The deficiency of vitamin D is correlated with cancers and a number of other serious health issues. According to research conducted in 2008, people who were vitamin D deficient at the time of being diagnosed with cancer were less likely to survive.
According to statistics, breast cancer is the second leading cause of cancer deaths in women in US. Moreover, it is estimated that 1 in 8 women will develop breast cancer over the course of her lifetime. Taking adequate amounts of vitamin D helps lower the likelihood of developing breast cancer. On the other hand, if woman was already diagnosed, insuring adequate intake of vitamin D may prevent disease progression and further spreading of cancer to the bones.
Most American women consume about one-fourth the recommended daily allowance of vitamin D, which is 200IU. Japanese women get at least 1,200IU a day, which is apparently related to traditional Japanese diet. It is interesting that once Japanese women move to United States their breast cancer rates skyrocket.
A study concluded in University of California in San Diego found that women with highest levels of vitamin D in their blood had 50 percent lower risk of breast cancer than those with the lowest. This means that the higher is your vitamin D levels, the lower is the risk. Unfortunately it might not be easy to achieve the blood level that would cut your risk by 50 percent. To do that you would need to take 2,000IU daily and spend 10-15 minutes in the sun.
It is still a good idea to take Vitamin D supplement that provide at least 1000IU and eat diet rich in vitamin D. The best food sources include red salmon (800IE in 3 1/2 ounces), pink salmon (500IE in 3 1/2 ounces), fresh sardines (1500IE in 3 1/2 ounces), mackerel (500IE in 3 1/2 ounces), tuna (200IE in 3 1/2 ounces), and vitamin D-fortified-milk. But the richest source of vitamin D is eel, which contains 4,700IE per 3 1/2 ounces.