The Truth Behind Aging and Blood Viscosity
The idea that our blood becomes thinner as we age is a persistent myth, often stemming from observations of easy bruising or slower wound healing. However, hematological studies present a more complex picture. For most healthy individuals, normal aging is associated with an increase in blood viscosity, not a decrease. Several factors contribute to this change in the blood's flow properties, which play a significant role in tissue perfusion and overall cardiovascular function.
Why Blood Actually Becomes Thicker with Age
Increased blood viscosity is a result of several key physiological changes that occur over the lifespan. These include:
- Elevated Fibrinogen Levels: A persistent, low-grade inflammatory state, common with aging, can lead to higher levels of the protein fibrinogen in the blood. Fibrinogen is crucial for blood clotting, but higher concentrations can increase the thickness of the blood plasma and promote greater aggregation of red blood cells.
- Impaired Red Blood Cell (RBC) Deformability: Healthy red blood cells are flexible, allowing them to squeeze through the body's smallest capillaries. With age, these cells can become more rigid and less able to deform. This rigidity is a significant contributor to increased whole blood viscosity and can hinder blood flow, especially in the brain's tiny blood vessels.
- Enhanced RBC Aggregation: Higher levels of fibrinogen and other factors cause red blood cells to stick together more readily, a process called rouleaux formation. This aggregation increases blood viscosity, especially at low shear rates (i.e., in smaller vessels where blood flow is slower).
- Reduced Total Body Water: Normal aging causes a reduction in total body water, leading to less fluid in the bloodstream and a decrease in overall blood volume. While this doesn't directly thin the blood, it's another factor that can influence its composition and flow characteristics.
Understanding Common Misconceptions
Many of the symptoms sometimes wrongly attributed to "thin blood" are, in fact, caused by other age-related factors. Here's a comparison to clarify some common misunderstandings:
| Observation / Belief | Scientific Reality | Explanation |
|---|---|---|
| Easy Bruising | Possible causes: Fragile capillaries, certain medications, or thinner skin. | While often associated with thinning blood, bruising is more likely caused by weaker blood vessels and skin in older adults. Blood-thinning medication can also increase bruising. |
| Feeling Cold | Possible causes: Slower metabolism, reduced circulation, or diminished cold tolerance. | Age-related changes in metabolism and decreased peripheral circulation, not blood viscosity, are often responsible for a reduced tolerance to cold temperatures. |
| Slower Wound Healing | Possible causes: Decreased immune function, nutrient deficiencies, or reduced circulation. | The body's slower response to repair damaged tissue is a complex process involving many factors, not just blood flow. It is not an indicator of thin blood. |
| Bleeding that Takes Longer to Stop | Possible causes: Use of blood-thinning medications or a lower number of platelets (thrombocytopenia). | This is a side effect of anticoagulant drugs, which inhibit clot formation, or a sign of a distinct medical condition, not a natural change of aging. |
Medications and the Role of Anticoagulants
It is important to differentiate between natural age-related changes and the effects of medication. Some seniors are prescribed anticoagulants, often referred to as "blood thinners," to reduce their risk of blood clots, heart attacks, and strokes. These medications, such as warfarin or Eliquis, do not actually make the blood thinner but rather inhibit the clotting process. This significantly increases the risk of excessive bleeding, which is a concern for older adults.
It is crucial for any senior taking these medications to follow their doctor's instructions carefully and report any signs of unusual bleeding. Assessing the risk-benefit ratio of these medications is a key part of managing care for elderly patients.
Promoting Healthy Blood and Circulation as You Age
Even though your blood may naturally become thicker, proactive steps can help support healthy blood flow and cardiovascular function as you get older.
- Stay Hydrated: Dehydration can cause blood to thicken. Drinking plenty of water throughout the day is one of the simplest and most effective ways to maintain optimal blood thickness and support overall health.
- Regular Physical Activity: Regular exercise, like walking or swimming, can significantly improve cardiovascular health. It gets your heart pumping and blood flowing, promoting better circulation throughout the body. Some studies also suggest physical activity may improve hemorheological parameters in older subjects.
- Balanced Diet: A heart-healthy diet rich in fruits, vegetables, whole grains, and lean proteins helps maintain healthy blood vessels and supports cardiovascular function. Certain nutrient deficiencies can also affect platelet levels.
- Manage Chronic Inflammation: Because chronic, low-level inflammation can increase blood viscosity, managing inflammatory conditions through a healthy lifestyle is important. For information on inflammatory diseases, see the National Institutes of Health page on the topic.
- Medication Management: Work with your doctor to regularly review and manage any medications you take, including anticoagulants. They can help assess the benefit-risk ratio and ensure appropriate dosing.
Conclusion
The idea that blood thins with age is a myth based on visible, though often unrelated, symptoms like bruising. In reality, physiological changes associated with aging, including increased fibrinogen and reduced red blood cell flexibility, can cause blood to become thicker. While this may increase the risk for certain cardiovascular issues, maintaining a healthy, active lifestyle and managing any prescribed medications can help support healthy blood flow and overall cardiovascular wellness as you age. Always consult with a healthcare provider for personalized advice on your blood health.
