In recent years, there has been a growing concern regarding the amount of vitamin D people are getting. This vitamin is important for normal mineralization and growth of bones. Milk has commonly been fortified with vitamin D to decrease deficiencies, but studies have shown how excessive light exposure can decrease vitamin levels in milk. Many studies have been done to test the stability of vitamins in milk. They have shown how excessive light exposure can decrease the vitamin levels in milk. Unlike vitamin A and riboflavin, the decay of vitamin D as a result of light exposure has not been as thoroughly studied. A major reason for this decay is the type of container used to hold the milk. Opaque, made of high density polyethylene, containers tend to better protect the fortified vitamins. Translucent, made of polyethylene terephthalate, containers are more susceptible to vitamin loss by light exposure but are more environmentally friendly. Another issue deals with the smaller bottles of milk often found in convenience stores. These small bottles are constantly exposed to the bright lights in the store’s coolers. The loss of vitamin D because of too much light only adds to the already low amount in some milk as well as the growing number of deficiencies.