Is it true that cheese "reduces the risk of dementia"? Analyzing the Japanese and Swedish studies by the numbers

Is it true that cheese "reduces the risk of dementia"? Analyzing the Japanese and Swedish studies by the numbers

"Eating cheese may reduce the risk of dementia"—such a "happy headline" has spread across European media and quickly went viral on social media. The starting point of this topic was an article from Fuldaer Zeitung. It introduces the "potential of cheese to help in prevention" based on Japanese epidemiological research and a long-term follow-up study from Sweden.


However, to conclude, what can be said at this point is not "Cheese has been proven to 'work'" but rather "A 'correlation' was observed where those who ate cheese had a lower incidence" . Misunderstanding this could lead to an extreme shift in dietary habits.


1) Japanese study: Less incidence over three years with cheese once a week or more

The Japanese study introduced in the article is explained by the summary site DeutschesGesundheitsPortal, with data from the "JAGES (Japan Gerontological Evaluation Study)" cohort from 2019 to 2022.


The subjects were residents aged 65 and over who were not certified as needing care. They were roughly divided based on their initial dietary habits (frequency of cheese consumption) into "rarely eat (less than once a week)" and "eat once a week or more," and the incidence of dementia over three years was tracked.


The key point is the numbers.

  • Group eating cheese once a week or more: The incidence of dementia over three years was about 3.4%

  • Group rarely eating cheese: Over three years, it was about 4.5%

  • The difference is about 1.06 points (a small "absolute difference")

  • In statistical models, the result was relatively about 24% lower


The important point here is that the expression "24% lower" tends to be taken out of context. In absolute terms, it is "a difference of about one person out of 100", and since it is an observational study, the researchers themselves suggest that it may be influenced more by "the overall lifestyle of people who eat cheese (exercise, education, income, dietary patterns, etc.)" than by cheese itself.


2) Swedish study: Lower risk correlation 25 years later with 50g/day of high-fat cheese

Another pillar of the article is the long-term Swedish study. This study tracked approximately 27,670 people, with a median follow-up period of about 25 years. As a result, 3,208 people were diagnosed with dementia, based on large-scale data.


A characteristic of this study is that it "looked at dairy products by fat content," and to put it simply,

  • People who eat high-fat cheese (20% fat or more) at 50g/day or more have a lower incidence than those who eat less (less than 15g/day)

    • A lower correlation with all dementia (HR 0.87)

    • A lower correlation with vascular dementia (HR 0.71)

  • People who consume high-fat cream (30% fat or more) at 20g/day or more also have a lower risk correlation than those who do not consume it

  • Low-fat dairy products, milk, yogurt, and butter did not show a clear correlation (at least in this study)


What makes this study interesting is that it highlights “only cheese and cream stand out” rather than simply "dairy products." Various hypotheses can be considered, such as differences in fermentation, nutrients, and ways of consumption.


On the other hand, it is repeatedly pointed out in expert comments that "causation cannot be claimed as it is an observational study", and "the dietary survey was conducted only once in the past, and eating habits could have changed over the 25 years". This is both the "highlight" and the "pitfall."


3) Why "Cheese might be good" resonated: Three reasons SNS reacted

This topic was particularly suited for social media among nutrition news. In fact, on Instagram, posts introducing the study's numbers lined up, and high-spirited comments were seen. For example,

  • Comments like "Good news! My brain gonna be sharp forever," with a "cheese is the best" vibe

  • "I’m good then," a "victory declaration" by those who already eat cheese

  • Posts sharing the numbers as they are, like "3.4% vs 4.5%"


However, the higher the enthusiasm for spreading, the more criticism also increases on social media.

  • "Correlation ≠ causation"

  • "Is high fat okay for cardiovascular risk?"

  • "Is it okay to increase cheese with high salt content?"

  • "In the end, wasn't it just that people who live healthily also happened to eat cheese?"


—such cautious opinions also emerge. Furthermore, as overseas media articles spread through "translation," headlines tend to become stronger, leading to reinterpretations like "Cheese prevents dementia!" which can easily cause backlash and counterarguments.


4) "So, should we eat cheese?" A realistic answer

Considering all of the above, the conclusion is simple.

There is still no basis to increase cheese like a "medicine."
However, it can serve as material for considering dietary choices.


As a realistic compromise, the following approach is safe.

  • For those who already like cheese and eat it regularly

    • There is no "reason to prohibit" from this study (except in cases of pre-existing conditions or lipid restrictions)

  • For those who rarely eat cheese

    • It is premature to "increase it for dementia prevention." Prioritize more certain lifestyle factors (exercise, sleep, blood pressure, glucose metabolism, etc.)

  • If you do eat it

    • The direction of "enjoying a small amount" within the balance of total calories, salt, and saturated fat is safer than "increasing the amount"


Also, the guidelines from World Health Organization and large-scale reports related to The Lancet repeatedly emphasize that the overall lifestyle has a greater impact than a "single food." Because the topic of cheese is interesting, it's important not to leave behind "the other fundamentals".


5) Conclusion: Cheese research is more about "interpretation" than "hope"

What this article teaches us is not that "cheese is a panacea," but rather that
there are things that cannot be explained by the simple equation of "fat = bad", and
the numbers in observational studies are remarkably prone to misunderstanding.


Social media will continue to amplify "Can disease be prevented with XX?" Therefore, before jumping to headlines,

  • What is the follow-up period?

  • How big is the difference (absolute difference)?

  • Are they claiming causation? Or not?

  • To what extent were other lifestyle factors adjusted?


Even just checking these points can change how information "enters your body."
Enjoy cheese, but don't rush to conclusions, and let's wait for the next study.


Sources

Related Articles