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Prevention of breast cancer requires more vitamin D in the blood

Prevention of breast cancer requires more vitamin D in the bloodOne in nine Danish women gets breast cancer, and the situation is not improving, on the contrary. One of the reasons why breast cancer is so widespread is that so many women lack vitamin D, and it looks as if the official recommendations for this nutrient are too low. A new American study has shown that those with higher amounts of vitamin D in the blood have a lower risk of the dreaded disease. The question is how much vitamin D do we need for optimal disease prevention, and what role does the nutrient play for those who have already been diagnosed with breast cancer?

Decades of research have shown that lack of vitamin D is linked to an increased risk of developing breast cancer. The sun is our primary source of vitamin D, but we spend far too much time indoors compared with earlier, and with more of us being overweight and using too much suncream because of sun awareness campaigns, it is increasingly difficult for us to get enough of this vital nutrient. This is only made worse by the fact that the sun sits too low in the sky during the winter period for us to be able to synthesize the vitamin, and the consequent deficiency of vitamin D can be a matter of life or death.

The higher your vitamin D levels, the lower your risk of breast cancer

Researchers from the University of California San Diego School of Medicine have demonstrated that having higher blood levels of vitamin D is associated with a significantly reduced risk of developing breast cancer. Their large population study is published in the science journal PLoS One in collaboration with Creighton University, Medical University School of South Carolina, and GraasrootsHealth, which is a non-profit organization that informs about vitamin D research and its therapeutic benefits.
The scientists collected data from two randomized clinical trials with 3,325 and 1,713 participants respectively and compared breast cancer risk and blood levels of vitamin D (measured as 25-hydroxyvitamin D3). All women were at least 55 years old with an average age of 63. Various data was gathered in the period from 2002 to 2017. At baseline, none of the women had breast cancer. They were followed for four years on average. During this period, the researchers measured the women’s vitamin D levels. They also took into account their age, BMI, smoking habits, and use of calcium supplements, all of which can influence the risk of breast cancer.
Over the course of the two studies, 77 women were diagnosed with breast cancer, and many could have avoided the disease by making sure to have enough vitamin D in their blood.

Because it takes several years for breast cancer to develop, it is a good idea to get plenty of vitamin D all your life.

The result: Blood levels of vitamin D should be at least 60 ng/ml

The research team from the University of California San Diego School of Medicine noted that blood levels of vitamin D had to be at least 60 ng/ml, which is far more than the official American recommendations of 20 ng/ml. The GrassrootsHealth organization has argued that minimum levels should be at least 50 ng/ml (the minimum level in Denmark).
There is a heated debate over vitamin D, and there seems to be certain health benefits from introducing a further increase of the minimum level, at least if you want optimal prevention of breast cancer and many other diseases.
The US scientists found that participants with vitamin D levels higher than 60 ng/ml only had one fifth of the risk of developing breast cancer, compared with women whose levels were below 20 ng/ml. In other words, having high levels of vitamin D in the blood can lower your risk of breast cancer by 80 percent.
One of the scientists behind the study, Professor Cedric F. Garland, has pointed for the past decades to the link between vitamin D levels and the risk of developing breast cancer, colon cancer, lung cancer, bladder cancer, and even leukemia.
As mentioned, the new study is based on earlier population studies, which primarily include white, post-menopausal women. Garland therefore calls for studies of younger women and other ethnic groups. Still, he argues, that the new study shows a clear link between lack of vitamin D and an increased risk of developing breast cancer.

Studies show that vitamin D has several anti-cancer properties

  • It strengthens the immune system and helps it destroy abnormal cells
  • It inhibits inflammation
  • It regulates a number of different genetic activities
  • It regulates estrogen levels

Lack of vitamin D worsens the prognosis for women with breast cancer

A Brazilian study looked at the relation between lack of vitamin D prior to breast cancer therapy and the prognosis and found that lack of vitamin D worsened the prognosis for women with breast cancer. It is therefore not enough to treat breast cancer with surgery, chemotherapy, and radiation. One also has to optimize levels of vitamin D, selenium, and other relevant nutrients to help the body function optimally.
How do we make sure to get enough vitamin D – and what is the upper limit?Professor Garland suggests taking a supplement of around 100-150 micrograms of vitamin D daily to raise blood levels of the nutrient to over 60 ng/ml. It takes less during the summer period, where one can easily produce a similar amount by spending time in the sun. During the winter, however, it is not possible to produce enough vitamin D at our latitude, and because there is only little vitamin D in the diet, supplements are necessary.
The jury is still out on the matter of getting optimal amounts of vitamin D. Ageing, having dark skin, being overweight, and having type 2 diabetes are all factors that increase the need for the nutrient, by the way. On the other hand, we do not want too much vitamin D, either. In terms of the upper safe limit for daily intake of vitamin D, the European Food Safety Authority (EFSA) has set the limit at 100 micrograms for older children and adults, including pregnant and lactating women.
It is always a good idea to have your vitamin D levels measured, and they should ideally lie in the range between 75-100 ng/ml. Having blood levels of vitamin D above 125 ng/ml may cause side effects such as nausea, constipation, weight loss, heart rhythm disturbances, and kidney damage.

Vitamin D, supplements, and absorption

Vitamin D is a lipid-soluble vitamin, which we humans absorb and utilize the best when it is bound to an oil of some kind. It is safe to supplement with vitamin D in doses from 40-100 micrograms daily.

Important: Magnesium is important for the body’s ability to utilize vitamin D

Sun exposure enables the skin to convert a type of cholesterol into a vitamin D precursor. Our further ability to make use of the vitamin depends on several factors. First, the liver must convert vitamin D to 25-hydroxyvitamin D3 (which one can measure in the blood). After that, the kidneys convert this intermediate form into an active form of vitamin D. The different enzyme processes involved in this conversion require the presence of magnesium, so lacking magnesium may actually mean that we are less able to utilize vitamin D from sun exposure or from supplements.


University of California – San Diego. Greater Levels of vitamin D associated with decreasing risk of breast cancer. June 15, 2018

De Sousa Almeida-Filho B et al. Vitamin D is associated with poor breast cancer prognostic features. J Steroid Biochem Mol Biol 2017

Hutch News. High blood levels of vitamin D linked to reduced estrogen – and potentially lower breast cancer risk. 2016

Susan Scutti: High Blood Levels Of Vitamin D Help Protect Women Over 50 From Cancer: Study

Anne Marie Uwitonze, Mohammed S Razzaque. Role of magnesium in Vitamin D Activation and Function. The Journal of the American Osteopathic Association. 2018

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