How powerful is diet, really?
Can diet prevent colon cancer?
These are timely questions considering the rise in colorectal cancer in people under 50.
Why are colorectal cancers rising in younger adults?
It’s a question that concerns everyone.
One possible clue may lie in the way diet affects inflammation, insulin, and metabolism.
In this “Spotlight Interview”, first published in my weekly newsletter, I speak with Dr. Fred Tabung, whose team analyzed data from nearly 1 million adults in both the US and Europe and found that people eating more anti-inflammatory, less insulin-spiking, and higher-quality diets had roughly a 16% to 20% lower risk of colorectal cancer. Importantly, this trend was true across different populations, cultures and dietary behaviors.
Dr. Tabung leads the Diet, Metabolism, and Cancer Prevention Outcomes Lab at The Ohio State University, where he is also a professor of Internal Medicine. He has authored more than 140 articles published in high-impact, peer-reviewed journals, and his research focuses on how dietary patterns influence cancer development and progression.
Read my interview with him below:
Your recent study showed that a low-insulinemic and anti-inflammatory diet significantly reduced the risk of colorectal cancer. What does a “low-insulinemic” or “anti-inflammatory” diet actually look like in everyday life?
Think of it as a habitual pattern of eating and less as a rigid or prescriptive diet plan. A low-insulinemic diet is one that doesn’t spike your insulin levels repeatedly throughout the day — so it favors specific vegetables such as green-leafy vegetables like lettuces and other dark greens, dark-yellow vegetables like carrots, summer squash, etc, …whole fruits like apples, pears, grapes, raisins, avocado, etc,…nuts, legumes, yogurt, cheese, and coffee & tea; while limiting sugary drinks, refined grains, and processed foods.
An anti-inflammatory diet overlaps considerably with that, and also emphasizes fatty fish, vegetables, and foods rich in fiber and polyphenols — the compounds that give color to berries.
Both dietary patterns are less about individual “superfoods” and more about the overall balance of your plate over weeks and months, not what you ate once a month at a party.
Did it surprise you that your findings were fairly consistent across such different populations?
Honestly, yes and no. The intellectual seeds for this hypothesis were actually planted years earlier, in a 2017 review synthesizing nearly two decades of evidence on dietary patterns and colorectal cancer risk. That early work identified two dietary patterns consistently associated with CRC (colorectal cancer) risk, and planted the question: could we measure these patterns in a standardized, reproducible way across very different populations?
It directly inspired the research program that led to the current study.
We hypothesized that because these dietary patterns target fundamental biological pathways, insulin signaling and chronic inflammation, rather than any one culture’s food traditions, they might be more universally relevant. Seeing that confirmed across nearly a million people in North America and Europe was genuinely gratifying. The low-insulinemic pattern in particular showed remarkably low statistical heterogeneity across cohorts, telling us the signal is robust and not an artifact of any single population.
That consistency also pushed us to think more carefully about how we move these findings from epidemiology into clinical practice, which is the focus of a recent perspective we published in Advances in Nutrition (Tabung & Giovannucci, 2026).
In that paper, we argue that metabolic dietary patterns show more consistent and robust associations with chronic disease than conventional nutrient- or calorie-focused approaches, and we propose a translational framework built around several key tenets: preserving metabolic integrity, clarifying food and beverage targets, addressing items with uncertain or counterintuitive metabolic properties, accounting for food combinations and preparation methods, integrating food processing level, and ensuring cultural adaptability.
Crucially, we are not just theorizing about translation – we are actively doing it. We recently completed a Phase I pilot study that tested whether the low-insulinemic dietary pattern can be moved from an epidemiologic construct into a fully operational, clinically delivered intervention.
Over 12 weeks, 32 postmenopausal women at elevated breast cancer risk completed a multi-component program including weekly group education, individual motivational interviewing and nutrition counseling, hands-on food demonstrations, and personalized grocery delivery – all with 100% retention after initiation. This study demonstrates that a precision dietary pattern grounded in metabolic epidemiology can be designed, delivered by registered dietitians, and accepted by people who carry real cancer risk, and that is exactly the kind of translational bridge we set out to build.
If someone wanted to lower their colorectal cancer risk through food, what’s one practical change your study makes you feel more confident about?
In terms of beverages, swap out sugary beverages – sodas, sweetened juices – for water, coffee, or tea. This single shift reflects one of the most consistent features across both the low-insulinemic and anti-inflammatory dietary patterns we studied. Added sugar (and a lot of it comes from sugar-sweetened drinks and refined/processed sugary foods) drive insulin spikes and promote inflammation and reducing them while replacing with coffee or tea (which contain beneficial polyphenols and have favorable metabolic effects) captures a lot of what makes these dietary patterns protective.
For people who feel overwhelmed by nutrition advice, what’s the biggest takeaway?
You don’t have to overhaul your entire diet overnight. One of the most encouraging findings from our study is that meaningful risk reduction appeared even at modest levels of dietary improvement — not just in people who were eating perfectly. The message isn’t “eat this exact list of foods.” It’s more like: move gradually toward more specific vegetables, fruits, legumes, and minimally processed foods, and away from processed meats and sugary drinks and sweetened foods. Small, sustainable shifts in the right direction matter a lot for metabolism. And crucially, three very different dietary scoring systems, each measuring a different concept in the diet, all pointed to the same conclusion, which gives us confidence that there are many paths to a healthier diet.
Are you doing more research in this area?
Absolutely, and we are currently working on multiple exciting directions. One is understanding why these dietary patterns are protective at a biological level — and that is where blood metabolomics comes in. The work will help us identify specific biological pathways — and potentially specific biomarkers — that link diet to colorectal cancer risk.
Another big question we are exploring is: what is happening inside the body to explain these protective effects? One answer may lie in the gut microbiome, the trillions of bacteria living in our digestive tract. In ongoing work, we looked at whether people whose gut bacteria “match” a healthy dietary pattern actually fare better after a colorectal cancer diagnosis. The short answer is yes, patients whose gut and tumor microbial profiles reflected a low-insulinemic dietary pattern had meaningfully better survival outcomes. That’s a striking finding, because it suggests that what you eat may shape the microbes in your gut and even the microbes within tumors, in ways that influence how cancer progresses.
We are also asking whether these dietary patterns matter for cancers beyond the colon. In a study focused on Black women diagnosed with breast cancer, we found that women who ate in a more low-insulinemic way were less likely to have tumors with certain “switched on” molecular signals that drive aggressive cancer growth. They also had better survival outcomes. This is particularly meaningful because Black women face disproportionately higher breast cancer mortality, and dietary patterns that target specific biological pathways – rather than just general healthy eating – may offer a meaningful and equitable tool for addressing that disparity.
The big picture goal of all this work is to take what we are learning at the population level and turn it into practical tools – for doctors, dietitians, and individuals – to actually use diet as a precision strategy for cancer prevention, improved cancer treatment response and survival.
If you would like to suggest someone for a “Spotlight Interview”, send me a note at erin@bloomingwellness.com.
You can also listen to my podcast with Dr. Tabung on whether diet can prevent colon cancer here!
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