Food iron is absorbed by the intestinal mucosa from two separate pools of heme and nonheme iron. Haem iron is found in animal foods such as red meat, chicken and fish. And non-haem iron is abundant in plant-based foods, including whole grains, beans, fruits and vegetables. Heme iron is absorbed with better efficiency from the intestine than nonheme iron.
The presence of ascorbic acid in the diet increases the absorption of nonheme iron. The dominant form of iron in foods is Fe3+, which is much less bioavailable than Fe2+. One of ascorbic acid's main attributes is its ability to reduce ferric to ferrous iron.
Ascorbic acid aids iron absorption by creating a chelate with ferric iron Fe3+ at a stomach acid pH that stays soluble at the alkaline pH of the duodenum, the first section of the small intestine.
In addition, ascorbate, ascorbic acid salt, donates an electron, acting as a free radical scavenger and reducing iron oxidation states to Fe2+, which is the only bioavailable form for enterocyte cells. Fe2+ is the only iron that can be absorbed through iron transporters of intestinal enterocyte cells.
In vivo observations showing an enhancement of iron absorption in the presence of ascorbic acid have been attributed to ascorbic acid's chelating and reducing properties. Reduction was previously thought to be an essential function of ascorbic acid prior to Fe2+ uptake by the divalent metal transporter (DMTl).
However, Fe3+ reduction has now been shown to be due to the action of ferrireductase Dcytb (duodenal cytochrome b) located at the brush border membrane of duodenal enterocytes. This suggests that ascorbic acid's main role is to promote iron solubility.
Four ounces (1/2 cup) of orange juice is enough to increase iron absorption. Other sources of vitamin C include citrus fruit, fresh bell peppers, strawberries, cantaloupe, and fresh broccoli.
Inadequate iron absorption leads to iron deficiency anemia. Iron deficiency is the most common nutritional deficiency worldwide.
Vitamin C enhance iron absorption
