The Science Behind Blood Viscosity and Aging
Blood viscosity is a measure of the thickness and stickiness of blood, which affects how easily it flows through your blood vessels. While blood's components change throughout our lives, a progressive increase in viscosity is a well-documented part of the aging process. Understanding the components of blood and how they are affected by aging can help clarify why this change occurs and what it means for your health.
Key factors influencing age-related blood thickening
Several specific biological changes contribute to the increase in blood viscosity with age:
- Red Blood Cell Deformability: Red blood cells (RBCs) must be flexible to squeeze through the body's narrowest capillaries. With age, these cells become stiffer and less able to change shape, a phenomenon driven by oxidative stress and changes in the cell membrane. This reduced flexibility increases resistance to blood flow, especially in the microcirculation.
- Red Blood Cell Aggregation: Aged RBCs have a greater tendency to clump together, forming structures known as rouleaux. This aggregation is primarily caused by an age-related increase in plasma fibrinogen, a protein that promotes this clumping. Enhanced aggregation significantly elevates blood viscosity, particularly at low flow rates.
- Plasma Viscosity and Fibrinogen: The fluid portion of blood, or plasma, becomes more viscous as we age, largely due to higher levels of plasma proteins, most notably fibrinogen. Fibrinogen is an acute-phase reactant, meaning its concentration rises in response to inflammation. As aging is associated with a state of chronic, low-grade inflammation (often termed 'inflammaging'), this leads to persistently elevated fibrinogen levels.
- Reduced Total Body Water: Normal aging causes a reduction in total body water, which means there is less fluid in the bloodstream, subsequently decreasing overall blood volume. Dehydration is a common issue in older adults and can further exacerbate blood viscosity.
Comparing normal vs. high blood viscosity
| Feature | Normal Blood Viscosity | Higher Blood Viscosity (Age-related) |
|---|---|---|
| Blood Flow | Smooth, efficient, and requires minimal cardiac effort to pump. | Thicker and stickier, requiring the heart to work harder to maintain circulation. |
| Microcirculation | Red blood cells are flexible and pass easily through small capillaries, ensuring proper tissue oxygenation. | Stiffened red blood cells struggle to navigate capillaries, leading to impaired blood flow and reduced oxygen delivery to tissues. |
| Aggregation | Minimal or controlled clumping of red blood cells. | Increased red blood cell aggregation (clumping), especially at low flow rates, which further impedes circulation. |
| Risks | Lower risk of developing chronic cardiovascular and neurological conditions. | Higher risk of heart attack, stroke, metabolic syndrome, cognitive decline, and other age-related diseases. |
The downstream effects of age-related blood thickening
Because every organ relies on the efficient delivery of oxygen and nutrients via the bloodstream, increased blood viscosity has systemic consequences. The heart, in particular, must increase its workload to pump the thicker blood through the body. This can lead to or worsen conditions like hypertension. In the microcirculation, where stiff red blood cells and aggregated clumps impede blood flow, tissue perfusion can be compromised. For example, decreased blood flow to the brain has been linked to age-related cognitive decline.
This isn't to say that all older adults will experience severe blood thickening or related issues. Genetic factors, comorbidities, and especially lifestyle choices play a significant role in mitigating or exacerbating this age-related process.
Lifestyle modifications to manage blood viscosity
While aging is unavoidable, there are proven lifestyle interventions that can positively influence blood fluidity and overall cardiovascular health:
- Stay Hydrated: Dehydration is one of the most direct causes of thickened blood. Drinking plenty of water throughout the day helps maintain proper plasma viscosity and blood volume.
- Exercise Regularly: Regular physical activity promotes healthy blood flow and can improve blood and plasma viscosity. Even moderate activities like brisk walking can be beneficial. It helps prevent blood from pooling and improves circulation.
- Eat a Heart-Healthy Diet: A diet rich in fruits, vegetables, and healthy fats (like those found in olive oil and fish oil) can support better circulation and reduce inflammation. Conversely, limiting animal fats can help control inflammation.
- Manage Inflammation: Since chronic low-grade inflammation contributes to higher fibrinogen levels, managing inflammatory conditions is key. A healthy diet and regular exercise are excellent for this, as is quitting smoking.
- Address Underlying Conditions: For some, conditions like polycythemia vera can cause excessive red blood cell production, leading to thick blood. Managing underlying diseases is a critical part of treating problematic blood viscosity.
Conclusion
In summary, the answer to "Does your blood get thicker when you get older?" is yes, but it is a complex process involving multiple factors, not just age alone. The natural decline in red blood cell deformability, increased aggregation, and higher plasma fibrinogen contribute to enhanced blood viscosity. While this process can elevate the risk for cardiovascular and neurological issues, it is not an unchangeable fate. Lifestyle choices, including hydration, regular exercise, and a healthy diet, can significantly impact blood fluidity and improve overall circulatory health in later life. Proactively managing these factors can help mitigate the risks associated with age-related blood thickening, supporting healthy aging and a lower risk of chronic diseases. For many, blood viscosity is a modifiable risk factor, and addressing it is an important step toward better health.
Blood viscosity and aging: key takeaways
Aging increases blood viscosity: Studies confirm that whole blood and plasma viscosity increase with advanced age, affecting overall circulation.
Red blood cells become less flexible: With age, red blood cells become stiffer and lose their deformability, hindering their passage through narrow capillaries.
RBCs tend to aggregate more: Increased levels of fibrinogen in aging plasma promote the clumping of red blood cells, which slows blood flow, especially at low shear rates.
Chronic inflammation is a factor: The low-grade inflammation associated with aging contributes to higher plasma fibrinogen levels, a primary driver of increased plasma viscosity.
Dehydration is a contributing cause: A reduction in total body water and lower blood volume in older adults can increase blood viscosity.
Increased risks for cardiovascular issues: Elevated blood viscosity is a significant risk factor for cardiovascular events, stroke, and cognitive decline.
Lifestyle interventions can help: Regular exercise, proper hydration, and a healthy diet rich in anti-inflammatory foods can help improve blood fluidity and mitigate age-related thickening.
FAQs
What is blood viscosity?
Blood viscosity is a measure of the thickness and stickiness of your blood, which directly impacts how easily it flows through your blood vessels. Higher viscosity means the heart must work harder to pump blood, which can strain the cardiovascular system.
Why does blood viscosity increase with age?
Blood viscosity increases with age primarily due to several factors: increased stiffness and aggregation of red blood cells, higher concentrations of plasma proteins like fibrinogen (linked to chronic inflammation), and reduced total body water.
What are the symptoms of high blood viscosity in older adults?
Symptoms can be non-specific, including headaches, fatigue, dizziness, and shortness of breath. Severe cases can lead to blood clots, blurred vision, or confusion. Many people don't notice symptoms until a cardiovascular event occurs.
How is high blood viscosity diagnosed?
High blood viscosity, or hyperviscosity syndrome, is diagnosed through blood tests, including whole blood and serum viscosity tests. These may be supplemented by tests for complete blood count (CBC) and blood proteins.
Can exercise help reduce blood thickness?
Yes, regular physical activity is beneficial for improving blood fluidity. Exercise improves overall circulation and can help counteract age-related factors that contribute to increased blood viscosity, like red blood cell stiffness and aggregation.
What role does diet play in blood viscosity?
A heart-healthy diet can positively influence blood fluidity by providing nutrients that reduce inflammation and support overall cardiovascular health. Staying hydrated by drinking plenty of water is also crucial, as dehydration is a direct cause of blood thickening.
Are there treatments for high blood viscosity?
Treatment depends on the underlying cause. For conditions like polycythemia vera, treatments can involve therapeutic phlebotomy (blood draws) to reduce red blood cell counts. In cases involving excess immunoglobulins, treatments like plasmapheresis may be used. Lifestyle changes are often recommended to manage and mitigate age-related increases in viscosity.
