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Vitamin D lowers estrogen levels and your risk of breast cancer

Vitamin D lowers estrogen levels and your risk of breast cancerAccording to a new study, supplementing with large doses of vitamin D may lower blood levels of estrogen, which may be vital for the prevention and treatment of the dreaded disease.

Although women have generally become better at following dietary guidelines, maintaining their ideal weight, limiting their alcohol intake, exercising, and refraining from smoking, they still get breast cancer. While there are many factors involved in this disease, lack of vitamin D is one that is overlooked, and it appears the official recommendations are far too low.
Decades of research have shown that lack of vitamin D is widespread at northern latitudes and is associated with an increased risk of several cancer forms, including breast cancer. The new study, however, reveals that vitamin D may lower estrogen levels in the blood, thereby reducing ones risk of breast cancer. This is also the case for overweight women who often have elevated estrogen levels.

Larger amounts of vitamin D used in the study

The study was conducted at the Fred Hutchinson Cancer Research Center in Seattle, the United States, and included postmenopausal, overweight and obese women who were given daily supplements of vitamin D (50 micrograms) for a year. The researchers observed that those women whose vitamin D levels had increased the most, had the largest reduction in their blood levels of estrogen. This potentially lowers their risk of breast cancer, as it is known that too much estrogen increases your risk of the disease.
Because it takes many years for breast cancer to develop, it appears to be an advantage to make sure to get enough vitamin D and to have normal blood levels of estrogen as part of a long-term prevention strategy.

The women had low vitamin D levels to begin with

Dr. Caitlin Mason and Dr. Anne McTiernan headed the trial, which was a randomized, controlled study of over 218 overweight and obese women with too low blood levels of vitamin D at baseline. For one year, half the women were instructed to follow a weight loss program combined with a 50 microgram/day supplement of vitamin D. The other half followed a weight loss program and took an identical dummy pill (placebo).

Vitamin D lowers sex hormones independently of weight loss

After one year, the researchers observed that those women whose vitamin D levels had increased the most – ranging from values that were too low to higher values within the normal range – had a corresponding drop in estrogen and other sex hormones. They also observed that the drop in sex hormones was not related to weight loss. This observation is highly relevant – especially for those women who find it difficult to lose weight.

Did you know that both vitamin D and steroid hormones like estrogen are synthesized from cholesterol?

Is vitamin D an alternative antiestrogen?

According to McTiernan, the study reveals that vitamin D supplementation in the long run may reduce the risk of breast cancer and may therefore become a new alternative to antiestrogen drugs like Tamoxifen that are known to cause side effects. Therefore, McTiernan points out, it is vital to find new treatments that are able to lower elevated estrogen levels in all women in a safe way.
It has been shown earlier that weight loss lowers estrogen levels significantly. Now, researchers know that vitamin D does the same, provided your levels of the nutrient are within the normal range. However, scientists disagree on what the optimal levels should be. According to the new study, a positive effect was seen with daily supplements of 50 micrograms, but researchers still don’t know if even larger quantities of vitamin D would have had an even better effect on the hormone balance.

Overweight and lack of vitamin D is a dangerous cocktail for your health

This is because overweight individuals are not as good at synthesizing and utilizing vitamin D and because they produce more estrogen

We are only able to produce vitamin D during the summer

Summer sun is our primary source of vitamin D. A person who is dressed in light clothing is able to produce around 50 micrograms of vitamin D in 20 minutes. A few hours spent in the sun in a swimsuit enables the same person to produce substantially more.
Leading scientists claim that the current RI (Reference Intake) level for vitamin D is not sufficient, as it does not cover the body’s actual need for the nutrient. Also, humans were exposed to a lot more sunlight earlier, at least at latitudes where sunshine is more prevalent. The ability to produce vitamin D and store it in the liver is impaired in individuals who are older, overweight, diabetic, or have dark skin. For that reason, these people need more vitamin D than others.

Vitamin D deficiency has become increasingly common over the past decades because of

  • more time spent indoors
  • increasing overweight
  • avoiding the sun
  • the use of sun factor crème
  • prolonged use of cholesterol-lowering statins
  • more people with dark skin                                                                                                                                                                                                                                              

New optimal threshold levels require supplementation – especially during the winter

When you measure vitamin D levels in the blood in the form of 25-hydroxyvitamin D3, the official threshold levels are 50 ng/ml. However, leading experts believe that this is insufficient and recommend levels of 75-100 ng/ml for optimal disease prevention. Because we are unable to produce vitamin D during the winter at our latitudes, and because our diet only provides minimal amounts of the nutrient, it is advisable to take a strong vitamin D supplement – especially during the wintertime – in order to have optimal concentrations in the blood for prevention against breast cancer and many other diseases.

Vitamin D, supplements, and absorption

Vitamin D is lipid-soluble which is why we get the best effect by taking vitamin D in oil in capsules. Leading experts believe that it is perfectly alright to take 50-100 micrograms of vitamin D daily. This is not more than what we synthesize in our skin on a sunny day during summer.

Long-term prevention

Because it takes several years for breast cancer to develop, it is a good idea to get enough vitamin D all year around and throughout life as part of a long-term strategy for prevention.          


Hutch News. High blood levels of vitamin D linked to reduced estrogen – and potentially lower breast cancer risk
Study found the hormone-lowering effect to be independent of weight loss. 2016 |
By Kristen Woodward / Fred Hutch News Service

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

Sharon L. McDonnel, Cedric F Garland et al: Serum 25-Hydroxyvitamin D Concentrations ≥40 ng/ml Are Associated with >65% Lower Cancer Risk: Pooled Analysis of Randomized Trial and Prospective Cohort Study
Plos One: 2016

Biokemisk Forening: D-vitaminbehov og mangel i Danmark 2009

Iowa State
University: New promise for diabetics with vitamin D-deficiency. ScienceDaily. 2016

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