The Primary Culprits: Testosterone and EPO
The most significant and well-documented causes of supplement-related high red blood cell (RBC) counts, or erythrocytosis, are hormonal treatments and certain performance-enhancing drugs. Understanding the mechanisms behind these is crucial for anyone using them, or considering their use.
Testosterone Replacement Therapy (TRT)
Testosterone replacement therapy is a common treatment for low testosterone (hypogonadism) in men. One of its recognized and frequently monitored side effects is an increase in hemoglobin and hematocrit levels, which reflects a higher RBC count. The mechanism involves testosterone stimulating the production of erythropoietin (EPO), a hormone made in the kidneys. EPO, in turn, signals the bone marrow to produce more red blood cells. While beneficial for men with low testosterone-related anemia, excessive production can lead to serious risks. The increase in RBC count from TRT is dose-dependent, and the method of administration can influence the degree of elevation; for instance, intramuscular injections are often associated with a higher risk of erythrocytosis than transdermal gels or patches.
Recombinant Erythropoietin (rEPO)
Recombinant EPO is a drug that mimics the body's natural erythropoietin. It is legitimately used in medical settings to treat anemia associated with chronic kidney disease or chemotherapy. However, it is infamously misused in endurance sports for blood doping. Athletes use it to increase RBC mass, which enhances oxygen delivery to muscles and boosts stamina. This practice is banned by the World Anti-Doping Agency (WADA) due to its life-threatening health risks. The misuse of rEPO leads to an uncontrolled surge in RBCs, making the blood excessively thick and increasing the likelihood of blood clots, heart attack, and stroke.
Vitamins and Minerals: The Cautious Approach
For most healthy individuals, standard vitamin and mineral supplements are unlikely to cause a pathologically high RBC count. However, for those with pre-existing conditions or iron overload, certain supplements must be handled with care.
Iron Supplements
Iron is an essential mineral for hemoglobin production, which is a key component of red blood cells. For people with iron-deficiency anemia, iron supplementation is necessary to increase RBC levels and restore health. Conversely, in individuals with a high RBC count, especially those with conditions like polycythemia vera (PV), adding iron can exacerbate the problem. In PV, the bone marrow is already overproducing blood cells, and supplementing with iron provides more fuel for this process, which is why patients with this condition are typically advised to avoid iron supplements.
B Vitamins (B12 and Folate)
Vitamin B12 and folate (B9) are vital for the formation of red blood cells. Deficiencies can cause anemia, leading to low RBC counts. However, in people with certain blood disorders like PV, supplementation with B12 and folate could further contribute to increased RBC production, making careful monitoring essential. A healthcare provider can assess whether supplementation is appropriate based on an individual's specific blood work and diagnosis.
The Dangers of Elevated RBC: Erythrocytosis
Erythrocytosis is the medical term for an abnormally high RBC count, which can result from supplement use. This condition increases the viscosity (thickness) of the blood, which makes it flow more slowly and can lead to a number of dangerous complications.
Common symptoms of high RBCs include:
- Headaches
- Dizziness or fatigue
- Blurry vision
- Shortness of breath
- Itchy skin, particularly after a warm shower or bath
- Numbness or tingling in extremities
Serious risks associated with erythrocytosis include:
- Blood Clots: The thickened blood is more prone to clotting in veins and arteries.
- Stroke: A clot can travel to the brain, blocking blood flow.
- Heart Attack: Clots can block arteries supplying blood to the heart.
- Deep Vein Thrombosis (DVT): A blood clot in a deep vein, usually in the legs.
- Pulmonary Embolism (PE): A clot that breaks off and travels to the lungs.
Comparison of RBC-Increasing Substances
| Substance | Type | Mechanism for Increased RBC | Primary Health Risks from Overproduction |
|---|---|---|---|
| Testosterone (TRT) | Hormone Therapy | Stimulates erythropoietin (EPO) production in kidneys, signaling bone marrow to create more RBCs. | High blood viscosity, increased risk of blood clots, stroke, and heart attack. |
| Recombinant EPO | Performance-Enhancing Drug | Directly boosts red blood cell production, dramatically increasing RBC mass and oxygen-carrying capacity. | Severely thickened blood, catastrophic blood clots, stroke, heart attack, and death, especially exacerbated by dehydration. |
| Iron Supplements | Mineral Supplement | Provides essential raw material (iron) for hemoglobin production, which forms part of RBCs. | In individuals with normal or high iron stores, it can contribute to erythrocytosis; in polycythemia vera patients, it fuels further uncontrolled RBC production. |
| B Vitamins (B12 & Folate) | Vitamin Supplement | Necessary for DNA synthesis and RBC maturation in the bone marrow. | While typically safe, in patients with myeloproliferative disorders like PV, it may support an already overactive RBC production process. |
Conclusion: Prioritize Medical Supervision
While the market is flooded with supplements, the risk of developing a dangerously high red blood cell count primarily stems from specific hormonal therapies and illicit performance-enhancing drugs. Testosterone replacement therapy and the misuse of recombinant EPO are the most significant culprits. The risk with common vitamins and minerals is much lower, though improper use, such as taking iron supplements when not deficient, can still be problematic, especially for those with certain blood disorders. Given the potential for serious cardiovascular complications associated with erythrocytosis, it is critical to seek medical supervision before starting any supplement regimen that could affect blood cell counts. Regular monitoring through blood tests is the most effective way to ensure safety and prevent adverse effects. If you are considering testosterone therapy or are being treated for anemia, a healthcare provider can help you navigate the risks and benefits safely.
References
- Viva Vitality MN. "Does Testosterone Increase Red Blood Cells?" vivavitalitymn.com, 24 April 2025, https://www.vivavitalitymn.com/does-testosterone-increase-red-blood-cells/.
- Sport Integrity Australia. "EPO - What You Need To Know." sportintegrity.gov.au, 29 October 2024, https://www.sportintegrity.gov.au/news/integrity-blog/2024-10/epo-what-you-should-know.
- Cleveland Clinic. "High Red Blood Cell Count: Symptoms, Meaning, Causes." my.clevelandclinic.org, https://my.clevelandclinic.org/health/symptoms/17810-high-red-blood-cell-count.
- Dr. Oracle. "Does Polycythemia Vera (PV) respond to iron supplementation?" droracle.ai, 16 May 2025, https://www.droracle.ai/articles/122562/polycythemia-vera-give-iron.
- Hone Health. "High Hematocrit on TRT? Here's How to Reduce It." honehealth.com, 13 February 2025, https://honehealth.com/edge/how-to-lower-hematocrit-on-trt/.
