Hi, this is Ray.

I want to tell you about a year I spent eating, by the standards of most modern adults, completely normally. I was 31, traveling a lot for work, eating most meals out or from grocery store prepared sections. My typical day: a granola bar and coffee for breakfast, a sandwich and chips for lunch, something microwavable for dinner, snacks throughout. I wasn't eating fast food every meal. I wasn't drinking soda. I thought I was eating reasonably. By all standard cultural measures, I was.

What I didn't know is that almost everything I was eating (the granola bar, the chips, the sandwich bread, the microwave meals, the snacks) fell into a category researchers now call "ultra-processed foods." Most of my caloric intake was coming from products that had been transformed through industrial processes that don't happen in any home kitchen, designed to be shelf-stable, hyper-palatable, and convenient. I was eating like most Americans. And like most Americans, I assumed this was fine.

Toward the end of that year I started noticing that something was off cognitively. Focus was harder than it should have been. Memory felt foggier. Mental energy was lower in ways I couldn't quite name. I assumed I was just tired, or stressed, or aging earlier than I'd expected. It didn't occur to me that what I was putting in my body was directly affecting what was happening between my ears.

The research on this has gotten dramatically clearer over the past five years, and what it shows should change how every learner thinks about food. The connection between ultra-processed foods and cognitive decline isn't a fringe finding from one suspect study. It's a robust pattern across multiple large studies, across multiple countries, with mechanisms that are increasingly well-understood. Today's newsletter is about that. What ultra-processed foods actually do to the brain, why they affect learning more than most people realize, and what to do about it without becoming the kind of person who lectures other people about their food choices. Let's get into it.

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Let me start with the terminology, because it gets misused constantly. The scientific category here is called the NOVA classification, developed by researchers at the University of São Paulo. It divides foods into four groups based on the extent of processing they've undergone.

Group 1 is unprocessed or minimally processed foods… fresh fruits and vegetables, whole grains, eggs, fresh meat, fish, milk, plain yogurt. Group 2 is processed culinary ingredients used in home cooking… oils, butter, salt, sugar, vinegar. Group 3 is processed foods… canned vegetables, traditional cheeses, fresh bread, cured meats made with simple preservation techniques. Group 4 is ultra-processed foods… industrial formulations made primarily from substances extracted from foods, additives, and minimal whole food content.

The defining feature of ultra-processed foods isn't whether they're packaged or convenient. It's whether they contain industrial ingredients you'd never find in a home kitchen… high-fructose corn syrup, hydrogenated oils, modified starches, protein isolates, artificial flavors, emulsifiers, preservatives that don't exist in nature. As one summary put it, the category includes packaged ready-to-eat snacks and meals, sugary beverages, sweetened breakfast cereals, and cured meats made with industrial preservatives. Notably, this includes a lot of products marketed as "healthy"… many protein bars, "natural" snacks, plant-based meat alternatives, flavored yogurts, granolas, and breakfast cereals that have been heavily reformulated through industrial processes.

The scale of consumption is genuinely striking. In the United States, ultra-processed foods now account for about 55-58% of daily caloric intake. In other words, more than half of the average American's food isn't actually food in any traditional sense… it's industrial product engineered to mimic food. This is a recent phenomenon. Two generations ago, the percentage was a small fraction of what it is now. The shift has happened fast, and the research is just starting to catch up with what it means for human health, including cognitive health.

The picture from the research is consistent enough now to take seriously. Let me walk through what some of the major studies have found.

The Brazilian ELSA-Brasil study, published in JAMA Neurology in 2022, followed about 11,000 public service workers ages 35 to 74 for roughly a decade. According to the findings, people whose diets had the highest levels of ultraprocessed foods (20% of calories or more) showed a 28% faster rate of overall cognitive decline, and those eating the highest levels of ultraprocessed foods also showed a 25% faster rate of executive function decline. These aren't small numbers. A 28% faster rate of cognitive decline, sustained over years, produces dramatically different cognitive trajectories. And the threshold for this faster decline was only 20% of calories, which is well below the American average.

A Massachusetts General Hospital analysis based on the REGARDS study found similar patterns and added the inverse finding. According to coverage of the research, eating more unprocessed or minimally processed foods had a protective effect on brain health, with the Mediterranean, DASH, and MIND diets independently associated with reduced risk of stroke and cognitive decline. The relationship isn't one-directional. Ultra-processed foods hurt brain health. Whole foods protect it. The same person can move in either direction by changing what they eat.

A Virginia Tech analysis found specific patterns worth knowing. According to the researchers, there was a 17 percent increase in cognitive issues among people who consumed at least one serving of ultra-processed meat a day, and for each serving of soda consumed, there was a 6 percent increase in cognitive impairment. A single daily serving of ultra-processed meat. A single soda. These aren't extreme consumption levels. They're the consumption levels many people consider normal or even modest.

Perhaps the most concerning finding for working-age adults came from a 2025 Australian study. According to coverage, for every 10% increase in ultra-processed food consumption (roughly equivalent to adding a standard bag of chips to your daily diet), there was a measurable decline in cognitive function and an increase in dementia risk factors. Notably, the association held up even among people who otherwise followed a healthy diet. That last part matters. The damage from ultra-processed foods isn't fully offset by eating other healthy foods alongside them. As one expert quoted in the article noted, "you can't necessarily salad your way out" of high ultra-processed food consumption. The processed foods do their own damage that the salads don't reverse.

And this isn't just about old age. A Harvard Health analysis noted that people who eat lots of these foods (including chips, sodas, packaged baked goods, deli meats, and fast food) may face a meaningfully higher risk of cognitive decline compared with those who favor whole, minimally processed foods. The effects compound over decades. The dietary patterns you have now are shaping the cognitive trajectory you'll have later. Younger learners aren't exempt from these patterns. They're just earlier in the timeline.

The research has also been clarifying WHY these foods affect cognition, which is useful because understanding the mechanisms makes the connection feel less abstract.

Chronic inflammation. Ultra-processed foods are designed to be hyperpalatable, which generally means high in refined sugars, refined fats, and salt. According to research from the University of Florida's Center for Cognitive Aging, excess sugar and fat can contribute to chronic inflammation, and ultra-processed foods might exacerbate harmful inflammation. Although inflammation is a normal immune response to injury or infection, chronic inflammation can be detrimental to the brain. The brain is particularly sensitive to inflammation. Sustained inflammation impairs memory formation, slows cognitive processing, and accelerates the breakdown of brain tissue over time.

Gut-brain axis disruption. Your gut microbiome (the trillions of bacteria living in your digestive system) communicates extensively with your brain through hormonal, neurological, and immune pathways. Ultra-processed foods, which typically lack fiber and contain emulsifiers and preservatives, appear to alter the gut microbiome in ways that affect cognition. As the Florida researchers explained, the gut microbiome helps with digestion, but it also influences the immune system, while producing hormones and neurotransmitters that are critical for brain function. Damage the microbiome through industrial food, and the downstream signals to the brain change. The brain operates differently as a result.

Nutrient displacement. Even if ultra-processed foods themselves were neutral, eating a lot of them means eating less of the foods that actively support brain health. The omega-3s, polyphenols, B vitamins, and other nutrients that whole foods provide aren't in ultra-processed foods. Higher ultra-processed consumption means lower consumption of brain-supporting nutrients. The brain isn't getting what it needs. As one study summary noted, increased consumption of UPFs displaces the consumption of nutrient-dense foods, further contributing to lower overall dietary quality. The displacement is real and consequential.

Blood sugar volatility. Many ultra-processed foods produce sharp blood sugar spikes followed by crashes. These swings affect cognitive performance directly. The post-spike crash produces brain fog, irritability, and difficulty concentrating. Sustained over time, the volatility appears to damage the brain's insulin response in ways that affect long-term cognition. Some researchers now refer to Alzheimer's disease as "type 3 diabetes" because of the connection between insulin dysfunction and cognitive decline.

Cardiovascular effects. Ultra-processed foods are linked to higher rates of cardiovascular disease, which affects blood flow to the brain. As the Harvard analysis noted, a growing body of evidence links ultra-processed foods to obesity, diabetes, hypertension, and high LDL (bad) cholesterol… all known risk factors for cognitive decline. Brain health and cardiovascular health are tightly connected. The diet that's bad for your heart is bad for your brain through the same mechanisms.

For learners specifically, these findings have practical implications worth taking seriously. Your cognitive performance today is shaped by what you've been eating recently. Your cognitive trajectory over years is shaped by what you eat consistently. The food choices aren't separate from the learning project. They're part of the platform the learning is sitting on.

The good news is that the research consistently shows that reducing ultra-processed food consumption produces measurable benefits, even for people who don't make other changes. You don't have to overhaul your entire life. You just have to gradually shift the balance toward less ultra-processed and more whole or minimally processed foods. The benefits are dose-dependent (smaller shifts produce smaller benefits, larger shifts produce larger ones) and they accumulate over time.

You also don't have to be perfect. The research isn't suggesting that any ultra-processed food is catastrophic. The patterns that matter are the long-term averages of your diet. An occasional bag of chips is fine. A daily diet that's 60% ultra-processed is what's producing the cognitive damage in the studies. Move from 60% to 40% and you've made a real change. Move from 40% to 25% and you've made a bigger one. The trajectory matters more than perfection.

Okay, the practical part. Based on the research, here's how to reduce ultra-processed food consumption without becoming neurotic about food.

Learn to identify ultra-processed foods. The general rule: if a product has more than five ingredients, contains ingredients you wouldn't find in a home kitchen, or has been engineered for shelf stability and hyperpalatability, it's probably ultra-processed. Reading ingredient lists is the most practical skill here. The shorter the list, and the more it consists of recognizable foods, the less processed the product is.

Focus on what to add, not just what to remove. It's easier to add whole foods than to subtract ultra-processed ones. Make sure your meals include vegetables, fruit, whole grains, eggs, fish, beans, nuts. As these foods make up more of your intake, ultra-processed foods naturally make up less. The displacement happens both ways.

Cook more, even simply. The biggest predictor of low ultra-processed food consumption is cooking at home. You don't have to be a great cook. Scrambled eggs, simple soups, basic stir-fries, roasted vegetables. The cooking itself shifts the food category toward less processed. Even rough cooking beats most packaged alternatives.

Replace the most damaging items first. Some ultra-processed foods are worse than others. Sugary drinks, processed meats, and ultra-processed snacks (chips, packaged baked goods) show up in the research as particularly damaging. Cutting these is more valuable than cutting other ultra-processed items.

Don't try to be perfect. The research isn't measuring perfection. It's measuring averages. If your diet is currently 60% ultra-processed and you can get it to 35-40%, you've made a substantial change that will likely produce real cognitive benefits over years. Trying to get to 0% is neither necessary nor sustainable for most people.

Watch the convenience trap. A major driver of ultra-processed food consumption is convenience. Busy weeks become ultra-processed weeks because cooking takes time and packaged food doesn't. The fix is usually about logistics… batch cooking, having quick whole food options available, making the healthy choice the easier choice in your specific situation.

Be skeptical of "healthy" packaged foods. Many products marketed as healthy are heavily ultra-processed. Protein bars. Plant-based meat substitutes. "Natural" snacks. The marketing isn't the same as the science. Read the ingredient lists. If it doesn't look like food, it isn't quite food, even if the label says it is.

Here's what I want you to take from all this. The conversation about food and health has been dominated for decades by debates about specific nutrients… fat versus sugar, low-carb versus low-fat, animal versus plant. These debates miss what the more recent research suggests is the more important variable: not what's IN the food, but whether the food itself is real food at all. Ultra-processed foods seem to do damage that can't be fully explained by their nutritional content. The processing itself appears to matter, in ways the food industry has been slow to acknowledge.

For learners, the implication is straightforward. If you want your brain to work as well as it can over years, the food you put into it matters. The patterns most modern adults have absorbed… half or more of calories from ultra-processed sources… are producing measurable cognitive damage that affects everything from focus during study sessions to long-term capacity for learning. The fix isn't dramatic. It's incremental movement toward more whole foods and fewer ultra-processed ones.

The cultural framing of food choices as primarily about weight or vanity has obscured what's actually at stake. You're not just eating for your body. You're eating for your brain. The brain you have in five years is being built by the food you eat in the next five years. The cognitive capacity you'll have at 50, 60, 70 is being shaped by dietary patterns you're establishing now. The investment in your future cognitive health costs little (just eating closer to actual food more of the time) and pays back in capacities you'll need for the rest of your life.

If you've been eating like most modern adults eat, please consider that the food itself is part of why learning has felt harder than you think it should. The fix isn't moral. It isn't about discipline. It's about quietly shifting what you put on your plate toward things that are actually food. Your brain will reward the shift in ways you'll notice within weeks. The compounding over years is substantial.

Even hobbits ate real food. Seed-cakes, mushrooms, bread, vegetables from gardens. The hobbits were healthy. Maybe the food was part of why. We've drifted a long way from how humans ate for most of history. We can drift back, gradually, one meal at a time.

Keep learning (and keep eating real food),

Ray