Effect of Vitamin D Supplementation on Blood Pressure and Insulin Sensitivity

This study looks at whether taking vitamin D supplements can help lower blood pressure and improve the body's ability to use insulin (which regulates blood sugar). It focuses on people who have low vitamin D levels, particularly in Tongan, Maori, and European communities. You may be eligible if: - You are 40 years or older (if Tongan or Maori) or 65 years or older (if European) - Your vitamin D level (25OHD) is below 50 nmol/L (a blood test will show this) You may NOT be eligible if: - You are currently being treated for diabetes or high blood pressure - You are already taking vitamin D supplements or cod liver oil - Your blood calcium level is too high - You spend a lot of time outdoors in the middle of the day - You have recently had a holiday in a very sunny location or are planning one during the study Talk to your doctor about whether this trial might be right for you.