Am J Clin Nutr. 2011 Feb;93(2):338-47. Epub 2010 Nov 24.

Cassidy A , O’Reilly EJ , Kay C , Sampson L , Franz M , Forman J , Curhan G , Rimm EB .

School of Medicine, University of East Anglia, Norwich, United Kingdom and Renal Division, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA.

BACKGROUND: Dietary flavonoids have beneficial effects on blood pressure in intervention settings, but there is limited information on habitual intake and risk of hypertension in population-based studies.

OBJECTIVE: We examined the association between habitual flavonoid intake and incident hypertension in a prospective study in men and women.

DESIGN: A total of 87,242 women from the Nurses’ Health Study (NHS) II, 46,672 women from the NHS I, and 23,043 men from the Health Professionals Follow-Up Study (HPFS) participated in the study. Total flavonoid and subclass intakes were calculated from semiquantitative food-frequency questionnaires collected every 4 y by using an updated and extended US Department of Agriculture database.

RESULTS: During 14 y of follow-up, 29,018 cases of hypertension in women and 5629 cases of hypertension in men were reported. In pooled multivariate-adjusted analyses, participants in the highest quintile of anthocyanin intake (predominantly from blueberries and strawberries) had an 8% reduction in risk of hypertension [relative risk (RR): 0.92; 95% CI: 0.86, 0.98; P < 0.03] compared with that for participants in the lowest quintile of anthocyanin intake; the risk reduction was 12% (RR: 0.88; 95% CI: 0.84, 0.93; P < 0.001) in participants =60 y of age and 0.96 (0.91, 1.02) in participants >60 y of age (P for age interaction = 0.02). Although intakes of other subclasses were not associated with hypertension, pooled analyses for individual compounds suggested a 5% (95% CI: 0.91, 0.99; P = 0.005) reduction in risk for the highest compared with the lowest quintiles of intake of the flavone apigenin. In participants =60 y of age, a 6% (95% CI: 0.88, 0.97; P = 0.002) reduction in risk was observed for the flavan-3-ol catechin when the highest and the lowest quintiles were compared.

CONCLUSIONS: Anthocyanins and some flavone and flavan-3-ol compounds may contribute to the prevention of hypertension. These vasodilatory properties may result from specific structural similarities (including the B-ring hydroxylation and methyoxylation pattern).

PMCID: PMC3021426 [Available on 2012/2/1]
PMID: 21106916 [PubMed - in process]

Flavonoids (bioflavonoids in the media) are phenylpronanoids, a class of plant-derived organic compounds that are biosynthesized from the amino acid phenylalanine and belonging to the polyphenol group, characterized by the presence of more than one phenol group per molecule. Flavonoids are most commonly known for their antioxidant activity.

Polyphenols are a group of chemical substances found in plants, characterized by the presence of more than one phenol group per molecule. Polyphenols are generally further subdivided into tannins, and phenylpropanoids such as lignins and flavonoids.

Phenylpropanoids are a class of plant-derived organic compounds that are biosynthesized from the amino acid phenylalanine. This class includes: cinnamic acids, cinnamic aldehydes and monolignols, coumarins and flavonoids, stilbenoids. They have a wide variety of functions, including defense against herbivores, microbial attack, or other sources of injury; as structural components of cell walls; as protection from ultraviolet light; as pigments; and as signaling molecules.