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Polyphenols in citrus fruits: major actors in vascular protection

Although it is widely known that consuming fruits with a high polyphenol content has a beneficial effect on health, it is more difficult to attribute a protective effect to a particular compound. Researchers in the Inra-Université de Clermont I Joint Research Unit for Human Nutrition (UNH) in Clermont-Theix have highlighted the specific effects on vascular protection of major polyphenols in grapefruit and orange. These results were obtained in the context of a major research programme being carried out in the Unit on the importance of polyphenols in human nutrition.

Tranches d'orange, citron et pamplemousse.. © INRA, MAITRE Christophe
Updated on 06/03/2013
Published on 02/08/2011

Epidemiological studies have clearly established the health benefits of regularly consuming fruits and vegetables, notably for the prevention of cardiovascular diseases. Citrus fruits are some of the most widely consumed, mainly in the form of juice, with a clear dominance of orange juice. Citrus fruits contain vitamin C associated with various phytomicronutrients: carotenoids and specific polyphenols (hesperidin in orange, naringin in grapefruit or eriodyctiol in lemon). The role of these micronutrients in vascular protection is still far from being elucidated, and researchers at the UNH are trying to understand their mechanisms of action.

A clinical study to better understand the role of hesperidin in orange juice

In the context of a public funding initiative with the Florida Department of Citrus (FDOC), UNH researchers carried out a nutritional interventional study to characterise the effects of consuming orange juice on vascular protection and to determine the specific role of hesperidin. The results of this clinical study, performed in 24 healthy but slightly overweight men (55-65 years old) demonstrated a positive effect of regular orange juice consumption on diastolic blood pressure (lowered) and on endothelial function that plays a central role in vascular tone (by regulating vessel dilation). For the first time, the research team was able to demonstrate that hesperidin was largely responsible for these effects.

The effect of naringin in grapefruit

In the context of the ANR AGRUVASC project, UNH scientists, working in collaboration with two partners in Bordeaux (ENITA Bordeaux and the University Research Team for Vascular Risk Factors – Bordeaux University Hospital) studied the effects of naringin supplementation at a nutritional dose (equivalent to that supplied to humans by a glass of grapefruit juice) in different mouse models of atherosclerosis. The results clearly demonstrated the beneficial effects of naringin consumption in mice receiving an atherogenic (high-fat) diet. Thus animals supplemented with naringin experienced a reduction in serum cholesterol levels, a decrease in biomarkers for endothelial dysfunction and an improved susceptibility to insulin. These observations may in part explain the anti-atherogenic effect of this polyphenol.

From a mechanistic approach in vitro and in animal models to clinical studies: UNH expertise

Scientists in the Micronutrients, Metabolism and Health team (MiMeS) of the UNH and the National Centre for Nutrition and Health, have acquired expertise in studying the impact and mechanisms of action of micronutrients and their source foods in the nutritional prevention of vascular diseases. Their research takes account of the effect of protective micronutrients used under both standard dietary conditions and in physiological or metabolic settings that may involve a higher demand for micronutrients. To respond to the research objectives fixed, the Unit benefits from a very broad range of methods and tools, ranging from cell models and investigations in animals (mini-pigs, rodent models of disease) to clinical studies on nutrition. All the results obtained integrate data arising from both in-depth explorations of vascular function and fundamental research in nutrigenomics.

Scientific contact(s):

  • Christine MORAND (04 73 62 40 84) Unité de Nutrition Humaine – UNH, Equipe Micronutriments Métabolisme et Santé (MiMeS), INRA Clermont-Ferrand-Theix, 63122 SAINT-GENES-CHAMPANELLE, France
Associated Division(s):
Nutrition, Chemical Food Safety and Consumer Behaviour
Associated Centre(s):