Effect of Fruit and Vegetable Consumption on Immune Function in the Elderly (ADIT)

The immune system undergoes a range of changes as individuals become elderly. These may manifest as an increasing susceptibility to infection or a tendency to develop autoimmune or malignant disease. Multiple underlying factors contribute to this phenomenon of immunological aging, and in this study the investigators will examine the possibility that inadequate diet may be one such contributing factor. Fruit and vegetable intake, which can be low in the elderly, is associated with reduced chronic disease risk. This proposal will test the hypothesis that increased fruit and vegetable intake may positively affect clinically relevant measures of immune function. One hundred healthy volunteers aged 65-85 years following a low fruit and vegetable diet (<=2 portions/d) will be recruited and randomised to continue following their normal diet, or to consume at least 5 portions of fruit and vegetables daily for 16 weeks. Immune function and biochemical markers of nutritional status will be assessed before and after the intervention period.

• Behavioral: 5 portions
  Subjects randomised to the intervention group will be provided with a selection of fruit and vegetables once a week (from a local supermarket) and will be asked to consume 5 portions of fruit and vegetables per day. For the purposes of this study, a portion will be as defined by the Food Standards Agency, i.e. an 80 g serving (one apple, orange or banana, or 3 heaped tablespoons of vegetables).
• Behavioral: 2 portions
  Subjects randomised to the control group will be provided with a selection of fruit and vegetables once a week (from a local supermarket) and will be asked to consume 2 portions of fruit and vegetables per day. For the purposes of this study, a portion will be as defined by the Food Standards Agency, i.e. an 80 g serving (one apple, orange or banana, or 3 heaped tablespoons of vegetables).

• Experimental: 1
  5 portions fruit and vegetables/day
  Intervention: Behavioral: 5 portions
• 2
  2 portions fruit and vegetables/day
  Intervention: Behavioral: 2 portions

Inclusion Criteria:

• Age 65-85 years
• Habitual consumption of fruit and vegetables <= 2 portions daily

Exclusion Criteria:

• Those on special diets, taking nutritional supplements or medications known to affect immune function or absorption of nutrients
• Excessive alcohol consumption (>28 U/week men or >21 U/week women)
• BMI>35 kg/m2
• History of diabetes or dementia
• Pneumovax II vaccination within previous 2 years
• Inability to provide informed consent
• Any other problem which would prevent adherence to a high fruit and vegetable diet
• Recent infection (<3 weeks since completion of any antibiotic course or symptoms of viral illness)