2 min read

What you need to know about bioavailability

What you need to know about bioavailability
Photo by julien Tromeur / Unsplash

Often we assume the quantity of nutrients & macros we read on the label of our products, is the amount that our bodies absorb if we eat. However, it is way more complicated than that!

What is bioavailability?

❣️ Intake ≠ availability. The amount that is listed on the label is the measure in the food, not the amount that is per se absorbed by the gut. (1)

The proportional amount that is actually absorbed and can be used in our body = bioavailability. (1)

Why is it relevant?

Some foods have a higher bioavailability than others. This can result in the fact that foods that seem to have different amounts of nutritional value, actually have the same amount of bioavailable nutrients for your body! (2)

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Example with calcium: Plant foods like leafy greens contain less calcium overall but have a higher bioavailability than dairy. Calcium in milk has a bioavailability of about 30% absorption in comparison with 50% in leafy greens. So, if 1 cup of milk lists 300 mg of calcium, about 100 mg will be absorbed and used by the body. If 1 cup of leafy greens lists 200 mg of calcium, about 100 mg is absorbed. Therefore, eating 1 cup of leafy greens has the same amount of bioavailable calcium as 1 cup of milk, although the absolute amount of calcium in milk is much higher. (2)

Important factors that affect the bioavailability of nutrients

 
 🍏 The amount you actually eat

 🧬 How easily the nutrient itself can be absorbed (the size of the nutrient and other chemical properties, f.e. changed by preparation of the food (raw, cooked, etc.)

 🚫 Factors that decrease or ✅ increase absorption: inhibitors and enhancers

 💩 How easily the nutrient is excreted by your body

 👫 How well you as a person can absorb the nutrient (depending on gender, age, body composition, and health status)


(1)

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Example: some plant foods (like spinach) have "anti-nutrients" (like phytate and oxalate) that decrease the bioavailability of minerals by forming non-digestible complexes with them. (1,3)
More about bioavailability of specific nutrients & tips in future posts. Stay tuned for more!

References

  1. Hambidge KM. Micronutrient bioavailability: Dietary Reference Intakes and a future perspective. Am J Clin Nutr. 2010 May;91(5):1430S-1432S. doi: 10.3945/ajcn.2010.28674B. Epub 2010 Mar 3. PMID: 20200261; PMCID: PMC2854910.
  2. Calcium. Hsph.harvard.edu. Available at: https://www.hsph.harvard.edu/nutritionsource/calcium/ (Accessed: November 28, 2022).
  3. Melse-Boonstra A. Bioavailability of Micronutrients From Nutrient-Dense Whole Foods: Zooming in on Dairy, Vegetables, and Fruits. Front Nutr. 2020 Jul 24;7:101. doi: 10.3389/fnut.2020.00101. PMID: 32793622; PMCID: PMC7393990.
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Eva Verbiest

Eva Verbiest

Netherlands