The Effects of Orange Juice on Plasma Lipids
Condition: Insulin Resistance; Obesity; Dyslipidemia
MeSH terms: Insulin Resistance; Dyslipidemias
Study type: Interventional

Summary: 
      The aim of this study is primarily to investigate the ability of antioxidants found in orange
      juice (OJ) to improve the serum lipid profile. Overweight or mildly obese men, who are
      otherwise healthy, but with elevated serum total cholesterol concentration will be recruited.
      The time commitment for subjects is ~14wks. Subjects will attend the laboratory on 5
      occasions after fasting from midnight. The 1st is a medical screening. Laboratory visits 2 &
      5 will take ~90min and will be separated by 3 months, during which time subjects will consume
      250ml of an orange drink (either OJ or an orange flavoured control drink) once a day. During
      visits 2 & 5, subjects will have a scan to assess their %body fat using a low-dose x-ray
      machine, a 20ml blood sample taken and a small sample of fat tissue (about the size of a
      haricot bean)taken from underneath the skin of the belly. Subjects will record their food
      intake for 3-days in weeks 3, 7 and 11 of consuming the drink, and come to the lab for visits
      3&4 during weeks 4&8. Laboratory visits 3&4 repeat measurements taken in the 1st (screening)
      visit.
    

Detailed description: 
      Background:

      Overweight and mild obesity are associated with insulin resistance and mild elevations in
      lipid risk factors which are not usually sufficiently abnormal to merit treatment. Such
      people are encouraged to lose weight to reduce their risk of progressing to type 2 diabetes
      and coronary heart disease, but there is clearly a potential role for dietary modifications
      to maximize any potential benefit of this weight loss. Flavonoids are known to have vascular
      effects which might enhance substrate delivery to metabolically active tissues, and thus
      improve insulin sensitivity. Moreover, there is much interest in the potentially beneficial
      effect of flavonoids on serum lipid profile.

      There are many different dietary sources of flavonoids, with fruits such as apples, berries
      and citrus being rich sources. However, some researchers have expressed concern that a high
      dietary intake of 100% juice may contribute to the development of insulin resistance, obesity
      and the Metabolic Syndrome (Bazzano, Li et al. 2008), although this is not universally
      accepted (Fujioka, Greenway et al. 2006; O'Neil and Nicklas 2008). To date, there have been
      no studies investigating the effects of citrus fruits on indices of cardio-metabolic health
      in people who are presently healthy but are at risk of developing some features of the
      Metabolic Syndrome.

      Aims:

      To investigate the effects of orange juice (OJ) intake on appetite hormones, blood pressure
      and plasma lipids. In addition we aim to investigate any gene expression changes associated
      with OJ consumption, in particular in adipose tissue.

      Experimental protocol and methods:

      Overweight or obese men (BMI 27-35), who are otherwise healthy, will be recruited onto the
      study. They will attend the 'David Greenfield Human Physiology' laboratories on 5 convenient
      mornings, following an overnight fast. The 1st visit is a medical screening and will involve
      signing a consent form, completing medical screening, food frequency and activity
      questionnaires, having height, weight, and hip/waist circumference measurements taken and a
      sample of blood taken for CBC, urea, electrolytes, LFT, TFT, glucose and insulin analysis.
      Subjects will then be asked to complete a 3-day diet diary for macronutrient assessment. The
      2nd visit will involve having a DEXA body composition scan, an adipose tissue biopsy and a
      blood sample taken for white blood cell harvest, serum lipids, glucose, insulin, cytokines,
      appetite hormones and catecholamine analysis. Starting on the following morning, subjects
      will then consume an orange drink (either OJ or a carbohydrate matched orange flavoured
      drink) once a day for 12 wks. A 3-day diet diary for macronutrient assessment will be
      recorded during wks 3,7and 11 of taking the drink, and measurements made at screening will be
      repeated on visits 3 and 4 which will take place in weeks 4 and 8. The final laboratory (5th)
      visit will be identical to visit 2.
    

Intervention name(s): Orange Juice
Intervention type(s): Dietary Supplement
Intervention description(s): 250ml of orange juice or a sugars matched orange drink daily
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Participant)
Primary purpose: Basic Science
Keywords: Men; Orange Juice; Cholesterol; Obesity