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Polyphenols and oxidative stress

In recent years, multiple studies have been published about the effects of plant polyphenols on numerous medical conditions.

As you may know, polyphenols with their different classes (flavonoids, stilbenes, lignans, etc.) are ubiquitously found in plants and seeds; they are well known for their anti-oxidative properties that exceed the potency of most other natural substances.

You see, many degenerative diseases are caused by the oxidative stress that the cell encounters during its lifetime; oxidative stress means that reactive oxygen species (aka free radicals) are released inside and around the cell. The purpose of these free radicals is to protect the cell from foreign pathogens.

For instance, one of the methods the cell uses to destroy the cell membrane of bacteria is the release of hydrogen peroxide which is part of the free radicals family.

Unfortunately, no system is perfect. Often times, these substances will damage the cell’s components (DNA, proteins, and lipids), killing the cell as a result; chronic exposure to free radicals has dire consequences on the cell and the organism.

One factor that is believed to play a major role in developing degenerative diseases such as cancer, cardiovascular diseases, stroke, diabetes mellitus, and some pulmonary diseases, is the chronic exposure to oxidative stress. This theory has become more widely accepted in recent years.

Of course, it’s not the only culprit, but it’s one of the main contributors to developing these debilitating diseases.

This was the gateway to the interest around polyphenols.

Now that we know the role of free radicals in the pathogenesis of multiple diseases, as well as the mechanism polyphenols use to counter the oxidative stress, let’s take a look at the diseases that can be prevented with long-term consumption of physiological concentrations of polyphenols.

Diabetes mellitus

Multiple studies have found a link between the consumption of adequate amounts of polyphenols and lower blood sugar levels.

Polyphenols were also a potent stimulator of insulin sensitivity, further lowering blood sugar and the risk of developing type 2 diabetes.

In 2017, a study was published by Giuseppe Grosso and his colleagues where they followed up 5806 normoglycemic (normal blood sugar levels) participants for a period of 2-4 years.

They were divided into two groups, the first group consumed high contractions of polyphenols while the other group didn’t.

The results were just staggering! The group who consumed the highest amounts of polyphenols rich-foods was found to have a 57% reduction in the risk of developing type 2 diabetes.

Cardiovascular diseases

As we mentioned earlier, the main way polyphenols act to reduce the risk of degenerative diseases is by reducing oxidative stress, and thus reducing inflammation; the latter being one of the most important risk factors of developing cardiovascular diseases (Myocardial infarction, Blood hypertension, Peripheral artery disease, arrhythmias, etc.).

Additionally, polyphenols were found to reduce the LDL (bad cholesterol) and increase HDL (good cholesterol) in blood circulation eliminating another major risk factor.


When it comes to polyphenols and reducing the risk of cancer, the data isn’t so decisive.

Theoretically, polyphenols have potent anti-oxidative and anti-inflammatory properties which should have some benefits in preventing cancer.

Numerous reputable sources claim that polyphenols play some role in the prevention of multiple types of cancer (e.g. lung, prostate, and breast cancers).

However, other studies and meta-analyses have found that polyphenols have no effect on the prevention or treatment of cancer.

What is clear though, is that more studies need to be done to confirm or deny the effects of polyphenols on cancer.

Blood clots

When you get injured with a sharp object and you start bleeding, platelets circulating in your bloodstream start to clump together at the site of the lesion to stop the bleeding.

This is physiological and necessary for our survival. If it wasn’t for platelet aggregation, each time we get injured, we’ll bleed out to death.

However, sometimes this physiological process becomes pathological! Blood clots will start to form randomly causing some fatal medical conditions such as strokes, deep vein thrombosis complicated with pulmonary embolism, myocardial infarction, etc.

Polyphenols were found to stimulate the anticoagulant factors reducing the risk of clot formation.


Aside from the diseases mentioned above, polyphenols have been shown to help with the following conditions:

  • Obesity
  • Inflammation (arthritis)
  • Asthma
  • Some psychiatric disorders

Take-home message

Polyphenols have been documented to help with the prevention and/or treatment of various diseases; however, before starting to develop polyphenols-based supplements, more research needs to be done to get a better idea of their mechanism of action, benefits, and side effects.

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