Are you getting enough vitamin D?

Research shows that women with low levels of vitamin D have a higher risk of breast cancer. Most types of cancer, including breast cancer, seem to respond well to vitamin D, but it doesn’t cure cancer, it merely controls it. Therefore vitamin D may play a role in controlling normal breast cell growth and may be able to stop breast cancer cells from growing.

Steps you can take
The two most reliable ways to boost your vitamin D level are to get more direct sunlight exposure and take vitamin D3 supplements. Eating foods rich in vitamin D can also help, but is less effective.

Whilst sun exposure offers vitamin D benefits, it does have risks. Sun exposure increases your risks of skin cancer, including melanoma, the most dangerous type. Daily exposure to the sun in the middle of the day for 6-8 minutes is the best way to get your vitamin D, with the more skin exposed the better. But any longer than that and experts recommend that you cover up. And remember, if we get too much sun (eg in Perth: more than 10 minutes in summer in the middle of the day) not only does the skin start to burn, but the sun can destroy the vitamin D in our skin.

There is a lot of debate about what an ideal vitamin D blood level is so before you take any supplements, talk to your doctor about the risks and benefits of the product, as well as what a good vitamin D serum level is for you.

The international photobiology consensus is 120nmol/L for the general population. People with a history of cancer should be higher than that. Most people need 2000iu minimum per day, with cancer patients usually needing more than that as a small vitamin D dose does not make any difference in cancer control.

If your level is low and you are currently taking a supplement, have your vitamin D level checked in a few months and adjust your dose accordingly. When you get to your target level, don't stop taking them otherwise your level will fall again and remember to take them regularly. It’s also important to note that consistently taking too much vitamin D (levels above 750nmol/L) can cause you to have too much calcium in your blood, so work with your doctor on what is best for you.

Foods rich in vitamin D include; herring, salmon, catfish, oysters, mackerel, sardines and trout. But it is important to choose your fish carefully to avoid any species that may have high levels of mercury. Taking 1-3 teaspoons of fish oil per day as a supplement can also help, but it can only be consumed in small amounts otherwise you might reach toxic vitamin A levels. Read the label and calculate your dose carefully.

Johnson, K.  (2012). Vitamin D: 'Surprise' Prognostic Marker in Breast Cancer, Medscape, December 10, 2012.