Can Beets Help Diabetic Brain Fog? A New Review Maps the Mechanism
A 2026 review in the European Journal of Clinical Investigation maps how dietary nitrate from beets and leafy greens might address the cognitive decline that often travels with type 2 diabetes, and where the evidence actually stands.
Photo: Ksenia Pixelesse / Unsplash
Can Beets Help Diabetic Brain Fog? A New Review Maps the Mechanism
The brain fog part comes up almost as an afterthought. A patient comes in about their A1C, or their metformin dose, or the weight that keeps fluctuating, and somewhere in the visit they mention they've been forgetting things: words, names, where they left their phone. Or that they feel mentally slow in a way that started roughly when the diabetes diagnosis did. The standard plan doesn't have a protocol for this. It has a glucose target.
A 2026 review in the European Journal of Clinical Investigation is the most recent paper to take that gap seriously. Published by a research group at the Center for Neuroscience and Cell Biology at the University of Coimbra, it maps the biological pathways through which dietary nitrate could, in principle, counter the specific type of cognitive decline that travels with type 2 diabetes. Dietary nitrate is the compound concentrated in beets, spinach, arugula, and other leafy greens. The mechanism is real and layered. The clinical evidence is still early. Knowing what each of those things actually means is the useful part of the paper.
Why diabetes and cognitive decline travel together
The cognitive piece of type 2 diabetes gets less attention than it deserves in most treatment conversations. Epidemiologically, the risk of dementia runs roughly twice as high in people with T2D as in people without it, and the subtler changes in processing speed and memory show up well before anything clinically qualifies as dementia.
Several things drive this. Persistent high blood sugar promotes oxidative stress throughout the body, including the brain. It damages small blood vessels, and the brain is heavily dependent on those small vessels staying clear and responsive. It disrupts insulin signaling in neurons. The brain is an insulin-sensitive organ, and that signaling matters for energy metabolism and for the structural changes that support memory. And it drives chronic low-grade inflammation that interferes with virtually all of the above.
None of this is unique to any one patient's case. It's the shared biology behind why people with poorly controlled type 2 diabetes often feel mentally slower, and why bringing glucose down, while necessary, doesn't always fully undo the cognitive side once it's established. A 2022 review in Pharmacological Research covered the same ground in the context of drug therapies, noting that while some newer diabetes medications show early promise for neuroprotection, the mechanisms driving T2D-associated cognitive decline remain a target without an established treatment.
What dietary nitrate has to do with it
Nitric oxide is a small molecule the body synthesizes on its own, and it does a lot. It relaxes and widens blood vessels, dampens inflammation, reduces oxidative stress, and plays a role in how neurons communicate and how insulin receptors function in brain tissue. The trouble is that all four of the pathways described above also degrade the body's ability to make nitric oxide through its usual enzymatic route: hyperglycemia, oxidative stress, vascular damage, and impaired insulin signaling.
Dietary nitrate offers a back door. You eat it, bacteria in your mouth and gut convert it to nitrite, and from there it becomes nitric oxide through a reaction that doesn't depend on the broken enzymatic pathway. The Gonçalves review walked through this carefully. Dietary nitrate can promote glucose homeostasis, reduce the oxidative damage that disrupts brain cell function, improve cerebral blood flow through better vascular tone, and support the brain insulin receptor signaling that the disease progressively undermines.
A companion 2026 review in International Journal of Molecular Sciences, examining dietary nitrate-rich vegetables and aging populations broadly, added an additional layer: in beetroot specifically, nitrate works alongside betalains and polyphenols that independently reduce oxidative stress and modulate inflammation. The synergistic effects between these compounds may amplify the benefits beyond what nitrate alone would produce. That doesn't make beets a pharmaceutical. It does make the argument for eating them more mechanistically interesting than "vegetables are healthy."
What the clinical trials actually found
The Gonçalves review is a review, not a clinical trial. It maps plausible mechanisms and synthesizes the existing evidence rather than reporting a new experiment. Being clear about that distinction keeps this conversation useful.
The most directly relevant human trial was a small, careful double-blind crossover study published in Nitric Oxide in 2014. It enrolled 27 adults with type 2 diabetes, randomized them to 250 ml of beetroot juice (providing 7.5 mmol of nitrate per day) or a nitrate-depleted placebo version that matched in taste and appearance, and ran each condition for two weeks. Simple reaction time improved significantly in the beetroot arm: 327 milliseconds versus 342 in the placebo arm, a difference of about 14 milliseconds. None of the other cognitive measures in the battery moved. The sample is small, and 14 milliseconds of reaction time isn't a dramatic transformation. Still, it is a measurable, statistically significant signal in a T2D population, and it points in the same direction the mechanism predicts.
A 2023 crossover trial in European Journal of Nutrition tested a different population and a different form of supplementation. Forty-four healthy adults (no T2D) received either a concentrated beet-based chewable supplement or placebo. A single dose improved memory consolidation at short and long-term recall, frontal lobe function, and cognitive flexibility. Different population, different outcome measures, different dose, so the two trials don't stack cleanly. What they share is the directional signal: dietary nitrate from beetroot produces measurable cognitive effects in humans.
Where the evidence stops short
The optimal dose for cognitive benefit in T2D hasn't been established. Neither has the question of how long sustained intake would need to run to produce clinically meaningful improvements in memory or processing speed in a T2D population. Individual responses vary substantially, for a reason worth naming: the conversion of nitrate to nitrite depends on bacteria in your mouth, and oral microbiome composition differs considerably between people. A depleted oral microbiome may extract less nitric oxide from the same amount of dietary nitrate. That can come from frequent antiseptic mouthwash use or a history of antibiotics.
The Gonçalves review is explicit about this. It calls for well-designed long-term clinical trials with cognitive outcomes as primary endpoints before dietary nitrate can be framed as an established intervention for T2D-associated cognitive decline. That framing is exactly right. The mechanistic case is solid; the clinical proof isn't there yet.
How this fits into a T2D plan in practice
The cognitive piece of type 2 diabetes belongs in the conversation from the start, not as something to revisit once the glucose numbers are stable. The diet changes that address glucose, things like fewer refined carbohydrates and more whole plants, naturally include the leafy greens, beets, and spinach that carry meaningful dietary nitrate. It's the same vegetables doing more than one job, so the nitrate angle doesn't ask the patient to add anything new.
I made the parallel case for the gut microbiome angle in the blood-sugar-and-gut post from May. That piece covers how fermentable fiber from the same plant foods feeds the bacteria that tune insulin sensitivity. The dietary-nitrate mechanism in today's post is a different pathway through the same food. Beets and spinach and leafy greens are pulling multiple levers at once, which is why the food-first framing keeps coming back in the research.
For the broader diabetes picture, including what standard treatment often skips, I keep the longer view at the diabetes resource hub.
A note on the diabetes course: Dr. Jordan Knieff and I are building a comprehensive diabetes course inside Wayfinder's Well that covers metabolic health from the naturopathic-first angle, including the cognitive piece and the dietary levers beyond glucose control. That course is still in development, and I'll announce the launch date once it's set. If you want a structured way to work through the full picture rather than reading individual posts out of sequence, that's where I'd point you.
If brain fog is part of your experience and you're managing diabetes, it's worth raising directly with your provider. It's not a residual complaint to wait out. The disease is driving it through specific mechanisms, and there are reasons to address it alongside glucose management, not after it.
FAQ
Can beets improve brain fog in type 2 diabetes?
The current evidence doesn't settle this definitively. A 2026 review in the European Journal of Clinical Investigation mapped the biological mechanisms through which dietary nitrate from beets and leafy greens could, in principle, counter the cognitive decline that often accompanies type 2 diabetes. One small clinical trial in T2D patients found that beetroot juice improved reaction time compared to placebo. That's a promising signal, not proof of clinically meaningful cognitive improvement across the board. More trials are needed.
What is dietary nitrate and where is it found?
Dietary nitrate is a compound found abundantly in beets, spinach, arugula, and other leafy greens. Once you eat it, bacteria in your mouth and gut convert it to nitrite and then to nitric oxide, a molecule that widens blood vessels, reduces oxidative stress, and plays a role in regulating how cells use energy. It's distinct from the nitrate in processed meats, which comes packaged with nitrosamine-forming conditions that dietary vegetables don't carry.
How does type 2 diabetes affect the brain?
Type 2 diabetes disrupts the brain through several intersecting pathways: persistent high blood sugar promotes oxidative stress and inflammation, impairs the small blood vessels the brain depends on, and disrupts the insulin signaling that neurons use for energy and memory formation. Over time, these changes show up as slowed processing, word-finding problems, and reduced executive function. The risk of dementia is roughly double in people with type 2 diabetes compared to those without it.
How much beetroot juice would I need to see an effect?
The best available trial in T2D patients used 250 ml, roughly one cup, of beetroot juice daily for two weeks, providing about 7.5 mmol of nitrate per day. That amount improved simple reaction time. A separate crossover trial in healthy adults used 3 grams of a concentrated beet extract and found improvements in memory and frontal lobe function. There's no established therapeutic dose for this indication, and individual responses vary significantly based on oral microbiome composition.
Is dietary nitrate safe for people with diabetes?
Dietary nitrate from vegetables is generally considered safe for people with type 2 diabetes. One thing to flag: it tends to lower blood pressure modestly, which matters if you're already on blood-pressure medication, so tell your prescriber if you're adding significant beet juice to your routine. People with impaired kidney function should check with their doctor before substantially increasing nitrate-rich foods, since nitrate excretion depends on kidney clearance.
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