Iron is one of the top most common nutrient deficiencies in the world, particularly affecting children and women of reproductive age. Iron deficiency is said to affect up to 25% of the world's population (1).
But why is it so common?
Iron status can be impacted by many things including poor nutrition, impaired digestion, rapid growth, pregnancy, menstruation, low intake of bio-available iron, pathogenic infections, and the use of medications such as antibiotics.
Iron is a mineral that can be tricky for the digestive system to absorb and dietary choices can also influence iron status.
Foods that decrease iron absorption
Oxalates
Oxalates are molecules found in certain foods that can affect the assimilation of nutrients such as calcium and iron by binding to minerals in the gut and preventing optimal absorption (2).
Sources of oxalates include rhubarb, spinach, chocolate, beetroot greens, swiss chard, quinoa, almonds, cashews, peanuts and leeks.
Many food sources of oxalates are healthy and it's not about completely avoiding them. Individuals with compromised digestion may have more difficulty with oxalate foods therefore gut healing will be an essential part of optimizing nutrient absorption including iron.
Cooking foods that are high in oxalates as well as pairing them with calcium rich foods can help to reduce the amount of oxalates absorbed (3).
Caffeine
Coffee and tea have both been shown to potentially reduce iron absorption via various mechanisms (4).
Polyphenols, a type of antioxidant, both found in coffee and tea are associated with decreased iron levels (5)(6).
Now, stay with us here! You can still keep your hot cup of comfort, you might just want to change the timing.
Timing tea and coffee consumption appropriately away from meals has been shown to make a difference in iron status. Drinking tea or coffee with meals decreases iron absorption more significantly than if you were to drink the same beverage between meals (7).
If you are struggling with low iron and want to hold onto your morning cuppa it might be worthwhile keeping your consumption between meals!
Phytic Acid
Phytic acid, also known as phytate, is a compound found in foods such as beans, legumes, nuts, and grains and it has the ability to inhibit the absorption of minerals such as iron (8).
Now, since we know that these foods are actually healthy and should be included as part of a balanced diet we don't want to completely eliminate them if we can.
It is important to note that foods high in phytic acid can impair iron absorption when consumed during the same meal but without affecting your overall day's consumption. This means food timing can make a difference by consuming iron rich foods away from foods high in phytate as well as preparing foods in a way that decreases phytic acid levels.
Cooking thoroughly as well as soaking, sprouting and fermenting can help to reduce the phytic acid content of your food. Consuming vitamin C and heme iron foods can also help to counteract the effects of phytic acid.
Calcium
Calcium is another essential mineral for health though it has been shown to compete with iron for absorption and affect iron status (9)(10).
Again this has been shown to affect iron status during a same meal but not the overall day. This means it may be wise to separate iron rich foods and calcium rich foods to obtain the most nutrients possible. And this goes for supplements as well.
Foods rich in iron
As the body cannot produce iron naturally we must obtain it regularly from our diet, especially if we are more prone to deficiency.
There are two sources of iron found in food: heme iron and non heme iron. Heme iron is recognized as being more readily absorbable than non-heme iron (11).
Heme iron is only found in animal foods such as red meat, pork, egg yolks, chicken, turkey, organ meats, shellfish, and fish. While non-heme iron is found in plant foods such as pumpkin seeds, oatmeal, dried peaches, asparagus, dark leafy greens, beans, quinoa, tofu, dark chocolate, chickpeas and lentils.
Foods that increase iron absorption
There are many foods that can actually increase iron absorption and that should be included alongside iron rich foods.
Combining animal sources of iron, heme iron, with plant based sources of iron, non-heme iron, can also make a difference in improving iron levels (12).
If you are vegan or vegetarian including plenty of vitamin C rich foods is essential it can make non-heme iron more absorbable and facilitate absorption (13)(14). However even if you do eat animal products, including foods high in vitamin C is also a good idea.
What are these foods? Citrus fruits, berries, leafy green vegetables, tomatoes, bell peppers, papaya, broccoli and brussels sprouts are examples of vitamin C rich fruits and vegetables to include in your diet.
Cooking, storage and processing of these foods degrades the vitamin C found and can thus lower its iron enhancing effects so we suggest eating these foods closest to their natural form as possible (15).
About the Author
Laurence Annez