Vitamin D and Breast Cancer

As a naturopathic doctor, I always evaluate my patient’s Vitamin D levels. One reason it is so important to have your Vitamin D status evaluated yearly is because of its great immune support. Research has even suggested that women with lower Vitamin D levels are at higher risk of developing breast cancer in their lifetime. This is because Vitamin D may play a role in controlling normal breast cell growth and may be able to reduce breast cancer cells from growing in the first place.

So what should your Vitamin D levels be and how can you improve your levels? First off, the range of “normal” Vitamin D has a big range from 40-100ng/ml but what you are looking for is to be in the “optimal” range which is actually closer to 60-80ng/ml. This is the range that has been shown to provide the most support against breast cancer cell growth.

When it comes to improving your Vitamin D levels, it is important to know your exact Vitamin D status (which is completed with a simple blood test), prior to adding Vitamin D supplements. Typically, I recommend taking 5,000IU of Vitamin D per day. This will help increase your Vitamin D status. If someone is really low, like a Vitamin D status of 12 ng/ml, I may decide to increase their daily dose to Vitamin D to 10,000IU/day for a week and then reduce them down to 5,000IU/day.

What if you already have breast cancer? Is it too late to start implementing Vitamin D? Absolutely not, implementing Vitamin D in someone with breast cancer can actually help support their immune system and help them fight against this horrible disease. You will only want to supplement Vitamin D if you are low in the Vitamin. But from experience working in integrative care with many oncology departments, all of our patients with cancer were low in Vitamin D. The reason why is still not clearly understood but we definitely know there seems to be a correlation between cancer and low vitamin D status.

3 thoughts on “Vitamin D and Breast Cancer

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  1. I usually take 3,000 IU. Most of the population is deficient in vitamin D and don’t even know it. Especially in colder geographic locations that have long cold seasons or winter, like in Canada, USA, UK, etc.


      1. That’s really good to know and is eye opening — because I live up in Canada where basically 6 months of the year is cold/winter in my province and people must be very covered up. I really thought that in sunny Arizona, people would be getting enough sun and Vitamin D.


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