Working with purified iron ferritin extracted from marrowfat peas, the research team found that if ferritin is protected from the stomach acid pH, it is absorbed by gut cells in a process called endocytosis.
“Technology already exists that would enable us to produce coated capsules that could effectively transport the ferritin through the stomach and into the intestine where it can be absorbed,” said Susan Fairweather-Tait, professor of human nutrition at UEA’s Norwich Medical School.
Forms of ferrous iron are widely used as oral supplements due to their relatively high bioavailability.
However, they are also associated with side effects such as gastrointestinal intolerance, which can result in noncompliance.
Oxidative stress generated by ferrous iron salts has been proposed as one of the main reasons for gastrointestinal intolerance – a side effect that native pea ferritin might avoid as it produces less reactive oxygen species (ROS).
Starting with the purified iron, the team began testing it in cells designed to mimic the human gut.
These cells—caco-2 cells—are a well-characterised intestinal cell line often used to study nutrient absorption and transport.
The cells were mixed with the ferritin protein previously exposed to acid conditions – similar to those found in the stomach – and then again under pH conditions closer to neutral –similar to the body’s small intestine.
The results, published in the Journal of Nutrition, showed that when the ferritin was exposed to acid conditions, it broke down and the iron was released. It then behaved like other plant-derived iron with only small amounts being absorbed.
If the ferritin is introduced to the cells under neutral pH conditions, however, it remains intact and can be absorbed by cells in the gut via endocytosis.
Further results found the native pea ferritin produced 60% less ROS production in comparison to FeSO4.
Ferritin ‘a very effective dietary supplement’
“These results show that the iron from ferritin could be absorbed by the small intestine by an alternative mechanism to plant-derived iron, if the stomach acid pH is avoided,” explained Dr Ildefonso Rodriguez Ramiro, from UEA’s Norwich Medical School.
“This means that, in the right conditions, the ferritin could be a very effective dietary supplement.”
The research echoed these views commenting that the relatively high bioavailability and low cost of production counted for pea ferritin’s promise as a food supplement.
“There is recent evidence that interactions of recombinant soybean ferritin with some phenolic acids (e.g., gallic acid and its derivatives) inhibit its degradation during simulated digestion,” the study concluded.
“Therefore, further research is warranted to explore potential alternatives to deliver in vivo this protein in its native conformation in the intestinal lumen as a novel food supplement.”
Source: The Journal of Nutrition
Published online ahead of print: doi.org/10.1093/jn/nxy096
“Pea Ferritin Stability under Gastric pH Conditions Determines the Mechanism of Iron Uptake in Caco-2 Cells.”
Authors: Antonio Perfecto, Ildefonso Rodriguez-Ramiro, Jorge Rodriguez-Celma, Paul Sharp Janneke Balk, Susan Fairweather-Tait.