Effects of vitamin D and probiotic supplements in older people

INTERVENTION: Participants will be given IDs from 001 to 104. These IDs have been randomly allocated to treatment groups using a randomisation programme, with randomisation stratified for sex based upon a 50:50 distribution. 1. Control 2. Vitamin D (calcifediol) 10 micrograms/day 3. Lactobacillus plantarum TIFN101 5 billion colony forming units/day 4. Both vitamin D (calcifediol) and Lactobacillus plantarum TIFN101 Interventions will be delivered as capsules in blister packs with two capsules to be taken each day for 12 weeks. CONDITION: Older people (aged 70+ years) living in the community ; Not Applicable PRIMARY OUTCOME: ; Measured at study entry and exit (week 12):; 1. Serum 25‐hydroxyvitamin D3 concentration (nmol/l) measured by immunoassay; 2. Colonisation with the probiotic organism detected in faeces (number of organisms per g faeces) measured by 16S RNA; 3. Serum CRP concentration measured by ELISA (mg/dl); SECONDARY OUTCOME: ; All measured at study entry and exit (12 weeks); 1. Blood immune cell phenotypes (number of each cell type per microlitre of blood) measured by flow cytometry; 2. Plasma inflammatory markers (mg/l) measured by immunoassay; 3. Faecal microbiome taxonomy (numbers of different organisms per g faeces) measured by 16S RNA; 4. Weight (kg), body mass index (kg/m²), body fat mass (kg and % body weight), body lean mass (kg and % body weight), mid arm upper circumference (cm), waist circumference (cm), hip circumference (cm), waist:hip ratio, measured by weighing scales, tape measure and bioelectric impedance; 5. Hand grip strength (kg) measured using a dynamometer; 6. Dietary intake (amounts of foods and nutrients) measured using the EPIC food frequency questionnaire and intake24 recall; 7. Quality of life (questionnaire plus visual analog scale) measured using the EQ5D5L questionnaire; 8. Physical activity measured using the Physical Activity Scale for the Elderly (PASE) questionnaire; 9. Respiratory symptoms measured using the Wisconsin Upper Respiratory Symptom Survey (WURSS); 10. Blood glucose (mml/l), insulin (U/l) and HOMA‐IR measured by enzyme‐linked colorimetric assays; 11. Blood lipids (total, LDL and HDL cholesterol, triglycerides; all mmol/l) measured by enzyme‐linked colorimetric assays; 12. Blood adipokines (leptin, adiponectin, leptin/adiponectin ratio, visfatin and resistin; mg/l) measured by ELISA; 13. Blood markers of intestinal barrier integrity (mg/l) measured by ELISA; 14. Blood PTH (pg/ml) and calcium (mg/dl), as markers of vitamin D homeostasis; 15. Faecal metabolome measured by nuclear magnetic resonance (NMR); 16. Urinary metabolome measured by NMR; INCLUSION CRITERIA: 1. Community dwelling males and females aged 70+ years 2. Body mass index 18.5‐35 kg/m² 3. Willing to adhere to the study protocol 4. Able to provide written informed consent