The topic of vitamin D supplementation is a vast minefield of purported benefits - and lack thereof. Now, a new study suggests taking vitamin D supplements improves exercise performance and lowers the risk of heart disease. The study, conducted by researchers from Queen Margaret University in Edinburgh, UK, is presented today at the Society for Endocrinology annual conference in the Scottish capital. Vitamin D is produced in the body with ultraviolet B rays from sun exposure, and it can also be consumed through diet or supplements. Sources of the vitamin include oily fish and eggs, but it can be difficult to get enough through diet alone. In the body, vitamin D helps control calcium and phosphate levels in the blood, and it plays an essential role in bone and teeth formation.
Previous studies have suggested low levels of vitamin D in the body are to blame for increased Alzheimer's risks and the acceleration of multiple sclerosis. In geographical areas where the sun is not abundant, many populations turn to vitamin D supplementation for health benefits.
Researchers from this latest study, led by Dr. Emad Al-Dujaili, say previous studies have suggested that vitamin D can block the action of an enzyme called 11-βHSD1, which assists in making the stress hormone cortisol.  High levels of this stress hormone can increase blood pressure by restricting the arteries, narrowing blood vessels and encouraging the kidneys to retain water, say the researchers. Because vitamin D may reduce levels of cortisol in the body, the researchers theorized that it could improve exercise performance and lower risk factors for cardiovascular issues. o test their hypothesis, the researchers gave 13 healthy adults either 50 μg of vitamin D per day or a placebo during a 2-week period.
After the 2 weeks, results showed that the study subjects who received vitamin D supplements had lower blood pressure and lower cortisol levels - as measured in urine tests - compared with the subjects who were given a placebo. Additionally, a fitness test revealed that the adults taking vitamin D were able to cycle 6.5 km in 20 minutes, compared with only 5 km at study baseline, and they also showed lower signs of physical exertion after supplementation - as revealed by systolic and diastolic blood pressure. Medical news Today