‘Anti-Nutrient’ compounds. What is the impact of Tannins?
Nutrients in some plants are not always easily digested as they contain antinutrients.
Antinutritional Factors are plant compounds that reduce the absorption of nutrients from the digestive system.
They are responsible for deleterious effects related to the absorption of nutrients and micronutrients. However, some anti-nutrients may exert beneficial health effects at low concentrations.
Plant-based foods, beyond micro- and macronutrients, contain significant concentrations of bioactive plant compounds.
Despite the need to increase plant-food consumption, there have been some concerns raised about which of the plant-based foods and to which quantity they are beneficial because of the various ‘anti-nutrient’ compounds they contain.
For example, phytic acid, lectins, tannins, saponins, amylase inhibitors, and protease inhibitors have been shown to reduce the availability of nutrients. However, when used at low levels they have also been shown to reduce chronic diseases such as: reducing the blood glucose and insulin responses to starchy foods and/or the plasma cholesterol and triglyceride.
Overall, longstanding evidence and studies suggest that consuming a diet rich in plant-based foods plays a significant role in the prevention and reduction of chronic diseases, such as cardiovascular disease, cancer, stroke, dementia, diabetes, cataracts, and others.
What are tannins?
Tannins (commonly referred to as tannic acid) are water-soluble polyphenols that are present in many plant foods.
They’re present in the wood, bark, leaves, and fruit of plants as various as oak, rhubarb, tea, walnut, cranberry, cacao, and grapes in order to protect those vulnerable parts of the plants. They have weak acidity (pKa around 6).
They play a crucial role in plant defense against pathogens, herbivores, and changing environmental conditions. In the food industry and in medicine, tannins are important because of their proven positive effect on human health and disease treatment.
Which foods contain the most tannins?
Coffee, tea, beer & wine. Tannins are responsible for that astringent, mouth-coating feeling you get from biting into an unripe pear or plum.Mature wines are often described as having “resolved” tannins, which are smooth, soft, and no longer astringent. Therefore, mature wines are easier to drink as the effect of the tannins has been reduced.
f.e. an apple that is harder to eat has been cut earlier than it should have and contains a lot of tannins compared to a ripe apple.
Which foods contain the least tannins?
Berries, nuts, seeds, fruit juices.
Studies show that high consumption of tannins is considered as anti-nutrient since they can interfere with 1) mineral absorption 2) digestive enzymes 3) cause protein aggregation. Protein aggregation is when amino acids clump together and cannot be digested and utilized in the body. An amino acid is a molecule* that has a carboxylic acid group and an amine group that is each attached to a carbon atom called the α carbon.
*A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds.
They have been reported to be responsible for decreases in feed intake, growth rate, feed efficiency, net metabolizable energy, and protein digestibility in experimental animals.
Also, they reduce iron availability before absorption through the formation of insoluble antinutritional-mineral complexes.
As the majority of enzymes belong to proteins, it is widely believed that tannins decrease enzymatic activity as a result of enzyme complexation. Although studies over the past decades have established tannins as potential inhibitors of enzymatic activity some studies found only a minor decrease in their activity.
Suggestions
- Avoid consuming tannins ( tea, wine, or beer ) during your meals and mineral-rich foods. Rather, consume them one hour before or after any meals.
- Reduce the consumption of grains and legumes and focus on a rich plant-based food diet.
- Cooking food eliminates anti-nutritional factors. For example, Raw egg white, raw milk, and many protein-rich plants (beans, soy, lentils, and grains) contain trypsin inhibitors. But cooking the egg white and using heat, fermentation, or even germination for plants causes the trypsin inhibitors to degrade.
https://efdiatrofin.gr/roditosuperfood/
https://www.winemag.com/2018/09/11/tannins-wine-guide/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7600777/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5641916/#open201700113-bib-0036
TANNINS, Mineral Absorption, & Health + What I Ate Today
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5641916/#open201700113-bib-0036
https://www.healthline.com/nutrition/how-to-reduce-antinutrients
https://www.fondation-louisbonduelle.org/en/2016/10/17/what-is-an-antinutritional-factor/
