A vitamin D-cancer link

© Pauladan | Dreamstime Stock Photos & Stock Free Images

© Pauladan | Dreamstime Stock Photos & Stock Free Images

Vitamin D has been linked to a defence against a growing list of illnesses including various types of cancer. But many people have been quick to point out that the association has been just that – a connection and that may be it.

For example, those individuals with low levels of vitamin D in their blood are more likely to develop colon cancer and those with high blood levels are less likely. But research showing that that they may be simply be related and that the cause and effect research has been missing.

Now new research demonstrates there may be more to this connection. Vitamin D, which has been shown to affect immune system function, may activate the immune system cells (T-cells) which kill off cancer cells.

Scientists, from the Dana-Farber Cancer Institute, looked at 170,000 participants in two large ongoing studies at Harvard University, the Nurses’ Health Study and the Health Professionals Follow-up Study. All were free of colon cancer at the start of the study in the 1990s when various procedures such as the collection of various blood samples were conducted. The scientists then selected two groups of individuals – ones who were diagnosed with colon cancer during the study and those who were free of the disease.

The scientists assessed information about the tumours and blood levels of vitamin D and found that the immune system cells did indeed function better when vitamin D levels are higher. In other words, those T –cells are more potent killers when it comes to attacking cancer.

When it comes to most nutrients, dietary sources are usually your best bet. But when it comes to vitamin D, especially at this time of year, vitamin D sources are in short supply. It’s one time when looking for a nutrient in a bottle is your best bet.


Do you take vitamin D supplements? What about family members? Please share in the comment section below.

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Categories: Nutrition News

Author:Rosie Schwartz

Rosie Schwartz is a Toronto-based consulting dietitian and writer.

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4 Comments on “A vitamin D-cancer link”

  1. Chris
    February 24, 2015 at 2:10 pm #

    I think there is vit D in my calcium tablets. I was told by daughters endocrinologist everyone in Canada should be taking Vit. d because we are deficient.

  2. February 24, 2015 at 6:05 pm #

    Thanks for your comments, Chris. Yes, I would agree with your daughter’s endocrinologist. Living in Canada means that we don’t experience strong enough rays of the sun to manufacture vitamin D for about 9 months of the year and if you wear sunscreen during the summer, then it’s a year round problem. As for the amount of vitamin D in calcium supplements, I would say it’s not enough.

    Many health groups, including the Canadian Cancer Society, are recommending that we up our intake to 1,000 IU per day for adults, an amount you cannot readily achieve through food alone. Others are suggesting even higher amounts such as 2,000 IU daily. Keep in mind that the Upper Tolerable Limit listed by Health Canada is 4,000 IU per day.

    There is also now some discussion that there are statistical problems with the recommendations by Health Canada which may mean the amounts should be even higher. In the meantime, I would check what your vitamin D totals are and increase them accordingly.

  3. Madonna Kelly
    February 24, 2015 at 8:00 pm #

    When I was living in Texas where we got a lot of sun my vit D levels were actually lower then when I lived in Canada. I think I intentionally avoided the sun more there and maybe that was the reason. My GP recommended 4000 IUs a day. Is it possible that now people are becoming more aware of the dangers of sun exposure that we are becoming Vit D deficient ? Thanks!

    • February 25, 2015 at 10:40 am #

      Absolutely, Madonna! Sunscreen blocks the production of vitamin D, a process that normally occurs when skin is exposed to sunlight of sufficient UV strength. As we became aware of safe sun practices, vitamin D levels plummeted. That is where the supplements come in.

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