I like to go out in the sun, but I don't want a sun burn so I use lots of sunblock. How much time in the sun do I need to get enough vitamin D? Can I get enough vitamin D from my diet or do I need to take supplements?
Answer: Your body makes vitamin D when you are exposed to the ultraviolet B (UVB) rays in sunlight. You probably need from 15 to 30 minutes of exposure to the skin on your face, arms, back or legs (without sunscreen) three times per week. The older you are the longer it takes the sunlight to do the work. BE CAREFUL not to allow yourself to burn, as it has been associated with skin cancer, but sunscreen SHOULD NOT be used when you are trying to get enough Vitamin D from the sun.
The amount of exposure also depends on the time of the year. In the Northern Hemisphere, the UVB is more intense during the summer months and less intense during the winter months. In fact, if you live north of the 42-degrees latitude, you will have a difficult time getting enough vitamin D from the sun from November through February. If you live north of a line drawn on a map from the northern border of California to Boston, Massachusetts, you will probably need additional vitamin D from the foods you eat during the winter.
The intensity of UVB rays is also reduced by clouds, pollution and UVB will not travel through glass, so sitting next to a window will not give you enough sunlight to make vitamin D.
Vitamin D is found in oily fish like tuna and salmon and vitamin D supplements. Most people can easily tolerate 1-4,000 Units per day of the vitamin, but the more sun you expose yourself to safely, the lees vitamins you will need. Ideally, we should try to get all of our nutrients from our food and from our environment - not pills!
Vitamin D is necessary for absorption and utilization of calcium, so you need adequate amounts of vitamin D for healthy bones. A deficiency of vitamin D in children will cause rickets in children and osteomalacia in adults. Research studies also suggest that getting enough vitamin D may help to prevent high blood pressure, multiple sclerosis, and some forms of cancer.