Vitamin D and Breast Cancer: Just another Fad?

I must admit that I tend to get a bit grumpy when people start to talk about cancer and diet.  Usually it's someone lecturing me as I attempt to order the double chocolate mousse for dessert about how I mustn't because ' sugar feeds cancer'.  Alright, I know, I know.  Sugar isn't good for me.  But frankly it isn't good for any of us middle aged flabby people and I'm often in much better physical condition than the person lecturing me, so if I choose to tuck into a double chocolate mousse to ease my remaining hours on earth then that's my business, thank you very much.

On the other hand, I confess that I am sneakily becoming more interested in the links between diet and cancer, though there is such an overwhelming mass of articles from people advocating different food types, supplements, herbs, spices etc that it is difficult to pull the wheat from the chaff (so to speak).  I'm afraid I tend to roll my eyes with exasperation when yet another recommendation comes my way for eating some obscure grain from a plant that only grows on the upper reaches of mountains in Peru in the month of August.  Well, okay, I haven't actually seen that one.

But a little research shows that there are some genuine, scientifically proven dietary changes that are worth making.  One of the recommendations that initially had me rolling my eyes with an internal sigh was the one that's doing the rounds about vitamin D.  Was this just another fad?

Possibly not.  There is a solid selection of research that has proven a link between vitamin D levels and breast cancer.  Women with breast cancer have been shown to be more likely to have low vitamin D.  Women with higher levels of Vitamin D who already have breast cancer are likely to have smaller tumours and better survival rates.  Women with low vitamin D and breast cancer are twice as likely to have the cancer come back.

But before you dash to the fish shop for a double helping of mackerel, there is a word of caution.  There is certainly a link between vitamin D and breast cancer but the nature of that link is unclear. 

There is a theory that vit D receptors on cells can link to vit D which then prevents the cancerous cells from dividing and spreading.  But, because most scientific studies have been observational, it is possible that the link isn't causal at all.  Perhaps it's just a biomarker: if you have low vit D then it's one indication that your cancer is more serious.

That sends a nervous shiver down my spine because my recent check up found just one thing wrong with me: low vit D levels.  At the time I gave a relieved chuckle.  Low vit D!  Is that all!  But perhaps I should take it more seriously?

Yes and no.  There's no reason to worry that low vit D levels shows anything in particular about your cancer.  Especially if you live in Belgium.  While it is true that foods like oily fish and eggs are good sources, the majority of our vit D is produced when our skin is in contact with the sun.  That means that pretty EVERYONE in Belgium has low vit D levels.

On the other hand, it's a good idea to make sure that you don't have vit D deficiency anyway, because we do know that it has an important role to play in helping the body absorb calcium and to help the immune, muscle and nervous systems work properly.  Fifteen minutes of sun on the skin at least three times a week should do it.  If you live in Belgium and are more likely to get fifteen minutes of rain on the skin, then you might need supplements (though be aware that it is possible to get too much vit D and end up with too much calcium in the blood so it might be best to ask when you get your blood tests done).

Personally, I think this is just the excuse I needed to go back to Portugal and eat sardines in the sunshine.  Followed by a double chocolate mousse.