What foods raise RDW levels? A nutritional guide

January 1, 2026 •

5 min read

An elevated red cell distribution width (RDW) often indicates underlying nutritional deficiencies, a common cause of anemia. Understanding what foods raise RDW levels by providing essential nutrients is key to managing this condition and supporting overall red blood cell health.

Quick Summary

RDW measures the size variation of red blood cells, and elevated levels often signal deficiencies in key nutrients like iron, folate, and vitamin B12. Adjusting your diet to include rich sources of these vitamins and minerals can help normalize red blood cell production.

Key Points

RDW is a Blood Health Indicator: An elevated RDW means your red blood cells vary widely in size, a condition known as anisocytosis.
High RDW Often Signals Nutrient Deficiencies: A lack of iron, vitamin B12, or folate are common nutritional causes of high RDW.
Iron-Rich Foods Help Address Microcytic Anemia: Diets high in heme iron (meat, liver) and non-heme iron (spinach, lentils) can help normalize red blood cell size.
B12 and Folate Correct Macrocytic Anemia: Consuming foods like meat, fish, eggs, dairy, leafy greens, and legumes can help regulate red blood cell size when a deficiency is present.
Certain Foods Inhibit Absorption: Tannins in tea and coffee, and phytates in grains, can block iron absorption, potentially worsening deficiencies.
Lifestyle Affects RDW Levels: Beyond diet, getting adequate sleep, exercising, and avoiding alcohol and smoking are important for supporting healthy blood parameters.

Understanding Red Cell Distribution Width (RDW)

Red Cell Distribution Width (RDW) is a measurement of the variation in size and volume of red blood cells (RBCs). It is typically part of a complete blood count (CBC) test ordered by a healthcare provider. A high RDW, or anisocytosis, means that the red blood cells are more varied in size than what is considered normal. This can be an early indicator of a problem with red blood cell production, often preceding changes in other blood parameters.

When your body is deficient in certain vitamins and minerals, it can struggle to produce a consistent size of red blood cell. For instance, in the early stages of a deficiency, the bone marrow might produce a mix of large and small, misshapen cells, leading to a wider size distribution and a higher RDW score. Conditions like iron-deficiency anemia, vitamin B12 deficiency anemia (megaloblastic anemia), and folate deficiency anemia are strongly linked to elevated RDW.

Foods That Can Influence High RDW Levels

Certain foods are crucial for providing the necessary vitamins and minerals that support healthy red blood cell production. Deficiencies in these nutrients are a primary reason why a person might see a rise in their RDW levels. By consuming these foods, one can help correct these deficiencies and potentially lower RDW.

Iron-Rich Foods

Iron is a vital component of hemoglobin, the protein in red blood cells that carries oxygen. Iron deficiency is a very common cause of high RDW, as the body produces smaller-than-normal red blood cells (microcytic anemia).

Heme Iron Sources (Highly Absorbed):
- Red Meat: Beef, lamb, and other red meats are excellent sources of heme iron.
- Organ Meats: Liver, in particular, is extremely rich in iron.
- Seafood: Clams, oysters, mussels, and sardines provide high levels of iron.
Non-Heme Iron Sources (Lower Absorption):
- Dark Leafy Greens: Spinach and kale contain significant amounts of non-heme iron.
- Legumes: Lentils, chickpeas, and beans are plant-based iron powerhouses.
- Nuts and Seeds: Pumpkin seeds, almonds, and cashews are great snack options.
- Fortified Cereals: Many breakfast cereals and breads are fortified with iron.

Vitamin B12-Rich Foods

Vitamin B12 is essential for producing healthy, uniformly-sized red blood cells. A deficiency can lead to the production of abnormally large red blood cells (macrocytic anemia), significantly increasing RDW. Vitamin B12 is primarily found in animal products.

Meat: Beef, chicken, and other poultry are good sources.
Fish: Salmon, trout, and tuna are packed with B12.
Dairy: Milk, cheese, and yogurt provide B12.
Eggs: A simple and effective way to boost B12 intake.
Fortified Foods: Vegetarians and vegans can find B12 in fortified breakfast cereals, nutritional yeast, and plant milks.

Folate (Vitamin B9)-Rich Foods

Folate is another B vitamin critical for DNA synthesis and red blood cell formation. Like B12 deficiency, low folate can cause megaloblastic anemia, leading to an elevated RDW.

Green Vegetables: Spinach, broccoli, Brussels sprouts, and asparagus are high in folate.
Fruits: Oranges and other citrus fruits contain folate.
Legumes: Lentils, chickpeas, and peas are excellent sources.
Nuts and Seeds: Peanuts are particularly good.
Fortified Grains: Many breads, cereals, and flours are fortified with folic acid, the synthetic form of folate.

Foods and Habits That Hinder Nutrient Absorption

While eating the right foods is important, certain dietary habits and food items can interfere with nutrient absorption, indirectly contributing to high RDW levels.

Calcium-Rich Foods: High-calcium dairy products can inhibit the absorption of non-heme iron. It is best to consume dairy at a different time than iron-rich plant-based meals.
Tea and Coffee: Tannins found in tea and coffee can bind to iron, reducing its absorption. Drinking these beverages between meals rather than with them can mitigate this effect.
Phytates: Found in whole grains, legumes, and seeds, phytates can also hinder iron absorption. Soaking or sprouting these foods can reduce their phytate content.
Excessive Alcohol: Chronic and excessive alcohol consumption can negatively impact red blood cell production and hinder the absorption of vitamins like B12 and folate.

Comparison Table: Nutrient-Rich Foods for RDW Support


Nutrient	Animal-Based Sources	Plant-Based Sources	Key Advantage	How it Affects RDW
Iron	Red Meat, Liver, Seafood	Spinach, Lentils, Fortified Cereals	Heme iron is more easily absorbed by the body.	Corrects microcytic anemia, normalizes RBC size.
Vitamin B12	Meat, Eggs, Dairy	Fortified Cereals, Nutritional Yeast	Readily available and bioavailable.	Corrects macrocytic anemia, normalizes RBC size.
Folate (B9)	Liver, Eggs, Poultry	Dark Leafy Greens, Legumes, Citrus Fruits	Folate is essential for cell formation.	Corrects macrocytic anemia, normalizes RBC size.

Management and Lifestyle Factors Beyond Diet

While diet is a critical factor, other elements influence RDW levels. Medical conditions like chronic liver disease, kidney disease, diabetes, and infections can also cause elevated RDW. Therefore, a holistic approach is vital for management.

Regular Exercise: Staying physically active can support healthy blood circulation and overall cell production.
Adequate Sleep: Studies have shown a correlation between a good night's sleep (7–8 hours) and lower RDW levels.
Avoid Smoking: Smoking can negatively affect red blood cell production.
Manage Underlying Conditions: Adhering to your doctor's treatment plan for chronic diseases is essential for maintaining blood health.

For a more comprehensive understanding of the RDW test and its results, you can consult reliable medical resources such as the information provided by MedlinePlus, a service of the U.S. National Library of Medicine.

Conclusion

Foods that raise RDW levels are not a single category but rather foods containing or lacking key nutrients that influence red blood cell size variation. An elevated RDW is a significant indicator of nutritional deficiencies, particularly a lack of iron, vitamin B12, or folate. Addressing these deficiencies through a balanced, nutrient-dense diet is a primary step in correcting the issue. For instance, incorporating iron-rich meats and leafy greens, B12-rich fish and dairy, and folate-rich legumes and vegetables can be highly effective. Simultaneously, avoiding foods and drinks that inhibit nutrient absorption, like excessive tea or coffee with meals, is crucial. Since high RDW can also stem from other medical conditions, it is always important to consult a healthcare provider for an accurate diagnosis and personalized treatment plan.

Frequently Asked Questions

RDW stands for Red Cell Distribution Width, a measure of the variation in red blood cell size. A high RDW means your cells vary significantly in size, which can be an early sign of a nutritional deficiency (like iron, B12, or folate) or other underlying health issues such as anemia.

For iron deficiency, focus on heme iron from animal sources like red meat, liver, and seafood, as it's more easily absorbed. For plant-based options, include leafy greens like spinach, legumes like lentils, and fortified cereals, and pair them with vitamin C to enhance absorption.

Vitamin B12 is primarily found in animal products. Good sources include beef, chicken, fish (like salmon and tuna), eggs, and dairy products such as milk and yogurt. Fortified cereals and nutritional yeast are excellent alternatives for vegans and vegetarians.

A diet low in folate (vitamin B9) can cause megaloblastic anemia, where the body produces abnormally large red blood cells. This increase in size variability is a direct cause of a high RDW score.

It is advisable to limit intake of tea, coffee, and high-calcium dairy products during iron-rich meals, as they can inhibit iron absorption. Excessive alcohol consumption can also interfere with B12 and folate absorption.

Yes, water-soluble vitamins like folate can be lost when vegetables are overcooked or boiled. Steaming or microwaving vegetables for shorter periods can help preserve more of their nutrient content.

Adequate sleep (7-8 hours), regular exercise, and avoiding smoking and excessive alcohol consumption can help support healthy red blood cell production and circulation, which may contribute to normalizing RDW levels.

No, while diet is a common factor, high RDW can also be caused by chronic illnesses like liver or kidney disease, heart disease, infections, or inherited blood disorders. A doctor's diagnosis is necessary to determine the underlying cause.