Hello SOTGC community,
Indeed, what’s with all the hype over vitamin D deficiency? First of all, what is vitamin D and what role does it play in our bodies? Vitamin D is a fat soluble vitamin that is not only a nutrient that we consume but also a hormone that our bodies can make. When ultraviolet (UV) rays from the sun contact our skin it stimulates vitamin D synthesis. One of vitamin D’s jobs is to help the body absorb calcium and phosphorus which are used to maintain normal bone growth and remodeling. Vitamin D has also been found to play a role in defending the body against certain types of cancer. A lack of vitamin D has been known to lead to osteoporosis in adults and rickets in children.
So what happened? Why was there seemingly such a sudden increase in vitamin D deficiency within the last decade or so? Well, chances are that there wasn’t. Health providers have only recently started screening patients for levels of vitamin D and people experiencing vitamin D deficiency rarely exhibit obvious signs or symptoms. Efforts to combat skin cancer have also increased and people have started shielding themselves from the sun. Modern sunscreens provide far more complete and lasting protection than the old ones did and together these factors limit the amount of UV rays that can be absorbed and converted to vitamin D.
What should we do? This part is a little tricky. There are very few foods that are high in vitamin D and those that do include mainly dairy products and cereals fortified in vitamin D. Certain fatty fish such as tuna and salmon also offer modest levels of vitamin D. Multivitamins usually contain around 400 IU (International Units) of vitamin D which is now considered to be too low. The National Institutes of Health recommend increasing the minimum recommended daily amount of vitamin D for children over 1 and adults to 600 IU per day (400 IU for infants < than 1 year and 800 IU for adults over the age of 70). It is safe to take higher levels of vitamin D such as 800 or 1000 IU but taking too much can cause problems such as kidney stones. Toxicity is usually associated with daily doses in excess of 10,000 – 40,000 IU per day.
As we already know, vitamin D is produced when UV rays from the sun contact the skin and stimulate vitamin D synthesis. Some researchers are recommending that people spend 5-30 minutes in the sun without sunscreen between 10 am and 3pm at least twice a day. The American Academy of Dermatology warns of the greater risk of skin cancer and recommends that sunscreen always be worn when exposing one’s skin to the sun. The question over whether adequate amounts of vitamin D absorption from the sun can occur without an increased risk of skin cancer is still up for debate.