Prebiotics and Immune Function in Middle Aged Humans
Condition: Immune Function
Study type: Interventional
Phase: Phase 1/Phase 2

Summary: 
      Prebiotics are naturally occurring carbohydrates found in a variety of edible plants. They
      are not digested by mammalian enzymes, and so reach the gut intact, where they are fermented
      by some species of intestinal bacteria. This fermentation is thought to have several benefits
      for the host including improving immune function. There are numerous methods available for
      assessing the human immune response. Response to vaccination is thought to be a good method
      for this. Not many studies have examined the effect of prebiotics on the human immune
      response to vaccination. Thus the investigators propose to test the effect of a prebiotic on
      the immune response in healthy volunteers including their response to the current flu
      vaccine. The investigators hypothesise that the prebiotic will enhance the immune response
      including the response to the vaccine.
    

Detailed description: 
      Prebiotics are naturally occurring carbohydrates found in a variety of edible plants. They
      are not digested by mammalian enzymes, and so reach the gut intact, where they are fermented
      by some species of intestinal bacteria. This fermentation is thought to have several benefits
      for the host including improving the immune response. Inulin-type fructans (oligofructose and
      inulin) are classified as prebiotics. Inulin is found naturally in significant amounts in a
      variety of plants foods, such as bananas, leeks, onions, artichokes, wheat and chicory.
      Synergy1 is a prebiotic preparation produced by Beneo-Orafti, and containing a mixture of
      oligofructose and inulin derived from chicory. Fructooligosaccharides including Synergy1 are
      widely used by the food industry and are commonly found as a source of insoluble fibre in
      many biscuit, bakery, cereal and dairy products.

      There is increasing evidence that the changes in the intestinal microflora that occur with
      the consumption of fructooligosaccharides can modulate immune parameters, not only in the
      gut-associated lymphoid tissue, but also secondary lymphoid tissues and the peripheral
      circulation. Much of the evidence for beneficial effects of fructooligosaccharides on immune
      function comes from animal models e.g. rats, mice, dogs and pigs. Results from these studies
      show that the innate and adaptive immune systems of both the gut associated lymphoid tissue
      and the systemic immune system can be modified by fructooligosaccharides. However, there are
      few human studies so far which have investigated the effects of prebiotics on immune
      function, and these studies mostly rely on systemic markers of immunity. The results show
      little effect of fructooligosaccharides on innate immune function, but mixed results are
      reported regarding the adaptive immune system, suggesting that there may by improvement on
      this aspect of immunity with increased intake of fructooligosaccharides. The small number of
      published human studies led Watzl et al. (2005) to suggest that more human studies are needed
      to find out whether inulin and/or oligofructose have the potential to modulate systemic
      immunity in well-nourished individuals.

      There are numerous methods available for assessing the human immune response. These have been
      evaluated by a panel of European experts (Albers et al. 2005). Based on its biological
      relevance, sensitivity and practical feasibility, response to vaccination was identified by
      this panel as the gold standard for measuring the functioning of the immune system in vivo
      (Albers et al. 2005). A small number of studies have studied the effect of
      fructooligosaccharides on the human immune response using vaccination response as the
      outcome, but only four of these examined fructooligosaccharides in the absence of other
      additional nutrients and of these two studies were in infants. Thus, the number of studies
      examining the immunologic impact of fructooligosaccharides in adult humans and using the gold
      standard outcome is very limited. From a public health perspective, it would be of
      importance, if fructooligosaccharides can improve immune function especially in older adults
      who are at risk of age-related immune decline. Thus, we propose to use a commercially
      available influenza vaccine (Imuvac®) to stimulate the immune response in healthy human
      adults, and to use this to assess the effect of a well defined prebiotic preparation commonly
      used in the food industry (Synergy1).
    

Intervention name(s): Prebiotic; Placebo
Intervention type(s): Dietary Supplement; Dietary Supplement
Intervention description(s): Inulin type fructooligosaccharides; Maltodextrin as placebo
Other intervention name(s): Synergy1; Maltodextrin
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary purpose: Basic Science