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For your information/reference (backed by 90 scientific studies )
Dietary Supplement Fact Sheet: Iron

There are two forms of dietary iron: heme and nonheme. Heme iron is derived from hemoglobin, the protein in red blood cells that delivers oxygen to cells. Heme iron is found in animal foods that originally contained hemoglobin, such as red meats, fish, and poultry. Iron in plant foods such as lentils and beans is arranged in a chemical structure called nonheme iron [9]. This is the form of iron added to iron-enriched and iron-fortified foods. Heme iron is absorbed better than nonheme iron, but most dietary iron is nonheme iron [8]. A variety of heme and nonheme sources of iron are listed in Tables 1 and 2.

Iron absorption is also influenced by the type of dietary iron consumed. Absorption of heme iron from meat proteins is efficient. Absorption of heme iron ranges from 15% to 35%, and is not significantly affected by diet [15]. In contrast, 2% to 20% of nonheme iron in plant foods such as rice, maize, black beans, soybeans and wheat is absorbed [16]. Nonheme iron absorption is significantly influenced by various food components [1,3,11-15].

Meat proteins and vitamin C will improve the absorption of nonheme iron [1,17-18]. Tannins (found in tea), calcium, polyphenols, and phytates (found in legumes and whole grains) can decrease absorption of nonheme iron [1,19-24]. Some proteins found in soybeans also inhibit nonheme iron absorption [1,25]. It is most important to include foods that enhance nonheme iron absorption when daily iron intake is less than recommended, when iron losses are high (which may occur with heavy menstrual losses), when iron requirements are high (as in pregnancy), and when only vegetarian nonheme sources of iron are consumed.

Vitamin A helps mobilize iron from its storage sites, so a deficiency of vitamin A limits the body's ability to use stored iron. This results in an "apparent" iron deficiency because hemoglobin levels are low even though the body can maintain normal amounts of stored iron [39-40]. While uncommon in the U.S., this problem is seen in developing countries where vitamin A deficiency often occurs.

The World Health Organization considers iron deficiency the number one nutritional disorder in the world [33]. As many as 80% of the world's population may be iron deficient, while 30% may have iron deficiency anemia [34].