Eating yoghurt every day may ward off breast cancer, scientists claim.
A team from Lancaster University believe the “good bacteria” in probiotic yoghurt may dampen inflammation triggered by “bad bugs”.
Breast tissue contains “hormone-derived bacteria”, which can be benign or malignant, they claim.
Lactose-fermenting bugs - found in probiotic yoghurt - may be “protective” once they reach the breast ducts, they added.
The human body is made up of around 10bn bacterial cells.
While most are harmless, some can trigger inflammation.
In the short term, this swelling helps destroy germs. Over time, however, it can damage healthy cells.
An example is inflammation of the gums, known as periodontitis.
This been linked to cancer of the mouth, oesophagus, colon, pancreas, prostate and breasts.
One theory is “organisms from the mouth are carried through the blood to distant sites and cause direct tissue destruction and inflammation”, the scientists wrote in the journal Medical Hypotheses.
Breast cancer is the most common type of the disease in the UK, according to the NHS.
In the US, it is the second most prevalent cancer affecting women, after skin tumours, National Breast Cancer Foundation statistics show.
One in eight women in both countries will develop breast cancer at some point in their lives, data shows.
“There is a simple, inexpensive potential preventive remedy; which is for women to consume natural yoghurt on a daily basis,” the scientists wrote.
Probiotic yoghurt contains lactose-fermenting bacteria, similar to that found in breast milk.
“We now know breast milk is not sterile and lactation alters the microflora of the breast”, study author Dr Rachael Rigby said.
“Lactose-fermenting bacteria are commonly found in milk and are likely to occupy the breast ducts of women during lactation and for an unknown period after lactation.”
Each year a woman breastfeeds, her risk of breast cancer reportedly goes down by 4.3%.
Like breastfeeding, yoghurt could help ward off the disease.
“The stem cells which divide to replenish the lining of the breast ducts are influenced by the microflora, and certain components of the microflora have been shown in other organs, such as the colon and stomach, to increase the risk of cancer development,” the scientists wrote.
“Therefore a similar scenario is likely to be occurring in the breast, whereby resident microflora impact on stem cell division and influence cancer risk.
“Lactose-fermenting bacteria have the potential to displace pathogenic bacteria that cause periodontitis in both the oral cavity and in the breast.”
The scientists stress their theory is “not proven”, but supported by “available evidence”.