How Food Quietly Suppresses Intelligence — And Why Plant-Forward Eating Unlocks a Sharper Brain (Plus: The Hidden Cognitive Risks of Keto & Carnivore)

By: Marcy Schoenborn

Most people go through life believing intelligence is this fixed, inherited trait — something you’re either blessed with or not.

But once you understand how the brain actually works, it becomes painfully obvious:

Most people don’t have a “genetics” problem. They have a nutrition problem.

And here’s the part no one expects:

Many people become more intelligent in their 50s, 60s, and beyond —
not because aging magically sharpens the mind,
but because they finally remove the biological interference that held them back.

I’m 61, and my brain is cleaner, faster, calmer, and more creative than it ever was in my teens, 20s, 30s, or even 40s. I remember more. I learn faster. I make better decisions. I can hold more in my head at one time.

And I know exactly why.

It’s nutrition.

So let’s go layers deeper into the biology behind this — and then we’ll address the controversial part most people “feel” but don’t understand:
why carnivore and keto can actually work against long-term cognitive sharpness, even when they feel great in the beginning.

PART 1: The Hidden Ways Food Influences Human Intelligence

Most people think food is about weight. It’s not.
Food is electrical… chemical… informational.

Every bite you take either supports cognitive performance or blocks it.

Let’s start with the big four systems that determine how smart you feel on any given day:

1. Blood Sugar: The Brain’s Real-Time Fuel Delivery System

Your brain uses about 20–25% of your body’s total glucose.
Not too much, not too little — but steady.

When your blood sugar is stable:

• your prefrontal cortex stays online

• your memory centers operate smoothly

• your emotional regulation is stronger

• your attention span lengthens

• your decision-making becomes more accurate

But when blood sugar swings all day — like when you live on coffee, cereal, bread, energy bars, pastries, intermittent fasting done wrong, or “keto until dinner but then carbs at night” — your brain rides the roller coaster too.

High blood sugar = neuroinflammation
Low blood sugar = your prefrontal cortex literally shuts down

That means:

• you react instead of respond

• you forget simple things

• you can’t plan as clearly

• you overthink

• anxiety skyrockets

• your creativity drops

A plant-forward approach stabilizes blood sugar because of its fiber, volume, micronutrients, and slow-burning energy.

This is why many people feel mentally reborn when they shift to plant-forward eating.

2. Neuroinflammation: When Your Brain Thinks It's Under Attack

Inflammation in the body is one thing.
Inflammation in the brain is another.

It’s called neuroinflammation, and it’s one of the quietest killers of intelligence.

It affects:

• memory

• processing speed

• focus

• problem-solving

• emotional stability

• learning capacity

Foods that drive neuroinflammation include:

• sugar

• refined flour

• industrial seed oils

• processed meats

• high-heat fried foods

• ultra-processed packaged products

Plant-forward eating is naturally anti-inflammatory because it’s high in polyphenols, antioxidants, omega-3 precursors, flavonoids, and minerals that directly quench inflammation in neural tissue.

People often think they have ADHD, anxiety, or declining intelligence —
when in reality they have an inflamed brain.

3. The Gut–Brain Axis: Your Microbiome Is Running the Show

Your gut is not “down there.”
It’s part of your brain’s command system.

Over 90% of serotonin and nearly half of dopamine are produced in the gut.

When the gut is damaged — from antibiotics, stress, sugar, low fiber diets, processed foods, or meat-heavy eating — it directly impacts:

• mood

• motivation

• learning

• cognitive flexibility

• sleep

• memory recall

Healthy gut bacteria produce short-chain fatty acids like butyrate, which reduce neuroinflammation and enhance brain plasticity.

And here’s the kicker:

Fiber is the #1 way your body produces these brain-enhancing compounds.

Plant-forward eating = plenty of fiber.
Keto and carnivore = almost none.

We'll come back to that…

4. Nutrient Density: Your Brain Can’t Build Intelligence Out of Low-Quality Materials

Your brain needs:

• magnesium

• omega-3s

• B-vitamins

• antioxidants

• folate

• potassium

• polyphenols

• slow-burning carbohydrates

Plant-forward nutrition supplies these in abundance. Meat-heavy and low-carb eating simply cannot compete in this department.

Your cells can’t run without micronutrients — and the brain is the most nutrient-hungry organ you have.

When you are missing these nutrients for decades?
You don’t just feel tired — your intelligence is literally underpowered.

PART 2: Why You Might Be Sharper at 50, 60, or 70 Than You Were at 20

This surprises people, but it makes perfect biological sense.

In your younger years, you were likely:

• over-caffeinated

• undernourished

• inflamed

• stressed

• inconsistent with sleep

• eating highly processed foods

• lacking fiber

• vitamin and mineral deficient

Your brain was swimming upstream.

Now?
You’ve removed some of the interference.
You’re feeding your body real nutrients.
Your microbiome is healthier.
Your blood sugar is more stable.
Your hormones are calmer.
Your inflammation is lower.

Your intelligence didn’t magically increase.
Your brain finally got access to its full power.

PART 3: The Part Nobody Wants to Hear — Why Keto & Carnivore Can Work Against Long-Term Intelligence

Short-term? People feel amazing.
But I want to explain why they feel amazing — because this is where the illusion happens.

They removed:

• sugar

• flour

• junk food

• processed garbage

• alcohol

ANY plan would feel incredible after that.

But long-term biology is a different story.

Let’s break this down.

1. Zero or Low Fiber = Starved Microbiome

Keto and carnivore drastically reduce or eliminate fiber.

No fiber → less butyrate → less neuroprotection → less cognitive resilience.

People on these diets often see:

• lower stress tolerance

• mood instability

• reduced mental flexibility

• lower serotonin output

• slower cognitive recovery

If you starve your gut… you starve your brain.

2. Low-Carb Intake Can Impair the Hippocampus (Memory & Learning)

Your hippocampus prefers glucose.
It can survive on ketones — but it doesn’t thrive on them long-term.

Chronic low-carb intake has been associated with:

• reduced memory scores

• reduced verbal fluency

• slower processing

• impaired learning

Short-term clarity? Yes.
Long-term cognitive cost? Very possible.

3. High Meat Intake Raises TMAO, Linked With Cognitive Decline

TMAO is produced when gut bacteria metabolize certain compounds in red meat.

High TMAO levels are associated with:

• vascular inflammation

• endothelial dysfunction

• accelerated brain aging

• higher risk of Alzheimer’s

This is not fear-mongering.
It’s biochemistry.

4. Low Serotonin = Low Cognitive Stability

Your brain needs carbohydrates to get tryptophan (the serotonin precursor) across the blood–brain barrier.

Low-carb = low serotonin.

Low serotonin =
less stability, less optimism, less memory consolidation, less calm, less clarity.

5. Keto Can Suppress Thyroid Function

When carbs are chronically low, the body conserves energy.

It reduces active thyroid hormone (T3).

Low T3 feels like:

• slower thinking

• slower processing speed

• sluggish recall

• reduced motivation

• decreased cognitive stamina

The brain does not like “energy-conservation mode.”

PART 4: The Bottom Line — Intelligence Isn’t Falling Apart… It’s Being Blocked

Most people are not “losing intelligence.”
Their brain is inflamed, under-fueled, or microbiome-compromised.

Plant-forward eating:

• stabilizes energy

• reduces neuroinflammation

• feeds the microbiome

• protects the brain

• fuels neurotransmitters

• supports thyroid function

• improves blood flow

• restores nutrients

This combination creates the perfect environment for a sharper, more resilient, more capable mind.

If you’ve felt foggy, unfocused, emotionally inconsistent, forgetful, or “not as sharp as you used to be,” it’s not age.

It’s interference.

Remove the interference, and your brain will surprise you.

It’s not that people become smarter with age…
It’s that their brains finally get what they always needed.

www.scho.fit 

CITATIONS

Gómez-Pinilla, 2008; Kalsbeek et al., 2022; Miller & Raison, 2016; Spencer et al., 2017; Cryan et al., 2019; Dalile et al., 2019; Gu et al., 2021; Gibson et al., 2015; Benton et al., 2003; Biondi & Wartofsky, 2014; Zhu et al., 2020; Wurtman et al., 2003.