Scientists Say This Supplement Could Ease Brain Fog in Breast Cancer Survivors

• New research suggests a nutritional supplement may help relieve brain fog linked to cancer treatment for some patients.
• A small recent study found that oxaloacetate supplementation was associated with fewer cognitive symptoms in breast cancer survivors.
• Experts say more research is still needed.

Cancer treatments such as chemotherapy can bring intense side effects, making an already difficult diagnosis even harder on the body. But a recent small study published in JCO Oncology Advances suggests that a nutritional supplement may help reduce some treatment-related side effects.

Meet the experts: Patricia A. Ganz, M.D., the study author and director of cancer prevention and control research at the Jonsson Comprehensive Cancer Center at UCLA Health, and Breast Cancer Research Foundation scientist; and Larry Norton, M.D., a breast medical oncologist and medical director of the Evelyn Lauder Breast Center at Memorial Sloan Kettering.

The researchers tested whether the nutritional supplement oxaloacetate could help ease cognitive impairment symptoms, including brain fog, that often appear during and after cancer treatment. Among 18 early-stage breast cancer survivors who reported cognitive complaints and took part in the study, 16 said they noticed substantial improvements in cognition. The researchers also reported gains in self-reported overall fatigue, mental fatigue, and physical function after oxaloacetate supplementation.

The results are encouraging, but the study was so small that it is still too soon to draw broad conclusions. Here is what experts want you to know.

Why are the findings significant?

When a person is diagnosed with cancer, treatment naturally becomes the main focus. But side effects from those treatments, such as cognitive complaints, are often not given as much attention.

Those side effects are not rare, either: according to Patricia A. Ganz, M.D., they affect 20 to 25% of breast cancer survivors. Yet there are no medications specifically designed to treat them. That is part of what makes this study noteworthy. Ganz says oxaloacetate appeared to help not only cognitive complaints but also fatigue, insomnia, and physical functioning.

Researchers do not yet know exactly how it works, but they suspect oxaloacetate, a naturally occurring compound, may support cognition in two ways: by lowering excess glutamate, a neurotransmitter involved in learning and memory that can rise with inflammation, and by helping cells produce energy. Cancer and its treatments may affect both processes. These possible effects have also attracted interest as a treatment path for conditions with similar symptoms, such as the fatigue seen in long COVID.

Even so, the findings do not mean oxaloacetate supplements are ready for widespread use in cancer care. Only 18 people were included, so additional research is necessary. Potential side effects have also not yet been fully studied. “All medicines have good and not-so-good effects,” says Larry Norton, M.D. “For this reason, it is important to follow the well-established processes that determine if the balance of good outweighs the downsides. This has not yet been accomplished with this compound.”

Dr. Ganz agrees. “Right now, we cannot recommend this supplement without future testing, but it is very encouraging to know that there is a medication that can reverse these bothersome post-treatment symptoms,” she says.

What does this mean for cancer patients?

The study offers an encouraging sign that common side effects from cancer treatment may eventually have medications available to address them. Still, there is much that remains unknown about the cognitive changes many patients experience and what causes them.

“Cancer doctors and nurses are aware of these effects. We do discuss them with patients. And it is not just cancer treatments that can cause mental changes; many medicines and procedures (like anesthesia) can cause some mental ‘fogging,’” Dr. Norton explains. “We are also aware that there are correctable changes that can occur in anybody—anemia, sleep problems, depression, thyroid function, for example—that could be mistaken for drug-induced mental changes. So, the evaluation of ‘fog’ needs to be comprehensive.”

According to Dr. Norton, several factors may worsen cognitive impairment beyond cancer treatment itself, including stress and normal aging. “But it is now clear that some anticancer drugs are more likely than others to cause changes in brain functioning. Sometimes we can see changes on brain imaging, like an MRI,” he says.

He adds that side effects, including brain fog, are not universal. “Many receive cancer treatment with no negative effects. And most drug-induced changes in mental functioning—when they occur—are mild and transient,” he says. “So, fear of these effects is not a good reason to avoid potentially lifesaving medicines.” Based on current evidence, the lifesaving benefits of cancer treatment still outweigh its other risks.

And the same approaches used to manage brain fog caused by aging or menopause may also help cancer patients. “The use of lists, prompts on smartphones, stickers on objects, and reinforcement (like saying things like ‘I am now putting my keys on the piano’ and ‘I am now locking the door’ out loud) can help,” Dr. Norton says. “But an overlooked aid is exercise; both structured—like yoga—and outdoor walking or using an exercise bicycle really do help.”

The bottom line

Although oxaloacetate supplements are not ready to be recommended for treating cognitive symptoms in cancer patients, this small study marks an important early step toward better management of these issues.

There is still more to learn, including questions Dr. Ganz hopes to address in future research. “We did not have a comparison group that was given a placebo, so the true amount of improvement may be more modest,” she notes. “However, we plan to do that testing in a future study.”

In the meantime, the most important step is to speak up about any cognitive symptoms, because even without approved medications, other help is available. “Patients need to be reassured that their symptoms are real, that we want to take care of them in total, not just treat the cancer, and that there are ways to help them,” Dr. Norton stresses.

Dr. Ganz agrees. “Definitely let [your] doctors know that [you’re] having difficulty, as many things can cause these problems, such as having poor sleep or depressive symptoms,” she points out. “Both of these can be treated and help with the cognitive symptoms.”