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After treatment and remission

Vitamin myths

After leukaemia, many people look for vitamins and supplements to “boost immunity” or “prevent relapse”. This topic looks at common myths and the scientific facts.

Last updated: ~3 min read
Capsules and brighter fresh food.
Figure 1.Food first, then a supplement if needed.

01Short answer

Vitamins and minerals are important for health, but it is better to get them mainly from food. A balanced diet (topic “Nutrition in remission”) gives most people the vitamins they need. Supplements are needed only for a specific deficiency or when your doctor recommends them — for example, vitamin D and calcium for bones (topic “Liver”), B12 or iron when tests show a deficiency, or personal advice after a transplant. Common myths: “the more vitamins, the better” — no; some, such as vitamins A, D and E and iron, can be harmful at high doses. “Antioxidants prevent cancer” — large studies have not confirmed this, and in some cases high doses increased risk. “Natural means harmless” — herbal supplements can also interact with medicines and harm the liver. “Supplements boost immunity” — in healthy people there is no evidence. “Special vitamin formulas prevent relapse” — there is no scientific evidence. Supplements are not tested as strictly as medicines, and what is inside may differ from the label. Tell your doctor about all the vitamins, supplements and herbal products you take.

02Simple explanation

It is better to get vitamins mainly from food.

Supplements: for a deficiency or on your doctor’s advice.

More is not always better: high doses can be harmful.

“Natural” does not mean harmless.

Tell your doctor about every supplement.

03Scientific explanation

Food first: the NIH ODS notes that supplements cannot replace a healthy diet; they are useful when there is a specific need.

Antioxidants: according to the NCI, large randomised trials have not shown that antioxidant supplements prevent cancer; beta-carotene increased lung cancer risk in smokers.

Interactions: according to NCCIH and MedlinePlus, some supplements (such as St John’s wort) change how medicines work; tell your doctor about them before surgery or treatment.

Quality: the NIH ODS notes that supplements are not approved for safety and effectiveness the way medicines are; contents may differ from the label.

04What happens in the body?

Where should vitamins come from?

The best source is a varied diet: vegetables, fruit, whole grains, beans and lentils, fish and dairy.

When is a supplement needed?

When tests show a deficiency (vitamin D, B12, iron), at special times (pregnancy), or when your doctor recommends one for a specific reason.

The “more is better” myth

Vitamins A, D and E and iron can build up in the body and cause harm. Do not take more than the recommended dose.

A balance with a small and an overflowing pile.
Figure 2.Too little and too much can both harm.

The “natural is harmless” myth

Herbal products can also have strong effects, interact with medicines and harm the liver.

How to talk to your doctor

Bring a list or the packs of every vitamin, supplement, herbal tea and remedy. Your doctor and pharmacist will check for interactions.

A magnifying lens over a blank label.
Figure 3.Check supplements with your doctor.

When to call your doctor

Worrying signs — fever, bleeding, new pain, breathlessness — should be reported to your doctor between visits too. Getting in touch early is always better than waiting.

05A sensible approach to supplements

Steps.

Food first — Get vitamins from food.1Food firstGet vitamins from food.
Test — Check for a deficiency.2TestCheck for a deficiency.
Show — Show your doctor every supplement.3ShowShow your doctor every supplement.
Limit — Avoid very high doses.4LimitAvoid very high doses.
FoodVitamins come from food.
SafetyInteractions are checked.
NeedYou take only what you need.

06Myths and facts (simplified)

MythFact
More vitamins are betterHigh doses can be harmful
Antioxidants prevent cancerLarge studies have not confirmed this
Natural is harmlessInteractions with medicines are possible
Supplements boost immunityNo evidence in healthy people
Vitamins prevent relapseNo scientific evidence

* Discuss any supplement with your doctor.

07Key terms

Vitamin
A substance the body needs in small amounts.
Supplement
A vitamin, mineral or herb in a tablet, capsule or powder.
Deficiency
Having too little of a substance in the body.
Antioxidant
A substance that protects cells from oxidation.
Interaction
A supplement changing how a medicine works.
Pharmacist
A medicines specialist.

08Key points

  • Get vitamins from food.
  • Take a supplement only when needed.
  • Avoid high doses.
  • “Natural” is not harmless.
  • Tell your doctor about all supplements.
  • Do not believe promises of miracles.

09Frequently asked questions

What should I take for my immunity?

Best of all: balanced eating, sleep, activity and vaccinations.

Do I need vitamin D?

Sometimes; have your level checked and choose the dose with your doctor.

Can I drink herbal teas?

Most are usually fine, but some interact with medicines; ask your doctor.

Is a multivitamin harmful?

At normal doses usually not, but it is often not needed; talk to your doctor.

Does this information replace medical advice?

No. This is general education; only your treating doctor can assess your situation.

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. What should I take for my immunity?

  2. Do I need vitamin D?

  3. Can I drink herbal teas?

  4. Is a multivitamin harmful?

  5. Does this information replace medical advice?

My questions

12Sources

  1. NIH Office of Dietary Supplements. Dietary Supplements: What You Need to Know
  2. National Cancer Institute. Antioxidants and Cancer Prevention
  3. MedlinePlus (U.S. National Library of Medicine). Dietary Supplements
  4. National Center for Complementary and Integrative Health. Using Dietary Supplements Wisely
  5. National Cancer Institute. Complementary and Alternative Medicine
  6. NHS. Vitamins and minerals
  7. National Cancer Institute (NCI). Follow-Up Medical Care
  8. National Cancer Institute (NCI). Cancer Survivorship
  9. Cancer.Net (ASCO). Follow-Up Care After Cancer Treatment
  10. Leukemia & Lymphoma Society (LLS). Long-Term and Late Effects of Treatment
Medical disclaimerThis information is for educational purposes only and does not replace medical advice.
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