Maintaining good health does not necessarily rely solely on dietary supplements. Many essential bioactive molecules that support efficient physiological function are already present in everyday foods such as meat, grains, vegetables, and nuts. Among them, vitamin B6—often overlooked in daily nutrition—plays a critical role in metabolism, immune regulation, and cellular homeostasis. Recent research from Cold Spring Harbor Laboratory, published in Genes & Development, highlights the potential protective role of vitamin B6, particularly its active form pyridoxal 5′-phosphate (PLP), in reducing the risk of several cancers including lung, colorectal, and breast cancer. Epidemiological studies consistently show that higher plasma PLP levels are associated with lower incidence of these malignancies. Mechanistic studies further suggest that vitamin B6 may suppress tumor growth by modulating inflammation, supporting DNA synthesis and repair, and enhancing anti-tumor immune responses. Additional findings also indicate that PLP can maintain the functional “stem-like” state of CD8⁺ T cells, helping sustain their long-term anti-tumor activity. While many of these findings come from cellular and animal studies and require further clinical validation, they highlight the significant health value of adequate vitamin B6 intake through daily diet.
Vitamin B6: A Key Nutrient Hidden in Daily Meals
Is pursuing good health really dependent only on supplements? In fact, the everyday combination of meat, grains, vegetables, and nuts already contains many key nutritional molecules that support the body's efficient functioning.
One example is vitamin B6, a relatively low-profile nutrient obtained from the diet that can truly be considered a “hidden treasure.” A recent review published in Genes & Development by a research team from Cold Spring Harbor Laboratory in the United States reported that when vitamin B6 levels in the body are sufficient—particularly when its active form, pyridoxal 5′-phosphate (PLP), is maintained at normal physiological concentrations—it may exert significant protective effects against several cancers, including lung cancer, colorectal cancer, and breast cancer, thereby reducing their risk of occurrence.
DOI: 10.1101/gad.352770.125
Although vitamin B6 may seem inconspicuous, it is in fact a true “multitasker.” It is deeply involved in amino acid metabolism, neurotransmitter synthesis, and a range of other essential physiological processes, helping maintain the stability of the nervous system, metabolic functions, and overall energy balance.
However, the human body cannot synthesize vitamin B6 on its own and must obtain it from dietary sources. Foods that most people encounter almost every day—such as meat, whole grains, vegetables, and nuts—are all rich sources of vitamin B6.
From a chemical perspective, vitamin B6 does not exist as a single compound but rather as a “family” of related molecules. These include pyridoxine (PN), pyridoxal (PL), pyridoxamine (PM), and their respective phosphorylated forms. Among these, the form that exerts the most significant biological activity is pyridoxal 5′-phosphate (PLP).
How Vitamin B6 May Support Anti-Tumor Defense
A large number of epidemiological studies have shown that the higher the plasma level of PLP—the active form of vitamin B6—the lower the risk of multiple solid tumors. Related systematic meta-analyses have confirmed this relationship: higher dietary intake of vitamin B6 or higher PLP levels are significantly associated with a reduced risk of several cancers, including lung cancer, colorectal cancer, and breast cancer.
Cellular and animal experiments have further revealed possible mechanisms. When PLP levels are sufficient, the proliferation of tumor cells can be significantly suppressed, and tumor growth can be effectively slowed.
But how exactly does vitamin B6 exert these anti-tumor effects?
Taking lung cancer as an example, lung cancer currently has the highest mortality rate among cancers worldwide, causing more than 1.8 million deaths each year. Its development is closely associated with a chronic inflammatory microenvironment. Factors such as smoking, air pollution, and chronic infections continuously activate the classic inflammatory-tumor signaling axis known as NF-κB–IL-6–STAT3, driving normal lung tissue toward malignant transformation.
A high vitamin B6 status may act at this critical point. The review indicates that the higher the concentration of PLP in the blood, the stronger the protective effect against lung cancer. Researchers have also identified an indicator known as the “PAr index,” which reflects vitamin B6 metabolism and inflammatory status. A higher index suggests that vitamin B6 is being consumed more rapidly due to inflammation, leaving insufficient PLP available in the body. This may also indicate an increased risk of cancer.
Vitamin B6 also appears to provide significant protection against colorectal cancer.
As the third most common cancer worldwide, colorectal cancer causes approximately 935,000 deaths each year. Numerous prospective cohort studies have found that increasing daily vitamin B6 intake by 3–5 mg is associated with an 11%–17% reduction in colorectal cancer risk. When plasma PLP levels fall within the highest quartile, the risk of colorectal cancer can even be 30%–50% lower than that of individuals in the lowest quartile.
In other words, the more sufficient the body’s vitamin B6 “reserve,” the stronger the intestinal mucosa’s defense capacity when facing carcinogenic factors.
Why are these effects so pronounced? Researchers emphasize that inflammation is a key factor. Modern lifestyle factors such as smoking, obesity, and imbalanced diets act like “adding fuel to the fire” in the gut, continuously consuming vitamin B6 and leaving the body in a state of “subclinical deficiency.” One remarkable feature of vitamin B6 is its ability to help stabilize inflammatory processes.
Regarding breast cancer, the effects of vitamin B6 appear to be closely related to each woman’s hormonal status and genetic background.
For postmenopausal women, declining estrogen levels alter metabolic pathways and gene regulatory patterns. At this physiological turning point, the importance of vitamin B6 becomes even more pronounced. Several studies have shown that women with higher blood PLP levels after menopause have a significantly lower risk of developing invasive breast cancer. This protective effect appears particularly prominent in hormone receptor–positive breast cancers (ER+/PR+).
Importantly, the protective scope of vitamin B6 is not limited to hormone pathways alone. Some studies suggest that it may also offer potential protection against hormone receptor–negative breast cancers (ER−). This means that even when tumors no longer respond strongly to hormonal signals, vitamin B6 may still exert protective effects—for example, by suppressing chronic inflammation, alleviating oxidative stress, and maintaining the stability of DNA synthesis and repair.
In fact, in the broader context of cancer defense, vitamin B6 does far more than interact directly with tumor cells—it also plays a deep role in the immune system.
PLP can be captured by a non-classical immune-presenting molecule called MR1. When MR1 presents these “vitamin fragments” to a special group of MR1-restricted T cells, these immune cells become activated. This class of T cells possesses highly diverse T-cell receptors (TCRs), enabling them to recognize a broad range of targets and respond rapidly. Once activated, they can quickly join the immune response and significantly enhance overall anti-tumor immunity.
In addition, vitamin B6 is directly related to whether CD8⁺ T cells can operate at full capacity.
When CD8⁺ T cells become activated and carry out their cytotoxic functions, they rely heavily on a series of PLP-dependent transaminases to maintain energy supply and metabolic balance. If the activity of these key enzymes is inhibited, T cells may experience an “energy shortage,” leading to a noticeable decline in their killing efficiency.
In other words, without sufficient vitamin B6, even the most powerful immune cells may fail to perform at their full potential because their metabolic “power supply” is compromised.
Adequate Vitamin B6 Helps Maintain Immune Readiness
Interestingly, a previous study from a research team at Tsinghua University, published in the Cell-family journal Developmental Cell, found that vitamin B6 obtained through daily diet—and its active form PLP—not only participates in fundamental metabolism but also deeply influences the way the immune system functions. It helps CD8⁺ T cells maintain a more “youthful” and long-lasting state, making them less prone to exhaustion and better able to sustain anti-tumor activity.
This “youthful” state of T cells is referred to in immunology as “stemness.” In simple terms, CD8⁺ T cells are the immune system’s frontline “soldiers” responsible for killing cancer cells. However, under the long-term pressure of the tumor microenvironment, these cells can easily become “exhausted,” losing their ability to proliferate and gradually declining in function until they ultimately surrender their anti-tumor activity.
Nevertheless, a small subset of T cells appears particularly resilient. These cells retain stem-cell-like properties, allowing them to self-renew and maintain long-term functionality.
After analysis, the research team found that T cells treated with PLP showed significantly increased expression of markers associated with a “youthful” state (such as CD62L and TCF1), while markers associated with exhaustion (such as PD-1 and TIM3) were significantly reduced.
This suggests that PLP does not simply make T cells more activated. Rather, it maintains them in a more potent, stem-like state that is less prone to exhaustion, allowing these immune “fighters” to maintain long-term effectiveness without becoming depleted.
Notably, this research also holds potential clinical translational value. In a melanoma mouse model, researchers combined PLP with a commonly used immune checkpoint inhibitor—an anti-PD-1 antibody. The results showed a clear synergistic effect: the combination was more effective at inhibiting tumor growth than either PLP or anti-PD-1 therapy alone. It also significantly prolonged the survival of the mice, and some animals even achieved complete remission.
These findings suggest that PLP may not only optimize T-cell function on its own but also complement existing immunotherapies, making anti-tumor immune responses stronger and more sustained.
In this sense, everyday foods such as chicken, lean pork, salmon, spinach, potatoes, pistachios, and sunflower seeds truly contain hidden “nutritional treasures.” When properly incorporated into the diet, the vitamin B6 they provide can be converted in the body into compounds that support immune defense and maintain cellular stability.
References
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Mishra SK, Li B, Costa ASH, Van Aelst L, Zhang L. Multifaceted role of the vitamin B6 pathway in cancer: metabolism, immune interaction, and temporal and spatial regulation. Genes & Development. 2025;39(21–22):1271–1289. doi:10.1101/gad.352770.125.
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Wu J, Li G, Zhou J, Sun X, Wang H, Gong H, Jiang P. Vitamin B6 preserves the stemness-like phenotypes and antitumor ability of CD8+ T cells. Developmental Cell. 2025. doi:10.1016/j.devcel.2025.10.017.