If you are regularly eating fermented dairy foods such as yogurt, the chances are that you’ll have reduced risk of developing lung or oral cancer, research has suggested.
It’s the latest in a growing body of evidence showing that the foods we eat can have a surprising impact on our risk of certain cancers. While the new findings don’t prove that eating yogurt can protect us against these types of cancer, it does open exciting avenues for scientists to explore.
Dairy foods hold promises in cancer research
Dairy foods have come under the spotlight in cancer research since scientists discovered some of them may help protect against colorectal cancer.
Until now only a few studies have investigated links between dairy consumption and other types of cancer and so far, these studies have reported inconsistent results. Now, two groups of scientists have investigated the links between dairy intake and risk of lung or oral cancer, with intriguing results.
Studying the links between dairy foods and reduced lung cancer risk
Scientists from Oregon State University in the USA set out to understand whether lung cancer risk may be linked to the consumption of different dairy foods. To gather their data, the researchers used a diet history questionnaire to assess participants’ dairy food intake before they were diagnosed with lung cancer. The researchers then tracked these people over time to identify any cases of lung cancer. The study involved 101,709 adults, aged on average 65.5 years, and 1,583 cases of lung cancer were identified during their follow-up (1).
Eating fermented dairy food is associated with a reduced risk of lung cancer
Results revealed no significant association between total dairy intake and lung cancer risk and consuming dairy foods as a whole did not appear to increase or decrease the likelihood of developing lung cancer.
However, the researchers discovered a reduced risk of lung cancer among people who consumed more fermented dairy foods than those who consumed less fermented dairy. Such foods included yogurt, frozen yogurt, sour cream, cream cheese, and several cheeses. People who ate the greatest amount of these foods (at least 22.4 g per 1000 kcal) had a significant 15% reduced risk of developing lung cancer than people who ate the least (1 g or less per 1000 kcal).
This association was most apparent in heavy smokers, but the researchers found no such association when they looked at non-fermented dairy foods.
When it came to individual fermented dairy types, they found that eating more versus less yogurt was associated with a significant 22% reduced risk of developing lung cancer. No such association was seen with eating more versus less cheese. Hence the type of dairy food consumed might play a role in lung cancer risk.
The researchers also found no significant associations between low-fat or full-fat dairy food intakes, or between lactose intake from dairy foods, and the risk of lung cancer, suggesting that the association between lung cancer and type of dairy food is not related to the macronutrient content
‘Our findings lend support for an inverse association between fermented dairy product intake and lung cancer risk, especially among heavy cigarette smokers.’ – Doan LN, et al. 2023
Studying the links between dairy foods and oral cancer risk
A separate group of scientists from the University of Granada in Spain investigated the relationship between eating different dairy foods and the risk of developing oral cancer (2).
They analyzed data from 21 clinical studies, including 8,300 people with oral cancer and 50,971 healthy people. Their aim was to determine whether eating certain dairy foods including milk, cheese, yogurt and butter had any influence on the risk of oral cancer.
Regularly eating dairy foods may reduce the risk of oral cancer
Except for butter, regular consumption of all dairy foods studied was significantly associated with a reduced risk of oral cancer, compared with less regular consumption. In particular, people who regularly drank milk had a 27% reduced likelihood of developing oral cancer. Of the 21 studies that assessed the role of milk consumption on oral cancer risk, 18 agreed that milk was associated with a protective effect.
Similarly, regular yogurt-eaters had a significant 25% reduced risk of oral cancer, while regularly eating cheese was associated with a 21% risk reduction. All the eight studies that assessed yogurt consumption on oral cancer risk found an associated protective effect, while ten of the 14 studies that investigated cheese consumption found an association with a reduced risk of oral cancer.
How might fermented dairy foods help to protect against lung and oral cancers?
Scientists suggest several reasons why dairy foods – in particular, fermented ones – might play a role in preventing these types of cancer:
- Previous studies suggest that dairy foods have anti-cancer components – such as calcium, vitamin D, phytanic acid and conjugated linoleic acid – which may inhibit tumour growth (3,4)
- In particular, fermented dairy foods contain bacteria that may exert anti-cancer effects by modifying the mix of microbiota in our gut (5)
- This effect on the gut’s microbiota is linked to immune responses and may reduce inflammation within the lungs (5)
- Probiotic dairy products may change the composition of our saliva, inhibiting the growth in the mouth of Candida bacteria, which are associated with oral cancers (6)
Understanding the relationship between our diet and cancer risk is a complex task. While these recent studies provide valuable insights, more research is needed to confirm these associations and to understand better the mechanisms at play.