Scientists discovered that high doses of vitamin C might actually help tumors grow in people who carry a specific genetic mutation called SDHB. Using zebrafish as a model, researchers found that vitamin C supplementation triggered the growth of chromaffin cells—the cells that can develop into rare tumors called phaeochromocytomas and paragangliomas. This finding is important because it suggests that people with this genetic mutation should be cautious about taking high-dose vitamin C supplements. The research helps scientists understand what might trigger tumor development in people carrying this mutation and could lead to better treatments in the future.

The Quick Take

  • What they studied: Whether vitamin C supplements could trigger tumor growth in zebrafish that carry a genetic mutation similar to one found in humans with rare tumors
  • Who participated: Adult and larval zebrafish with mutations in the SDHB gene, which mimics the genetic condition found in some human patients
  • Key finding: About 12% of adult zebrafish with the SDHB mutation that received vitamin C supplements developed abnormal cell growth in their chromaffin cells (the cells that can become tumors). The vitamin C also increased harmful chemical imbalances in these fish.
  • What it means for you: If you carry the SDHB genetic mutation, you should talk to your doctor before taking high-dose vitamin C supplements, as they may increase your risk of tumor development. This finding does not apply to people without this specific genetic mutation.

The Research Details

Researchers used zebrafish as a model organism to study how vitamin C affects tumor development in animals with SDHB gene mutations. They studied two groups: adult zebrafish that carried one mutated copy of the gene (similar to human carriers) and young zebrafish that carried two mutated copies (a more severe form). The scientists gave some fish vitamin C supplements while others received no supplements, then tracked whether tumors developed and measured changes in their cells and genes.

The researchers used advanced techniques to examine what was happening inside the fish’s cells. They measured chemical compounds called metabolites to see how the fish’s bodies were processing nutrients differently. They also analyzed which genes were being turned on or off in response to the vitamin C, looking specifically at genes related to tumor development and stress responses.

This approach allowed scientists to observe early stages of tumor formation in living animals and understand the biological mechanisms involved, something that’s difficult to study directly in humans.

Using zebrafish as a model is valuable because their genes and biological processes are similar to humans, but researchers can observe tumor development in real-time in living animals. This study is important because it identified a potential trigger for tumor development in people with SDHB mutations, which could help doctors give better advice to patients about supplements and lifestyle choices.

This is a laboratory-based research study using animal models, which means the findings need to be confirmed in human studies before making definitive recommendations. The study was published in a peer-reviewed scientific journal, indicating it underwent expert review. However, because zebrafish are not humans, results may not translate exactly to human biology. The sample size and specific numbers of fish studied were not detailed in the abstract, which limits our ability to assess the statistical strength of the findings.

What the Results Show

When adult zebrafish carrying one mutated SDHB gene received vitamin C supplements, about 12% developed abnormal growth of chromaffin cells—the specialized cells that can develop into tumors. This is significant because these fish normally don’t develop tumors on their own, suggesting that vitamin C acted as a trigger.

The researchers also found that vitamin C changed the chemical balance inside the fish’s cells. Specifically, it increased the ratio of succinate to fumarate—two important molecules involved in cellular energy production. In people with SDHB mutations, this imbalance is thought to contribute to tumor development.

Gene expression analysis revealed that vitamin C activated several biological pathways associated with tumor growth. The most notable was the HIF (hypoxia-inducible factor) pathway, which is often overactive in cancer cells. Additionally, high-dose vitamin C increased oxidative stress markers, meaning it created harmful chemical reactions inside the cells that can damage DNA and promote tumor growth.

The study found that young zebrafish with two mutated SDHB genes (more severe than the human carriers) showed even stronger responses to vitamin C, with greater increases in oxidative stress. This suggests that the severity of the genetic mutation affects how sensitive someone might be to vitamin C’s tumor-promoting effects. The research also identified several biological mechanisms involved, including changes in iron metabolism and glucose transport, which are important for understanding how tumors develop.

This research builds on earlier work showing that zebrafish with SDHB mutations can model human disease. Previous studies established that these fish have low-level accumulation of succinate (a chemical that builds up when SDHB is defective), but they don’t spontaneously develop tumors. This new finding—that vitamin C can trigger tumor formation—provides the missing piece by identifying a potential environmental trigger. The results align with emerging evidence that antioxidants and supplements may have unexpected harmful effects in people with certain genetic conditions.

This study was conducted in zebrafish, not humans, so the findings may not directly translate to people. The percentage of fish that developed tumors (12%) was relatively small, and the study didn’t track long-term outcomes. The abstract doesn’t specify exactly how many fish were studied, making it difficult to assess the statistical reliability of the results. Additionally, the study used laboratory conditions that may not reflect real-world vitamin C exposure in humans. Finally, this research only applies to people with SDHB mutations and cannot be generalized to the general population.

The Bottom Line

People who carry SDHB gene mutations should avoid high-dose vitamin C supplements without consulting their doctor. This recommendation is based on laboratory evidence showing vitamin C can trigger tumor-related cell growth in animals with this mutation. For people without SDHB mutations, this research does not suggest avoiding vitamin C. Anyone with a family history of phaeochromocytomas or paragangliomas should discuss genetic testing and supplement safety with their healthcare provider.

This research is most relevant to people who have been diagnosed with or carry the SDHB gene mutation, and their family members who may also carry the mutation. It’s also important for doctors who treat patients with these rare tumors or genetic conditions. People without SDHB mutations should not be concerned about normal dietary vitamin C intake based on this research. Patients considering high-dose supplements for any reason should discuss this study with their healthcare provider.

In the zebrafish model, tumor-related cell growth appeared relatively quickly after vitamin C exposure, but the timeline for tumor development in humans would likely be much longer. People with SDHB mutations who have been taking vitamin C supplements should not panic, but should contact their doctor to discuss their individual risk and whether they should stop supplementation. Regular monitoring through imaging and blood tests is typically recommended for people with SDHB mutations regardless of supplement use.

Want to Apply This Research?

  • Users with SDHB mutations should track daily vitamin C intake from all sources (supplements, food, and fortified products) and log any new symptoms or health changes. They should record the date, amount, and source of vitamin C consumed, along with any physical symptoms or medical appointments.
  • If you carry the SDHB mutation, use the app to set a reminder to discuss your current vitamin C intake with your doctor and create a plan to eliminate high-dose supplements if recommended. You can use the app to track when you’ve had this conversation and to monitor any changes your doctor suggests.
  • Set up monthly check-ins to review your supplement intake and ensure you’re following your doctor’s recommendations. Use the app to track scheduled medical appointments and imaging tests, which are important for monitoring tumor development in people with SDHB mutations. Create alerts for any new symptoms that should be reported to your healthcare provider.

This research is based on laboratory studies in zebrafish and has not been confirmed in human clinical trials. The findings apply specifically to people with SDHB gene mutations and should not be interpreted as applying to the general population. If you carry an SDHB mutation or have a family history of phaeochromocytomas or paragangliomas, consult with your healthcare provider or a genetic specialist before starting, stopping, or changing any supplements. Do not make changes to your current supplement regimen based solely on this research without medical guidance. This information is for educational purposes and is not a substitute for professional medical advice, diagnosis, or treatment.