Because iron from plant sources is less easily absorbed than the heme-bound iron of animal sources, vegetarians and vegans should have a somewhat higher total daily iron intake than those who eat meat, fish or poultry. Legumes and dark-green leafy vegetables like broccoli, kale and Asian greens are especially good sources of iron for vegetarians and vegans. However, spinach and Swiss chard contain oxalates which bind iron, making it almost entirely unavailable for absorption. Iron from non-heme sources is more readily absorbed if consumed with foods that contain either heme-bound iron or vitamin C. This is due to a hypothesised "meat factor" which enhances iron absorption.Following are two tables showing the richest foods in heme and non-heme iron. In both tables, food serving sizes may differ from the usual 100g quantity for relevancy reasons. Arbitrarily, the guideline is set at 18 mg, which is the USDA Recommended Dietary Allowance for women aged between 19 and 50. Food recommendations for children
Children at 6 months should start having solid food that contains enough iron, which could be found in both heme and non-heme ironHeme iron:

Red meat (for example, beef, pork, lamb, goat, or venison)
Fatty fish
Poultry (for example, chicken or turkey)
EggsNon-heme iron:

Iron-fortified infant cereals
Tofu
Beans and lentils
Dark green leafy vegetablesIron deficiency can have serious health consequences that diet may not be able to quickly correct; hence, an iron supplement is often necessary if the iron deficiency has become symptomatic. Blood transfusion
Blood transfusion is sometimes used to treat iron deficiency with hemodynamic instability.
Sometimes transfusions are considered for people who have chronic iron deficiency or who will soon go to surgery, but even if such people have low hemoglobin, they should be given oral treatment or intravenous iron. Intravenous iron therapy for non-anaemic, iron-deficient adultsCurrent evidence is limited to base any recommendations that intravenous iron therapy is beneficial for treating non-anaemic, iron-deficient adults. Further research in this area is needed as current body of evidence is very low quality. Cancer research
The presence of Helicobacter pylori in the stomach can cause inflammation and can lower the threshold for the development of gastric cancer. In the setting of iron deficiency, H. pylori causes more severe inflammation and the development of premalignant lesions. This inflammatory effect appears to be mediated, in part, through altered bile acid production including an increase in deoxycholic acid, a secondary bile acid implicated in colon cancer and other gastrointestinal cancers. See also
Bahima disease
CO2 fertilization effect

Notes
References
Further reading
. Zeglam A, Abugrara A, Kabuka M. Autosomal-recessive iron deficiency anemia, dystonia and hypermanganesemia caused by new variant mutation of the manganese transporter gene SLC39A14. Acta Neurol Belg. 2019 Sep;119(3):379-384. doi: 10.1007/s13760-018-1024-7. Epub 2018 Sep 19. PMID 30232769. External links

"Recommendations to Prevent and Control Iron Deficiency in the United States". U.S. Centers for Disease Control and Prevention. "Advice for Improving your Iron Intake" (PDF). University of South Hampton, NHS Foundation Trust. Archived from the original (PDF) on 29 November 2015.