You may think your diet is on point—whole grain toast, brown rice, quinoa, maybe even a smoothie with fruit and oats. But according to neurologist Dr. David Perlmutter, author of Grain Brain, what many of us consider "healthy" could actually be setting the stage for long-term brain problems like Alzheimer’s, ADHD, and chronic headaches.
In his groundbreaking book, Perlmutter challenges mainstream nutrition advice and explains how a diet high in carbohydrates—even so-called complex ones—can quietly damage the brain over time. Instead, he recommends something quite different: more fat, less sugar, and a new way to think about cholesterol.
Why Carbs Could Be Hurting Your Brain
According to Dr. Perlmutter, eating carbs—even healthy-seeming ones like whole wheat bread or brown rice—raises your blood sugar, which over time can lead to insulin resistance. That’s the same condition behind type 2 diabetes, and research now links it to a higher risk of dementia.
In fact, Alzheimer’s is increasingly being called “Type 3 diabetes” because of this connection. One Mayo Clinic study found people who ate more carbs had an 89% higher risk of developing dementia, while those who ate more fat had a 44% lower risk.
And here's a shocking fact: whole grain bread actually spikes your blood sugar more than table sugar. It’s not just what you eat—it’s how long it keeps your blood sugar high that matters.
The Role of Cholesterol and Fat in Brain Health
Forget what you’ve heard about cholesterol being the bad guy. Dr. Perlmutter explains that cholesterol is essential for brain function. It helps create new brain cells, supports nerve communication, and even protects the brain from damage.
The brain makes up just 2–3% of our body weight, but it holds about 25% of our total cholesterol. That’s no accident—it’s a key building block. Studies show that people with higher cholesterol levels may actually have up to a 70% lower risk of dementia.
The same goes for saturated fat. The study from the Mayo Clinic he references found that people who ate more saturated fat (from sources like eggs, coconut oil, and grass-fed beef) had a 36% lower risk of dementia.
What About Statins and “Bad” LDL Cholesterol?
Dr. Perlmutter is critical of the push to lower cholesterol with statins, especially since memory loss is now listed as a side effect of some of these drugs. He also questions the long-standing label of LDL as “bad cholesterol,” pointing out that it’s more about how LDL is damaged—especially through sugar exposure—that increases risk.
In other words, it’s not about the cholesterol number itself, but how it interacts with your diet, particularly if you eat a lot of carbs.
The Gluten Debate: Fad or Fact?
Even if you don’t have celiac disease, gluten may still be a problem. Dr. Perlmutter points to research showing that gluten triggers a protein called zonulin, which makes the gut—and even the blood-brain barrier—more permeable. This can lead to inflammation, which is linked to conditions like Alzheimer’s, Parkinson’s, and multiple sclerosis.
He argues that going gluten-free isn’t a fad—it’s simply going back to the way humans ate for over 99% of our history.
What Does He Eat?
Dr. Perlmutter follows his own advice. His daily meals include:
- A three-egg omelet with greens and olive oil for breakfast
- Salmon, steamed veggies, and a salad for lunch
- Dinner with wild fish or grass-fed beef and lots of above-ground veggies
- Some wine during the week, though he admits he could drink a bit more for the health benefits
His fridge? Minimal—he and his wife keep food fresh and shop frequently.
Bottom Line:
Dr. Perlmutter’s Grain Brain makes a compelling case that a high-carb, low-fat diet—long considered the gold standard of healthy eating—may actually be harming our brains. Instead, he recommends loading up on healthy fats, ditching the grains, and keeping an eye on blood sugar to protect long-term brain health.
Source:
https://drperlmutter.com/books/grain-brain-by-david-perlmutter/
https://academic.oup.com/jnci/article-abstract/105/15/1132/926341
https://advances.nutrition.org/article/S2161-8313(22)01116-4/fulltext
https://www.nejm.org/doi/full/10.1056/NEJMoa1215740
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