Too much caffeine can affect the hormones in their bodies, scientists
believe, playing havoc with their bust size.
The more coffee the women drank, the smaller their breasts, the researchers
also found.
Almost 300 women took part in the study, which questioned them on how many
cups of coffee they drank in an average day and measured the size of their
bust.
According to the results, published in the British Journal of Cancer,
drinking three or more cups a day was enough to cause a smaller breast size.
The effects of the stimulant rose for every cup drunk.
Around half of the women in the study carried a gene mutation which appeared
to link coffee intake and breast volume, according to the findings.
"Drinking coffee can have a major effect on breast size," said Helena
Jernstrom, from Lund University in Sweden, who led the study.
"Coffee-drinking women do not have to worry their breasts will shrink to
nothing overnight.
"They will get smaller, but the breasts aren't just going to disappear."
She added: "However, anyone who thinks they can tell which women are coffee
drinkers just from their bra measurements will be disappointed.
"The problem is that there are two measures for a bra, the cup size and the
girth, so you wouldn't be able to tell."
Women who drank more than three cups of coffee a day had breasts an average
of 17 per cent smaller than those whose who drank less than three cups a
day.
Women with bigger breasts are at a higher risk, the scientists also found.
But the study was unable to conclude whether drinking large amounts of
caffeine every day also affected the density of the breasts.
However, the study found that a large consumption of coffee could have a
positive impact on the health of the breasts.
Drinking caffeine regularly appeared to reduce the risk of breast cancer
among the volunteers, who had been specifically selected from families at
high risk of contacting the disease.
The scientists believe that the effects of coffee are linked to its impact
on the female sex hormone, oestrogen, and the fact that it can also affect
levels of the male sex hormone, testosterone.
