What Deficiency Makes You Really Cold? An In-Depth Guide

November 17, 2025 •

4 min read

According to the World Health Organization, iron deficiency anemia affects approximately 30% of the world's population, making it the most common nutritional deficiency and a frequent cause of feeling really cold. For many, persistent cold hands and feet or a general sensitivity to low temperatures may point towards an underlying nutrient deficiency affecting the body's ability to regulate its temperature effectively.

Quick Summary

This guide explains the primary deficiencies linked to a constant feeling of coldness, including iron, B12, and folate deficiencies. It details how these nutrient shortfalls impact blood circulation, metabolism, and nerve function, leading to cold intolerance. Also covered are other conditions that can cause persistent cold sensitivity.

Key Points

Iron Deficiency Anemia: Often causes cold intolerance due to a lack of hemoglobin, which reduces oxygen delivery and heat production throughout the body.
B12 and Folate Deficiencies: Can lead to megaloblastic anemia, impairing red blood cell and nerve function, which results in poor circulation and cold extremities.
Hypothyroidism: An underactive thyroid gland slows down metabolism, a key heat-generating process, making one feel consistently cold.
Low Body Weight: Insufficient body fat, which acts as natural insulation, makes underweight individuals more susceptible to cold temperatures.
Dehydration: Water is essential for metabolic heat production, so inadequate hydration can slow down metabolism and lead to cold sensitivity.
Raynaud's Phenomenon: A condition where small blood vessels in the fingers and toes spasm, restricting blood flow and causing intense cold sensations.

The Connection Between Nutrient Deficiencies and Feeling Cold

Feeling colder than those around you can be an uncomfortable and confusing experience. While individual body composition and metabolism play a role, a persistent sensitivity to cold, known as cold intolerance, is often a symptom of an underlying health issue, particularly a nutrient deficiency. The body’s ability to generate and conserve heat, a process called thermoregulation, is complex and requires several essential vitamins and minerals to function properly. When the levels of these nutrients drop, it can slow down your metabolism and impair blood circulation, leaving you feeling chilly even in a warm room.

Iron Deficiency and Anemia

Iron is arguably the most common deficiency associated with feeling cold, primarily because it leads to anemia. Iron is a crucial component of hemoglobin, the protein in red blood cells responsible for transporting oxygen from your lungs to your body's tissues.

Decreased Oxygen Transport: With an iron deficiency, your body can't produce enough healthy red blood cells, leading to insufficient oxygen delivery. Less oxygen means less metabolic activity in the tissues, which reduces heat production.
Impaired Thermoregulation: Studies have shown that iron deficiency impairs the body's adaptive thermogenesis—the process of generating heat in response to cold.
Impact on Thyroid Function: Iron is also necessary for the production of thyroid hormones, which regulate metabolism. A deficiency can lead to lower levels of these hormones, further contributing to cold intolerance.

The Role of B Vitamins (B12 and Folate)

Deficiencies in certain B vitamins, particularly B12 and B9 (folate), can also cause cold sensitivity by leading to a specific type of anemia. These vitamins are vital for the production of red blood cells, and a shortfall results in megaloblastic anemia, where red blood cells are fewer and abnormally large.

Vitamin B12 Deficiency: Low B12 levels disrupt healthy red blood cell formation and nerve function. This can cause reduced oxygen transport and nerve problems, such as peripheral neuropathy, which can manifest as tingling, numbness, and cold hands and feet.
Folate (B9) Deficiency: Folate works closely with B12 in creating red blood cells. A deficiency leads to similar anemic symptoms, including fatigue and cold intolerance, as it hinders proper oxygen delivery.

Other Nutritional Causes

While iron and B vitamins are the most direct culprits, other nutritional issues can also contribute to feeling cold.

Low Body Weight: Individuals with a very low body mass index (BMI) have less body fat, which acts as natural insulation. With inadequate fat stores, the body is less able to conserve heat.
Dehydration: Water is a key component of metabolic processes that generate energy and heat. Being dehydrated can slow down your metabolism, making you more sensitive to temperature changes.

Deficiency-Related Cold Sensitivity vs. Other Conditions

Cold intolerance can be caused by more than just nutrient deficiencies. Other medical conditions can also impact the body's thermostat, requiring a proper diagnosis from a healthcare professional.


Feature	Nutrient-Related Cold Sensitivity (Anemia)	Hypothyroidism	Raynaud's Phenomenon	Peripheral Artery Disease	Low BMI (Anorexia)
Mechanism	Impaired oxygen delivery due to lack of healthy red blood cells.	Slowed metabolism due to insufficient thyroid hormones.	Spasms in small blood vessels restrict blood flow to extremities.	Plaque buildup narrows arteries, reducing blood flow to limbs.	Lack of insulating body fat and low metabolic rate.
Key Symptoms	Fatigue, weakness, pale skin, cold hands/feet.	Fatigue, weight gain, dry skin, constipation, thinning hair.	Fingers/toes turn white or blue when exposed to cold or stress.	Pain, numbness, or weakness in legs, one leg colder than other.	Extreme weight loss, distorted body image, severe food restriction.
Diagnostic Test	Complete Blood Count (CBC) and iron/B12 level tests.	Thyroid-stimulating hormone (TSH) and free T4/T3 tests.	Physical exam, sometimes involving a cold-stimulation test.	Ankle-brachial index (ABI) test, ultrasound.	Psychological evaluation, BMI assessment.

Lifestyle and Dietary Adjustments

Addressing a nutrient deficiency often requires dietary changes and, in some cases, supplements. Always consult a healthcare provider before starting any supplement regimen to ensure proper dosage and type. For deficiencies causing cold sensitivity, a few key strategies are often recommended:

Increase Iron Intake: Consume more iron-rich foods like red meat, poultry, fish, beans, and dark leafy greens. Pairing these with foods high in vitamin C (like citrus fruits or broccoli) can enhance iron absorption.
Boost B Vitamin Consumption: Incorporate more B12-rich foods such as meat, eggs, and dairy. For vegans, fortified cereals and B12 supplements are essential. Folate can be found in leafy greens, legumes, and fortified grains.
Maintain Hydration: Drink plenty of water throughout the day. Water supports metabolic function and helps regulate body temperature.
Moderate Exercise: Regular, moderate physical activity can improve circulation and boost metabolism, helping the body generate more heat.
Manage Underlying Conditions: If your cold sensitivity is due to a condition like hypothyroidism, managing it with prescribed medication is crucial for correcting metabolic and temperature regulation issues.

Conclusion: Seeking a Medical Diagnosis

While a deficiency in iron, vitamin B12, or folate is a common cause of feeling really cold, it is important not to self-diagnose. Other, more serious health conditions, like hypothyroidism, can present with similar symptoms. A healthcare provider can perform a simple blood test to check for nutrient deficiencies and thyroid function. They can accurately identify the root cause of your cold intolerance and recommend the most effective treatment plan, whether it involves dietary adjustments, supplements, or managing an underlying medical condition. Addressing the cause will not only help you warm up but will also improve your overall health and well-being.

Learn more about the science of iron and thermoregulation from the NIH

Frequently Asked Questions

Deficiencies in vitamin B12 and folate (vitamin B9) can cause you to feel cold by leading to megaloblastic anemia, a condition characterized by fewer, larger red blood cells that cannot efficiently transport oxygen.

Iron deficiency reduces the body's ability to produce hemoglobin, which is vital for carrying oxygen in the blood. Lower oxygen transport impairs the body's metabolic heat production, resulting in chronic cold hands, feet, and an overall feeling of coldness.

Yes, hypothyroidism (underactive thyroid) is a common cause of cold intolerance and shares symptoms like fatigue with nutrient deficiencies. It slows down the body's metabolism and heat generation, and a healthcare provider can distinguish it from a deficiency with a blood test.

The thyroid gland produces hormones that regulate metabolism, the process by which your body creates energy and heat. If the thyroid is underactive, metabolism slows, and the body's ability to generate heat is impaired, leading to cold intolerance.

Besides deficiencies, other factors include low body weight (less insulating fat), poor blood circulation from conditions like peripheral artery disease, and certain medications. Sleep deprivation and chronic illness can also affect thermoregulation.

You should see a doctor if your cold intolerance is a new or persistent symptom, or if it is accompanied by other symptoms like fatigue, dizziness, pale skin, or weight changes. A healthcare professional can perform tests to diagnose the underlying cause.

Yes, as vitamin B12 is primarily found in animal products, vegetarians and especially vegans are at a higher risk of B12 deficiency. Folate deficiency can also occur, though plant-based diets rich in leafy greens typically provide plenty of this nutrient. Regular testing and fortification are important.