The Red Cell Distribution Width (RDW) is a measurement reported as part of a standard blood test that reflects the variation in size of your red blood cells (RBCs). A high RDW score, medically termed anisocytosis, means there is a significant difference between the largest and smallest RBCs in your bloodstream. This variation indicates inconsistent RBC production, which can compromise the cells’ ability to efficiently transport oxygen. While a high RDW is not a diagnosis, it signals an underlying issue disrupting normal blood cell production. The following steps explore dietary and lifestyle adjustments that may help normalize this measurement, but all blood test results require discussion with a medical professional for proper diagnosis and management.
Understanding Elevated RDW
An elevated RDW score often points to issues in the bone marrow’s ability to produce uniform red blood cells, primarily due to nutritional deficiencies. Specific vitamins and minerals are required to synthesize hemoglobin and build healthy red blood cells. A lack of these substances results in cells abnormal in size.
Iron deficiency is a common cause; its lack results in smaller red blood cells (microcytes). Conversely, deficiencies in Vitamin B12 or Folate (Vitamin B9) impair DNA synthesis, causing the bone marrow to release abnormally large, immature red blood cells (macrocytes). A high RDW often results from a mix of new, differently sized cells alongside older cells, or when multiple deficiencies exist. Chronic inflammatory conditions, such as kidney or liver disease, can also interfere with cell production and maturation, elevating the RDW score.
Targeted Nutritional Strategies
Dietary changes targeting specific nutrient gaps are the most effective strategy for lowering RDW caused by nutritional issues. To address iron deficiency, focus on consuming highly bioavailable heme iron, found in animal products like lean beef, poultry, and fish. Non-heme iron, found in plant sources such as lentils, spinach, and fortified cereals, should be paired with Vitamin C-rich foods (e.g., citrus fruits or bell peppers) to enhance absorption.
For Vitamin B12 deficiencies, the focus should be on animal products including meat, eggs, and dairy, as B12 is not naturally present in plant foods. Individuals following a vegan diet or older adults with reduced stomach acid may need fortified foods or supplements. Folate (B9) is critical for cell division and is abundant in dark leafy greens such as kale and spinach, as well as legumes like black beans and chickpeas. Consuming these folate-rich foods ensures the body has the necessary building blocks for new, healthy red blood cells.
Addressing Non-Dietary Factors
Beyond specific nutrient intake, several lifestyle factors influence the overall health and uniformity of red blood cells. Maintaining adequate hydration is important, as severe dehydration can temporarily increase the concentration of blood components, potentially affecting RDW measurement and overall blood viscosity. Excessive alcohol consumption is detrimental, as it interferes with the absorption and metabolism of B vitamins (especially folate and B12) and suppresses bone marrow activity.
While diet is preferred for long-term normalization, severe deficiencies may require therapeutic intervention with medical-grade supplements. For instance, a doctor may prescribe high-dose iron tablets or Vitamin B12 injections for those with significant malabsorption issues. RDW can also be a marker of underlying chronic illnesses, such as celiac disease, inflammatory bowel disease, or kidney dysfunction, which require targeted medical treatment beyond diet and lifestyle modifications.
Monitoring and Medical Follow-up
The process of normalizing RDW levels requires consistent effort and careful monitoring under a doctor’s supervision. After implementing significant dietary or lifestyle changes, blood work is typically retested within four to twelve weeks to assess the effectiveness of the intervention. This retesting period allows enough time for the bone marrow to produce new populations of red blood cells in response to the improved nutrient availability.
Medical follow-up is necessary to diagnose the specific root cause, such as distinguishing between different types of anemia. A doctor uses the RDW in conjunction with other blood indices, like Mean Corpuscular Volume (MCV), to pinpoint the exact deficiency or medical condition. Patients should seek immediate medical review if they experience severe symptoms like extreme, unexplained fatigue, persistent shortness of breath, significant pallor, or a new onset of balance issues, as these can signal severe anemia or a rapidly progressing underlying condition.