Does eating sugar cause breast cancer?  A quick google search will lead you to two very different opinions on this question. 

Cancer cells use sugar as fuel.  So one obvious conclusion to make is that eating sugar will make cancer grow. 

On the flip side, all of our cells use sugar as fuel.  And our bodies break down all sorts of foods — sweets, breads, even fruits and legumes, which ares supposed to be healthy foods — into sugar.  Based on this, some people suggest that eating sugar can’t possibly affect cancer growth. 

In a way, both views are right.  That’s because it’s likely not the sugar itself, so much as it’s effect on your body that impacts cancer growth.  Let’s take a look at what happens when we eat sugar.   And hopefully, this explanation will help things make a little more sense.

What happens when you eat sugar?

Let’s say you eat a cookie.  The sugar from that cookie goes into your blood stream,  increasing your blood sugar level.  In response, your body releases insulin to tell your cells to take in the sugar.  That way your cells get the fuel they need, and your blood sugar levels go back down.  If all is working well, blood sugar and insulin levels should stay relatively stable.  The problem occurs when you consume an overall high- sugar diet.  The frequent consumption of sugar leads to chronically high blood sugar.  The body, in turn, makes more insulin in order to keep up. 

Eventually, with all that insulin, the cells essentially stop listening.  That means the cells don’t take up as much sugar.  You need to make more and more insulin, trying to get things back into balance.  You are left with chronically high blood sugar, high insulin, and unresponsive cells.

How does this relate to cancer?

While the role of sugar itself might be a bit controversial, studies do show that high insulin stimulates growth of certain cancers — breast cancer being one of them— and that high insulin levels correlate with a worse prognosis in those with breast cancer.   

Research has also shown that cancer cells often have more insulin receptors on them than our regular cells do, which means they are even more affected by our insulin levels than the healthy cells are. 

And to complicate things further, another hormone called insulin-like growth factor (IGF-1) also increases with high blood sugar levels.  IGF-1 also stimulates tumour growth and it inhibits the breakdown of cancer cells.

In conclusion…

If you eat a healthy, low sugar diet, one piece of pie isn’t likely to make a difference in your cancer risk.  But having chronically high blood sugar, insulin, and IGF-1 levels will.  This is supported by research that shows that overall higher sugar diets do increase breast cancer risk. 

So when it comes to sugar, your best bet is to decrease your overall consumption of sweets, breads, pastries, and anything that really tends to boost your blood sugar levels.

What about fruit, whole grains and legumes?  These foods contain more fibre, so they don’t tend to raise your blood sugar levels as much, making them a healthier choice when it comes to cancer risk.

So, if you are craving something sweet, grab a piece of fresh fruit.  And instead of sugar,  honey, or syrup, choose stevia or xylitol as sweeteners.  They are much better in terms of blood sugar levels.

You might also be interested in…

Balance Your Hormones for Breast Health

Flax Seeds for Breast Cancer Prevention


DeCensi A, Gennari A. Insulin Breast Cancer Connection: Confirmatory Data Set the Stage for Better Care.  Journal of Clinical Oncology 29, no.1 (January 2011) 7-10.

Yu H, Rohan T.  Role of the Insulin-Like Growth Factor Family in Cancer Development and Progression. JNCI: Journal of the National Cancer Institute, Volume 92, Issue 18, 20 September 2000, Pages 1472–1489.

Polischman N, Coates RJ, Swanson CA et al. Increased risk of early-stage breast cancer related to consumption of sweet foods among women less than age 45 in the United States. Cancer Causes Control. 2002 Dec;13(10):937-46.

Sieri S, Pala V, Brighenti F et al. High glycemic diet and breast cancer occurrence in the Italian EPIC cohort. Nutr Metab Cardiovasc Dis. 2013 Jul;23(7):628-34.

About The Author

About The Author

Dr. Rachel VandenBerg, ND is a naturopathic doctor and clinic co-director at Healing Path Centre for Natural Medicine in Waterloo, Ontario. Her practice focusses on fertility, women's health and breast cancer care.