Blueberry derivative may lower hypertension risk
MedWire News: Individuals who consume more than one serving of blueberries per week may have a 10% lower risk for hypertension than those who consume no weekly servings of the fruit, study results suggest.
The association between blueberry consumption and hypertension is most likely the result of the high content of the flavonoid anthocyanin in blueberries, say the authors.
They add: "Our findings are exciting and suggest that an achievable dietary intake of anthocyanins may contribute to the prevention of hypertension."
In the American Journal of Clinical Nutrition, Eric Rimm (Harvard School of Public Health, Boston, Massachusetts, USA) and colleagues explain: "These data are important because anthocyanins are present in commonly consumed fruit, such as blueberries, cranberries, and strawberries, which can be readily incorporated into the diet.
"An average portion of blueberries, blackcurrants, or blood orange juice can contain very high amounts of anthocyanins (>500 mg)."
Using food-frequency questionnaires completed every 4 years over a 14-year follow-up period, Rimm and team assessed the flavonoid intake of 133,914 women and 23,043 men (mean age of 36 years).
Analysis of the questionnaire results revealed that although the majority of the cohort's total flavonoid intake came from tea (flavan-3-ol), the consumption of blueberries and strawberries made the greatest contribution to total anthocyanin intake.
In all, 34,647 participants (83.8% female) developed hypertension during the follow-up period.
When Rimm et al arranged all participants in quintiles according to anthocyanin intake, participants in the highest quintile (mean 18.0 mg/day) had an 8% lower risk for hypertension than those in the lowest quintile (mean 6.7 mg/day; p<0.03). This risk reduction was amplified to 12% among those aged 60 years or younger, and lessened to 4% in those aged over 60 years (p<0.001, p=0.02, respectively for interaction).
Pooled analyses of the anthocyanin intake of participants aged 60 years or younger revealed a 10% hypertension risk reduction among those who consumed more than one serving of blueberries per week compared with no blueberry consumption weekly (p=0.02).
The consumption of more than one serving of strawberries per week also reduced hypertension risk compared with no weekly consumption of strawberries; however this reduction was nonsignificant and less than that seen with blueberry consumption, at 3%.
Rimm and team found no association between the consumption of other individual flavonoid subclasses and hypertension risk reduction; however, pooled analyses suggested that flavonoid compounds from subclasses with B-ring hydroxylation and methoxylation patterns (flavones and flavan-3-ol subclasses) were associated with reduced rates of hypertension in the cohort.
The researchers conclude that the study findings "warrant further investigation, including intervention studies to test optimal doses of anthocyanin-rich foods for the prevention of hypertension and to underpin guidelines for the prevention and treatment of hypertension."
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By Lauretta Ihonor