Carbs Can’t Prevent Dementia
Why you shouldn’t worry about low-protein, high-carb diets just yet
For anyone interested in eating well, the modern world is a confusing place. Every week a different message is blared at us from a hundred different sources: “Eat less fat! Eat more fat! Broccoli is both the cause of and cure for every disease!”.
The latest story is no exception. News outlets from around the world have been screaming out that low-carb diets may actually be bad for your health. Apparently, carbs are not only not bad for you, they might in fact prevent dementia.
This is not a small claim. Dementia is terrifying in part because we don’t have good treatments for it. Any diet that may help in preventing the disease would be a truly massive thing for us all.
Sadly, the story is far less interesting than you may have heard.
Bread, pasta, and rice won’t stop your brain aging.
Stupendous Science
The new study that everyone is talking about was an examination of how diet effects different parts of the brain, hormones, and some behaviours. The researchers took a group of participants, followed them through their lives, and looked at how diets that ranged in their carb/protein ratio changed these reactions. They found that those who ate a diet lower in protein but higher in carbs performed almost as well as those who ate a calorie-reduced diet on a number of measures, and had changes in their clinical markers that were similar as well.
Essentially, they concluded that eating more carbs prevented brain aging, and that this might be one way to prevent dementia in the future.
Cue the media noise that mainlining rice will stop you from getting dementia, and that carbs are the key to a long, healthy life*.
Unfortunately, as the scientists themselves acknowledge, this study isn’t really applicable to you and I.
Carbs probably aren’t the key to preventing dementia.
Scandalous Science
There are a number of issues with this study that make it virtually impossible to use as evidence that carbs prevent dementia, but let’s start with the biggest, glaring hole that was ignored by most media reports.
This study looked entirely at mice.
Now, rodent research is vital to science. There are obvious difficulties with following humans for most of their lives, and then dissecting their brains to understand the changes that a diet may have had on them. But taking research done in mice and applying it directly to humans is extremely problematic. Mice are not people, and while we have modeled their brain aging processes, we can’t directly compare this to human issues like dementia.
This study also wasn’t really about carbs primarily. The main diving force behind increasing carbs was to lower protein intake, because protein is related in a number of ways to dementia. While this has a lot of implications for various diets — hard to eat low-carb if you have to reduce protein intake to below 7% of your diet — it means that the study doesn’t necessarily mean that high-carb diets are good at all. Lowering protein in other ways might be just as beneficial.
These mice also weren’t really fed low-carb diets. Even the lowest carb diet in the study was above 60% carbs by composition, which is actually higher than most people eat. It’s also quite tough to compare this to a person’s diet, because nutritional pellets don’t translate well into our day-to-day life.
There were other issues with the media reporting on this study. While there is some evidence that low-protein/high-carb might play a role in preventing dementia, there’s also evidence that low-carb diets might be effective too. The high-carb/low-protein diet also didn’t prevent dementia per se— it just prevented behavioural issues almost as much as a calorie-restricted diet.
Media Malarky
So what does this study actually mean?
Not all that much.
If you’re a mouse doing tests in a lab, this study might be very important to your future mental health. But for humans in the real world, it’s going to be a very long time before these results are translated into actual clinical benefits.
Ultimately, this study was a very early effort into providing an effective intervention for dementia. This is really important, because our current interventions to prevent dementia are mostly focused on getting people to lose weight, and that often does not work, but it’s still very early days.
As an example of this, the next steps suggested by the researchers aren’t for people to gorge on bread; they suggest repeating this experiment in other types of mouse to see if the results can be replicated.
And remember: the mice who ate lots of carbs still didn’t do as well as those who just ate less. While we can argue forever about the relative benefits of various diets, one thing is very clear: if you can eat less on any diet, you will be healthier than the alternative.
Just don’t believe the hype.
Pasta isn’t going to save your brain just yet.
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*The obvious irony that they cheerfully reported differently only days ago when a new low-carb study argued precisely the opposite clearly didn’t strike them too hard.
