What is bioavailability?

Learn what bioavailability is and why it matters when buying vitamins, nutrients, and supplements.

Bioavailability is the measure of how much of a substance is used and absorbed by the body.

When it comes to bioavailability, most vitamins, minerals and other health supplements leave a lot to be desired. Unless you know what to look for when you’re buying supplements, you’re probably flushing a lot of hard-earned money down the drain. Literally.

Let’s break down what bioavailability is, why it matters, and key questions to ask when to ensure you’re reaping all the benefits of your supplements.

What is bioavailability?

In simple terms, bioavailability is how well your body absorbs and uses a supplement when it enters the body.

The bioavailability of a supplement is important, as it increases the amount of the desired nutrient your body is able to absorb, without you having to take higher doses.

What is the difference between absorption and bioavailability?

Bioavailability is a sub-category of absorption. Where absorption simply refers to the movement of a substance from entering the body into the bloodstream, bioavailability is the extent to which the substance is absorbed and used.

What is bioavailability in biology?

In biology, the term ‘bioavailability’ is understood as a measure of the fraction of a drug that reaches its desired biological destination. However, the term traditionally referred to how quickly a certain vitamin, mineral, or other nutrient entered your bloodstream.

For example, studies on magnesium and on vitamin D supplementation typically use blood tests to identify how much of either nutrient is in a blood sample after someone has taken a magnesium or vitamin D pill.

But that doesn’t always tell you the whole story. Just because a nutrient has entered your bloodstream doesn’t mean it’s getting to where it needs to go, or even being used effectively.

This may explain why there are so many conflicting studies on certain nutrients. Using vitamin D as an example again, researchers know vitamin D has its benefits, but the research results on vitamin D supplements are often inconclusive .

Could this be because certain vitamin D supplements may elevate your blood levels of the vitamin, but are not actually being absorbed and used efficiently? And how can you, as a savvy supplement shopper who wants your supplements to actually do their job , ensure your body is truly getting the nutritional support it needs?

This led to a newer take on the definition of bioavailability:

True bioavailability = how well your body absorbs and uses a supplement

So what is the bioavailability of a drug?

It’s the extent it becomes completely available to the place in your body where it will be used.

Dr. David Kitts, an experimental medicine scientist at the University of British Columbia, breaks down the traditional definition into two separate terms:

  • Bioaccessibility

  • Bioavailability

Bioaccessibility is how quickly a supplement is broken down by your digestive system, and the specific vitamin, mineral or other nutrient is made available to your body. Think of that as the “old” idea of bioavailability.

Meanwhile, Dr. Kitts says that true bioavailability is the "rate and extent to which the therapeutic moiety (drug) is absorbed and becomes available at the organ site."

Bioavailability meaning

To put it into everyday language, this new-and-improved meaning of bioavailability refers to how well your body absorbs and uses a specific nutrient in the right place, at the right time.

“Take magnesium as an example,” we noted in a previous Heights article on using our best-selling Vitals⁺ as a replacement for other supplements . “Many cheaper supplements use magnesium oxide or magnesium sulfate, but these types of magnesium aren't as easily absorbed by your body as magnesium citrate or magnesium aspartate.”

Now you know the ins and outs of the term*,* how can you measure the bioavailability of supplements you’re buying?

The bioavailability of supplements

When buying supplements, it’s important to look beyond the milligrams on the label or the promises made by the manufacturer, and to take a peek at their ingredients to establish whether they actually work.

The bioavailability of supplements can be affected by a variety of factors, which can be identified by asking these 3 questions:

1. Does the supplement use the most absorbable form of the vitamin mineral or nutrient?

Just because a supplement has a high dose of a nutrient, it doesn’t mean your body can actually absorb and use it. That’s why bioavailability is so important, after all.

In fact, when it comes to some commonly used ingredients, your body has such a hard time absorbing them that the supplement might almost be worthless!

Take an omega 3 supplement, for instance. The most absorbable and effective types of omega 3 are EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). However, many omega 3 pills contain a form of omega 3 known as alpha-linolenic acid.

Researchers have found that in some people, your body converts as little as 0.3% of ALA into EPA (the conversion success rate to DHA is a bit better at 4%).

In other words, when you take an omega 3 supplement made with ALA, 99% of it is basically ineffective.

2. Does the supplement use the purest form of the ingredient?

While our Vitals⁺ only uses active ingredients , with no fillers or toxins, many manufacturers do not use the purest, most concentrated form of the actual nutrient you want. This, of course, reduces the amount entering your body and the bioavailability of the supplement.

Let’s use medium-chain triglyceride (MCT) supplements as an example. Many people take MCT supplements for cardiovascular benefits and other health reasons.

Some brands may contain pure MCT oil, where the coconut oil has been put through a process known as fractionation to isolate the MCTs themselves. Other supplements, however, just use pure coconut oil, which is made up of only an estimated 55% MCTs .

Basically, it doesn't contain all that much of the thing you actually want.

3. Do the ingredients interact with each other (or with other supplements you’re taking)?

Some nutrients boost the bioavailability of other nutrients. Some c ommonly combined pairings that make each individual nutrient more effective include:

  • vitamin D and calcium

  • vitamin B12 and folate

  • zinc and copper

  • iron and vitamin C

Likewise, taking a fat-soluble vitamin (e.g., vitamin A, vitamin E, etc.) with a meal containing fat helps boost the bioavailability of vitamins.

The opposite can also happen, where some nutrients limit the bioavailability of another nutrient. For example, high doses of vitamin C may reduce the effectiveness of several B vitamins.

In conclusion...

Ensure all of your supplements:

  • use the most absorbable form of a specific nutrient

  • contain the purest ingredients

  • do not contain ingredients that negatively affect the bioavailability of other nutrients

Vitals⁺ was designed with bioavailability in mind

Whilst this might be the first time you’re exploring bioavailability and it’s importance, the effectiveness and absorption of specific nutrients have always been front and center for us at Heights.

That’s why we only use the purest ingredients that have been vetted by third-party reviewers, and we always select the best forms of each vitamin or mineral to ensure maximum bioavailability.

Similarly, every ingredient in Vitals⁺ has gone through rigorous research under the supervision of Chief Science Officer Dr. Tara Swart, and Sophie Medlin, our Head of Nutritional Research.

Learn more about the exceptional bioavailability of our Vitals⁺ and why Heights only offers the highest quality nutrients for better brain health and improved mental well-being.


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