et al. (2014). Molecular Nutrition & Food Research, 58(3), 527-539. doi:10.1002/mnfr.201300545
• Schiborr C, et al (2014). Mol Nutr Food Res, 58(3), 516-527.
• Fang JY, et al. (2017). Drug Delivery, 24(1), 1-9.
• EFSA Journal (2012). Scientific Opinion on health claims related to EPA and DHA. EFSA Panel on Dietetic Products, Nutrition and Allergies.
• US FDA (2014). Guidance for Industry: Bioavailability and Bioequivalence Studies Submitted in NDAs or INDs.