Iron – what functions does it have in the body?
It is the main component of hemoglobin, a type of protein in red blood cells that carries oxygen from the lungs to all parts of the body. Without sufficient amounts of iron, not enough red blood cells will be produced to transport oxygen, leaving us tired and weak [1].
Iron is also part of myoglobin, a protein that carries and stores oxygen in muscle tissues. It is also important for healthy brain development in children and for the proper production and function of various cells and hormones.
In people involved in professional endurance sports (for example, running) or who train very frequently and intensively, iron deficiency is quite common. It most often affects women [2]. Physical exertion promotes iron loss, so it’s a good idea to do blood tests that include this element at least once a year. In addition, the reactions that occur during training result in lower iron absorption as compared to physically inactive people. An athlete’s body, on the other hand, needs a little more of it, because iron is involved in the process of muscle recovery and reconstruction. All the more reason to keep it under control!
What are the symptoms of iron deficiency?
The most common ones include:
- feeling tired and weak,
- dizziness,
- problems with concentration,
- sensitivity to cold,
- shortness of breath,
- rapid heartbeat,
- paleness,
- hair loss and brittle nails.
Pregnant and menstruating women, children (due to rapid growth), seniors, vegetarians and vegans, regular blood donors, people with cancer, gastrointestinal disorders, heart failure and endurance athletes are mainly at risk of iron deficiency [4].
If iron deficiencies persist for several months, anaemia can ensue. Complications of anaemia include, for example, neurological problems.
What products is iron found in?
This element comes in two forms:
– heme – is found only in animal products, i.e. red meat, poultry and fish; it has very good absorption rate (15-35%) [3].
Rich sources of heme iron include, for example:
- oysters and clams,
- beef or poultry liver,
- giblets,
- tinned sardines or tuna,
- beef,
- chicken.
The second type of iron:
– non-heme – is mainly found in plant-based products: cereals, legumes, vegetables and fruit. Its absorption rate is much lower (2%-20%). Interestingly, however, as scientific studies show, our bodies mostly draw from this source, because we eat far more plant-based products than animal ones.
Rich sources of non-heme iron include, for example:
- oat flakes,
- beans,
- dark chocolate (at least 45% of cocoa mass),
- lentils,
- spinach,
- potato with peel,
- nuts and seeds,
- chickpeas,
- wholegrain products.
What supports better absorption of iron?
First of all, the presence of vitamin C and magnesium in the form of citrate. So, it is best to supplement iron in combination with these components or follow a diet rich in vitamins and minerals. This is especially recommended for non-meat eaters, who take in mostly non-heme iron in their food.
Note! Supplementation with vitamin D and B12 has been proven to be helpful for very physically active people, preventing iron loss due to training [5].
What hinders the absorption of iron?
The so-called phytates, or phytic acid salts, which can be found in some legumes, cereals and nuts, are mainly responsible for this process. A second component that inhibits iron absorption may be polyphenols, which are very abundant especially in green and black tea. Importantly, both polyphenols and phytates are beneficial for health and have positive effects on the human body. As for hindering the absorption of iron – this will mainly concern people who need to supplement deficiencies. In such a situation, it’s a good idea to increase the amount of vitamin C (it neutralises phytates) and magnesium in your diet, and try to drink black and green tea about two hours after an iron-rich meal.
Read more about polyphenols in the article about the properties of tea!
How much iron should we absorb?
The recommended intake for adults aged 19-50 is:
- 8 mg per day for men,
- 18 mg for women before 51 (menstruating),
- 27 mg for pregnant women [8].
The recommended intake for adolescents aged 14-18 is:
- 11 mg for boys,
- 15 mg for girls.
People aged 51+ and seniors should consume 8 mg of iron per day. The tolerable upper intake level for iron is 45 mg per day for all men and women aged 14+. For younger age groups – 40 mg [10].
Should sports people supplement iron on their own?
Definitely not. Excess of this element can be toxic to the body. Vitamin D overdose can have similar effects. Symptoms usually include bowel problems, upset stomach, nausea and abdominal pain.
As we mentioned earlier, first you need to test your blood iron levels, and then determine with your doctor the dose of the supplement. When a person is found to be iron deficient, blood tests should be repeated every 6-8 weeks and the results should be consulted with a specialist on an ongoing basis [6].
Researchers point out that maintaining normal iron levels in athletes is supported by a diet containing adequate amounts of carbohydrates [9].
Can sourdough and beet juice prevent anaemia?
It is widely believed that sourdough from beets is excellent for replenishing iron deficiencies and preventing anaemia at the same time. Unfortunately, research does not confirm this:
“If we assume that absorption of iron from beets and beet juice does not exceed 5%, and the iron norm for a woman of reproductive age is 18 mg, to cover the body’s needs for this component (iron), we would have to eat 21 kilograms of beets every day or drink 26 litres of beet juice, which is impossible” [7].
The conclusion is that the daily diet should be very diverse and rich in a variety of fruit, vegetables and legumes. With a single ingredient, it will be difficult to fully make up for the deficiency.
Read also: “Beetroot – A Vegetable With Superpowers. What Benefits Does It Provide to Athletes?”
An iron-rich diet is important for athletes!
Slight iron deficiencies are treated gradually and not always by taking supplements. It is very important to have a daily diet that includes many products rich in heme and non-heme iron, vitamin C and magnesium.
An example dish for non-meat eaters is a salad of: beans, lentils and fresh spinach, with pumpkin seeds and a dressing of olive oil, mustard and lemon juice.
...................
References:
[1] Abbaspour N, Hurrell R, Kelishadi R. Review on iron and its importance for human health. J Res Med Sci. 2014 Feb;19(2):164-74. PMID: 24778671; PMCID: PMC3999603.
[2] [5] [6] [9] Solberg A, Reikvam H. Iron Status and Physical Performance in Athletes. Life. 2023; 13(10):2007. https://doi.org/10.3390/life13102007.
[3] [4] Iron. Fact Sheet for Health Professionals, https://ods.od.nih.gov/factsheets/Iron-HealthProfessional/.
[7] dr inż. Bożena Wajszczyk, Na anemię buraki?, https://ncez.pzh.gov.pl/abc-zywienia/na-anemie-buraki/.
[8] [10] Iron, https://www.hsph.harvard.edu/nutritionsource/iron/