Iron in brief
Iron is a mineral and has several functions in the body. It’s most widely known to facilitate oxygen transport, play a role in making DNA, and take part in the production of energy in our cells. Signs and symptoms of iron deficiency include fatigue, paleness of the skin, brittle nails, cracks in the sides of the mouth, and frequent infections. Ongoing iron deficiency may lead to iron-deficiency anemia.
Heme: This form of iron is from animal-based sources such as meat, poultry and fish. It has high absorption rates.
Non-heme: This form of iron is from plant-based sources, highlighted below. It has lower absorption rates compared to heme-sources.
Because of the lower absorption of the non-heme sources of iron, it's recommended that those of us following a plant-based lifestyle consume 1.8 times the recommended amount for those who consume heme iron sources. The values in brackets below reflect the adjusted recommendations for those of us following a plant-based lifestyle:
- Men 19+ years: 8 mg daily (15 mg for vegetarians/vegans)
- Women 19-50 years: 18 mg daily (32 mg for vegetarians/vegans)
- Women 51+ years: 8 mg daily (15 mg for vegetarians/vegans)
- Pregnant women 19-50 years: 27 mg daily (49 mg for vegetarians/vegans)
- Breastfeeding women 19-50 years: 9 mg daily (16 mg for vegetarians/vegans)
It's also advised that iron intakes stay below 45mg/day from food and supplement sources combined.
Note that pregnant women, athletes, and those with medical conditions leading to chronic blood loss are likely to have higher iron requirements and differences in iron absorption. It may be beneficial to speak with a doctor or dietitian regarding iron intake and requirements.
Although consuming 1.8 times more iron sounds unachievable, it's absolutely feasible to obtain enough iron to meet our needs when eating well-balanced and nourishing plant-based foods. This will be touched on in more detail below.
It's absolutely possible to get enough iron when eating well-balanced and nourishing plant-based foods.
Plant-based iron sources
Here are just a few plant-based iron food sources that could contribute to our daily iron needs.
4-6 mg iron per serving
- Oatmeal, cooked (¾ cup)
- Bulgar, cooked (1 cup)
- Lentils, cooked (¾ cup)
- Pumpkin seeds (⅛ cup)
2-4 mg iron per serving
- Blackstrap molasses (1 tbsp)
- Tempeh/fermented soy product (¾ cup)
- Tofu, cooked (¾ cup)
- Beans (most varieties), cooked (¾ cup)
- Tomato puree (½ cup)
- Spinach, cooked (½ cup)
- Edamame, cooked (½ cup)
Many plant-based foods that contain iron also have what we call phytates. These bind to non-heme iron and interfere with absorption. To minimize this, we can soak our grains, nuts, seeds and legumes to reduce the phytate content in them. This in turn increases our iron absorption. Learn more about the benefits of soaking in our soaking article.
Another culprit from lower iron absorption is tannins. These are are compounds commonly found in black tea, espresso, coffee, and red wine. When these beverages are consumed with meals, they can decrease non-heme iron absorption. We recommend consuming these beverages about 30 minutes before or after a meal to avoid the tannins from interfering with iron absorption.
As there are strategies to reduce interference of iron absorption, there are also strategies we can use to enhance our iron absorption. Vitamin C is known to increase the body's ability to absorb iron. Due to this, it's often recommended to enjoy iron-rich foods with vitamin C-rich foods, such as citrus fruits, kiwis, strawberries, sweet bell peppers, potatoes, and broccoli. Having berries with oatmeal, spinach with oranges in smoothies, or tofu with bell peppers in a stir fry are several examples.
Vegetarians & vegans
For vegans and non-vegans alike, it's important to ensure that we're consuming iron-rich foods with each meal. The recommendations being 1.8 times more for vegetarians and vegans may sound unachievable, but this recommendation takes into account the iron-inhibiting foods that may interfere with absorption.
It's also important to keep in mind that those of us following a plant-based lifestyle generally have lower iron stored in the body. When our iron stores are low, we're able to absorb more iron from foods. Low iron stores aren't much to be concerned about, as long as we're consistently consuming a variety of iron-rich plant-based food sources, in addition to combining these foods with vitamin C-rich foods and decreasing iron inhibitors. Low serum iron levels are also not much of a concern, as studies have also shown that having more iron stored in the body may not provide any additional benefit.
A note on anemia
Anemia is a condition where the number of blood cells in our body is lower than normal. There are various causes of anemia. Iron deficiency anemia is the low number of blood cells caused by iron deficiency.
Groups that are at high risk of developing iron-deficiency anemia are women of reproductive age, pregnant women, athletes, and those who of us who have medical conditions leading to chronic blood loss. As these groups usually have increased iron needs, it's often recommended to speak with a doctor or dietitian to discuss strategies in preventing iron-deficiency anemia.
It’s also important to note that while iron deficiency is the most significant and common cause of anemia, it is not the only cause of anemia. People may become anemic as a result of other long-standing health issues regardless of iron intake through the diet.
For those who are diagnosed with iron-deficiency anemia through a blood test, iron supplements are often recommended to resolve the issue. Once an adequate level has been reached, though, long-term maintenance is best achieved with the consistent consumption of iron-rich foods combined with foods rich in vitamin C, as opposed to ongoing supplementation. This is to avoid the risk of consuming excess iron, which may have negative health outcomes. As always, whenever possible, food sources are recommended before supplements.
Important notes regarding supplementation
General supplementation: if it’s determined supplementation is needed, please see a medical doctor for a prescribed dosage and duration. The amount needed is always case-specific and taking incorrect doses can be harmful.
Multivitamins: these can also contain iron. We can be observant of this amount when calculating our total intake.
Fortification: in certain countries, commonly eaten foods are fortified with iron. For example, in Canada, products such as flour, pasta and breakfast cereals have iron added. It's worth checking if foods in our country are fortified and taking this into account when assessing our intake.
Doctor's orders: we only recommend taking a supplement if it's recommended by a family physician or dietitian, as there are some negative consequences to taking too much. See a family doctor for support if needed.
As briefly mentioned above, consuming too much iron can have several negative health outcomes:
- Constipation or diarrhea
- Vomiting, nausea
- Increased risk of disease, such as heart disease
- Liver dysfunction
- Increased production of free radicals and oxidative damage
It's unlikely to overload on iron if we're getting iron from plant-based sources because the nonheme iron absorption is controlled. Taking iron supplements, on the other hand, increases the risk of overloading on iron, so we generally recommend consistent consumption of iron-rich foods for long-term maintenance of iron levels.
- There are 2 types of iron. Non-heme iron is the form that's derived from plant-based sources. Heme iron is the form that's derived from animal sources.
- The recommendation for iron intake is 1.8 times higher for those following a plant-based lifestyle. This takes into account the low absorption rates of non-heme iron.
- Tannins and polyphenols in foods can interfere with iron absorption. Soaking grains, nuts and seeds prior to cooking in addition to consuming coffee and tea apart from meals are ways to improve our iron absorption.
- Iron-rich foods are often recommended to be consumed with vitamin C-rich foods. This is to increase our body's ability to absorb iron from foods.
- The iron recommendation of 1.8 times higher for those following a plant-based lifestyle is achievable, as long as efforts are made to reduce absorption interference, and iron-rich foods are consumed with vitamin C-rich foods.
- Inadequate iron intake can increase the risk of iron deficiency anemia, which is the low number of red blood cells caused by insufficient iron levels in the body.
- Iron supplementation is often only recommended to resolve iron deficiency short-term. Long-term maintenance of iron levels in the body is best achieved with consistent consumption of iron-rich foods with vitamin C-rich foods.