What signs indicate ‘thick blood’? Can drinking more water help? Here’s the truth.

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“Feeling groggy in the morning, slow thinking, and seeing stars when standing up after squatting? Beware, this is a warning sign of increased blood viscosity!” ——You must have seen such articles in your social media circles.

Accompanied by alarming images of blocked blood vessels, along with threats like “increased blood viscosity can lead to blood clots, heart attacks,” it instantly induces anxiety.

But the question is, can we really judge “blood viscosity” by “morning dizziness, blurred vision, shortness of breath when squatting”? Is “blood viscosity” really the direct cause of heart attacks and strokes?

Today, let’s discuss this seriously misunderstood topic.

Misunderstood “High Blood Viscosity”

First, it is important to clarify that:In the diagnostic system of modern medicine, there is no independent disease diagnosis called “high blood viscosity”.

In medicine, there are indeed “hemorheological” indicators, such as whole blood viscosity, plasma viscosity, red blood cell deformability, etc., which can describe the state of “increased blood viscosity”. But it is more a description of a phenomenon, rather than a disease name that can be diagnosed and treated independently.

Just like a thermometer can measure that a person has a fever, but “fever” itself is not a disease, it could be due to upper respiratory tract infections, autoimmune diseases, or other different causes. Similarly,increased blood viscosity is just a phenomenon that may accompany diseases such as hypertension, diabetes, hyperlipidemia, but it is not a disease that is clearly defined.

The widely circulated claim online is: “Dizziness upon waking up, blurred vision, and shortness of breath when squatting” are the three major signs of high blood viscosity.

However, from a medical perspective,this diagnostic criterion is highly problematic.The main issue is that these symptoms are too common and may have a wide range of possible causes, making them unrecognizable:

Therefore, in daily life, it is impossible for us to judge blood viscosity based on these vague signals.

Back to the concept of “high blood viscosity,” the reason it is deeply rooted in people’s minds is essentially the result of commercial marketing deliberately amplifying anxiety.

These claims simplify complex medical issues into a terrifying formula of “high blood viscosity = blood vessel blockage = life-threatening” and then promote various health products, blood purification therapies, and even regular infusions to “unblock blood vessels,” building a whole commercial ecosystem around the concept of “high blood viscosity”.

What Really Needs Attention?

If you really want to know your “blood viscosity” level, hemorheological tests can indeed provide us with some information.

Hemorheological tests mainly assess indicators such as whole blood viscosity, plasma viscosity, and red blood cell status, but it should be noted that these indicators are affected by many factors, such as red blood cell count, plasma protein concentration, temperature, dehydration status, etc., so interpretation must be based on specific clinical contexts for comprehensive judgment, and it is not appropriate to simply attribute an increase in one or two indicators to high blood viscosity.

However, in actual clinical practice, the significance of hemorheological test results alone is quite limited. It is mainly used as an auxiliary diagnosis for diseases such as hypertension, coronary heart disease, and cerebral thrombosis, and it is not a core necessary examination, nor is it a routine physical examination item, so it should not be used as the primary screening for cardiovascular and cerebrovascular diseases.

So, if we want to pay attention to the health of the cardiovascular and cerebrovascular system, what indicators should we focus on? According to the expert consensus published by the Chinese Medical Doctor Association, the real risk factors for cardiovascular and cerebrovascular diseases include:

In China, to this day, cardiovascular and cerebrovascular diseases are still the leading cause of death in adults, so instead of worrying about the specific values of “blood viscosity,”it is better to focus on controlling the real risk factors.

Are Those “Reduce Blood Viscosity” Claims Reliable?

There are various dietary methods circulating online that claim to reduce blood viscosity: black fungus, onions, shiitake mushrooms, hawthorn, garlic… The specific claims are also very tempting: “Black fungus contains gum, which can adsorb impurities in the blood,” “Onions contain sulfides, which can inhibit platelet aggregation,” “Shiitake mushrooms contain eritadenine, which can lower cholesterol,” and so on.

However, from the perspective of evidence-based medicine,these claims lack sufficient scientific evidence.

Firstly, the aforementioned claims mostly have limited evidence, mainly based on preliminary in vitro studies or animal experiments, lacking support from large clinical trials.

Secondly,

the active ingredients in food need to be in sufficient dosages to have a pharmacological effect.
The amount of black fungus and onions consumed daily, the content of their “active ingredients” is far from reaching a therapeutic dose.

Lastly, even if some food components show certain effects in in vitro experiments or animal experiments, it cannot be directly inferred to humans. There is a huge gap between the effects of in vitro tests and actual efficacy in the body, as the human body is a very complex environment with many variables that can affect the results.

Therefore, the aforementioned foods can be part of a balanced diet, which is helpful for overall cardiovascular health, but they cannot replace drug treatment. If there are diseases such as hyperlipidemia, hypertension, diabetes, etc., standard treatment under the guidance of a doctor is still necessary.

Another popular claim is: “Drink warm boiled water on an empty stomach in the morning, before meals, and before bed, each time 150-200 milliliters, which can dilute the blood, improve vascular health, and prevent thrombosis.”

This claim overstates the role of drinking water.Adequate water intake is indeed helpful for maintaining health, including keeping normal blood viscosity and preventing dehydration. Dehydration is also one of the risk factors for thrombosis formation, but we cannot expect to prevent thrombosis by drinking water alone.

Because although drinking water can replenish circulating volume, it does not improve unhealthy vascular endothelium, nor can it clear plaques or narrowing blockages within blood vessels, both of which play an equally important role in thrombosis formation. Therefore, it is biased to emphasize the prevention of thrombosis by drinking water alone.

In addition, people in our country particularly like to emphasize drinking warm boiled water, thinking that warm boiled water is more nourishing and can dilate blood vessels. This is actually a misconception. Because whether it is warm boiled water, room temperature water, or ice water, the impact on the human core body temperature from the amount of water intake is minimal, and it will not cause blood vessels to dilate or constrict due to this difference in heat.

Many elderly people like to go to the hospital for blood transfusion or find some institutions for so-called “blood purification” treatment when the seasons change, claiming that it can “flush blood vessels, reduce blood viscosity, and prevent thrombosis”.

In fact, there is no reliable medical evidence to show that blood transfusion or blood purification can clear vascular plaques or prevent thrombosis by reducing blood viscosity.

On the contrary,such unnecessary treatments are not only ineffective but may also bring significant risks, such as infection, increased cardiac burden, electrolyte disorders, and even severe complications like septic shock.

So, please remember, blood vessels are not water pipes and cannot be cleared by “flushing”.

Scientific Prevention is the Right Path

Back to the blood viscosity issue discussed at the beginning of the article, what people are essentially worried about is cardiovascular health, fearing that “high blood viscosity” will lead to “blood vessel blockage”.

So instead of monitoring and worrying about blood viscosity, it is better to truly control those indicators that are really related to cardiovascular health from the start: blood pressure, blood sugar, blood lipids, and weight, and start with lifestyle, eat well every day, exercise regularly, sleep well, quit smoking and drinking, and have regular scientific and reliable medical check-ups.

Only in this way can we truly reduce the risk of cardiovascular diseases, instead of constantly pursuing blood viscosity standards. After all, preventing cardiovascular and cerebrovascular diseases relies on a scientific lifestyle and standardized medical management, not excessive anxiety about “high blood viscosity”.

Thank you for your patience in reading this far. The healthy living tips I hope you can take away today are:

If you find this article helpful, please share it with your loved ones and friends, especially those who are anxious about “high blood viscosity.” Your one share may help them avoid many detours.