What is bioavailability (and why does it matter?)

Not all supplements are created equal and more importantly, not all are well absorbed. 

Bioavailability refers to the proportion of a nutrient that is absorbed and made available for use in the body. 

Not just what you take, but what your body can actually: absorb, convert, transport and utilise at a cellular level. Ultimately determining whether a supplement is effective. 

When we ingest a supplement, it undergoes a journey. It has to move through multiple steps: 

• Release from the supplement
• Absorption through the gut
• Conversion into an active form (if required)
• Transport to tissues
• Utilisation in the body

And at any point along this journey, absorption can be reduced, limited or lost entirely. 

Why not all supplements have good bioavailability

The form matters

Not all forms of a nutrient behave the same. Some forms are already active and easily utilised. Others require conversion, which not everyone does efficiently. The same nutrient can have very different outcomes, depending on individual differences. 

The body has limits

Absorption is not unlimited. Your body regulates how much we absorb, and more is not always better. In some cases, higher doses can overwhelm these systems rather than improve outcomes. 

Example: high doses of folic acid can exceed the body’s ability to convert it into its active form, potentially, leading to unmetabolised folic acid and reduced efficiency. 

Nutrients don’t work in isolation

In whole foods, nutrients exist within a complex matrix, interacting with: other vitamins, minerals, enzymes and plant compounds.

These interactions can enhance absorption and utilisation. That’s why a diverse, whole-food dit remains foundational.

In contrast, nutrients in supplements are isolated, meaning they lack these natural synergies, influencing how effectively they are used. 

Competition and interactions

Nutrients can both support and compete with each other.

Some nutrients compete for absorption: 

• Iron and calcium
• Zinc and copper
• Fat improves absorption of fat-soluble vitamins 

Others enhance absorption:

• Vitamin C improves iron absorption

Meaning formulation, and how nutrients are combined matters. 

Your body influences absorption

Bioavailability is personal. Our body isn’t passive and adapts depending on our needs. 

It changes depending on:

• Gut health
• Nutrient status
• Genetics
• Life stage
• Medications 
  

The same supplement can work differently for different people.

Formulation quality matters

Before a nutrient can even be absorbed, the supplementation itself must first break down properly.

Factors that influence this include:

• Fillers and binders
• How well the supplement dissolves
• Stability of the nutrients 

Where supplements can be beneficial

While whole foods should always be the foundation, supplements can play a valuable role when used intentionally. 

They can bypass the limitations of the food matrix

In whole foods nutrients are embedded within a complex structure. Meaning they can be:

• Trapped in plant cell walls
• Bound to compounds like fibre or phytates
• Affecting how much your body can absorb
• Iron and zinc are often less bioavailable in plant foods due to these binding compounds. 

Supplements can deliver these nutrients in a more available, unbound form, making them easier to absorb in some cases.

They can use more bioavailable forms

Nutrients exist in multiple forms. Well-formulated supplements can use forms that are:

• More easily absorbed
• Already active
• Less reliant on conversion

Allowing the body to utilise them more efficiently.

They allow for targeted, therapeutic dosing.

For times when food alone simply isn’t enough. Think pregnancy, nutrient deficiencies and increased physiological demands.

Supplements allow for: precise dosing, consistent intake and faster correction of deficiencies.

Formulation should be intentional.

At Land Lab, formulation is approached with bioavailability in mind. 

Using active, bioavailable forms of key nutrients:

• Levomelfolate glucosamine (equiv. Levomefolic acid B9)
• Mecobalamin (B12)
• Pyridoxal 5-phosphate monohydrate (equiv. Pyridoxine B6)

Alongside well-absorbed mineral forms:

• Zinc (as zinc citrate dihydrate)
• Selenium (as selenomethionine)

And including nutrients like iodine, choline and vitamin D in clinically relevant amounts. A prenatal that is designed to be recognised, absorbed and used.

A supplement is only as effective as what your body can absorb and use.

Bioavailability depends on:

• The form
• The formulation
• The digestive environment
• And the individual taking it

Bioavailability does not equate to bioequivalence. Different forms of the same nutrient may be similarly absorbed, yet produce very different physiological effects. Which is why some supplements are highly effective, and others can pass through the body with little to no benefit.