Nutrition and breast cancer prevention

Nutrition and breast cancer prevention

The health risks associated with sugar were broadcast into all our homes earlier this year when Jamie Oliver took the issue to number 10. The list of sugar’s crimes is endless; damage to our children’s teeth, obesity, diabetes, cardiovascular disease and high cholesterol to name a few.  If that doesn’t convince us to cut it out, it’s also implicated in one of the biggest health concerns of the century.  Cancer and specifically Breast Cancer.

It’s all down to hormones


Insulin; sugar’s wingman. It’s best known as a hormone we release every time we eat sugar to restore our blood balance.  But, far from being monogamous, insulin is quite the lothario.  It loves to frolick with other hormones if given the chance, causing a host of health issues.  Eating too much sugar from processed and simplified carbohydrates long term, such as fizzy drinks, white bread, pasta, cakes, sweets and even fruit juices, leads to hyperinsulinemia (that’s high insulin to the non science savvy).  It’s a sign of insulin resistance; a condition when cells stop responding to the hormone.  But it’s the effects of excess insulin on estrogen that increases our risks of breast cancer.1  

We’ve long understood the risks of cancer involved with estrogen exposure to breast tissue.2 Put simply, estrogen is a sex hormone that develops female characteristics of the body.  In order for estrogen to travel in the body safely, it needs to bind to a protein known as sex-hormone binding globulin (SHBG). Specifically, it’s unbound estrogen that’s linked to breast cancer.  Particularly amongst postmenopausal women.  It’s free to bind to breast tissue and promote cell growth, aka a tumour. The problem is, high insulin from excessive sugar consumption prevents SHBG production.  This leads to an availability of free estrogen to bind to breast tissue, promoting cancer growth.  It’s horrifying.

The benefits of Omega 3 for breast cancer prevention  

The solution seems obvious.  Cut down on sugar.  But for many of us the metabolic damage from long term sugar consumption is much more complex and may require more support.  There are a number of dietary measures to help target insulin resistance and its risks for breast cancer.  Swapping refined carbohydrates for their complex alternatives is a good start. That’s wholegrain brown bread, rice and pasta in place of white. Switch to pulses and legumes too.  These foods are high in fibre, which have been shown to improve blood sugar control, keeping insulin stable.3 Cinnamon promotes similar effects too.4

EPA and DHA Omega 3 reduces risks of breast cancer by 14 percent.

However, the research on Omega 3 EPA and DHA fish oil is most exciting.  A recent large scale review showed that EPA and DHA reduces risks of breast cancer by 14 percent.5 That’s astonishing.  For every 1000mg consumed each day, the risks reduce by a further five percent.  Interestingly, the results are exclusive to Omega 3 from fish oil.  They did not correlate to consuming general fish or plant based Omega 3s.


The way it works is not yet fully understood.  But it could be down to the beneficial effects of Omega 3 on insulin resistance.  Our cell membranes are made up of these essential fats.  They help to keep them flexible; important for effective cellular communication.  Membranes are like cell doors; the more EPA and DHA they have, the more lubricated the hinges are.  So substances can flow in and out easily.  This is important for insulin resistance because cells stop responding effectively to insulin. They become desensitized causing high levels of the hormone in the blood.  Good quality fish oil has been shown to help improve insulin sensitivity, helping to bring levels back down.6 Important for breast cancer prevention. 

Kay Ali is Head of Nutrition at Bare Biology. She is a registered member of BANT and a Senior Associate Member of the Royal Society of Medicine.

This article was originally written for The Lifestyle Library. 


  1. Kaaks R. Nutrition, hormones and breast cancer: is insulin the missing link? Cancer Causes Control. 1996; 7: 605-25.
  2. Rosner W. The functions of corticoidsteroid binding globulin and sex hormone binding globulin: recent advances. Endocrine Review, 1990; 11: 80-91. 
  3. Weickert M.O, Pfeiffer A.F.H. (2008) Metabolic Effects of Dietary Fiber Consumption and Prevention of Diabetes. American Society of Nutrition; 138: 439-442.
  4. Allen R.W, Schwartzman E, Baker W.L, Coleman C.I, Phung O.J (2013) Cinnamon use in type 2 diabetes: an updated systematic review and meta-analysis. Ann Fam Med; 11:452-9. doi: 10.1370/afm.1517.
  5. Zheng J.S, Hu X.J, Zhao Y.M, Yang J, Li D (2013) Intake of fish and marine n-3 polyunsaturated fatty acids and risk of breast cancer: meta-analysis of data from 21 independent prospective cohort studies. BMJ, 346 doi:
  6. Albert B.B, Derraik J.G.B, Brennan C.M, Biggs J.B, Smith G.C, Garg M.L, Cameron-Smith D, Hofman P.L & Cutfield W.S (2014) Higher omega-3 index is associated with increased insulin sensitivity and more favourable metabolic profile in middle-aged overweight men. Nature; Scientific Reports 4, Article number: 6697.


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