Post No. 10 What does bioavailability mean in terms of human nutrition?

 

Bioavailability in its simplest terms means the proportion of the nutrients that are consumed that are available to the body after food and drink has been consumed, digested (absorbed) and metabolised. Bioavailability is influenced by many factors e.g. age, lifestyle, health status, diet, nutrient concentration in the diet, and food structure [1]. Let’s look at some of these. 

• Age - as we get older we tend not to absorb as many of the nutrients in our food as we did when we were younger. Our gut ages with time and loses some of its function for digesting and absorbing nutrients [2, p.17] 
• Lifestyle - bioavailability can be affected by increased urinary secretion of nutrients (vitamins and minerals) or they can be lost through sweat. [3] Other lifestyle factors can have an impact too.
• Diet and nutrient concentration - the diet we eat and the nutrient levels in the foods we choose makes a difference in how many nutrients are then available in our body. 
• Food structure - the structure of the food is really important in terms of bio availability. A piece of fruit is much harder to digest than a juice drink, for example. Also the processing of the fruit, say an orange to make juice, can lead to some of the nutrients being lost, and some being concentrated in the juice portion. How we digest plant based foods is really important, there are lots of cell walls to break down. Some scientists talk about the ‘food matrix,’ this is a really good read [4] 

This week the posts will explore this complex world of what we eat and what we actually utilise in our bodies for wellbeing. 

[1] https://www.canr.msu.edu/news/are_you_absorbing_the_nutrients_you_eat 

[2] https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/953911/SACN_Nutrition_and_older_adults.pdf 

[3] https://doi.org/10.1093/advances/nmz082 

[4] https://doi.org/10.1002/jsfa.9298