Effects of Regular and Consequent Citrus Fruits Consumption on Vascular Protection
Condition: Cardiovascular Disease Risk Factors
MeSH terms: Cardiovascular Diseases
Study type: Interventional

Summary: 
      Epidemiological studies definitively show that fruit and vegetable consumption is positive
      for health and more specifically for cardiovascular diseases (CVD) prevention. In France,
      among fruits, those which are the most frequently consumed are citrus fruits essentially as
      juices and more specifically as orange juices. However, their health effects have been poorly
      studied so far. Citrus fruits contain vitamin C associated with various phytomicronutrients
      i.e. carotenoids (essentially -cryptoxanthin) and polyphenols. Each fruit contains specific
      compounds: hesperetin in orange, naringenin in grapefruit, eriodyctiol in lemon. Some
      scientific studies performed either in vitro or in animal models demonstrated properties of
      these micronutrients which could contribute to a positive health effect of citrus fruits on
      vascular protection. However data are still missing.

      The main goal of this project is to characterize the effect of orange juice consumption on
      vascular disease risk factors and to evaluate the specific role of their micronutrient
      compounds (polyphenols and carotenoids) in this protection. To reach this goal, a randomized
      "cross-over" clinical study will be performed on volunteers presenting a mild
      hypercholesterolemia. They will consume for 4 weeks an orange juice or a reconstituted drink
      similar to the orange juice for its composition in carbohydrates, minerals, vitamin C and
      folates but without phytomicronutrients. The effect of the juice consumption on the vascular
      function will be monitored exploring lipid abnormalities in plasma, measuring endothelial
      vasoreactivity (FMD) (Flow Mediated Dilatation), as well as endothelial dysfunction,
      thrombosis, inflammation and oxidative stress biomarkers in plasma. Comparison of urinary
      metabolomes after orange juice consumption or that of the reconstituted drink will lead to
      the identification of the metabolic pathways modulated by the orange juice micronutrients.

      Moreover ELISA tests for the two major flavanones from citrus fruits (hesperetin and
      naringenin) will be developed. They will be used to determine the plasma levels of these
      molecules in order to analyze the relation "ingested quantity - bioavailable quantity -
      physiological effect".

      The results obtained in this project will allow clarifying citrus fruit effects, and
      particularly orange juice, in vascular protection.
    

Detailed description: 
      Scientific context:

      Arteriosclerosis is a chronic pathogenic inflammatory-fibro-proliferative process of large
      and medium-sized arteries that results in the progressive formation of fibrous plaques which
      in turn, impair the blood flow in vessels. These lesions can either promote an occlusive
      thrombosis in the affected artery (heart attack, thrombotic stroke) or produce a gradual but
      relentless stenosis of the arterial lumen. A number of subtle dysfunctions occur at the
      cellular and molecular levels in the early stages of disease progression associated with the
      loss of cellular homeostatic functions of endothelial cells, smooth muscle cells and
      macrophages which constitute the major cell types in the atheroma environment.

      Several epidemiological studies shown a negative association between consumption of
      polyphenol-rich foods (fruits and vegetables) and CVD. This association has been partially
      explained by the fact that polyphenols interrupt lipid peroxidation which is implicated in
      the initiation of arteriosclerosis. Polyphenols contribution to the prevention of CVD could
      be attributable to their antioxidant capacity, hypolipidemic and/or anti-inflammatory
      properties as well as on their effects on metabolic pathways. Among fruits, citrus fruits are
      interesting sources of polyphenols (flavanones as glycosides) and carotenoids. A single glass
      of orange juice may contain between 40 and 140 mg flavanones, which may significantly
      contribute to the total daily polyphenol intake for the high citrus consumers. The clinical
      evidence of a role of citrus fruit consumption in the prevention of cardiovascular diseases
      concerns their hypocholesterolemic effect and the improvement of some biomarkers of oxidative
      stress, but the specific protective role of the phytomicronutrient provided by these
      beverages has never been considered. According to the type of citrus, the flavanone molecules
      are different: hesperetin in orange and clementine, naringenin in grapefruit and eriodyctiol
      in lemon. These molecules were shown to display antioxidant and hypolipidemic effects. Citrus
      also contains various carotenoids, like violaxanthin, lutein etc… as well as cryptoxanthin
      which acts as pro-vitamin A and has a positive role in CVD prevention. The specific health
      benefits brought by these phytomicronutrients are unknown and a clinical study with specific
      design to assess the contribution of citrus micronutrients has not been performed yet.
      Moreover, polyphenols and carotenoids are able to affect the expression of genes involved in
      atherogenesis. The interaction between these molecules on cellular responses is of particular
      interest. In fact, they could interplay in the cellular antioxidant network or directly
      (synergistically or antagonistically) affect gene expression. The unravellings of the
      mechanisms of regulation of transcriptional control of gene expression seems a promising
      future line of investigation. Newly developed high throughput technologies make a significant
      contribution to integrative biology. Studies on phytomicronutrients using the analysis of
      functional genomics and analysis of phenotypes by metabolic are still in its infancy.
      Integrated databases are necessary to understand their biological functions. The translation
      of basic scientific discoveries into applied nutrition is an increasing challenge.

      Social and economic context:

      CVD in adults are the main cause of morbidity and mortality in Western countries. In France,
      CVD are responsible for about 170 000 deaths a year i.e. 32% of all deaths, representing a
      total public heath expenditure estimated to 7.9%. As epidemiological studies show a
      protective effect of fruit and vegetable consumption towards CVD incidence, the National
      Programme for Nutrition and Health set up in France advices at least a 400g consumption of
      fruits and vegetable per day, equivalent to 5 items of crude or cooked fruits or vegetables.
      The present project will give a solid background for the understanding of the molecular
      mechanisms of the beneficial effects of polyphenols on human health.

      Scientifics and socio-economics goals:

      Scientific goals are to clearly establish the effects of phytomicronutrient consumption
      through orange juice on vascular risk factors. This orange juice intake will take place into
      a French traditional controlled diet. This means that the project deals with nutritional
      prevention of one of the major cause of death and health costs in France. It involves one of
      the most popular sources of citrus fruits. This goal will be reached through an
      interventional clinical study. The final aim of the present project is to give and diffuse
      nutritional advices on citrus fruits consumption towards consumers, and to make fruit juices
      producers aware of the interest to optimize the content of their juices in
      phytomicronutrients.

      Originality and new concepts:

      Primary originality of the present project is to focus on the specific contribution of the
      phyto-micronutrients fraction of citrus (polyphenols and carotenoids) within their natural
      food matrix to the cardiovascular protection. Such an approach is elicited by conducting a
      cross over randomized study including in its experimental design a regular intake of orange
      juice compared to the consumption of a beverage mimicking the composition of orange juice.
      This control beverage will contain the main nutrients of orange juice (carbohydrates, Vit C,
      Mg++, K+, folates) except polyphenols and carotenoids. It is now well established that CVD
      are closely associated with endothelial dysfunction. Thus the present study will focus on the
      endothelium by evaluating both functional (FMD) and systemic (plasma endothelial biomarkers)
      parameters.

      Selected biochemical parameters are usually measured in clinical studies to demonstrate the
      metabolic effects of studied nutrients. However, these approaches do not properly deal with
      the complexity of the interactions occurring between nutrients or with the multiplicity of
      their biological targets. The metabolic approach offers the novel opportunity to investigate
      the impact of complex food on the whole physiology of the human organism, through elucidation
      of subtle but highly significant metabolic changes. The present project will highlight the
      potentiality of metabolic technology to study the health effects of complex food and dietary
      patterns in free-living populations.

      Disposition of data on micronutrients bioavailability (plasma levels) and biological,
      biochemical and physiological effects will allow establishing correlation studies between
      "ingested-circulating-physiological effects".
    

Intervention name(s): Regular orange juice consumption
Intervention type(s): Behavioral
Intervention description(s): 600 mL /day.
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Prevention