Influence of vitamin D & a probiotic on inflammation and gut bacteria
Research type
Research Study
Full title
Influence of vitamin D and a probiotic on inflammation and gut bacteria
IRAS ID
304233
Contact name
Philip C Calder
Contact email
Sponsor organisation
67586
ISRCTN Number
ISRCTN10131460
Duration of Study in the UK
1 years, 1 months, 31 days
Research summary
Research Summary:
The number of older people in the population is increasing. However, many older people have health problems. Some of these are linked with increased inflammation with age, which increases the likelihood of some conditions like heart disease. Older people can also have weakened immune systems meaning that they are more at risk from infections (this has become clearly apparent during the COVID-19 pandemic) and that vaccines may not work so well. There may be many reasons for these age-related changes but one of these may be altered nutrition and another may be an alteration in gut bacteria (called microbiota). Vitamin D is an important nutrient to the immune system and older people often have low blood levels of vitamin D. Probiotics are live bacteria that colonise the lower gut (“bowel”) and bring about health benefits including helping the immune system to function better. We plan to conduct a randomised controlled trial of vitamin D, a probiotic, and the combination of vitamin D and the probiotic in people aged over 70 years. We will measure markers of immune function and inflammation in blood before and after the 3 month intervention. We will measure the types of bacteria in faecal samples collected before and after the intervention as an indicator of the gut bacteria. We will measure chemicals in urine samples collected before and after the intervention as indicators of a) the diet of the participants ad b) their gut bacteria. We hypothesise that taking vitamin D will increase blood vitamin D levels, that taking the probiotic will alter the gut bacteria, and that taking vitamin D and the probiotic (either alone or together) will reduce inflammation. This research is being funded by the Medical Research Council.
Summary of Results:
As people age their immune system can become weaker and they can show an increase in “low-grade” inflammation. Both these can increase the likelihood of ill health. Older people can also show changes in their gut bacteria. This can reflect changes in diet and use of medication. These three things (altered gut bacteria, immune decline, low-grade inflammation) might be linked, because we know that gut bacteria can influence our immune and inflammatory systems. Probiotics are live bacteria that colonise the bowel and help to support our health (including immune health). Many people in the UK, including many older people, have low levels of vitamin D in their blood partly because vitamin D is scarce in our diets and partly because of limited exposure to the sun. Vitamin D is also known to support immunity and help keep inflammation in check. Recent research also indicates that vitamin D acts as a prebiotic, meaning it helps healthy bacteria to grow in our bowel. We conducted a study in generally healthy people over 60 years of age. We wanted to see if vitamin D or a specific probiotic (called Lactobacillus plantarum TIFN101) could alter gut bacteria, improve markers of immunity measured in blood samples and decrease markers of low-grade inflammation measured in blood over a 12 week period. We also wanted to see if the combination of vitamin D and the probiotic had bigger effects than either one alone. To ensure our research was rigorous we included a control (placebo) group of participants who took “dummies” instead of vitamin D or the probiotic. So we had four groups altogether: placebo, vitamin D, probiotic, and vitamin D plus probiotic. We enrolled 78 participants across the four groups. They took the treatments each day for 12 weeks. We collected blood, urine and faeces at the start of the study and again at the end. 72 participants completed the study and they were equally spread across the for groups (18 participants completed the study in each group). Participants blood vitamin D level varied by the season in which they started the study and many participants were in the ”insufficient range”, although none were “deficient”. In both groups receiving vitamin D there was a large increase in blood vitamin D level (average increase was about 40%) and everyone in those groups was vitamin D sufficient at 12 weeks. By measuring bacterial DNA in faecal samples we found that those taking the probiotic alone had an increase in lactobacillus, showing that the probiotic had colonised the gut. However a really interesting finding was that if vitamin D and the probiotic were combined there were more changes in the faecal bacteria than if the probiotic was given alone. This confirms that vitamin D does act to change bacteria in the gut and helps the probiotic to colonise. So in regard to findings on blood vitamin D and gut bacteria the trial was successful in demonstrating the effects we hypothesised would happen. However, despite the changes in blood vitamin D and in the gut bacteria, there were no changes in immune cell numbers or function and only some small changes in the chemicals marking inflammation.
REC name
South Central - Hampshire A Research Ethics Committee
REC reference
21/SC/0403
Date of REC Opinion
25 Jan 2022
REC opinion
Further Information Favourable Opinion