Is soya safe?
Soya and soya products have been consumed for many years, particularly in Asia, and there has been much talk over their health benefits (that’s another blog!). Soya has made many food headlines over the past decade, however, concern about soya possible links with oestrogen sensitive breast cancer, have raised the question – is soya safe?
Soya has a high natural phytoestrogen (the isoflavones; genistein, daidzein and glycitein) content. These phytoestrogens have a similar chemical structure to oestrogen, competing for and weakly binding to certain oestrogen binding sites in the body.
The proposed link between oestrogen sensitive cancers and soya is a logical one! Could soya’s high phytoestrogen content compete for the oestrogen binding sites in body and increase the growth of oestrogen sensitive cancer cells? This was demonstrated in rats and mice and raised much of the concern and publicity around soya’s safety, however, it was later shown that rodents metabolize phytoestrogens differently to humans.
Is soya safe? – Binding sites
Soya phytoestrogens have been found to bind to different oestrogen receptor sites compared to the hormone oestrogen. This subtle difference in the oestrogen receptors that phytoestogens bind to, and their location in our body, has an important effect on the activation of specific oestrogen receptor sites. Subsequently, this specific receptor activation influences the proliferation and inhibition of breast cancer cells. This important difference in the specific receptors that phytoestrogens activates, plays an important role in answering the question, is soya safe?
Does soya increase the incidence of breast cancer in women?
There have been 7 recent observational studies (studies that follow patients up to identify an increased risk) investigating the relationship between soya intake and breast cancer recurrence in women who have previously had breast cancer. These studies looked at over 13,000 patients with a 3-7 years follow up period. None of the studies demonstrated an increased risk of recurrence, some even found a reduced risk. So, although the research has its limitations, it’s looking good for the soya bean!
Is soya safe? – What about processed soya products?
There is little evidence to demonstrate a risk between processed soya products, however, from a nutritional perspective, processing generally removes some of the good stuff and adds more of the bad (mainly sugar and salt). Reading the labels is important and where possible opt for less processed soya products, such as tofu, whole bean soya milk, dried soya mince or unprocessed soya, such as whole soya beans or edamame beans. Whole soya beans can now be purchased in many supermarkets frozen, making a quick, easy and tasty addition to a stir fry.
Is soya safe? – The Internet Dietitian’s conclusion!
The evidence to date concludes that soya foods are safe for women concerned about, or who have developed breast cancer. Those women can continue to include and enjoy Soya foods as part of a healthy balanced diet. But, it’s not just about soya! A third of cancers diagnosed in the UK each year are linked to smoking, diet, alcohol and obesity. Look at the bigger picture in the pursuit of health, as lifestyle changes can play a key role in preventing breast and other forms of cancer. Please contact Sian at The Internet Dietitian.com for more information.
If you have enjoyed reading this ‘Is soya safe?’ blog, you may be interested in reading ‘Health benefits of soya’ – coming soon!