Does sugar cause or feed breast cancer?

PUBLISHED ON: 29 September 2017

Claims that ‘sugar causes breast cancer’ or ‘sugar feeds cancer cells’ have appeared a lot in the news, but there is no evidence that sugar increases the risk of breast cancer developing or spreading. We look at where these stories might come from and the truth about sugar and breast cancer.

Does sugar ‘feed’ breast cancer cells?

All the cells in our body need energy to grow and survive. Cancer cells usually grow quickly and so need lots of energy. This energy comes from several sources including glucose (sugar). Glucose comes from sugary foods in our diet but also from foods containing carbohydrates, such as pasta or bread, which our bodies convert into glucose.

This may make it seem possible that if you had no sugar in your diet it could help stop cancer developing or growing. But all our other cells also need glucose to survive, and there’s no way of letting just the healthy cells get the amount of glucose they need and starving the cancer cells.

Can a sugar-free diet reduce the risk of breast cancer developing or spreading?

Experts agree that there is currently no evidence to suggest that following a sugar-free diet reduces the risk of breast cancer developing or spreading. 

While the possible link between sugar in the diet and cancer is often talked about, the research so far has not shown evidence of a direct link.

We often hear from people who’ve read things in the news or online about sugar causing breast cancer or encouraging breast cancer to come back or spread. For example, when the scientific journal Cancer Research published a study about sugar in January 2016 it lead to discussion on our online Forum and calls to our Helpline.

The study looked at the whether feeding mice (not people) a diet high in sugar increased the risk of breast cancer developing compared to those fed a sugar-free diet. It also looked at whether sugar increased the risk of the cancer spreading in mice who already had breast cancer. The results could not say whether sugar in the diet did have a direct effect on either of these.

Eating a healthy diet

Having a high sugar intake over time can contribute towards weight gain, and we know that being overweight can slightly increase the risk of developing breast cancer (after the menopause), other cancers and conditions such as heart disease and diabetes. Eating a healthy diet and being physically active are important, however most foods can be included as part of a healthy diet as long as you get the right balance. Foods containing sugar can be eaten in moderation.

While weight may slightly affect your risk, the biggest risk factors for developing breast cancer are being a woman and getting older, and for some having a significant family history.

There is some evidence that diet and lifestyle can affect the risk of breast cancer coming back (recurrence). Find out more about diet, lifestyle and recurrence risk.

Further information and support

For more information and support our free Helpline.

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