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

Flavonoids and hypertension

Plant compounds (polyphenols and flavonoids) have been reported to exert beneficial effects in the treatment of cardiovascular disease, including hypertension.

Flavonoids can be found in fruits, vegetables, nuts, seeds, in coffee, wine, or tea, with significant antioxidant effects. Flavonols, flavanols, and anthocyanidins are the main members of the group of natural phenolic compounds called flavonoids.

It is well known that nitric oxide (NO) from the endothelium plays a crucial role in regulating vascular tone and blood pressure. Nitric oxide causes vascular smooth muscle relaxation by activating soluble guanylate cyclase29 and by increasing cyclic guanosine 30 ,50-monophosphate (cGMP), which inactivates the release of intracellular calcium.

Flavones, a subgroup of luteolin-rich flavonoids, exert their antihypertensive effect by signaling and activating the cAMP/protein kinase A cascade, which will further activate NO synthase, the final result being the increased concentration of endothelial NO. Through this mechanism, vasodilation takes place, a process modulated by potassium and calcium channels.

A number of studies have shown that consumption of fruit, vegetables, wine and tea may protect against stroke, for which hypertension is the major risk factor.

Flavonoid’s antioxidant activity is well established, and epidemiologic studies have suggested associations between flavonoid intake and a lower risk of cardiovascular disease.
Flavonoids and hypertension

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

Cocoa, Diabetes and Hypertension

Hypertension and You Biochemical and physiologic associations among hypertension, diabetes, and cardiovascular disease have grown steadily, supported by basic, clinical, and epidemiologic research.

The possibilities for treating these pathologies include pharmacologic approaches, lifestyle adjustment, and diet modification. 

The identification of foods that have cardiovascular health benefits has become a major public health objective. There is now a large body of epidemiologic evidence that supports the concept that diets rich in fruit and vegetables attenuate or delay the onset of certain chronic diseases, including cardiovascular and related diseases.

However, the physiologic and molecular mechanisms by which fruit and vegetables act to reduce the risk of vascular disease remain elusive. The existence of data showing that the health benefits of fruit and vegetables are causally linked to their flavonoid content is a starting point from which to address such mechanistic uncertainties.

With respect to cardiovascular health, one class of flavonoids, the flavanols, is receiving increasing attention. Cacao, tea, grapes, and grapefruit are examples of edible plants that are rich in flavanols. Translational research that relates the consumption of these foods to cardiovascular health is very interesting research now a day. 

Cocoa, Diabetes and Hypertension