It’s estimated that up to 5% of the Australian population has iron deficiency or anaemia. If you’re not getting enough iron, it makes it difficult for your blood cells to deliver the oxygen your tissues and organs need – so it’s not a nutrient you want to lack.
Symptoms that you are lacking in iron include:
- Feeling tired or not having enough energy
- Having an upset stomach
- Finding it difficult to concentrate or remember things
- Having trouble keeping your body temperature regulated
- And easily catching infections or getting sick.
While the body can store iron, it cannot make it, so you need to get it from the food you eat. Haem-iron is the best form of iron, as up to 40% of it is readily absorbed by your body. In terms of its bioavailability, non-haem iron is absorbed much less efficiently than haem-iron.
Sources of Haem-iron
- Red meats
- Offal such as liver
Sources of Non-Haem Iron
- Green vegetables such as spinach, broccoli and silverbeet
- Nut and seeds
- Dried fruit
Foods That Inhibit Iron Absorption
Some dietary factors bind with non-haem iron, inhibiting absorption. These factors include the following:
Polyphenol Rich Foods – can inhibit iron absorption in the body. Polyphenols are found in various amounts in plant foods and beverages, including vegetables, fruits, some cereals and legumes, tea, coffee and wine. Coffee and tea both have a high content of polyphenols. One study determined that drinking a cup of black tea with a meal reduced iron absorption by 60-70%, regardless whether the tea was weak, normal or strong. However, when participants drank tea between meals, the reduction in absorption was only about 20%. To counteract the negative effect of polyphenols, be sure to leave a couple of hours between drinking your tea or coffee and eating a meal.
Phytate Rich Foods – such as walnuts, almonds, sesame, dried beans, lentils, peas, cereals and whole grains can reduce the amount of iron your body absorbs from iron-rich foods. Even low levels of phytates have a strong inhibitory affect on your body’s ability to absorb iron from foods by approximately 50-65%. This is why it’s so important to prepare your nuts, seeds, beans and legumes properly (ie by soaking, activating or sprouting).
Oxalate Rich foods – impair the absorption of non-heme iron. Oxalates are compounds derived from oxalic acid and found in foods such as spinach, kale, beets, nuts, chocolate, tea, wheat bran, rhubarb and strawberries and herbs such as oregano, basil, and parsley. The presence of oxalates in spinach explains why the iron in spinach is not absorbed. In fact, it is reported that the iron from spinach that does get absorbed is probably from the minute particles of sand or dirt clinging to the plant rather than the iron contained in the plant!
How to Improve Iron Absorption From Food
Meat, fish and poultry contain not only the well-absorbed haem iron, but also a peptide called the ‘MFP factor’ that actually promotes the absorption of non-haem iron from other foods that are eaten at the same time. Vitamin C also enhances non-haem iron absorption. It captures non-haem iron and stores it in a form that’s more easily absorbed by your body. Vitamin C also helps to synthesise red blood cells and iron is the main part of haemoglobin, which is found in the red blood cells. Foods high in vitamin C include citrus fruits, dark green leafy vegetables, capsicum, melons, strawberries and Camu Camu. In one study, taking 100 mg of vitamin C with a meal increased iron absorption by 67%.
Individual Variations That may Affect Iron Absorption
Iron absorption will also depend on an individual’s health, stage of life and iron status. Absorption can be as low as 2% in a person with severe gut issues and as high as 35% in a rapidly growing child. The body adapts to storing more iron when iron levels fall too low, or when you are pregnant, for example. Similarly, the body adapts to absorb less iron when iron stores are sufficient. As you might expect, vegetarian and vegan diets don’t benefit from the easy-to-absorb haem iron or the ‘MFP factor’, which enhances absorption. If you are vegetarian or vegan, I highly recommend speaking to your chosen health care practitioner to get individualised advice about dietary iron, and to find out whether or not you need specific supplementation.
- Iron is a vital mineral that’s essential for the function of your body. Two types of it are found in food — haem and non-haem iron.
- Meat, fish and poultry contain the haem-iron form, which is more easily absorbed by your body.
- Non-haem iron is mainly found in plant foods, but this form is harder for your body to absorb.
- You can improve your body’s absorption of iron by eating foods containing the MFP factor and vitamin C, during your meals – for example, by squeezing lemon juice over your seafood or chicken and leafy greens.
- Foods containing phytates, polyphenols and oxalates can hinder iron absorption, so be sure to prepare them properly.
- Whitney.E et al; Understanding Nutrition. 1st edition. 2011. Pg 446-450.