From what I understand animal iron and vegetable based iron are different. Heme iron is apparently more bio-available. According to what I have read humans only absorb 5% of the iron that is available in plants foods. Are there methods to absorb more iron from a plant-based diet or should a vegan supplement their diet with heme iron?
No, iron supplementation is not necessary for all vegans.
Furthermore, iron supplementation can be dangerous if it isn't a medical requirement. Any person considering adding iron supplements to their diet should have a conversation with their doctor or a registered dietitian to assess their individual needs and the safety of a particular supplement.
The human body tries hard to maintain a stable level of iron in the blood and liver (homeostasis). When iron storage is depleted we may present with iron deficiency anemia. But if levels get too high, we may present with iron overload.
There is no physiologic regulatory mechanism for excreting iron. Once it has been absorbed into your body, it mostly stays there; only a small amount (1-2 mg/day) is removed through normal processes like menstrural blood loss, gastrointestinal blood loss and skin shedding. For this reason, it is very important that the body regulates how much iron is absorbed.
Most whole foods contain some trace amounts of iron, even the common potato. For example, if you were to eat a diet of nothing but potatoes (2000 kcal/day) that would provide about 40 mg of iron, which is far more than our bodies require. So our digestive system (specifically enterocytes in the duodenum) down-regulates how much iron is absorbed in order to prevent iron overload.
Note: About 1 in 250 people of white/caucasian descent have a family history of hemochromatosis which causes the body to improperly down-regulate absorption of iron, causing more rapid iron buildup and overload. People with hemochromatosis should definitely not be taking iron supplements, which is part of why it's important to discuss this with a doctor.
Yes, it's true that heme/haem iron is absorbed more readily than non-heme iron, but that is not necessarily a good thing for the reasons shown above. If increased iron absorption is desired, the best thing to do is consume foods providing vitamin C (ascorbic acid) along with foods rich in non-heme iron. One effective combination is spinach and lemon juice.
Finally, iron deficiency anemia can be masked by B12 anemia. If iron deficiency is suspected, it is important to also ensure that sufficient B12 is present in the diet. Vitamin B12 supplements are safe, cheap, effective, and required for anybody following a strict vegetarian or vegan diet.
While a person on a mixed (animal/plant) diet, even the one who has really bad eating habits (unregular meals, a lot of junk food), rarely needs to worry how to get enough iron, vegans should counsciosly think to consume enough iron-rich foods. However, iron supplements are needed only in case of proven deficiency.
Plant foods high in iron (USDA.gov):
- Fortified cerelas (1 cup) = 6-18 mg
- Oats, instant (1 cup) = 6 mg
- Amaranth, teff (1 cup) = 5 mg
- Beans, chickpeas, lentils, (1/2 cup) = 2.5-5 mg
- Pumpkin seeds (1 oz) = 4 mg
- Spinach, boiled (1/2 cup) = 3 mg
- Quinoa, rice, spelt, wheat kamut (1 cup) = 3 mg
- Beets, canned (1/2 cup) = 3 mg
- Cornflakes (1 cup) = 2.5 mg
- Tofu (2 oz) = 2.5 mg
- Potatoes, sweet potatoes (1 cup) = 2 mg
- Barley, bulgur (1 cup) = 2 mg
- Figs, dried (2 oz) = 2 mg
- Sunflower seeds (1 oz) = 2 mg
- Cashew nuts (1 oz) = 2 mg
- Bread, white or whole-wheat (2 slices, 50 g) = 2 mg
- Cabbage (Chinese) (1 cup) = 2 mg
- Swiss chard (1/2 cup) = 2 mg
- Strawberries (1 cup) = 1.5 mg
(1 cup = 237 ml of prepared food; 1 oz = 28 g)
The bioavailability of iron from plant foods can be, in general, 50% lower than from animal foods. According to the Office of Dietary Supplements, Table 1, the Recommended Daily Allowance for iron for adult males on a mixed diet is 8 mg/day, and for adult male vegans should be multiplied by 1.8, so ~14 mg/day.
According to Nutrients Review, Vitamin C from fruits/juices, such as lemon, orange or apple juice, guava, pineapple or pawpaw, taken along with food, can increase iron absorption.
Things that can reduce iron absorption: low stomach acid (including taking antacids), tannins (in herbal and real tea, cocoa, coffee, sorghum, chilli), soy protein, maize...