Iron, an important mineral, is necessary for normal human functioning and development. Your body needs iron to transport oxygen and for cell growth. Certain foods provide the iron your body needs. An iron deficiency can cause fatigue, low immunity and poor work performance. If you have low iron levels, talk to your doctor about ways to increase iron. You should also avoid certain foods that may inhibit your iron absorption.
Although eggs are an excellent source of protein, they contain a substance that can hinder the body’s ability to absorb iron. Phosvitin, a specific protein containing phosphorus, affects iron-binding capacity. Eggs, especially the yolk, have phosvitin. The Iron Disorders Institute reports that eating one boiled egg with a meal can reduce the absorption of iron by as much as 28 percent. People with low iron should consume eggs separately from any foods that are high in iron so that their bodies can properly absorb the necessary nutrient.
Casein, a milk protein, can affect iron absorption. Calcium, an essential mineral, is the only known substance that affects the absorption of both types of iron, heme and non-heme. According to the Massachusetts Institute of Technology, calcium has a greater effect on non-heme iron absorption. Although small amounts of calcium do not affect iron intake, it is still a good idea to take any calcium supplements or consume dairy products and other calcium-containing foods separately from foods high in iron.
Polyphenols are major inhibitors of iron absorption. Many different foods have polyphenols or phenolic compounds, including cocoa, coffee, apples, peppermint, spices, walnuts, raspberries, red wine, grape juice, blackberries and blueberries. Researchers examined the effects of the polyphenols grape seed extract and epigallocatechin-3-gallate from green tea on heme and non-heme iron in a 2010 study published in the "Journal of Nutrition." Polyphenols bind to iron in the intestinal cells, making a non-transportable complex. The iron-polyphenols complex cannot enter the bloodstream and is excreted in feces.
Oxalates and Phytate
Oxalates, derived from oxalic acid, are present in different foods, such as kale, spinach, beets, nuts, rhubarb, strawberries and some herbs. Oxalates impair the absorption of non-heme iron, a type of iron found in plant-based foods. Although spinach is a good source of non-heme iron, the human body does not absorb the majority of it because spinach also has oxalates. Phytate, a compound found in legumes, rice and grains, can decrease iron absorption by 50 percent, according to the Massachusetts Institute of Technology.
- Office of Dietary Supplements: Iron
- Iron Disorders Institute: Diet
- Nutrition MD: Iron Deficiency Anemia: Nutritional Considerations
- Journal of Nutrition: Bioactive Dietary Polyphenols Decrease Heme Iron Absorption by Decreasing Basolateral Iron Release in Human Intestinal Caco-2 Cells
- Massachusetts Institute of Technology: Best Foods for Specific Minerals
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