Breast cancer

Breast cancer is the most common cancer affecting women in the UK. Many of the risk factors are related to diet and lifestyle. Despite the growing body of scientific evidence, there is a widespread reluctance to recognise the role of diet in breast cancer risk. When Viva! Health started this campaign in 2007, one in nine women in the UK had a lifetime risk of developing breast cancer. Now the lifetime risk is one in eight! An examination of the links between diet and lifestyle and breast cancer is long overdue.  

While breast cancer is now a disease that most women survive (thanks to earlier diagnosis and better treatment), the number of women facing this disease continues to rise. Since 1970s the incidence of breast cancer has increased by a staggering 80 per cent.

What about genes?

It’s not all in the Genes. Many people think that their risk of developing breast cancer is beyond their control; that ‘fate’ will decide. This type of genetic fatalism results from the much-publicised link between genes and breast cancer. However, less than 10 per cent of breast cancers are caused by faulty genes. The vast majority (over 90 per cent) are caused by environmental factors, including diet. Women who maintain a healthy weight, exercise regularly and have a low intake of saturated fat and alcohol tend to have a lower risk.

The role of diet

Breast cancer has been at the scientists’ centre of attention for many decades. It’s not only one of the most frequent types of cancer but it can be hormone sensitive which makes the treatment more difficult. Diet has been linked not only to the prevention and treatment of breast cancer but also to natural regulation of hormone levels. In the case of breast cancer, diet is of high importance both because of nutrient content and due to its effect on body weight. Being overweight is one of the risk factors for breast cancer.

So what are the effects of saturated fat, red meat and dairy foods? Can a plant-based diet rich in fruit, vegetables and wholegrain foods help? What effect, if any, do soya foods have?

What does the science say?

During the Shanghai Breast Cancer Study (Cui et al., 2007), a wealth of data from breast cancer patients and healthy women of similar age was collected and the risk of breast cancer in relation to diet evaluated. The authors noticed there were two dietary patterns – ‘vegetable-soya’, characterised by fruit and vegetables, pulses and grains; and ‘meat-sweets’ characterised by meat, fatty foods and sweets.  The analyses of the data revealed that the ‘meat-sweet’ pattern was significantly associated with increased risk of estrogen receptor-positive breast cancer among postmenopausal women and this association was even stronger if the women were overweight.

Another large study was conducted in Singapore where 34,000 women’s dietary patterns and health were followed for the average period of ten years (Butler et al., 2010). Similar to the study above, the researchers identified two dietary patterns, ‘meat-dim sum’ and ‘ vegetable-fruit-soya’. And the results revealed a direct relationship between diet and breast cancer risk in postmenopausal women – the greater the intake of the foods from the vegetable-fruit-soya category, the lower the risk of breast cancer. More specifically, the risk was 30 per cent lower in women who had the highest intake of these foods.

And when a long-term study followed women’s health and diets in Italy, it arrived at a comparable conclusion (Sieri et al., 2004). Women with mostly plant-based diets high in raw vegetables had up to 36 per cent lower risk of cancer than women who ate more animal-based and processed foods. The risk reduction was even higher for women who maintained a healthy weight.

Brennan et al. (2010) reviewed a myriad of studies on dietary patterns and breast cancer risk and reached a foreseeable conclusion – women consuming a diet high in plant-based foods, healthy fats and low in alcohol have a lower risk of breast cancer than women eating typical Western diets high in meat and animal fats.

As a part of the enormous Nurses’ Health Study, a Harvard scientific team investigated whether there is any link between the risk of breast cancer and dietary protein source (Farvid et al., 2014). During the 20 years of follow-up, it emerged that higher intake of red meat was associated with an increased risk of breast cancer. When the effects of different protein sources were estimated based on the dietary data, the scientists arrived at the conclusion that substituting one serving a day of red meat for one serving of pulses would mean a 15 per cent lower risk of breast cancer among all women and 19 per cent lower risk among premenopausal women.

Ferrari et al. (2013) focused on a different dietary component in their analysis of the EPIC (European Prospective Investigation into Cancer and Nutrition) study data. They investigated the relation between dietary fibre, its main food sources and breast cancer risk. The data showed that higher intake of fibre lowers the risk of breast cancer and the association was particularly strong with fibre from vegetables. This risk reduction was independent of the women’s menopausal status or cancer hormone sensitivity. The UK Women’s Cohort Study brought similar results – an increased fibre intake was linked to a lower breast cancer risk among British women (Cade et al., 2007).

To assess the influence of a radical diet change and exercise on women at risk of breast cancer, Barnard et al. (2006) enlisted volunteers on a two week program.  The women, who were all postmenopausal and overweight, agreed to follow a very low-fat, high-fibre diet consisting mainly of fruits, vegetables and wholegrains with very limited amounts of animal protein and daily aerobic exercise. At the end of the two-week period, their hormone levels decreased, including IGF-1 which dropped by as much as 19 per cent. The women also lost weight which is an important factor in breast cancer prevention and their blood sugar control improved. The serum isolated from the participants’ blood samples before and at the end of the trial was used on breast cancer cells in a cell culture to see if there would be any difference in the cell growth. The results were of major importance as the after the intervention, the cancer cell growth was significantly slowed down and considerably more cancer cells died compared to pre-intervention.

Probably the best known case study of diet change and breast cancer is Professor Jane Plant who had conducted extensive research on diet and breast cancer to treat her own condition. What she found out and the hundreds of studies she based her decisions on led her to a conclusion that a vegan diet is necessary for successful breast cancer treatment (Plant, 2007). Her advice has since helped thousands of women and has been supported by many experts.

Viva! Health has produced a scientific report; One in Nine which explains how breast cancer cases are rising and examines the evidence linking red meat and dairy to this disease. The fully-referenced report reveals how saturated animal fat, hormones and growth factors found in meat and dairy foods are implicated. The report also investigates which foods can help prevent and overcome breast cancer. Read how fruit and vegetables, fibre, folic acid, cruciferous vegetables (broccoli and cabbage) and soya can help fight this disease.

We have also produced a colourful 52-page guide called A Fighting Chance – A guide to healthy eating to help prevent and overcome breast cancer. The easy-to-read guide, based on the latest science, explains why meat and dairy foods are harmful and reveals different ways of eating healthier, tastier foods that don’t contain the harmful substances found in meat and dairy but do contain vital fibre and disease-busting compounds. The guide also contains a list of delicious superfood ingredients with an explanation as to why they can help combat illness and a useful seven-day meal plan with easy-to-follow, inspiring recipes.

The detrimental health effects of consuming cow’s milk and dairy products are more widely discussed in Viva! Health’s fully-referenced scientific report White Lies.