Many individuals are concerned that they will not get enough iron when they start to eat a plant based diet. The truth in the matter is that iron is prevalent in a wide variety of plant foods. In fact, an individual who properly consumes a plant-based diet gets just as much iron as individuals who do not eat plant-based!
Iron is a trace element which is needed by the body for the formation of blood. More than half of the iron found in our blood is in the form of haemoglobin (the red pigment in blood). Haemoglobin helps transport oxygen from the lungs to our tissues, and plays a role in activating enzymatic reactions and is necessary for collagen synthesis. It is also needed for regulation of cell growth and is required for good cognition and behaviour.
What about heme and non-heme iron?
I find a lot of people are confused about the difference between heme and non-heme iron. Heme iron is the iron found in animal proteins (meat, fish, poultry, eggs, dairy), and is more readily absorbed by the body than non-heme iron (an iron form found in plant foods). It is also important to recognize that the human body has no mechanism to rid itself of excess iron, and thus our bodies evolved to tightly regulate the absorption of iron (1).
When our iron stores are low, iron absorption is boosted to the intestines, and when our iron stores are high, iron absorption is blocked in the intestines. This mechanism only works with non-heme iron! When we consume animal products and are receiving heme-iron as our main iron source, our bodies can no longer regulate this iron intake (2). When we consume too much heme-iron (remember, heme-iron is from animal proteins), our intestines cannot regulate the iron influx, and thus, it passes right through the intestinal barrier, leading to a body that is technically considered “Iron Toxic.”
Iron toxicity leads to decreased absorption and utilization of vitamin E, diabetes, gut disturbances, hair loss, increased free radical production (iron is a pro-oxidant (3), which leads to oxidative stress and DNA damage, which can result in cancer, inflammation and worsened arthritis symptoms), liver disease and heart disease.
Non-heme iron and vitamin C:
The heme-iron in meat, as described above, is very readily absorbed into the bloodstream. Non-heme iron requires being released from its food components by the hydrochloric acid and digestive enzyme pepsin in the stomach. Non-heme iron must also be shuttled from the digestive tract into the bloodstream by a protein called transferrin.
Tannins found in coffee and green, black and some herbal teas can inhibit the absorption of this plant iron, whereas vitamin C is a strong enhancer of plant iron, and can overcome inhibitors in plant foods (inhibitors like tannins in tea and phytates found in legumes and grains). You should avoid the foods that inhibit iron absorption (coffee, cocoa, black, green and herbal teas), and focus on foods that promote iron absorption (high vitamin C foods) when consuming a plant-based meal.
Vitamin C is found in most fruits, with the highest being in citrus fruits. It is also found in green leafy vegetables like broccoli, kale, collards, swiss chard, and brussels sprouts as well as cauliflower and bell peppers (all colours).
Low iron stores are not necessarily unhealthy!
Low iron stores are associated with higher glucose tolerance and might help prevent diabetes (4). High iron stores have also been linked to cancer and heart disease (5).
How much Iron do you need?
Women need around 8-18mg of iron (depending on menstrual cycle – if cycling through menses, women should consume on the higher end of the spectrum), and men need around 8-11mg of iron, daily. Pregnant women should consume up to 30mg of iron daily.
Plant-based foods high in non-heme iron:
Here is a short list (including but definitely not limited to) of plant foods rich in iron! Be sure to combine these foods with a vitamin C containing plant food of your choice to help increase absorption!
1. Pumpkin seeds: 2 tbsp. = 8.6 mg
2. Spinach: 1 cup = 6.4 mg
3. Pine nuts: 2 tbsp. = 5.2 mg
4. Hemp seeds: 4.7 mg per 100 grams
5. Swiss chard: 1 cup = 4 mg
6. Figs: 10 figs = 4 mg
7. Sunflower seeds: 2 tbsp. = 3.8 mg
8. Parsley: 1 cup = 3.7 mg
9. Tomatoes: 1 cup = 3.4 mg
10. Coconut: 3.4 mg per 100 grams
11. Potatoes: 1 large = 3.2 mg
12. Beets & Beet greens: 1 cup = 2.7 mg
13. Sweet peas: 1 cup = 2.5 mg
14. Chia seeds: 1 oz. = 2.2 mg
15. Almonds: 2 tbsp. = 2 mg
16. Sprouts: 1 cup = 2 mg
17. Apricots: 10 apricots = 2 mg
18. Bok choy: 1 cup = 1.8 mg
19. Collards: 1 cup = 1.5 mg
20. Kale: 1 cup = 1.2 mg
21. Grapes: 1 cup = 1.2 mg
22. Broccoli: 1 cup = 1.1 mg
23. Avocado: 1 avocado = 1 mg
24. Brussels sprouts: 1 cup = 0.9 mg
25. Bananas: 1 banana = 0.5 mg
(1) Steele, T., Frazer, D., & Anderson, G. (2005). Systemic regulation of intestinal iron absorption. IUBMB Life, 57, 499-503.
(2) West, A., & Oates, P. (2008). Mechanisms of heme iron absorption: Current questions and controversies. World Journal of Gastroenterology, 14, 4101-4110.
(3) Kabat, G. & Rohan, T. (2007). Does excess iron play a role in breast carcinogenesis? An unresolved hypothesis. Cancer Causes Control, 18, 1047-1053.
(4) Hua NW, Stoohs RA, Facchini FS. Low iron status and enhanced insulin sensitivity in lacto-ovo vegetarians. Br J Nutr. 2001 Oct;86(4):515-9.
(5) Wood RJ. The iron-heart disease connection: is it dead or just hiding? Ageing Res Rev. 2004 Jul;3(3):355-67.
More information on plant-based iron: