Multivitamins, fish oil, and vitamin D can be beneficial to take during chemotherapy treatment. However, some vitamins can reduce the effectiveness of chemotherapy.

It can be difficult to get all the nutrients you need from your diet during chemotherapy treatment. Taking vitamins and other supplements can seem like a good way to solve this problem and promote overall health, but it’s not always the best idea.

Some vitamins may have negative interactions with chemotherapy drugs and can even make chemotherapy less effective. Talking with your oncologist can help you determine the safest vitamins for you.

Read more about the side effects of chemotherapy.

It’s always best to ask your oncologist about the benefits of taking vitamins during your chemotherapy treatment. As a rule, it’s a good idea to be cautious about using vitamins during chemotherapy. This is because vitamins and other supplements can potentially counteract the effects of chemotherapy medications.

This happens because certain vitamins give you more antioxidants.

Antioxidants usually help rid your body of the free radicals produced by metabolism and by substances such as tobacco. But when you’re undergoing chemotherapy, antioxidants can sometimes protect cancer cells, preventing chemotherapy from destroying them.

A 2020 study on vitamin and antioxidant use during treatment for cancers such as leukemia, lymphoma, breast cancer, and lung cancer found that people taking antioxidant supplements had worse overall treatment outcomes.

But that doesn’t mean it’s never a good idea to take vitamins during chemotherapy. For instance, some vitamins and other supplements can help address nutritional deficiencies that might happen during chemotherapy treatment. And some vitamins, such as vitamin D, are likely safe to take during treatment.

The best vitamins to take during chemotherapy depend on the type of cancer you have, your symptoms, and the recommendations of your oncologist. Your individual needs will determine which supplements are best for you. But there are some supplements that people commonly take during chemotherapy.

Some of the best supplements to take while on chemo are:

  • Vitamin D: Vitamin D is associated with higher survival rates in people with lung, colon, and breast cancers. It can also help reduce the risk of osteoporosis that is associated with some types of cancer and cancer treatment.
  • Fish oil: Fish oil provides omega-3 fatty acids, which are especially important for people who are experiencing nutritional deficiencies during chemotherapy. Omega-3 fatty acids have a range of health benefits.
  • Vitamin B12: Vitamin B12 is not typically considered an antioxidant. Some people find that it improves their energy levels during chemotherapy treatments. But some research has linked B12 use during chemotherapy to worse treatment outcomes.
  • Multivitamins: A daily multivitamin can be a good source of nutrients for people who experience changes in appetite and diet due to chemotherapy.

There are multiple ways you can support your immune system during chemotherapy treatments. Taking these steps can help reduce your risk of infection while you’re undergoing chemotherapy. Tips to help your immune system during chemo include:

  • Getting your annual flu shot: A flu vaccine can help protect you from infection. You can ask your doctor about the best timing for receiving the flu shot.
  • Getting any other recommended seasonal vaccinations: Not all vaccines are safe for people who are receiving chemotherapy, but some are a good idea. It’s best to ask your oncologist which vaccines they recommend for you.
  • Practicing good hand hygiene: It’s always important to wash your hands regularly with soap and warm water, especially if you’ve been outdoors or had contact with any surfaces that might be contaminated.
  • Avoiding contact with people who have infections: Infections can sometimes spread from person to person, so it’s best to limit your contact with anyone who has an active infection. If someone who lives with you is sick, try to disinfect surfaces and wash your hands often.
  • Avoiding contact with animal waste products: Animal waste can contain infectious bacteria. It’s a good idea to avoid touching it or to wear gloves if you need to.
  • Eating a nutritious diet: A healthy diet can help boost your immune system. If you’re having trouble eating due to chemotherapy, talk with your doctor about options such as meal replacement shakes and intravenous nutrition.
  • Getting plenty of sleep: Sleep is important for your whole body, including your immune system. Making sleep a priority can help your immune system during chemotherapy treatments.
  • Asking your doctor about protective medications: Preventive medications are sometimes an option for people who are receiving chemotherapy treatments. But these medications can cause serious side effects, and doctors typically recommend them only for people with a high risk of infection.

Vitamins are not always recommended during chemotherapy treatment.

Some vitamins are antioxidants and reduce the effectiveness of chemotherapy. But some other supplements, such as multivitamins, fish oil, and vitamin D, can be beneficial for people during chemotherapy treatment.

Before taking any vitamins or other supplements, it’s best to talk with your oncologist about the safest options for you.