Iron is an essential nutrient in the diet of herbivores and carnivores alike. The most widely recognized sources of iron are animal sources, especially red meat. You may not realize that optimal amounts of iron can be obtained from a plant-based diet. By incorporating plant based iron sources into a vegetarian or vegan diet, individuals can easily meet their iron requirements without having to defer to supplemental forms or animal based sources.
Iron is essential for human metabolic processes due to the structural role in necessary proteins. Most commonly known is the role of iron in hemoglobin and myoglobin proteins, which are responsible for carrying oxygen in red blood cells throughout our body and to the lungs. For this reason, when an individual is deficient in iron, or anemic, they usually lack energy and feel lethargic due to a lack of oxygen in the tissues of their body. Iron is also incorporated into the structure of enzymes called cytochromes, which eliminate toxins from the body and create units of adenosine triphosphate (ATP) that give cells energy.
Iron exists in heme and non-heme forms. Heme iron and non-heme iron are both present in animal foods whereas only non-heme iron is found in plant foods. In a mixed diet of heme and non-heme iron, iron absorption is approximately 18% whereas in a diet exclusive to plant foods, iron absorption is as low as 10% since non-heme iron is less efficiently absorbed. So how is it possible for vegans to meet their iron requirements if is seems that iron is barely being absorbed into our systems? Simply put, we only need to replace the iron that we lose on a daily basis through blood, skin, and intestinal losses. Women need to absorb around 1.5 mg of iron daily, and men, 0.5 mg. Based on the absorption rate, a female whom adopts a plant based diet would have to eat is 15 mg of iron to meet her requirements, as compared to 8 mg from only heme-sourced iron.
Through various population-based surveys, it was determined that the vegetarian diet is not associated with a higher risk for iron deficiency or poor iron intake. This can possibly be attributed to a plant based diet with high variability of whole foods rich in non-heme iron balanced with a variety of enriched iron sources and plant sources including grains and cereals.
Iron can be found in many staples of a plant-based diet. Iron is abundant in legumes, nuts, tofu, and leafy green vegetables. One serving of boiled spinach has 3.4 mg, and one serving of lentils has 4.1 mg, giving a great opportunity for a well planned plant based diet to meet the optimal daily iron requirement of an individual.
There are a few tips and tricks to maximize absorption by eating or avoiding certain foods when eating plant sources of iron. For example, non-heme iron absorption is increased by vitamin C because it allows iron to remain in its most easily absorbed form. By including foods with vitamin C along an iron containing meal like citrus fruits, strawberries or red peppers, iron absorption can be increased up to six times the regular rate.
There are also foods that can be avoided in regards to iron absorption. These are foods that contain nutrients, which bind to iron and prevent its absorption into the gastrointestinal tract, and therefore the bloodstream. Phytic acid is a storage form of phosphate found in many foods including whole grains, nuts, legumes, and seeds. Although it naturally provides many health benefits, it binds iron to create phytates, which prevents optimal absorption of non-heme iron. A plant-based eater may consider sprouting or fermenting grains to reduce the inhibition of iron absorption from phytic acid. Secondly, oxalates found in spinach are a nutrient that is not absorbed and can decrease the absorption of non-heme iron. However, it is important to note that vitamin C overrides any inhibiting effect that phytic acid or oxalates have on iron absorption.
If you are looking to integrate a wider variety of plant based iron sources into your diet, here are some helpful combinations to ensure the greatest nutritional benefit from the iron in what you are eating:
Stir-fry edamame beans or tofu with red and yellow bell pepper and broccoli… http://www.veganinsanity.com/recipes/tofu-teriyaki-bowl/#.VZmImVVViko
Blend a fruit smoothie with spinach, orange juice and silken tofu
Toss strawberries into a spinach salad and flavour with orange sections, lemon juice, and fresh herbs… http://www.ebfarm.com/recipes/strawberry-and-spinach-salad
Make a summer chickpea salad with corn, tomatoes, fresh herbs and lemon juice… http://www.epicurious.com/recipes/food/views/chickpea-salad-with-lemon-parmesan-and-fresh-herbs-364611
Saunders, A. Craig, W. Baines, S. Posen, J. Iron and Vegetarian Diets. MJA Open 1 Suppl 2 2012; 11-16