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Nutrition and daily life

Minerals: iron, calcium, potassium and other “building blocks”

Minerals are elements that pass from the soil into plants and from there into our food. They build bones, keep the heart and muscles working and carry oxygen. During leukemia treatment their levels are checked often. This topic explains the main minerals, where they come from and what to watch for during treatment.

Last updated: ~4 min read
On a dark navy background, a glass of milk and a wedge of hard cheese, a ripe banana, a baked potato in its skin, a bowl of cooked lentils, a piece of cooked beef, almonds and pumpkin seeds.
Figure 1.Everyday foods rich in minerals.

01Short answer

Some minerals are needed in larger amounts (calcium, phosphorus, potassium, sodium, magnesium) and others only in traces (iron, zinc, selenium, iodine). Iron is part of haemoglobin and carries oxygen, calcium builds bones, and potassium and magnesium are vital for the heart and muscles. In leukemia, anaemia is usually caused by a weakened bone marrow rather than a lack of iron; after many transfusions, iron can even build up. Some medicines, diarrhea and vomiting can lower potassium and magnesium. That is why mineral supplements are prescribed only by your doctor, based on blood tests.

02Simple explanation

Minerals are chemical elements the body cannot make itself. We get them only from food and drink.

Iron sits at the centre of haemoglobin in red blood cells and carries oxygen from the lungs to the tissues.

Calcium and phosphorus are the main building materials of bones and teeth. Calcium is also needed for muscle contraction and blood clotting.

Potassium, sodium and magnesium are electrolytes: they regulate heart rhythm, muscle and nerve function and fluid balance.

During treatment, mineral levels can go down as well as up. That is why they are checked with blood tests rather than topped up “just in case”.

03Scientific explanation

Iron and transfusions: according to MedlinePlus, every blood transfusion brings iron into the body; after many transfusions iron can build up, which is monitored with a ferritin test. Too much iron from supplements can be harmful, so the NHS advises taking it only when needed.

The cause of anaemia: according to the WHO, the most common cause of anaemia worldwide is iron deficiency. In leukemia, however, anaemia is mainly due to the bone marrow being unable to make blood cells and to the effects of treatment, so your doctor finds the cause with tests.

Electrolytes: according to MedlinePlus, an electrolyte panel measures sodium, potassium, chloride and bicarbonate. At the start of treatment, tumour lysis syndrome can make potassium and phosphate rise sharply; some antibiotics, antifungal medicines and diarrhea can lower potassium and magnesium.

Supplements: according to the 2022 ESPEN micronutrient guideline, mineral supplements are given mainly for a confirmed deficiency or increased losses. High doses of zinc and selenium can also be harmful.

04What happens in the body?

Major minerals and trace elements

Calcium, phosphorus, potassium, sodium and magnesium are needed in hundreds of milligrams a day. Iron, zinc, copper, selenium and iodine are needed in very small amounts — milligrams or micrograms. Both groups are vital.

Iron and oxygen

Iron inside haemoglobin binds oxygen. Meat, liver, fish, legumes and buckwheat are rich in iron. Vitamin C improves absorption of plant iron, while strong tea reduces it.

On a dark navy background, an enlarged translucent red blood cell with tiny glowing iron atoms at the centre of haemoglobin molecules holding blue oxygen spheres.
Figure 2.Iron at the centre of haemoglobin binds oxygen.

Transfusions and iron

Every blood transfusion brings iron. After long treatment it can build up in the liver and heart. Your doctor monitors this with a ferritin test and treats it if needed.

Calcium and bones

Dairy, cheese, cottage cheese, sesame and green vegetables provide calcium. Steroids and inactivity can weaken bones. Calcium and vitamin D work together.

Potassium and magnesium

Bananas, potatoes, dried fruit and legumes are rich in potassium; nuts, whole grains and green vegetables in magnesium. Some medicines and diarrhea lower them, while kidney failure and tumour lysis can raise potassium to dangerous levels.

On a dark navy background, a glowing balance scale inside a translucent blood vessel, its pans holding small spheres of different colours in even balance.
Figure 3.Potassium, sodium, magnesium and calcium must stay in balance in the blood.

What do blood tests show?

A biochemistry panel measures sodium, potassium, calcium, magnesium and phosphate. Ferritin shows iron stores. Your doctor always interprets the results together with the whole picture.

05Minerals: four steps

Get them from food, understand iron, check with tests, do not self-supplement.

From soil to plate — Minerals come with food.1From soil to plateMinerals come with food.
Iron for the blood — Haemoglobin carries oxygen.2Iron for the bloodHaemoglobin carries oxygen.
Blood tests — Electrolytes and ferritin.3Blood testsElectrolytes and ferritin.
Not on your own — Iron and potassium only with a doctor.4Not on your ownIron and potassium only with a doctor.
Steady heart rhythmElectrolytes in balance.
Strong bonesCalcium and vitamin D.
Safe treatmentNo risk of overdose.

06Key minerals (simplified)

MineralWhat it is forFood sources
IronHaemoglobin, oxygen transportMeat, liver, legumes, buckwheat
CalciumBones, muscles, clottingMilk, cheese, cottage cheese, sesame
PotassiumHeart rhythm, musclesBananas, potatoes, dried fruit, legumes
MagnesiumMuscles and nerves, heartNuts, whole grains, green vegetables
SodiumFluid balance, blood pressureSalt, processed foods
Zinc and seleniumImmunity, enzymesMeat, fish, eggs, seeds

* The table is general information. Mineral supplements, especially iron and potassium, are prescribed only by your doctor based on blood tests.

07Key terms

Mineral
An essential chemical element obtained from food.
Electrolyte
A mineral present in the blood as charged particles.
Haemoglobin
The iron-containing protein that carries oxygen.
Ferritin
A protein that shows how much iron is stored.
Iron overload
Excess iron after many transfusions.
Hypokalaemia
Low potassium in the blood.
Hyperkalaemia
High potassium in the blood.
Tumour lysis
Rapid breakdown of many cells, releasing minerals.

08Key points

  • We get minerals from food.
  • Iron carries oxygen.
  • Anaemia in leukemia is not always iron deficiency.
  • Iron can build up after transfusions.
  • Potassium and magnesium are monitored by blood tests.
  • With kidney disease, potassium may be restricted.
  • Do not start iron or potassium on your own.
  • Call your team about cramps or palpitations.

09Frequently asked questions

My haemoglobin is low. Should I take iron?

Not unless your doctor says so. In leukemia, low haemoglobin is usually due to the bone marrow and treatment. After many transfusions you may even have too much iron. A ferritin test shows this.

Will liver and red meat help my anaemia?

They provide iron and B12, are good food and must be fully cooked. But food alone will not fix anaemia caused by leukemia; your doctor decides on transfusions and treatment.

My potassium is low. Will a banana help?

Potassium-rich foods can help, but if the level is very low your doctor will prescribe a medicine. Taking potassium on your own can be dangerous.

Do I need calcium? I am on steroids.

Steroids can weaken bones. Your doctor will decide whether you need calcium and vitamin D based on your tests and treatment plan.

Is mineral water good for me?

Mineral water counts as fluid too. Some brands contain a lot of sodium. Choose sealed, safe water; if you have kidney problems or high blood pressure, ask your doctor.

Will zinc and selenium strengthen my immunity?

The immune system needs them, but supplements have no proven benefit without a deficiency, and too much is harmful.

10Questions for your doctor

Take these questions to your appointment. The ones you save are collected on the “My questions” page and stay on this device only.

  1. My haemoglobin is low. Should I take iron?

  2. Will liver and red meat help my anaemia?

  3. My potassium is low. Will a banana help?

  4. Do I need calcium? I am on steroids.

  5. Is mineral water good for me?

  6. Will zinc and selenium strengthen my immunity?

My questions

12Sources

  1. MedlinePlus (U.S. National Library of Medicine). Minerals
  2. MedlinePlus (U.S. National Library of Medicine). Iron
  3. MedlinePlus (U.S. National Library of Medicine). Potassium
  4. MedlinePlus (U.S. National Library of Medicine). Electrolyte Panel
  5. MedlinePlus (U.S. National Library of Medicine). Ferritin Blood Test
  6. NHS. Vitamins and minerals: Iron
  7. NHS. Vitamins and minerals: Calcium
  8. NHS. Vitamins and minerals: Others (magnesium, potassium, zinc, selenium and more)
  9. NIH Office of Dietary Supplements. Iron — Fact Sheet for Consumers
  10. NIH Office of Dietary Supplements. Magnesium — Fact Sheet for Consumers
  11. Clinical Nutrition (ESPEN), 2022. Berger MM et al. ESPEN micronutrient guideline
  12. World Health Organization (WHO). Anaemia — fact sheet
Medical disclaimerThis information is for educational purposes only and does not replace medical advice.
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