Bioavailability of Nutrients – Definition and Importance

Definition of Bioavailability - Nutrova

When you’re trying to identify the ‘best source’ of a nutrient, there are largely 2 important things to consider: 1) the quantity of the nutrient and 2) the ‘bioavailability’ of the nutrient.

The first is self-explanatory, but what exactly is ‘bioavailability’ and why does it matter? Read on to find out!

What is Bioavailability?

Simply put, ‘bioavailability’ is the measure of nutrient absorption, i.e how easily a nutrient can be absorbed by our body [1].

Before they can be used for their health benefits/functions, the nutrients we consume first need to be broken down, by our digestive system, into forms that our body can use. The nutrients that can be easily broken down are called ‘bioavailable’.

Macronutrients (carbohydrates, proteins, and fats) generally have high bioavailability – more than 90% of the amount we consume gets absorbed and used by our body [2].

Learn about protein supplements and how to pick one here.

On the other hand, micronutrients (vitamins, minerals, and antioxidants), can vary widely in the extent to which they are absorbed and used once consumed. That’s where the bioavailability of the nutrient needs to be accounted for [3].

Also read vitamins - myths and sensationalism.

There are a few exceptions here. For example, insoluble fibre (a form of fibre that doesn’t dissolve in water) is meant to pass through the body unabsorbed. So, despite not being broken further, it would still be considered ‘bioavailable’, given that it’s serving its intended use.

The concept is relatively simple. If ingredients aren’t absorbed and delivered in their ideal form to the target site in the body, and can’t perform their specific functions, they aren’t ‘bioavailable’.

Importance of bioavailability of nutrients

The bioavailability of the nutrients you consume is directly proportional to the positive effects they have on your overall health. When a nutrient is not bioavailable, it won’t be absorbed, which can result in its insufficiency or even a deficiency in the long run.

Definition of Bioavailability - Nutrova

For example, spinach contains the most calcium amongst all the leafy greens. However, only 5% of its calcium content is absorbed and used by the body [4]. This happens because of certain anti-nutrients (substances that block or interfere with the absorption of other nutrients) called ‘oxalates’ present in spinach [5, 6].

Read to know what are anti nutrients - the definition, function and methods of elimination.

In this example, the calcium in spinach has low bioavailability – which means, if you’re largely relying on getting calcium from spinach, you’re not actually getting it in optimum levels, resulting in an inadequate intake. In the long run, inadequate amounts of calcium can result in weak bones (osteoporosis) [7]. The takeaway message from this example isn’t to avoid spinach, which contains other valuable nutrients, but to consume a variety of sources of calcium (like dairy, soybean, chickpeas, almonds, etc.) to make sure you’re getting enough.

Bioavailability of Supplements

Bioavailability becomes extremely important while choosing dietary supplements. If we’re consuming a supplement that doesn’t have nutrients with high bioavailability, a significant amount of the nutrients will be lost. It sort of negates the whole point of supplementation. Choosing supplements formulated to have high bioavailability is the more effective way to get the nutrients we need.

Bioavailability of Food

Bioavailability is the key to getting the most nutrition out of the food that we eat. If the nutrients are not properly absorbed and utilized by the body, they would not be able to provide the intended results/benefits. Bioavailability, as a consequence, helps determine whether a person is able to reach a state of optimal health—which, at the end of the day, is what we are all striving for, right?

Also, read Nutrition Checklist for an Everyday Indian Diet, to know more about the nutrients you need to include in your food on a daily basis.

We hope you found this article helpful! We’re going to be exploring the topic of bioavailability in more depth in the near future, for anyone who’s interested in learning more. If there’s anything specific you’d like us to cover, leave a comment below!

Kainat Khan Mirajkar, PGD Dietetics and Applied Nutrition

Kainat is a Nutritionist with a PGD in Dietetics and Applied Nutrition and a Certified Diabetes Educator. With over eight years of experience in the field of nutrition and dietetics, she is Nutrova's in-house research and information expert.

More by Kainat Khan Mirajkar

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