mitos alimentos cancer de mama

Five Myths and FAQs about nutrition during breast cancer


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In this age of information, there is an endless amount of information about nutrition and breast cancer. Following a diagnosis, it’s common to have relatives and close friends offer all types of information on nutrition and diet, with the best of intentions. However, this often ends up confusing and overwhelming the person affected.

In today’s post, we’ll discuss the five most common myths and concerns about what your diet should look like if you’re going to start or are currently undergoing treatment for breast cancer.

Do I need to eliminate all sugar from by diet?

Although science shows that tumours primarily feed on glucose (often inaccurately referred to as “sugar”), there is no evidence that sugar intake in our diet will worsen the tumour. Similarly, completely removing any sugar from your diet will not cause the tumour to shrink or disappear.

However, this doesn´t let you off the hook entirely. Having a diet with a high added sugar content will worsen the overall quality of your diet, and there is a risk that you won’t tolerate the treatment as well.

Ideally, you should consume foods containing some sugar in an intrinsic way, such as fruit, fresh vegetables and whole grains. Also, you should avoid regularly or frequently consuming sugary foods that, if not for human intervention, would not exist, such as soft drinks, sweets, cookies or condiments.

Is the ketogenic diet good for breast cancer?

The theory of recommending a ketogenic diet for cancer patients arose from the idea of eliminating sugar from the diet to prevent sugar (glucose) from reaching the tumour.

A ketogenic diet is one in which foods rich in carbohydrates are eliminated altogether, and the consumption of foods high in fat and protein is increased. Although some studies are starting to show that this type of diet could be safe and beneficial in certain very-specific cases, it is in no way a diet that helps all cancer patients. In addition, more studies on the subject are still needed today before this diet can be used safely in clinical practice for the individual.

Will “detox” foods help me detoxify my body after chemotherapy sessions?

This question is quite common, and it is normal that you want to help your body clear the chemotherapy, so that you can feel better as soon as possible. However, it is important to remember that both your liver and your kidneys, among other organs, are already doing that cleansing work perfectly well themselves. It is important to note that, despite what they might promise us, most juices, drinks or “superfoods” sold for this purpose do not demonstrate a clear and tangible benefit of cleansing or detoxification after consumption.

Should I avoid soy?

Soy is one of the most commonly consumed legumes today, and one of the foods that generates the most doubts and fears in breast cancer. The nature of this fear lies in the fact that soy naturally contains a compound called phytoestrogen. This is a flavonoid found naturally in some plants that resembles human estrogen. It is therefore thought that this addition of soy “hormones” could worsen the tumour condition.

However, when scientists have tried to demonstrate this theory, what we find is that moderate consumption of soy or soy products is not only not dangerous, but could even be beneficial because of their high plant-based protein content. The American Cancer Society has stated that it might be helpful to consume soy after a diagnosis of breast cancer. However, the evidence behind this is still weak, and its consumption as a healthcare measure is not recommended. It will be years before we know the degree to which soy could be beneficial in breast cancer. What we do know, however, is that its consumption is safe and not dangerous.

Natural vitamins and supplements

Doubts about the use of natural supplements, multivitamins, and which are the best, are also very common when starting cancer treatment. Breast cancer is possibly one of the types of cancer in which there is a greater tendency to take anti-inflammatory and antioxidant supplements, among others.

The reality is that, most of the time, no clear and tangible benefit will be obtained after taking these supplements, and they may even limit the efficacy of some chemotherapy treatments due to a drug-nutrient interaction.

In addition, entities such as The American Institute for Cancer Research (AICR), or the World Cancer Research Fund International (WCRF) already recommend against taking them. If you have any questions about this matter, do not hesitate to discuss it with your medical and healthcare team.

Sources: American Institute for Cancer Research (AICR), World Cancer Research Fund International (WCRF),

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