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A Mediterranean or Ketogenic approach to Breast Cancer: Which diet is best?

A Mediterranean or Ketogenic approach to Breast Cancer: Which diet is best?

23 June 2021

Diet is often one of the first things breast cancer patients look to improve to support their recovery and help protect them from recurrence.  In this blog piece we take a closer look at 'A Mediterranean or Ketogenic approach to Breast Cancer: Which diet is best?'

Whilst there has been much research into the field there is limited evidence to support one definitive dietary therapy for breast cancer patients. Does diet really have an impact?

Yes it does!

Influence of diet on key mechanisms in cancer development

Many epidemiological studies show that the Western dietary pattern always fairs poorly when it comes to the risk of various cancers. The standard Western diet is commonly characterised by excessive intake of saturated fatty acids, trans-fatty acids and refined sugars. There is a significant over consumption of foods including red and processed meats, commercially prepared baked and fried foods, butter and margarines and sweet foods laden with fats and sugars. Not only is it highly pro-inflammatory, but the abundance of carbohydrates (found in grains, breads, cereals, baked goods, confectionary etc) increases blood sugar levels and insulin, which drives up growth promoting pathways.

Inflammation and Oxidative Stress

Chronic inflammation is a known contributing factor in cancer progression. Inflammation provides chemicals that alter cell signalling and growth promotion, and it produces free radicals which lead to sustained oxidative stress, associated with tissue damage and disease. The increased presence of free radicals may trigger alterations in gene expression levels which further drive cancer progression.

Dietary compounds can be pro - or anti-inflammatory. Repeated clinical trials have shown that patients with the lowest levels of inflammatory markers (such as IL-6) have the highest disease-free survival. So it makes logical sense, and it's evident in clinical research, that an anti-inflammatory diet is the way to go.

Additionally, dietary anti-oxidants work to neutralise free radicals helping to reduce cancer risk. Research shows that phytochemicals, naturally occurring compounds found in plant foods specifically help to suppress breast cancer by influencing cell signalling pathways and genes to reduce cell proliferation and protect against cancer progression and recurrence.

The Mediterranean Diet

A diet that is both anti-inflammatory and rich in antioxidants from plant foods is the Mediterranean diet.

The Mediterranean diet is associated with decreased breast cancer risk and reduced mortality. Foods typically consumed in the Mediterranean diet such as fruit and vegetables, olive oil, whole grains, fish and nuts are rich in phytochemicals which have been shown to exhibit anti-breast cancer properties. The Mediterranean diet provides an abundance of antioxidants that protective against oxidative damage by neutralising free radicals.

The Mediterranean diet is also characterised by a fat intake of 40-50% of daily energy with plenty of polyunsaturated fats from fish, and monounsaturated fatty acids from olive oil. Research has shown there is an inverse relationship between monounsaturated fatty acid intake from extra virgin olive oil and breast cancer risk, while fish has found to be anti-inflammatory and protective in many studies.

The Ketogenic Diet

At first glance, the Ketogenic diet is quite the opposite to the Mediterranean diet. It is rich in animal protein, dairy and fats, low in plant foods and fruit, and contains no grains (refined or whole) at all.

The idea of the Ketogenic diet as an anti-cancer diet is to manipulate macro-nutrient intake to negatively impact cancer cells' access to nutrients needed to support cell replication thus inhibiting tumour growth. Some cancer cells seem to rely on carbohydrate availability to meet energy requirements, using glucose as its primary fuel source. The Ketogenic diet would thus provide a targeted therapeutic dietary strategy to selectively starve cancer cells of fuel to inhibit their growth and survival. 

Sounds good, right?

Now, clinical research is still quite scarce. While in vitro studies sound compelling, randomised human clinical trials investigating the Ketogenic diet to treat breast cancer are limited. Most studies focus on brain tumours or advanced cancers with a poor prognosis, and results are tricky to interpret. One study however found there was an increase in overall survival rate of patients randomised to a ketogenic diet intervention group compared to the control group where Ketogenic diet was administered concurrently with chemotherapy prior to surgery.

However, other reviews of pre-clinical trials found that 60% of studies reported anti-tumor effect for Ketogenic diet, 17% reported no influence at all and 10% reported adverse or even pro-tumor effects. These findings suggest that a Ketogenic diet is not appropriate for all types of cancer, and the tumour response to ketone bodies may be influenced by tumour type or genetic background. Concerns have also been raised regarding potential side effects of ketogenic diet, such as nausea, vomiting, hypoglycemia, dehydration, fatigue and constipation, all of which can lead to poor tolerability and compliance.

Whilst most studies to date support the Ketogenic diet as a safe adjuvant cancer therapy conflicting findings regarding its effect on different tumour types prevent its recommendation as a blanket dietary therapy for breast  cancer patients.

The gist?

Diet, as a modifiable risk factor for breast cancer, has remarkable potential anti-cancer benefits, but it is important to consider individual circumstances and seek appropriate medical advice to determine the best diet to support recovery and long-term health. 

Overall, the Mediterranean diet elicits its anti-cancer effects through plentiful consumption of foods containing phytochemicals that have anti-oxidant and anti-inflammatory properties. Individual components of the Mediterranean diet including fruits, vegetables, olive oil, legumes, whole grains, nuts and fish have been linked to cancer prevention in meta-analyses of human studies. The diverse range of foods consumed in the Mediterranean will also likely support long-term compliance.

The Ketogenic diet may also have specific anti-tumour properties, however the evidence is still unclear as to who will benefit specifically. The restrictive nature of this diet results in compliance issues, and long term use may have other health complications. HOW we implement the Ketogenic diet is also important, as an over-reliance on animal produce and saturated fats is in fact a risk factor for other cancers.

Consideration should also be given to things such budget, cultural influences, family circumstances and who prepares the meals in the house. Ultimately you want to give yourself the best chance of recovery and remaining disease free, but be kind to yourself too, do what you can with the means you have and forgive yourself if you don't follow your diet to the letter 100% of the time. Always work with a health practitioner before making any changes to your diet.



About the Author: Claire Evans

Claire Evans is a nutritionist, yoga teacher, breast cancer survivor and part of the MIOG Community. Claire has worked in the health and wellness industry for over 15 years and has a strong research interest in food as medicine. Claire is passionate about supporting cancer survivors holistically with evidence-based therapies and helping to educate people to eat well to support optimum wellbeing.

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