Polyphenol and blood pressure

Hypertension is clinically defined as systolic blood pressure (SBP) ≥ 140 mmHg and/or diastolic blood pressure (DBP) ≥ 90 mmHg. Diet has been identified as a modifiable factor for preventing and controlling hypertension. Besides, epidemiological studies have suggested an inverse association between polyphenol intake and cardiovascular diseases.

The evidence suggests that the dietary intakes of polyphenol-rich foods, herbs and beverages including flavonols, anthocyanidins, proanthocyanidins, flavones, flavanones, isoflavones and flavan-3-ols, improves vascular health, thereby significantly reducing the risk of hypertension and CVD.

They are common constituents of the human diet, present in plant-derived foods and beverages, e.g., fruits, vegetables, nuts, seeds, herbs, spices, cocoa, tea, coffee, wine, and they represent more than 8000 phenolic structures.

Polyphenols are divided into five main classes according to their chemical structure: flavonoids, phenolic acids, stilbenes, lignans, and others that are largely present in a glycosidic form (glycosides of flavonoids, lignans, and stilbenes) or as esters (phenolic acids esterified to polyols such as quinic acid).

The flavonoid class is composed of several sub-classes, including anthocyanins, soflavones, flavones, flavonols, flavanones, flavan-3-ols, and the related oligomeric proanthocyanidins. Each of these sub-classes is contained in a pattern of different foods, mostly fruits and some vegetables, but also in teas, cocoa, and some alcoholic beverages.
Polyphenol and blood pressure

High blood pressure can be reduced by tea active substances

A study (published Archives of Internal Medicine 2012) of 95 patients from Western Australia suggested that drinking three cups a day of black tea can reduce blood pressure by 2-3 mmHg in both systolic and diastolic blood pressure.

Black tea is a good source of flavonoids. Flavonoids protect LDL cholesterol from oxidation, and this can reduce the risk of atherosclerosis, stroke, hypertension and heart attack.

Oral administration of tea polyphenols also yielded a decrease of blood pressure in patients. The reported active substances include tea extracts, polyphenols and tea tannin. Tea tannins (2 to 4 mg orally) could reduce the systolic blood pressure in rats. Investigation proved that tea components, especially TFDG and EGCG showed beneficial effect.

In addition, theanine, an amino acid found in tea produces a calming effect on the brain. It induces a feeling of relaxation and was found to be effective lowers the blood pressure of spontaneous hypertensive rates.

Tea polyphenols and caffeine may also ameliorate the development of hypertension by improving the renal circulatory state as a result of its direct action on the kidney, including the activation of the kinin-kallikrein-prostaglandin system in the kidney.
High blood pressure can be reduced by tea active substances