A research came up with a new model to know the needed amount of vitamin D by individual persons for optimum health.
According to Charles B. Stephensen, Agricultural Research Service (ARS) research physiologist, the skin tone, amount of sunlight that people receive and the food that they eat affects the amount of vitamin D on the body. They considered this study as first of its kind because it is the first study to tackle the needed vitamin D of individual people. Stephensen and his colleagues developed a preliminary model that can predict the vitamin D requirements of an individual.

According to Stephensen, scientists already know that the body is stimulated to make vitamin D when the rays from the sun reach the skin. He also added that there are some factors that can also affect the amount of direct sunlight a person receives aside from time spent in the sun. Stephensen said that factors like latitude, season, skin pigmentation and even the clothing that a person wears also affect the amount of sunlight that a person receives.

Stephensen and co-investigators worked with 72 young adults to develop the preliminary model. The volunteers provide information on the food that they eat and they wore photosensitive badges from seven in the morning until seven in the evening for seven to eight weeks so the scientist can determine the level of sun exposure of the volunteers.
They found out that volunteers with low amounts of sun exposure have lower levels of vitamin D. They suggest that additional vitamin D is needed to reach a target blood level of 75 nanomoles of vitamin D per liter of plasma.
According to Stephensen, some vitamin D levels that are indicated by the model exceed the level that is considered as safe. He said that more research with large number of volunteers can refine the predictive abilities of the model.