Black tea is a widely consumed beverage in the Middle Eastern region, and scientists believe that consistently drinking this could confer protective effects against breast cancer.
This was according to a large-scale systematic review conducted by researchers covering 65 studies across the Middle East and North Africa (MENA) region. Countries covered in the review included Iran, Jordan, Turkey, Saudi Arabia, Morocco, Iraq, and Algeria.
“The data showed that the daily consumption of black tea significantly reduced the risk of breast cancer in women by more than three times compared to control subjects,” the researchers said.
“Black tea is culturally very important in the MENA region, and its frequent intake could contribute to a stronger exposure to its bioactive compounds [that help in preventing] cancer.”
Among the bioactive compounds in black tea are catechins, theaflavins, and thearubigins which have been shown to neutralise free radicals and reduces oxidative stress, which in turn reduces the DNA damage that can lead to cancer.
“These polyphenols have been shown to inhibit the growth of cancer cells and induce apoptosis (spontaneous cell death) in tumour cells, potentially preventing the initiation and progression of cancer,” they added.
“Some studies also suggest that some of these compounds can influence the enzymes involved in oestrogen production, which reduces biologically active oestrogen and the risk of [hormone-related] breast cancer.”
That said, they also postulated that long-term, consistent consumption of black tea is likely to be required to get these protective effects.
“Outside of the MENA region, we also looked at eight studies conducted that linked black tea to reduced breast cancer risk, but five that saw a modest increase in risk,” they said.
“We believe that this is due to genetics, lifestyle and diets [as well as the fact that] black tea consumption is lower in these countries compared to the MENA region.”
Impacts of other foods
The review also looked at the potential impact of key food groups – such as vegetables, dairy and meat – on breast cancer risk.
“The MENA region has known a notable social and cultural change over recent decades [with] most MENA countries adopting more Westernised lifestyles,” the researchers said.
“Traditional diets in the MENA region often feature an abundance of fruit, vegetables, whole grains, and traditional foods, but with this globalisation and urbanisation there has been a shift towards westernised, industrialised diets,”
“These diets are characterised by increased processed foods, sugars, fats, animal products, as well as saturated and trans-fatty acids, [which] have contributed to an increased risk for breast cancer.”
Overall, protective effects were found for fruit, vegetable, fish and seafood consumption, but consumers have been warned that the results for red meat and dairy products are ‘inconsistent’ and ‘complex’.
“Half of all the red meat studies we reviewed reported a positive association, while the other half found no significant link,” they said.
“That said, it is noteworthy that cooking any type of meat to a well-done level causes the formation of [certain] hydrocarbons which are known to be carcinogenic.
“As for dairy, the relationship between milk consumption and breast cancer risk is complex as there are many factors influencing this, from the type of milk (whole, low-fat, or skim) to the amount consumed to other individual genetic and lifestyle factors.
“Evidence shows that milk consumption is associated with increased risk due to the presence of hormones such as oestrogen, but is also associated with giving a protective effect due to nutrients such as calcium and vitamin D.”
Plant-based diet not necessarily the answer
Despite any potential doubts about meat and dairy, the researchers did not recommend an outright switch to a plant-based diet as a possible solution.
“Most of the studies associating plant-based diets and breast cancer risk have been conducted in Iran, and the results have been varied,” they said.
“We classify plant-based diets as healthy or unhealthy depending on the composition, with healthy plant-based diets containing mostly minimally processed, nutrient-rich plant foods that provide a range of protective nutrients.
“Although most studies looking at healthy versions of this diet were inversely associated with breast cancer risk, unhealthy versions were strongly associated with it – showing that not all plant-based diets provide the same health benefits.”
