An inverse association exists between serum 25(OH)D concentrations and breast cancer risk in Saudi Arabian women. This trial was registered at clinicaltrials.gov as NCT01817231.

The role of vitamin D in breast cancer prevention is an area of active research and to date the limited evidence suggests an inverse association. Saudi women are thought to be at greater risk for vitamin D deficiency because of their skin type and reduced UV exposure. Yet, there is a lack of data regarding the vitamin D status of Saudi women. The purpose of this research is to describe vitamin D status in a de‐identified sample of women in Saudia Arabia, a data set being collected in the context of a case‐control study to compare vitamin D status in women with and without a diagnosis of breast cancer.

In Kingdom of Saudi Arabia, the traditional diet characterized by high fiber content and low fat, however, the diet in the Saudi Arabia has changed dramatically over the last two decades and has become more western fast food, which is lower in vitamin, and mineral, this unbalance diet can lead to obesity. Obesity is one of the major problems in Saudi Arabia, especially among women.Gaining weight since 18 years and became Obese in later life usually have inadequate vitamin D status due to the decrease vitamin D bioavailability from the cutaneous. In this study we examine whether the current and weight at 18 years can alter vitamin D status among a healthy Saudis' women. The participants were recruited as they presented their regular clinical check‐ups, and their blood was drawn. Their ages ranged between 20 and 75 years, the bio‐samples were taken from June 2009 through August 2009 (n=120). We hypothesized that women who maintained stable weight over time had a higher circulating of 25‐dihydroxyvitamin D3 (25(OH)2D3) compared to those who gained weight. The result: Women who gain weight during their lifetime have low vitamin D level compared to that maintains stable weight.