Flavonoids are a type of polyphenolic compound for which a variety of previous studies have demonstrated beneficial anti-viral, anti-allergic, anti-platelet, anti-inflammatory, and anti-tumor activities.  There are over 4,000 flavonoid compounds, and flavanones, found in high concentration in citrus fruits, coupled, are one specific type. Christine Morand, from the National Institute for Agronomic Research (France), and colleagues studied hesperidin (hesperetin-7-O- rutinoside), which comprises 90% of the total flavanones in orange juice.  The team enrolled 24 healthy, overweight men (ages 50 to 65 years) for a 12-week long study during which subjects consumed 500 mL orange juice for 3 weeks, 500 mL control drink plus hesperidin for 3 weeks, and 500 mL control drink plus placebo for 3 weeks.  The researchers found significant reductions in blood pressure after 4 weeks consumption of orange juice or the hesperidin rich drink, as compared to a placebo drink.  Specifically, both orange juice and the hesperidin drink significantly improved post-meal blood vessel reactivity, thus the researchers posit that hesperidin may be causally linked to the beneficial effect of orange juice. The team concludes that: “Diastolic blood pressure was significantly lower after 4 weeks of consumption of orange juice … orange juice … significantly improved postprandial microvascular endothelial reactivity.”