Dr. Christopher Gardner: The Science of Food
Navigating the science of nutrition can feel like a full-time job. We are bombarded with conflicting headlines, viral diet trends, and passionate arguments from every corner of the internet.
Stanford nutrition scientist Dr. Christopher Gardner cut through the noise, examining the evidence to reveal a clearer vision for what it truly means to eat well.
Table of Contents
A New Vision for Plant-Based Eating
Can a Vegan Diet Make You Younger?
Fermented Foods and Fiber for Gut Health
The Problem with Processed Foods
The Modern Epidemic of Food Sensitivities
Following the Money in Nutrition Science
Challenges in Scientific Communication
The Revolution Starts in the Kitchen
The Myth of the "Best" Diet
When asked whether there's one optimal diet for everyone, Dr. Christopher Gardner emphatically states that there isn't a single "best diet," highlighting humanity's remarkable adaptability.
"We're just incredibly resilient and we can do crazy, wild things," Dr. Gardner explains. He points to contrasting examples like the Tarahumara Indians—ultramarathon runners thriving on a high-carbohydrate diet of corn and beans—and the Alaskan Inuits who historically consumed a fat-heavy diet of whale, blubber, and polar bear.
Both populations thrived on these wildly different nutritional approaches, experiencing minimal modern diseases like diabetes, heart disease, or cancer.
Dr. Gardner references author Michael Pollan's observation about the extraordinary variety of diets humans can flourish on worldwide. The only consistent failure, according to Pollan, is the standard American diet with its abundance of processed, packaged foods.
Tragically, both the Tarahumara and Inuit populations have experienced health declines as their traditional diets have been replaced by modern processed foods.
The Truth About Protein
The Science Behind the RDA
Dr. Gardner explained that modern protein recommendations originate from nitrogen balance studies conducted during the Vietnam War era.
These studies established the average human requirement at 0.66 grams of protein per kilogram of body weight.
However, he emphasized a critical point: the Recommended Daily Allowance (RDA) is not this average. It's set two standard deviations higher, at 0.8 g/kg, to create a buffer that ensures 97.5% of the population meets their needs.
Huberman, however, raised a valid point, questioning whether these foundational studies are still relevant, as they were conducted in highly artificial lab conditions with limited movement—hardly resembling normal daily life.
Actual Intake vs. Recommendations
This debate over recommended intake becomes even more complex when looking at what people actually eat.
Dr. Gardner noted that national data shows the average American already consumes about 1.2 g/kg of protein daily—well above the RDA and in line with higher recommendations from many exercise experts.
This leads to the question of what happens to excess protein. Dr. Gardner explained that unlike fat and carbs, the body has no storage depot for protein; after being used for tissues and hormones, the excess is converted and eliminated.
From a practical standpoint, Huberman argued that protein’s value goes beyond simple numbers, providing satiety and nutrients. He suggested the real issue for many people isn't the protein itself, but the high-calorie combination of starches and fats often served with it, like the hamburger bun and cheese.
Dr. Gardner acknowledged this, but raised counter-concerns about the downsides of high meat consumption, including saturated fat and lack of fiber.
The Myth of "Incomplete" Plant Protein
Perhaps the biggest hurdle in the protein debate is a persistent myth about the quality of plant-based sources.
Dr. Gardner addressed it head-on: "The myth part is that plants are missing amino acids. They're not complete. I'm sure everybody listening today has heard quinoa, the only plant with all nine essential amino acids. Bullshit."
He clarified that all plant foods contain all nine essential amino acids; the difference is in their proportions. Grains might be lower in lysine while beans are lower in methionine, which is where the old concept of "complementary proteins" originated.
Bioavailability and Redefining Protein Quality
Huberman then raised another critical question: bioavailability, or whether the amino acids in plants can actually be absorbed and used by the body.
Dr. Gardner explained that humans typically absorb 80-90% of protein from plant sources. While animal proteins have a slight edge, the difference is less significant than commonly believed.
Perhaps most tellingly, Dr. Gardner shared that in his entire career, he has never met a medical professional who has treated a patient for protein deficiency.
To modernize the conversation, he and his colleagues have proposed expanding the definition of "protein quality" beyond just amino acids to include a food’s full nutritional package and its environmental impact. When viewed through this wider lens, plant and animal proteins emerge as far more comparable options.
A New Vision for Plant-Based Eating
What "Plant-Based" Really Means
Dr. Gardner’s research, including the 600-participant Diet Fit study, found that the biggest factor in success was not whether a diet was low-carb or low-fat, but whether it was implemented in a healthy way by avoiding added sugars and refined grains.
This led him to shift focus from diet wars to a more practical approach in collaboration with the Culinary Institute of America. He now champions the concept of a "protein flip"—where vegetables, grains, and beans are the main components of a meal, and meat is used as a condiment or side dish. This prioritizes making healthy food "unapologetically delicious" as a strategy for sustainable change.
This rebranding is necessary because, as Andrew Huberman points out, the term "plant-based" has become problematic, with most people equating it to veganism. Dr. Gardner acknowledged this challenge, noting that even after a two-hour session at the Google Food Lab, nearly 100 industry professionals failed to find a better term.
The Case for "Less Meat, Better Meat"
Part of this new vision involves re-evaluating meat consumption. Dr. Gardner highlights that Americans consume more meat than anyone else in the world. This high demand is met by concentrated animal feeding operations (CAFOs) with concerning practices. "If they had glass walls, probably most of the country would go vegan," he suggests.
While some advocate for alternatives like regenerative farming, Dr. Gardner points out the practical limitations, stating it would take "like three planets of agricultural land" to move all cattle to pasture.
He proposes a more realistic middle-ground approach: "Less meat, better meat would work fine." This means consuming smaller quantities of meat that has been raised more humanely and sustainably. While such meat costs more per pound, eating less of it means it might not significantly impact one's food budget.
Artificial Meat vs Conventional Meat
While Huberman initially criticized the long ingredient lists of modern meat alternatives like Beyond Meat and Impossible Foods, Dr. Gardner countered that conventional beef has its own list of "hidden" inputs like antibiotics and hormones. Furthermore, he noted these companies have reformulated their products to be "quite clean."
Dr. Gardner’s own research comparing Beyond Meat to conventional red meat yielded several surprising cardiometabolic benefits for the plant-based alternative, including lower LDL cholesterol, reduced TMAO levels, and weight reduction, with no increase in blood pressure.
This occurred despite common criticisms about sodium content. Interestingly, Dr. Gardner’s study found that when participants prepared the conventional ground beef themselves, they added salt, resulting in sodium levels identical to the pre-seasoned meat alternatives. This suggests that the way people actually prepare and consume these foods is a critical, often overlooked, factor.
Can a Vegan Diet Make You Younger?
The idea that your diet could reverse aging sounds like science fiction, but it’s a question Dr. Gardner put to the test in a remarkable study.
To isolate the effects of diet from genetics, his team recruited 22 pairs of identical twins and set them on divergent dietary paths. For eight weeks, one twin was assigned a healthy vegan diet while their genetically identical counterpart followed a healthy omnivorous one.
The results were striking. The twins on the vegan diet lost more weight, lowered their LDL (bad) cholesterol, and saw their fasting insulin levels drop.
Perhaps the most surprising finding, however, was related to biological aging. The vegan participants showed statistically significant improvements in their telomere length—the protective caps on our chromosomes that naturally shorten as we get older.
"The vegans, according to the biological clocks, were younger than their omnivorous twins just eight weeks later," Dr. Gardner explains, noting this wasn't even the primary outcome the study was designed to measure.
He is careful to note that his message isn't necessarily that everyone should go vegan. Rather, the study was designed to create a significant dietary difference between the groups to see if a signal could be detected in a short timeframe.
The dramatic results provide compelling evidence for the potential health benefits of plant-based eating, even for a brief period.
Fermented Foods and Fiber for Gut Health
In the world of gut health, two champions constantly vie for the top spot: fiber and fermented foods. To see which had a greater impact, Dr. Gardner’s team designed a head-to-head study.
They divided 36 participants into two groups: one was instructed to eat as much fiber as possible, while the other was tasked with consuming a high amount of fermented foods like yogurt, kefir, kombucha, and kimchi, aiming for about six servings a day.
The results were striking. The group eating fermented foods showed a significant increase in microbial diversity and a marked decrease in inflammatory markers.
Surprisingly, the high-fiber group did not see the same benefits as a whole. While some individuals improved, others experienced no change, and some even showed an increase in inflammation.
The mystery was solved when researchers looked closer at the participants' starting gut health. The high-fiber diet only benefited those who already had high microbial diversity to begin with.
For those with low diversity, the sudden influx of fiber was overwhelming—"like a fire hose of fiber," as Dr. Gardner describes it—and led to a negative response.
This led to a powerful, nuanced conclusion: fermented foods appear to be a beneficial starting point for almost everyone, helping to build a more diverse gut ecosystem. Fiber is also critical, but its benefits may depend on an individual's existing microbiome, highlighting the need for more personalized nutrition approaches.
The study was so impactful that, despite its small size, it has been cited over a thousand times and inspired long-term dietary changes in its participants.
The Problem with Processed Foods
The health impact of food additives and processed foods is a complex topic. As Huberman points out, a processed food's impact isn't just about caloric density; it's also about additives like dyes and binders, and characteristics like low fiber content.
Dr. Gardner explains that these additives are extremely difficult to study properly in humans, as they don't cause short-term changes in traditional cardiometabolic markers like cholesterol. This forces researchers to rely on animal studies with extremely high doses to identify potential risks.
Defining "Ultra-Processed": Beyond Nutrition Labels
To better classify these foods, nutrition science has adopted the NOVA classification system. Interestingly, this system is "agnostic to nutrition," meaning it doesn't focus on fat or fiber content.
Instead, its primary concern is the presence of additives themselves. "The whole point in making this was that there's something beyond that," Dr. Gardner explains.
The system identifies about 150 molecules as additives, some of which are surprising, like turmeric and pectin. Dr. Gardner also highlights the FDA's "GRAS" (Generally Recognized As Safe) designation, which allows food manufacturers to use ingredients without rigorous safety testing.
What began as a list of around 800 items has reportedly grown to approximately 10,000, creating a "problematic" situation. Many of these additives are purely "cosmetic," like emulsifiers that prevent salad dressing from separating or dyes that make food look more appealing.
Dr. Gardner notes the result is a food system that has "gone too far" in prioritizing convenience and shelf stability over nutritional quality. "Isn't it a little scary that the bugs don't even want to eat it because they can tell there's no nutrition in here?" he asks.
The Reality of the American Diet
Ultra-processed foods make up approximately 60% of what's available in American grocery stores today. While simply banning them seems logical, Dr. Gardner explains this would be "criminal" to the many families who rely on them.
For a busy family with parents working multiple jobs, quick meals are a necessity. What they may not realize is that seemingly healthful items—tomato sauce, salad dressing, yogurt, and even whole wheat bread—can all qualify as ultra-processed.
"Until we get to that place [of having better alternatives], you can't get rid of them all," Dr. Gardner states. "That's just cruel."
The United States vs. Europe
Huberman raises an interesting comparison with European countries, where people also lead busy lives but don't suffer the same rates of obesity and metabolic issues. A striking explanation emerges: many products sold by the same companies contain different, and often more, ingredients in the U.S.
Dr. Gardner notes, "I can't tell you how many Europeans or other folks from other countries have said, 'I bought the same product that I buy in my home country here, and it has twice as many ingredients.'"
This discrepancy suggests a path forward that goes beyond consumer education. Dr. Gardner argues that since companies already produce healthier versions of their products for other markets, policy changes could prompt them to reformulate their American products.
"If somebody's going to call me out on this, not only am I going to have to reformulate, it won't be hard because I do it in another country." This highlights a complex reality: addressing the problem of ultra-processed foods in America requires systemic change, not just eliminating options that millions of families currently depend on.
The Modern Epidemic of Food Sensitivities
A Surprising Study on Lactose Intolerance
Dr. Gardner shared an study he conducted on raw, unpasteurized milk after a producer claimed it could "cure" lactose intolerance. Intrigued by the testable claim, he designed an inexpensive study with people who self-identified as lactose intolerant. They were given raw milk, commercial milk, and soy milk, and then tested with a hydrogen breath test—an objective measure of lactose digestion.
The results were striking. First, 50% of the people who "swore they were lactose intolerant" didn't actually fail the breath test, meaning that while their symptoms were real, they were not technically lactose intolerant. "Something else was bothering them," Dr. Gardner noted.
Second, for those who were clinically lactose intolerant, the raw milk had no beneficial effect. "They had the same exact symptoms on the raw milk as the conventional milk," Dr. Gardner revealed.
Despite the definitive results, he noted with frustration that the raw milk company "still on their website says they cure lactose intolerance."
The Rise of Gluten and Wheat Sensitivity
In exploring the issue of gluten, Dr. Gardner highlights a concerning trend in the American diet: approximately 90% of all grains consumed in the U.S. are wheat products. This lack of dietary diversity is compounded by agricultural monocropping, which focuses on massive quantities of a single type of wheat, pushing aside heritage grains.
This imbalance may help explain the rising prevalence of gluten issues. Dr. Gardner shares a common anecdote about Europeans who can eat bread comfortably in Europe but experience intolerance when consuming American wheat products, suggesting something unique about the wheat or its processing in the U.S.
This is further complicated by the fact that 50% of what Americans consume are carbohydrates, with a troubling 40% consisting of "crappy carbs" like added sugars and refined wheat.
The Challenge of Diagnosis
Huberman raised the important question of how many people have a genuine, clinically diagnosable intolerance versus a negative food experience. Dr. Gardner acknowledged the complexity, pointing to research indicating that even among those with full-blown celiac disease, approximately half remain undiagnosed.
The spectrum of responses to gluten varies widely, making it difficult for healthcare professionals to definitively rule out sensitivity. Dr. Gardner's conclusion is to empower individuals to acknowledge their own bodily responses and investigate their personal food sensitivities, rather than dismissing experiences that don't fit neatly into clinical categories.
Following the Money in Nutrition Science
Dr. Gardner addresses the thorny issue of research funding when asked if he takes money from food industry companies. He candidly admits he has, from sources like avocado producers and most recently, Beyond Meat.
This generated significant controversy and accusations of being an "industry shill," as his research found that Beyond Meat products outperformed conventional red meat on several cardiometabolic markers.
The Reality of Industry Funding
Dr. Gardner explains that securing government funding is difficult, as agencies like the NIH often expect profitable companies to fund their own product testing.
While this creates potential conflicts of interest, he highlights a positive outcome from his Beyond Meat research: the company used his findings to improve their products. "They took out the coconut oil, took out some other ingredients, and added some more benign ingredients," Dr. Gardner explains. "They've actually reformulated multiple times."
Still, the pressure from industry is real and can be subtle. Dr. Gardner notes the influence is "a total continuum," sharing an anecdote where a company suggested he mention "no deleterious effects" of a supplement after his research found no benefits.
The Problem of Investigator Bias
The conversation shifts to a broader problem that goes beyond corporate influence. Dr. Gardner explains how a researcher's personal bias can significantly impact study outcomes. "I can have diet A versus Diet B and make a kick-ass diet A and a crappy diet B," he states. "So it's really unlikely that B will win."
To combat this, his solution has been to embrace "equipoise"—designing studies where both diets being compared are implemented at their absolute best.
He also outlines critical safeguards for all research, regardless of funding: pre-registering studies and their primary outcomes, using third-party data analysis, and making datasets publicly available. "Ultimately," he believes, "I don't think it's the industry as much as the investigator and how they handle it."
Why Public Funding Falls Short
The reliance on industry funding stems from a larger issue. When asked about seeking funding from the National Institutes of Health (NIH), Dr. Gardner explained that the proportion of the NIH budget allocated to nutrition studies is "infinitesimally small."
Despite numerous requests to establish a dedicated Institute of Nutrition, the resources for objective research remain scarce.
This is compounded by the sheer volume of nutrition questions requiring investigation. Having served on the Dietary Guidelines Advisory Committee, Dr. Gardner saw firsthand how most topics received only "limited strength" responses due to insufficient evidence. "More data needed" became a constant mantra.
Even if the NIH redirected a quarter of its budget, it wouldn't come close to answering all the public's questions. This lack of clear, scientific answers has led to a situation where the public has taken matters into their own hands, with individuals conducting their own personal experiments to discover what works for them.
Challenges in Scientific Communication
Once a study is published, a new battle begins: ensuring the findings are communicated accurately to the public. Dr. Gardner experienced this firsthand when his research was featured in a popular Netflix documentary.
The producers created a misleading narrative by focusing on a single outlier participant who lost lean muscle, leading viewers to accuse Dr. Gardner of hiding unethical results.
The reality was that he never had access to that specific data, and the participant's circumstances were highly unusual.
This challenge isn't limited to entertainment media. Dr. Gardner has also faced criticism from fellow scientists, such as physician Peter Attia, who claimed his methods "violated the principles of science" by not isolating single variables.
Dr. Gardner’s defense highlights a crucial evolution in his field: modern nutrition science has moved from studying individual nutrients to analyzing whole dietary patterns, where multiple factors necessarily differ.
This complex new media landscape, however, isn't entirely negative. While misinformation can spread quickly, social media also provides an unprecedented opportunity for direct engagement and correction.
Dr. Gardner shared a satisfying example where an online critic, after hearing his explanation for a misunderstanding, posted a video apology. "That was almost better than doing the study for me," Gardner admits.
The Problem with Mega-Farms
Dr. Gardner argues that the real issue isn't small versus large farms, but rather the prevalence of mega farms that have taken over American agriculture. He explains that while gigantic operations growing corn, soy, or potatoes can produce inexpensive food due to their scale, this system has created numerous problems.
"We have suicides in the dairy farmer community because of people losing their family business," Dr. Gardner notes, highlighting the human cost of agricultural consolidation. The number of dairy farms has been steadily decreasing while mega-dairy operations continue to grow.
This trend has created a crisis in rural communities where farming families struggle to convince their children to take over increasingly unprofitable operations.
Dr. Gardner reveals a concerning demographic shift: "We have a lot of really old farmers in the US." This aging population of agricultural workers represents a brain drain from an essential sector of the economy, as younger generations seek opportunities elsewhere.
The historical roots of this problem trace back more than 50 years to policy shifts encouraged by figures like Earl Butts, who promoted monocropping and agricultural consolidation. According to Dr. Gardner, Butts encouraged farmers to "Plant corn or soy, fence row to fence row, buy more land, buy the huge combine machinery to plant this. Don't be so diverse." This philosophy represented a significant departure from traditional diverse farming practices.
Dr. Gardner shares a poignant example of one Stanford colleague whose father had discouraged him from taking over the family farm, saying, "I've ruined the land. The biodiverse thing was great, but this monocropping thing has ruined it. Please go get another job."
Rather than promoting either small farms or mega operations, Dr. Gardner advocates for middle-sized farms that can provide farmers with a decent living while maintaining sustainable practices.
"I think there's something in the middle where you could make a respectable living, but would have to be a more diverse agricultural system than just corn or just soy or just a concentrated animal feeding operation. It had to be multiple crops, multiple livestock working together."
The Revolution Starts in the Kitchen
The Power of the Professional Chef
With approximately 50% of American meals consumed outside the home, Dr. Gardner argues that the most promising approach to improving eating habits is to work with culinary professionals. These chefs have the "superpower" of combining different food sources into flavorful, enjoyable meals.
Through collaborations like the Culinary Institute of America's "Menus of Change" initiative, Dr. Gardner works with chefs to transform institutional food settings like workplaces, schools, and hospitals.
Rather than reacting to fad diets, these professionals proactively shape food demand by creating options that are simultaneously delicious, nutritionally sound, and environmentally responsible. "The idea was that if you could do that across these different institutions, you could change the palate," Gardner explains.
From an Idea to the School Cafeteria
This concept has been remarkably successful in one of the most challenging environments: American school cafeterias. After the 2010 Healthy Hunger-Free Kids Act aimed to improve school meals, initial resistance from students led to wasted food. The breakthrough came when chefs were introduced into school environments.
Rather than just replacing pizza with hummus, these culinary professionals worked with students and staff to develop nutritious alternatives that were genuinely appealing.
Dr. Gardner now partners with the nonprofit "Eat Real," which certifies K-12 schools on nutrition and sustainability, already reaching a million schoolchildren. The results are remarkable: happier staff, enthusiastic students, and better food, proving that tasty, healthy meals can be achieved anywhere, not just in elite institutions.
Bringing the Lesson Home
The success in schools provides a powerful insight: the key to widespread change is taste.
Huberman acknowledged that if food service professionals can create delicious, healthy meals for thousands, then families can find affordable ways to apply this approach at home.
He draws a parallel to exercise: just as there is no pill to replace physical training, there is no substitute for engaging directly with our food. The solution to the convenience trap of processed foods involves a return to food preparation, centered on the simple principle of making nutritious food taste great.
Wrapping Up
What if the key to better health isn't choosing between low-carb or low-fat? What if the endless search for one "perfect" diet is the very thing holding us back? After navigating the maze of diet wars and conflicting studies, a clearer and more powerful picture emerges from the evidence.
The research shows that the most meaningful changes come not from rigid rules, but from embracing a flexible approach centered on whole foods.