Scientists talked about the effect of nutrition on excess iron

Tea and coffee consumed with food can reduce the absorption of non-heme iron, while red meat, iron supplements and vitamin C can increase its intake into the body. Nutrition can complement the treatment of iron overload, but it has not yet been proven that changing the diet allows you to stop bloodletting or medications. This was announced on September 15 by Medical Xpress with reference to a review published in the journal Nutrition Reviews.

What is the danger of excess iron

Dietary recommendations often refer to iron deficiency, which can lead to anemia, weakness, and poor health. However, excessive accumulation of this element also poses a threat to health.

Iron overload develops when it gradually accumulates in the body and is deposited in the tissues. The liver, heart, and pancreas may be affected first. Prolonged exposure to excess iron can cause scarring of the liver, impair the heart's ability to pump blood, and disrupt glucose control, increasing the risk of diabetes.

Scientists divide iron overload into primary and secondary. The primary one is associated with hereditary features, due to which the body absorbs more iron from food than it needs. Hereditary hemochromatosis is considered the most common form. The corresponding genetic variants are especially common in people of Northern European origin.

The body regulates the amount of iron mainly through its absorption in the intestine and does not have a full-fledged mechanism for actively removing its excess. Therefore, with hereditary hemochromatosis, phlebotomy remains the main treatment method — regular therapeutic removal of a certain amount of blood. Together with red blood cells, the body loses iron, after which it uses the accumulated reserves to form new blood cells.

Secondary overload may be the result of an illness or treatment. In particular, it develops in patients who require multiple blood transfusions. Each procedure brings additional iron into the body, which can accumulate in the organs over time.

What the review authors have studied

Experts analyzed 40 sources on nutrition, beverages, and dietary supplements for iron overload. The study included 38 peer—reviewed scientific papers and two sources of so-called gray literature - materials not published in traditional scientific journals.

Scientists have studied the effects of polyphenols, vitamins, minerals, alcohol, certain foods, and dietary changes. The results showed that nutrition can actually change the amount of iron absorbed. However, the practical benefits of a diet largely depend on the cause of the overload.

With hereditary hemochromatosis, a decrease in the absorption of iron from food is theoretically able to slow down its further accumulation. In case of secondary overload caused by regular transfusions, the bulk of the excess comes directly from the donated blood. Dietary restrictions in such a situation cannot eliminate the main cause of the disorder.

The authors called the work a coverage review rather than a meta-analysis. Her task was to collect and systematize the available data, but the researchers did not combine numerical results and did not calculate the overall effect of the diet. The quality of each source was also not evaluated using a single formal system.

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How tea affects iron absorption

The most interesting results were obtained for tea. It contains polyphenols, plant compounds that can bind to non—heme iron and make it difficult for it to be absorbed into the intestine.

Iron in food comes in two main forms. Heme is found mainly in meat, poultry and fish and is relatively easily absorbed by the body. Non-heme is present in plant products, fortified foods, and some supplements. Its assimilation depends more on the combination of foods in one meal.

A small clinical trial involved 18 people with hereditary hemochromatosis. Scientists have found that black tea, drunk with meals, reduced the absorption of iron. The participants were asked to drink tea or water with each meal. Over the next year, people in the first group accumulated about a third less iron reserves. However, the difference between the groups did not reach statistical significance. This means that the researchers could not rule out the influence of chance.

A later cross-sectional study involved 14 adults. Each of them received both an active supplement and an inactive capsule at different times. The composition of the studied remedy included extracts of black tea, cocoa and grape juice. The supplement reduced the absorption of non-heme iron from one meal by about 40%. However, the study evaluated only the short-term effect. It did not show whether the accumulation of iron in the body slows down with prolonged intake.

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Can coffee help

Coffee also contains polyphenols and is able to reduce the absorption of non-heme iron if drunk at the same time as meals. However, tea has been studied better directly in people with iron overload.

It is the time of drinking that matters. Polyphenols must be present in the digestive system at the same time as iron in order to bind to it and limit its absorption. Tea or coffee, drunk separately from meals, may have a less pronounced effect.

In this case, we are talking mainly about the non-heme gland. Drinks do not completely neutralize the iron coming from red meat and other sources of heme form.

Scientists also do not suggest drinking excessive amounts of tea or coffee. These drinks may be unsuitable for some people due to caffeine, gastrointestinal disorders, sleep disorders, or other conditions.

Why is it recommended to limit red meat

Heme iron, found in meat, poultry and fish, is absorbed more efficiently than non-heme iron. For this reason, people with hereditary hemochromatosis may be advised to reduce the frequency of eating red meat.

Especially a lot of iron is found in by-products, primarily in the liver. Their regular use can increase the amount of the element entering the body.

At the same time, the researchers do not urge all people with hemochromatosis to completely abandon meat. The diet should remain balanced and provide the body with protein, vitamins and other essential substances. The degree of limitations depends on the test results, severity of overload, liver condition, and treatment.

In addition, people with excess iron are usually advised not to take iron supplements and multivitamins without a doctor's prescription. In the UK, patients with hemochromatosis are also advised to avoid foods specifically fortified with iron, including some breakfast cereals.

Why uncontrolled intake of vitamin C is dangerous

Vitamin C enhances the absorption of non-heme iron. Therefore, with hereditary hemochromatosis, patients are usually advised to give up its high-dose supplements unless they are prescribed by a doctor.

At the same time, it is not proposed to ban ordinary fruits and vegetables. They contain fiber, antioxidants, and other beneficial substances, and the amount of vitamin C in them is usually significantly lower than in concentrated preparations.

Recommendations may vary for patients with transfusion-dependent beta-thalassemia. Some of them, despite their iron overload, develop vitamin C deficiency. In such cases, the doctor may prescribe a small dose simultaneously with certain iron chelators or after laboratory confirmation of a deficiency.

Self-administration of supplements is potentially dangerous. When overloaded, vitamin C can increase the amount of chemically active forms of iron in the blood, which damage cells and tissues.

Thus, the presence of an excess of iron does not exclude a deficiency of other substances. That is why general recommendations from the Internet cannot be automatically applied to all patients with hemochromatosis or thalassemia.

Why are raw shellfish dangerous for hemochromatosis?

A separate recommendation concerns raw and insufficiently cooked seafood, primarily oysters and other bivalves. They may contain bacteria of the genus Vibrio, which live in coastal waters.

In most people, the infection they cause is limited to gastrointestinal symptoms. However, when overloaded with iron, bacteria can multiply faster, and the disease can be much more severe, up to the pathogen entering the bloodstream and developing sepsis.

In this regard, the US National Institute of Diabetes, Digestive and Kidney Diseases recommends that people with hemochromatosis not consume raw or insufficiently cooked shellfish. This measure is not related to the amount of iron in seafood, but to the increased vulnerability of patients to infection.

Why is there no single diet yet?

The review results do not confirm the existence of a universal "iron overload diet." The analyzed studies differed in diagnoses, composition of participants, duration, and products studied. Many of them were conducted on small groups and assessed only short-term iron absorption or changes in laboratory parameters.

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Much less often, scientists studied really important long-term results: the frequency of organ damage, the need for phlebotomy, chelator doses, and the quality of life of patients. So far, it cannot be argued that changing the diet reliably reduces the frequency of therapeutic bloodletting or reduces the dosage of drugs. This requires larger and longer clinical trials.

In addition, excessive restrictions can lead to an unbalanced diet. A complete rejection of meat, fruits, vegetables or other large food groups without medical indications can cause a lack of protein, vitamins and minerals.

How nutrition can complement treatment

With hereditary hemochromatosis, experts may recommend avoiding iron and vitamin C supplements not prescribed by a doctor, limiting frequent consumption of red meat and alcohol, and drinking tea or coffee with food to reduce the absorption of non-heme iron.

In case of transfusion overload, recommendations should take into account the number of transfusions, the chelator regimen, and possible vitamin and mineral deficiencies. Restrictions suitable for a person with hereditary hemochromatosis will not always be useful for a patient with thalassemia.

The author of the article, nutrition specialist Alexandra Cremona, stressed that any dietary changes and supplements should be discussed with your doctor or clinical nutritionist.