Vitamin D affects nearly every cell in your body and its importance to your health is difficult to exaggerate. Vitamin D plays a role in:
- Healthy bones, including preventing osteoporosis – it helps your body absorb calcium
- Lowered risk of diabetes – improving your body’s sensitivity to insulin, thereby reducing insulin resistance
- Reduced blood pressure – a Boston University study showed that people with high blood pressure who were exposed to UVA and UVB rays for 3 months increased their vitamin D levels by more than 100% and normalized their blood pressure.
- Decreased rates of cancers of the breast, colon, prostate, ovaries, esophagus and lymphatic system. Vitamin D regulates cell growth and cell-to-cell communication and may slow or even reduce cancer progression.
- Protection against heart disease and other chronic diseases
- Strengthened immune system – reduces bacterial and viral infections, including the common cold and flu
- Lower incidence of depression and mental illness
- Weight loss – vitamin D improves your ability to shed pounds, as shown in a University of Cambridge study comparing subjects who took supplements vs those who took a placebo
So, what exactly is this powerful vitamin and how does it work? Vitamin D is actually not a vitamin but a prohormone. When our body is exposed to sunlight or receives vitamin D, the liver and kidneys activate and convert it into a hormone known as calcitriol, which is activated vitamin D. Activated vitamin D binds to a protein call the vitamin D receptor, which is present in just about every cell and affects many different body processes.
Your best source for vitamin D is sunlight, best achieved by exposing as much of your body as is comfortable without clothing, sunscreen or being behind glass which blocks UVB. The amount of time you should be exposed depends on a number of factors: Time of day – your skin produces more vitamin D if you expose it during the middle of the day. Where you live – the closer you are to the equator, the easier it is for you to produce vitamin D The color of your skin – the paler your skin, the more quickly you make vitamin D. The more skin you expose, the more vitamin D you make. The total time, based on all these factors, can vary from 5 or 10 minutes for very pale skin to 2 hours for very dark skin, but in no case is it necessary for you to burn. A good rule of thumb is that you should expose yourself for about half the time it would take for you to burn.
If you’re not able to get optimum sun exposure, the other option is to take vitamin D supplements. The Vitamin D Council recommends from 1000 IU/day for infants to 5000IU/day for adults.