Researchers tested whether blueberry extract could protect rat hearts from damage caused by doxorubicin, a powerful cancer-fighting drug that can harm the heart. They compared blueberry extract alone, a heart-protection medicine called dexrazoxane, and a combination of both. All treatments helped reduce heart damage, but the combination worked best. The study suggests that blueberries might become a helpful addition to cancer treatment plans to keep hearts safer, though more research in humans is needed before doctors could recommend it.

The Quick Take

  • What they studied: Whether blueberry extract and a heart-protection drug could prevent heart damage in animals receiving doxorubicin, a common cancer medicine known to harm hearts
  • Who participated: 56 laboratory rats divided into 7 groups, with each group receiving different combinations of blueberry extract, the heart-protection drug, and/or the cancer medicine
  • Key finding: Blueberry extract reduced heart damage markers by similar amounts to the standard heart-protection drug, and combining both treatments worked even better than either one alone
  • What it means for you: This research suggests blueberries might help protect hearts during cancer treatment, but this is early-stage animal research. Cancer patients should not change their treatment without talking to their doctor, as human studies are still needed to confirm these findings

The Research Details

Scientists divided 56 rats into seven groups to test different treatments. One group received normal care as a baseline. Another group received only the cancer drug doxorubicin to see what damage it caused. Three groups received either blueberry extract alone, the heart-protection drug alone, or blueberry extract plus the heart-protection drug. Two more groups received these treatments combined with the cancer drug. The researchers gave treatments for 14 days and measured heart damage using blood tests and tissue samples.

This type of study is called a controlled experiment because researchers carefully controlled what each group received and compared the results. By using multiple groups, they could see which treatments worked best and whether combining treatments was more effective than using them separately.

The researchers measured several markers of heart damage in the blood and examined heart tissue under a microscope to see physical damage. They also looked at specific molecules inside cells that show whether the heart is stressed or protected.

This research design is important because it allows scientists to test whether blueberry extract actually causes the protective effect or if it’s just a coincidence. By comparing blueberry extract to a known heart-protection drug, researchers could see if the natural extract works similarly to medicine. Testing combinations helps doctors understand whether using multiple protective strategies together might work better than one alone.

This study was published in Scientific Reports, a well-respected scientific journal. The researchers used a reasonable number of animals (56 total) and measured multiple markers of heart health to confirm their findings. They also examined heart tissue directly, which provides strong evidence. However, this is animal research, so results may not directly apply to humans. The study was well-designed with proper control groups, which strengthens the reliability of the findings.

What the Results Show

The cancer drug doxorubicin caused significant heart damage in rats, shown by increased harmful substances in the blood and heart tissue. When researchers gave blueberry extract before the cancer drug, the heart damage was greatly reduced. The standard heart-protection drug (dexrazoxane) also reduced damage effectively. Importantly, when researchers combined blueberry extract with the heart-protection drug, the protection was even stronger than either treatment alone.

The researchers measured specific proteins in the blood that indicate heart stress (called cTnT and NT-proBNP). These markers were very high in rats that received only the cancer drug, showing significant heart damage. In all treated groups, these markers returned to near-normal levels. The combination treatment produced the best results, with the lowest levels of these damage markers.

Microscopic examination of heart tissue confirmed these blood test results. Rats receiving only the cancer drug showed visible damage to heart cells. Rats receiving blueberry extract, the heart-protection drug, or both showed much less tissue damage. The combination group had the least damage overall.

The researchers also measured antioxidants in heart tissue—these are natural substances that protect cells from damage. The cancer drug reduced these protective antioxidants significantly. All treatments restored these protective substances, with the combination treatment showing the strongest restoration. Additionally, the study examined specific genes and molecules involved in cell protection. The cancer drug disrupted these protective systems, but all treatments helped restore them, suggesting multiple protective mechanisms at work.

Previous research has shown that doxorubicin damages hearts by creating harmful molecules called free radicals. This study confirms that finding and adds new information by showing that blueberry extract works through similar protective mechanisms as the standard heart-protection drug. The finding that combining treatments works better than either alone is consistent with how medical treatments often work—multiple approaches targeting different protective pathways can be more effective together. However, most previous research on blueberries and heart protection has been in test tubes or animals, so this study adds to growing evidence but doesn’t yet prove benefits in cancer patients.

This study was conducted in rats, not humans, so the results may not directly apply to people. The dose of blueberry extract used was much higher than someone could typically eat. The study only looked at short-term effects (14 days), so it’s unclear whether blueberry extract would provide long-term protection. The research didn’t test whether blueberry extract might interfere with the cancer drug’s ability to fight cancer—an important question for real patients. Additionally, only one type of cancer drug was tested, so results may not apply to other chemotherapy drugs. Finally, this was a single study, so results need to be confirmed by other researchers before making clinical recommendations.

The Bottom Line

Based on this animal research, blueberry extract appears promising for protecting hearts during cancer treatment, but the evidence is still preliminary. Cancer patients should NOT start taking blueberry supplements based on this study alone. Instead, patients receiving doxorubicin should discuss heart protection options with their oncologist, who may recommend established approaches like heart-monitoring tests or approved heart-protection medications. Future human studies are needed before blueberries can be recommended as a standard protective treatment.

This research is most relevant to cancer patients receiving doxorubicin chemotherapy and their doctors. Researchers studying natural ways to protect hearts during cancer treatment should also pay attention. People interested in preventive nutrition may find this interesting, but it’s too early to apply these findings to general health. This research does NOT apply to people not receiving doxorubicin, as the protective effect was only tested in the context of this specific cancer drug.

In this animal study, heart protection was measured just 14 days after treatment. In real cancer patients, heart damage from doxorubicin can develop over months or years. If blueberry extract eventually proves helpful in humans, it would likely need to be taken during and after chemotherapy, with heart health monitored regularly through blood tests and heart imaging. Benefits would probably not be immediately obvious but would be measured through reduced heart damage markers over time.

Want to Apply This Research?

  • Users receiving doxorubicin chemotherapy could track daily blueberry or blueberry extract consumption (in grams or servings) alongside their chemotherapy schedule and any heart-related symptoms like shortness of breath, fatigue, or chest discomfort. This data could be shared with their healthcare team.
  • If a user’s doctor approves, they could set a daily reminder to consume blueberries or blueberry extract at a consistent time. The app could track this habit and provide motivation through streak counters or reminders, while also allowing users to log any symptoms they notice.
  • Users should log any heart-related symptoms, energy levels, and exercise tolerance alongside their blueberry consumption. The app could generate reports showing patterns over weeks and months, which users can share with their oncologist during regular check-ups. This helps track whether any changes in heart health correlate with blueberry consumption, though users should understand this is not a replacement for medical monitoring.

This research is preliminary animal study evidence and should not be used to guide personal medical decisions. Doxorubicin is a serious cancer medication with important benefits that must be weighed against risks. Cancer patients should never modify their chemotherapy or add supplements without explicit approval from their oncologist. While blueberry extract appears safe in this study, it may interact with cancer drugs or other medications. Heart damage from doxorubicin requires professional medical monitoring. Consult your healthcare team before making any changes to your cancer treatment plan or adding supplements.