The function of an MFP factor is to enhance iron absorption, according to Nutrition 411. MFP factors are found in meat, fish and poultry. Other factors that can enhance iron absorption include vitamin C, citric and lactic acid, hydrochloric acid, and sugar.
Vitamin C can be found in oranges and other citrus fruits. Hydrochloric acid is produced by the stomach. Foods that inhibit iron absorption include fibers in fruits and vegetables, phytates in spinach, calcium and phosphorus in milk and dairy products, and tannic acid and polyphenols found in tea and coffee. Foods that are rich in iron are fish and shellfish, lean meat, organ meat like liver, beans and legumes, tofu and other soy products, and vegetables such as spinach, broccoli and asparagus.