We needed further research—ideally, controlled trials—to validate the MIND diet's effectiveness. And now the wait is over.
An important update on the MIND diet, a dietary pattern that has garnered attention for its potential to support brain health and reduce the risk of cognitive decline.
Nutrition Diva is hosted by Monica Reinagel. A transcript is available at Simplecast.
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Hello, and welcome to the Nutrition Diva podcast, where we explore the science of eating and living well. I'm Monica Reinagel, your host, and I'm glad you’re here.
Today, I have an important update to share on the MIND diet, a dietary pattern that has garnered attention for its potential to support brain health and reduce the risk of cognitive decline. However, I have to admit that the new findings are a bit of a disappointment for those who placed their hopes (or their career ambitions) in the MIND diet as a hedge against dementia.
But first, let's do a quick recap of the MIND diet and its origins.
The MIND diet is a combination of the Mediterranean and DASH diets, with a focus on foods that have been associated with cognitive health. It promotes ten “brain healthy” foods and discourages five foods. You’re encouraged to eat plenty of vegetables, especially the green leafy kinds, berries, nuts, legumes, whole grains, fish, poultry, olive oil, and wine. The foods that you’re supposed to limit are red meat, butter and margarine, pastries and sweets, fried and fast food, and cheese. (More on that last one in a moment.)
Researchers from Rush University hypothesized that following this diet could keep your brain healthy, preserve your cognitive abilities as you age, and perhaps even ward off dementia and Alzheimer’s disease. To test their theory, they reviewed dietary and medical records for almost 1,000 people to see how closely their diets adhered to the MIND guidelines and how they fared in terms of brain health.
They found that those whose eating patterns conformed most closely to the MIND diet principles were only half as likely to develop Alzheimer’s as those whose diets conformed the least well. The risk for those whose diets conformed only moderately well still was reduced by a third.
On the strength of these observations, which were published in 2015, researchers put out a popular book, which naturally sold very well. (Who among us is not interested in hanging on to the old gray matter as we age?) However, the entire enterprise was based on observational evidence. We needed further research—ideally, controlled trials—to validate its effectiveness.
And now the wait is over. A randomized controlled trial, published last month [July 2023] in the New England Journal of Medicine enrolled over 600 older adults without cognitive impairment but with a family history of dementia. The participants were also all considered to be overweight, according to their BMI.
The subjects were randomly assigned to follow either the MIND diet or a control diet (essentially, no change in diet) for three years. Both the test diet and the control diet were also calibrated to be slightly lower in calories than what they had been eating previously. Both groups received counseling to support adherence to their assigned diet, as well as guidance for weight loss.
Now, let's get to the findings. Brace yourself, because they might not be quite what you were hoping for.
The good news is that after three years, both groups showed improvements in their global cognition scores, indicating enhanced cognitive performance. However, there was no significant difference between the two groups in terms of cognitive improvement.
Despite the observational evidence supporting the MIND diet's potential benefits, the results from this randomized controlled trial did not demonstrate a clear advantage in terms of cognitive health.
Although this study's prospective design is considered to be a higher level of evidence than the observational studies we had before, one advantage that the observational studies had was longer duration. It's certainly possible that even three years isn't enough to see the full impact of healthier diet choices, whether that's the MIND diet or another similar healthy eating pattern. If we checked again in ten years, perhaps the group following the MIND diet would have better outcomes.
It's also important to note that this study specifically targeted those who showed no cognitive impairment at the beginning of the study, but who had a family history of dementia. It's possible that the MIND diet would have different effects in other populations or in individuals who already have cognitive impairment.
Secondly, it's interesting that the researchers chose to focus this study on individuals who were overweight. Both the test diet and the control diet included mild caloric restriction, leading to weight loss in both groups. To my mind, this introduces an unnecessary confounding factor into the study.
Caloric restriction has been studied extensively for its potential benefits on brain health and longevity. It’s been shown to have various effects, such as reducing oxidative stress and inflammation and promoting neuroplasticity. The fact that both groups saw similar improvements in cognitive function suggests that caloric restriction or weight loss (which was around 3-5% of starting weight on average) may have played a more significant role than the specific dietary changes.
And here’s another interesting thing: all subjects in this study had what the researchers considered to be a suboptimal diet at baseline. So, the folks who did the MIND diet presumably got a big upgrade in their diets while the control group continued to eat the same crappy diet, but a little less of it. Surprisingly, this big upgrade in dietary quality did not seem to have a substantial impact on cognition (at least within the three-year timeframe of the study).
So, far from establishing the MIND diet as uniquely beneficial to brain health, this study calls into question how big a role dietary quality plays at all.
Even if the MIND diet is eventually proven to have a positive impact on cognition (perhaps by a longer controlled trial), there’s still the question of whether the MIND diet is any better than a generally healthy dietary pattern. In other words, is there something truly distinctive about the foods that are included and discouraged in the MIND diet, or would any healthy dietary pattern be equally effective? More research would be needed to answer these questions.
In the meantime, what does all of this mean for you? Even though the MIND diet’s impact on brain health, specifically, is less than we hoped, the MIND diet emphasizes nutrient-dense foods that have been consistently linked to overall health and well-being. You could certainly do worse! That said, not all of the foods recommended in the MIND diet are equally supported by research.
For one thing, the evidence on the reputed health benefits of wine has been largely discredited.
Secondly, I think the evidence on poultry as an anti-aging food is pretty weak. I suspect that its association with cognitive (or other measures of) health may have more to do with what people who eat more poultry are eating less of, as a result. If poultry is replacing barbecued ribs, you might see more of a benefit than if poultry were replacing salmon or tofu.
Similarly, while whole grains do contain valuable nutrients, such as fiber, people who eat more whole grains also tend to eat fewer refined grains. I suspect that a lot of the health benefits attributed to eating more whole grains actually stem from eating fewer refined grains.
So, when it comes to specific recommendations like consuming poultry twice a week or whole grains three times a day, feel free to adjust them based on your personal preferences and needs. I’m not convinced they have a significant impact on cognitive health.
On the other side of the equation, I also have reservations about the MIND diet’s stance on cheese.
The MIND diet advises limiting cheese consumption due to its saturated fat content. However, the evidence for cheese specifically increasing the risk of Alzheimer's or cognitive decline is weak. In fact, recent studies have suggested that diets high in full-fat dairy products, like cheese, may not carry the same risks as diets high in saturated fats from other sources.
Barring more specific evidence, I think moderate consumption of cheese is unlikely to have a significant negative impact on cognitive health.
While it may be disappointing to hear that the MIND diet may not be a silver bullet against brain aging, remember that nutrition is just one aspect of maintaining cognitive health. Engaging in regular physical activity, managing stress, getting enough sleep, and staying socially active are all essential for promoting brain health.
That's all for today's episode. Thank you for joining me. If you have any questions or topics you'd like me to address in future episodes, send them to nutrition@quickanddirtytips.com, or you can leave me a voicemail at 443-961-6206.
If your question has more to do with habits and health behaviors, you might also enjoy my other podcast. It’s called the Change Academy, where we explore the art and science of creating positive behavior change, both in our own lives and in our workplaces and communities. You can find it on all the major podcast platforms. Just search for Change Academy.