Bioflavonoids (2015, 2016) & Hypertension


Learn more about high blood pressure.


Previous research has established that various individual antioxidants and other phytochemicals are able to reduce blood pressure. In this pilot study, researchers evaluated the effect of a combination of such nutrients. All are in the family of bioflavonoid bionutrients.

They investigated a combination of these extracts:

  • 300mg grape seed/skin,
  • 100mg green tea,
  • 60mg resveratrol, and
  • 60mg quercetin, ginkgo biloba and bilberry.

In a placebo-controlled, double-blind, crossover trial 18 subjects with high blood pressure 130mmHg systolic or 85Hg diastolic were tested. A crossover trial is one in which subjects are given first one test item and then after time for it to wash out of the system, are given a different one. The two results can then be compared for the same subjects - rendering it a more realistic result given the differences in each person's physiology.

The subjects received the nutritional supplement or placebo for 28 days; there was a 2-week washout period, and then the other test item was given for another 28 days. At the beginning of the study period and at the end of each 28 day period blood pressure was measured.

Regardless of whether placebo was given in the first 28 days or the second 28 days, blood pressure was unchanged. However for the nutritional supplement, diastolic pressure lowered an average of 4.4mmHg, systolic pressure was unchanged, and the arterial pressure was reduced generally.

In addition, enzyme activity was measured at each point in the trial. Enzymes implicated in serum angiotensin was similar in both products, but nitrite concentrations were significantly increased after supplementation. In addition the cells that line blood vessels increased.

Noting the type of reaction of cells from the aorta when treated with these polyphenols the researchers were able to determine the mechanics of the process. Nitric oxide production changes stimulated by eNOS activation causing the reduced blood pressure. They concluded that such supplements may have clinical relevance as stand-alone or adjunct therapy to help reduce blood pressure.

Researchers: S. Biesinger, H. Michaels, et al
Published: A combination of isolated phytochemicals and botanical extracts lowers diastolic blood pressure in a randomized controlled trial of hypertensive subjects., European Journal of Clinical Nutrition, January, 2016.


A previous study focused on the bioflavonoid anthocyanins, which are important in helping to normalize a number of health-effecting factors such as oxidative stress and inflammation.

These scientists investigated whether two juices rich in anthocyanins could lower high blood pressure. The study was a randomised, placebo-controlled, double-blind study lasting 12 weeks. The study included 134 healthy patients aged 50-70 years:

  • 72 with high normal range blood pressure (130/85 to 139/78mmHg)
  • 62 with stage 1-2 hypertension (140/90 to 179/109)

The subjects drank 500 ml daily of one of the 3 combinations for 12 weeks:

  • a commercial juice based on red grapes, cherries, chokeberries and bilberries (245.5 mg/100g)
  • a similar juice but enriched with extracts of black currant press residue (305.2mg/100g)
  • a placebo juice (76mg/100g)

Blood pressure was measured at the beginning of the study period, at six weeks and at 12 weeks. Systolic pressure was markedly reduced in both of the juices with higher levels of the nutrients compared to the placebo juice. This was true for the entire study group, but especially for the patients with stage 1 or 2 hypertension.

The researchers concluded that these nutrient-rich berry juices containing high levels of polyphenols may help to lower high blood pressure, especially in patients with hypertension.

Researchers: T. Tjelle, L. Holtung, et al
Published: Polyphenol-rich juices reduce blood pressure measures in a randomised controlled trial in high normal and hypertensive volunteers, British Journal of Nutrition, October, 2015.