The Effect of Calcifediol (Hy.D 25 SD/S) and Vitamin D3 on Muscle Strength in a Frail Elderly Population

Inclusion criteria

• 25(OH)D levels 20-50 nmol/L.
• age 65 or older.
• physically frail (pre-frail or frail, based on the criteria designed by Fried et al.) (30). Frailty will be defined as a clinical syndrome in which one or more of the following criteria are present: unintentional weight loss (4.5 kg in past year), self-reported exhaustion (CES-D questionnaire), weakness (grip strength), slow walking speed and low physical activity (Minnesota questionnaire). More details on these criteria are described in chapter 6.3.2.
• body mass index between 18.5 and 35 kg/m2.
• willingness and ability to comply with the protocol, including performance of the knee extension strength test.

Exclusion criteria

• Medical Illness:

• malabsorption syndrome: known intestinal malabsorption, celiac diseases, inflammatory bowel disease;
• diseases that may enhance serum calcium concentration: sarcoidosis, lymphoma, kidney stone in the last 10 years, primary hyperparathyroidism;
• abnormal indices of calcium metabolism, uncontrolled hypocalcaemia;
• diagnosed renal insufficiency;
• diagnosed cancer; currently diagnosed or undergoing treatment.
• Hypercalcemia: serum calcium adjusted for albumin of > 2.6 nmol/L.
• Medication: interfering with vitamin D metabolism and vitamin D supplementation (bisphosphonate, PTH treatment, tuberculostatica, anti-epileptica).
• Subject not able (when medically necessary/ advised) or not willing to stop the use of vitamin D containing supplements during the study.
• (Expected) increase in exposure to sunlight (e.g. travelling to a sunny resort) during intervention period.
• Patient heavily consumes alcohol containing products defined as greater than > 21 drinks of alcoholic beverages per week.
• Planned surgery which can affect study measures (taking into account duration of hospitalisation and recovery).
• Participation in another clinical trial.