The Journey of Nutrients: From Ingestion to Cellular Function
When you consume a vitamin or enjoy a meal, the nutrients you ingest begin a complex journey. Initially, they break down in your stomach and enter your bloodstream. But what happens after that? How do these nutrients transition from your arteries into the cells where they perform essential functions? What determines whether certain nutrients nourish your brain while others bolster your immune system?
In human blood, there are approximately 5,000 different metabolites, the end products of nutrition. However, scientists are still unraveling the mystery of how most of these metabolites enter cells. This understanding is crucial for linking our dietary intake to health maintenance and for demystifying the $200 billion supplement industry, which operates on the assumption that dietary elements reach their intended destinations.
Moreover, this knowledge could transform cancer treatment. Cancer cells consume nutrients at a faster rate and in larger quantities than normal cells, providing them with the energy needed to grow and spread.
Mapping Nutrient Highways: The Work of Kivanç Birsoy
Kivanç Birsoy, who leads the Laboratory of Metabolic Regulation and Genetics at Rockefeller University, is dedicated to mapping nutrient pathways with meticulous curiosity and a bold vision. His research focuses on transporters—tiny protein channels that function like specialized delivery trucks, transporting molecular cargo from the bloodstream into and within cells.
In a recent interview, Birsoy discussed the significance of understanding these transporters for human health and disease.
The Role of Transporters in Health and Disease
Most vitamins and supplements available in stores have not been studied in ways that demonstrate their actual effects in the body. Take vitamin C, for instance. Many people believe it helps them fend off colds, but studies offer mixed results. Some suggest it is beneficial, while others find it ineffective. Even when a supplement appears helpful, the optimal dosage and the individuals who would benefit most remain unclear.
The issue is that most studies only show correlations. They might indicate that people who take a particular supplement are healthier, but they cannot prove the supplement is the cause. To truly understand what a nutrient does—and does not do—we must determine how and when nutrients enter our cells and what happens to them once inside. This is the focus of Birsoy’s lab.
Cancer Cells: Resourceful and Resilient
Birsoy was captivated by the resourcefulness of cancer cells. They grow and spread at an extraordinary rate, far exceeding that of normal cells, which means they require significantly more fuel. Interestingly, tumors do not merely rely on available fuel; they rewire their metabolic machinery to extract more nutrients from their environment or to survive when resources are scarce.
Early in his career, Birsoy realized that identifying the specific nutrients cancer cells need and how they acquire them could potentially cut off their supply.
Targeting Cancer’s Nutrient Supply
Birsoy’s research has identified vulnerabilities in cancer cells that could be exploited to halt tumor growth or spread. In one study, his lab demonstrated how cancer cells activate a gene that enables them to absorb the amino acid aspartate from their surroundings. Cells with this gene grow faster. Currently, the lab is investigating drugs that disrupt a cancer cell’s ability to produce or absorb aspartate.
In another study, Birsoy’s team discovered that some cancer cells heavily depend on an antioxidant called glutathione to protect themselves from damage and facilitate their spread. These cells require much more glutathione than normal cells. By blocking the transporter responsible for delivering glutathione into cancer cells, the team can prevent the cells from spreading.
Implications for Antioxidant Use
This information is crucial because conventional wisdom suggests antioxidants are beneficial. Generally, they are. However, in certain situations, such as some cancers, specific antioxidants could actually fuel disease.
By targeting these pathways with drugs, it may be possible to directly kill cancer cells or enhance the immune system’s ability to attack them, especially if we can prevent cancer cells from hoarding the nutrients they use to evade immune detection.
The Complexity of Transporters
The challenge is immense, as there are thousands of different transporters, each specialized to move specific nutrients. The research begins with genetic studies of humans. If someone has a mutation in a gene linked to a transporter, it often manifests as an issue with certain nutrient levels in their blood.
Once a potential transporter or sensor is identified, it is tested by removing the gene from isolated cells or animal models. This approach led to the discovery of SLC25A39, the transporter for glutathione. Initially, the team searched for proteins that responded to changes in glutathione levels. They confirmed SLC25A39 as the correct transporter by blocking it and observing that cells were suddenly deprived of glutathione.
Beyond Transport: SLC25A39 as a Sensor
SLC25A39 is not just a transporter; it also acts as a sensor that helps cells maintain balanced glutathione levels. This balance is crucial because issues with glutathione transport have been linked to conditions such as cancer, neurodegeneration, and aging.
Recently, the team identified a transporter responsible for moving a vitamin-like lipid called choline into cells. Scientists knew that mutations in a particular transporter gene cause the rare disease posterior column ataxia with retinitis pigmentosa (PCARP), leading to blindness and neurodegeneration. However, the reason was unclear. The team showed that the issue arises because cells cannot obtain enough choline when the transporter malfunctions.
Potential for Life-Changing Discoveries
This discovery is not only fascinating but also potentially life-changing. The team is already collaborating with doctors to design clinical trials using high levels of choline to slow or even halt the progression of blindness in individuals with this disorder.
Exploring Mitochondrial Nutrient Transport
The research also extends to understanding how nutrient transporters move molecules into mitochondria, the cellular structures that function as power plants, converting nutrients into energy. Understanding how mitochondria absorb and process these nutrients could be key to treating disorders linked to mitochondrial dysfunction, including neurodegeneration and aging.
The Future of Transporter Research
Many transporters are associated with diseases and drug targets. The overarching goal is that by mapping how transporters function, we can develop better drugs and use nutritional supplements more effectively. This knowledge may also enable us to customize dietary intake to improve health outcomes. While this requires extensive basic biology research, it has the potential to impact millions of lives. The progress is already evident.
🔗 **Fuente:** https://medicalxpress.com/news/2025-06-qa-discusses-nutrients-body-cancer.html