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For some breast cancer survivors, completing treatment doesn’t mean the end of their symptoms. Memory lapses, difficulty concentrating, and persistent fatigue can continue for years, interfering with daily activities and quality of life.
A small clinical trial led by researchers at the UCLA Health Jonsson Comprehensive Cancer Center suggests a nutritional supplement may help ease some of those lingering effects.
All 16 breast cancer survivors who completed eight weeks of treatment with oxaloacetate, a molecule naturally found in the body that helps cells produce energy, reported significant improvements in cognitive symptoms. Researchers also documented reduced fatigue, better physical functioning, and gains in certain measures of cognitive performance.
The findings, published in JCO Oncology Advances, offer a potential new approach to treating cancer-related cognitive impairment, commonly called “chemo brain” or “brain fog.” However, researchers caution that larger, controlled studies are needed to determine whether the supplement is effective.
“Cancer-related cognitive impairment can persist long after treatment ends and can have a significant impact on a person’s daily life, yet we still have very few effective treatments for it,” said Dr. Patricia Ganz, a distinguished professor of medicine at the David Geffen School of Medicine at UCLA and the UCLA Fielding School of Public Health, and first author of the study.
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Why Brain Fog Persists After Breast Cancer Treatment
An estimated 15% to 25% of breast cancer survivors experience persistent cognitive difficulties following their diagnosis and treatment.
Although these symptoms have traditionally been associated with chemotherapy, researchers now recognize that their causes are more complex. Cancer itself, endocrine therapy, inflammation, hormonal changes, and other biological and behavioral factors may contribute.
Researchers have become interested in oxaloacetate because inflammation associated with cancer and its treatments may disrupt glutamate signaling and cellular energy production in the brain, potentially contributing to cognitive difficulties and mental fatigue.
Oxaloacetate plays a role in both processes, prompting researchers to investigate whether taking it as a supplement could help alleviate symptoms.
What the UCLA Clinical Trial Found
The phase II trial enrolled 18 women with early-stage breast cancer who were between one and five years from diagnosis and reported significant cognitive difficulties.
Participants averaged about 50 years old. Most had previously received chemotherapy, and nearly 90% were receiving endocrine therapy during the study.
Each participant took 500 milligrams of oxaloacetate twice daily for eight weeks.
Researchers assessed cognitive symptoms using patient-reported questionnaires and standardized neuropsychological tests measuring memory, attention, processing speed, and executive function. They also evaluated fatigue, sleep, anxiety, depression, and overall physical and mental health.
Sixteen women completed the treatment, and all reported significant improvements in cognitive symptoms.
On the study’s primary measure of perceived cognitive impairment, average scores increased from 29.1 before treatment to 55.5 after eight weeks, moving the group from a range considered impaired to one considered normal.
Improvements appeared after four weeks and generally increased through the end of treatment.
Participants also reported significantly less fatigue, including mental fatigue, and better physical functioning. Objective testing showed improvements in processing speed and executive function, which involves skills such as planning, focusing, and managing tasks.
What the Findings Mean for Nurses
For oncology nurses and other healthcare professionals involved in cancer survivorship care, the study highlights the importance of recognizing cognitive difficulties that may persist long after active treatment ends.
The findings also underscore the value of patient-reported symptoms alongside objective cognitive testing. In this trial, participants reported substantial improvements in cognitive difficulties, while standardized assessments identified gains in specific cognitive domains.
Although the results are encouraging, oxaloacetate remains an investigational approach rather than an established treatment for cancer-related cognitive impairment.
Side Effects and Study Limitations
Oxaloacetate was generally well tolerated, although gastrointestinal symptoms were the most common side effects, including indigestion, bloating, constipation, diarrhea, and nausea.
Two participants discontinued treatment because of gastrointestinal symptoms. No serious adverse events were reported.
The researchers emphasized that the study was small and did not include a placebo or comparison group. As a result, they cannot determine whether oxaloacetate caused the improvements.
Larger Clinical Trial Planned for Late 2026
The UCLA research team is preparing a randomized, placebo-controlled phase II trial involving breast cancer survivors with cancer-related cognitive impairment, expected to open in late 2026.
Researchers are also conducting preclinical studies in mice to better understand how oxaloacetate works and whether it improves fatigue and physical functioning under placebo-controlled conditions.
“These early findings give us a strong reason to continue studying oxaloacetate as a potential approach for managing cognitive problems after breast cancer treatment,” Ganz said.
