How Food Choices Shape Memory, Cognition & Cravings | Dr. Scott Kanoski
Dr. Scott Kanoski discusses how diet impacts memory and cognition, particularly through gut-brain communication via the vagus nerve and acetylcholine signaling. He explores GLP-1 drugs, the microbiome's role in memory, and how high-sugar and processed foods impair hippocampal function, even after dietary changes.
Summary
Dr. Scott Kanoski, a neuroscientist studying the intersection of hunger, memory, and appetite, discusses how dietary choices profoundly impact brain function. His research reveals that animals exposed to high-sugar diets during development show lasting hippocampal-dependent memory deficits that persist even after switching to healthy diets, suggesting critical developmental windows for nutritional influence.
Regarding GLP-1 drugs (Ozempic, Wegovy), Kanoski explains these glucagon-like peptide-1 agonists work at super-physiological levels—roughly 1000-fold higher than naturally occurring GLP-1. While primarily developed for diabetes management, they suppress appetite through paracrine signaling on the vagus nerve's sensory terminals in the gastrointestinal tract. The mechanism appears largely peripheral rather than central, though newer generation drugs' brain penetration remains controversial. Side effects like nausea cause many users to discontinue treatment within two years.
Kanoski's lab studies how the gut communicates eating information to the brain, particularly to the hippocampus, which is crucial for memory but receives extensive inputs about metabolic state. When animals eat, acetylcholine levels in the hippocampus show a characteristic ramp-up pattern during meals that persists at elevated baseline levels afterward—presumably supporting memory encoding of eating locations and contexts. This system evolved because remembering where food was consumed held survival value.
Regarding artificial sweeteners, research shows mixed results in humans but suggests potential developmental concerns. In rodents given stevia, ace-K, or saccharin during juvenile development at FDA-acceptable intake levels, adult animals showed altered sweet taste receptor expression, larger insulin spikes to glucose, and memory impairments. However, Kanoski emphasizes this is preliminary preclinical work with important caveats about translation to humans.
On ultra-processed foods, Kanoski's team examined heat-treated diets to isolate specific processing effects. High-temperature cooking triggers the Maillard reaction, producing advanced glycation end products (AGEs) associated with diabetes and aging. Animals on AGE-enriched diets showed memory impairments; these were reversible when researchers reintroduced a heat-eliminated lactic acid-producing bacterium (Lactococcus), demonstrating specific microbiome-memory connections.
The microbiome emerges as a critical mediator between diet and cognition. Kanoski found that high-sugar consumption eliminates certain beneficial bacterial populations while enriching problematic ones like Parabacterioides (negatively correlated with memory). By either eliminating detrimental bacteria or enriching beneficial ones, memory deficits can be rescued, though the field remains nascent—there's no clear consensus on which bacteria are universally "good" or "bad" across contexts.
Exercise provides protective effects: animals on unhealthy diets show lasting memory impairments even after dietary correction, but these deficits can be reversed through exercise, likely via improved metabolic function and brain changes. The relationship between diet, metabolism, and brain health suggests links between midlife dietary patterns and later dementia risk, though Kanoski emphasizes this is correlational rather than causative.
Kanoski's recent work involves vagal nerve stimulation devices to potentially improve memory outcomes in animal models of Alzheimer's pathology. He references epidemiological data from Taiwan showing individuals who received vagotomies (truncal vagus nerve lesions for ulcers) showed increased dementia risk later in life, suggesting the gut-brain axis may be relevant to neurodegeneration.
On dopamine and food reward, Kanoski explains that palatable foods engage mesolimbic dopamine pathways more robustly than bland foods, but context matters—food-restricted animals show dopamine release to bland food too. Notably, the reward system shows plasticity: people who reduce sugar consumption report that previously palatable foods become distastefully sweet, demonstrating that taste preferences can be recalibrated through dietary choices.
Oxytocin's role in food intake is more nuanced than traditionally understood. While brainstem oxytocin signaling reduces meal size and increases satiation, hippocampal oxytocin signaling facilitates social facilitation of eating—people eat more when with familiar companions, and this effect requires hippocampal oxytocin, suggesting oxytocin's function depends heavily on neural context and social circumstances.
About this episode
Dr. Scott Kanoski, PhD, is a Professor of Human and Evolutionary Biology and Neurobiology at the University of Southern California. We discuss how different foods impact memory and cognitive function as well as cravings. We also discuss how GLP-1 drugs work to control hunger in the brain and body, the role of the gut microbiome, and the effects of artificial and low calorie sweeteners on hunger and satiety. This episode highlights how nutrition impacts much brain health and learning capacity and how our memory impacts food choices too. Read the full episode show notes at hubermanlab.com. Thank you to our sponsors AG1: https://drinkag1.com/huberman Function: https://functionhealth.com/huberman Helix Sleep: https://helixsleep.com/huberman LMNT: https://drinklmnt.com/huberman Our Place: https://fromourplace.com/huberman Timestamps (00:00:00) Scott Kanoski (00:02:33) GLP-1, Natural GLP-1 Production; GLP-1 Drugs, Microdosing (00:07:06) GLP-1 Drugs & Benefits (00:10:36) Sponsor: Our Place & Helix Sleep (00:13:24) GLP-1 & Hunger Suppression, Vagus Nerve; Food Noise (00:18:39) Artificial Sweeteners & Appetite, Preclinical Studies (00:26:50) Memory & Meals; Stress; Eating & Individualization, Fasting (00:33:42) Memory Impairments, Western Diet, High Sugar, Processed Food (00:42:33) Sponsor: AG1 (00:43:46) Dementia, Alzheimer’s Disease & Western Diet; Exercise (00:49:40) Vagus Nerve, Hippocampus & Memory, Hormones (00:57:10) Sugar & Fat Consumption, Memory; Engineering Food for Quality (01:04:32) GLP-1s, Nutrient Deficiency, Weight Loss & Other Effects (01:11:33) Sponsor: LMNT (01:12:54) Vagus Nerve & Hippocampus, Eating & Acetylcholine (01:21:05) Hippocampus, Memory & Food; Interoceptive Awareness & Western Diet (01:27:21) Omega-3s; Microbiome & Processed Foods (01:34:00) Microbiome, Antibiotics, C. diff Infection (01:37:23) Sponsor: Function (01:39:01) Foods to Enhance Microbiome; Rising Obesity & Highly Processed Food (01:43:39) Dopamine & Food Choice, Change Food Cravings (01:49:50) Food Addiction, Highly Processed Foods; Political Lobbying (01:56:43) Oxytocin, Reduced Food Consumption, Social Eating (02:00:11) Zero-Cost Support, YouTube, Spotify & Apple Follow, Reviews & Feedback, Sponsors, Social Media, Neural Network Newsletter Learn more about your ad choices. Visit megaphone.fm/adchoices
Key Insights
- High-sugar diets consumed during juvenile development cause lasting hippocampal memory deficits that persist into adulthood even after switching to healthy diets, suggesting critical developmental windows for nutritional influence on brain structure.
- GLP-1 drugs work at approximately 1000-fold higher concentrations than naturally occurring GLP-1, functioning primarily through paracrine signaling on vagus nerve terminals rather than direct brain action in newer formulations.
- The hippocampus receives extensive metabolic state information through both neural pathways (vagus nerve via acetylcholine) and humoral signals (circulating hormones like insulin, leptin, and ghrelin), making it not just a memory center but a metabolic sensor.
- Acetylcholine levels in the hippocampus during eating show a characteristic ramp pattern throughout meals, ending at elevated baseline levels afterward, presumably enabling memory encoding of eating contexts and locations for survival-relevant future foraging.
- Preclinical research on artificial sweeteners during development (stevia, ace-K, saccharin at FDA-acceptable levels) shows altered sweet taste receptor expression and memory impairments in adult animals, though clinical translation remains uncertain.
- Heat-processing of food induces advanced glycation end products (AGEs) that impair memory in animal models, but memory deficits can be fully reversed by reintroducing a single eliminated bacterial species (Lactococcus), demonstrating specific microbiome-cognition links.
- The microbiome field lacks consensus on universally 'good' or 'bad' bacteria because bacterial effects are highly context-dependent and context-dependent across different dietary and physiological conditions.
- Vagotomy (surgical vagus nerve lesion) performed decades ago in Taiwan populations for ulcer treatment correlates with increased dementia risk in later life, suggesting gut-brain disconnection may contribute to neurodegeneration.
- Exercise can rescue memory deficits caused by early-life unhealthy diets even without dietary correction, indicating that physical activity provides independent neuroprotective benefits beyond metabolic improvement.
- Food reward dopamine signaling shows substantial plasticity—individuals who reduce sugar consumption report that previously palatable foods become distastefully sweet, demonstrating recalibration of the reward system through dietary choice.
- Humans with bilateral hippocampal damage can consume three meals sequentially without remembering eating any, yet report similar hunger-satiety ratings, indicating the hippocampus is required to interpret interoceptive signals rather than detect them.
- Most GLP-1 users discontinue treatment within two years due to side effects (nausea, vomiting) or lean mass loss, limiting long-term clinical data on potential micronutrient deficiencies in lean populations using these drugs.
- Artificial sweetener consumption in rodents produces larger insulin spikes to glucose in adulthood compared to controls, suggesting the sweet taste-calorie mismatch may dysregulate glucose anticipatory physiology.
- Oxytocin's effect on food intake is bidirectional and context-dependent: brainstem oxytocin reduces meal size, but hippocampal oxytocin facilitates social facilitation of eating in familiar social contexts.
- The field shifted from studying beneficial dietary interventions on healthy baselines (difficult) toward studying harmful diet effects on cognition (easier), resulting in a knowledge gap about foods that enhance memory beyond baseline health.
Topics
Transcript
When I started studying how diet impacts neurocognition and memory function, the first model we were studying was a high sugar model. The animals basically had ad libitum access to a sugar solution about the same percentage of calories as a soft drink that we consume, and otherwise they had healthy food and water. And with this model, the animals show hippocampal dependent memory deficits when they're older. And these seem to persist later into life, even though they're not consuming the sugar anymore. There may be a role for the microbiome. There's some changes in the bacteria in the gut from the sugar model that may have a functional connection to the memory impairments. We've also looked at models…
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