Recent linked studies published in The BMT found that higher fruit intake during adolescence could reduce the risk of breast cancer, while high alcohol intake later in life is associated with an increased risk.
Consumption of fruits and vegetables are thought to offer protection against breast cancer, but there is conflicting evidence since most studies analyzed the relationship midlife or later, which could occur after breast tissue is the most vulnerable to influences.
In the first study, researchers observed 90,000 nurses for a period of 20 years. The nurses reported their diet in early adulthood and their usual diet during adolescence, if remembered.
Researchers found that patients who reported a high fruit consumption, 2.9 v .5 servings per day, had a 25% lower risk of breast cancer in middle age.
Consumption of apple, banana, and grapes during adolescence was associated with a reduced risk of breast cancer, while consumption of oranges and kale in early adulthood also reduced the risk. Researchers did not find any link between fruit juices and cancer risk.
Researchers said these findings are in line with advice to eat more fruits and vegetables to prevent cancer.
In the second study, researchers observed the health of 22,000 post-menopausal women to see how alcohol intake affected the risk of breast cancer and heart disease.
Researchers found that women who increased their intake by 2 drinks per day for 5 years had a 30% increased risk of breast cancer, but had a 20% decreased risk of heart disease compared with women with stable alcohol intake, according to the study.
The risk of breast cancer or heart disease was not found to be associated in women who decreased their alcohol intake over 5 years. Researchers said their findings show that alcohol is associated with breast cancer and heart disease, but in opposite ways.
"There may be some benefit with low to moderate intakes of alcohol, but this could be outweighed by an increased risk of breast cancer and other morbidities," the study authors wrote. "Furthermore, risk of ischaemic heart disease can be reduced substantially by other lifestyle changes, as well as by drugs such as statins shown to be effective in primary prevention."
Researchers conclude that both studies are observational, so other factors need to be taken into consideration before any conclusions are formed.