Research Reveals Plant-Based Diets Reduce Risk of Multimorbidity

Every new dataset points to the same conclusion: eating more plants and fewer animal products lowers the risk of disease. Not just one disease, but several at once.

A study published in The Lancet Healthy Longevity has now added another layer to this truth. Researchers analysed data from more than 400,000 adults across six European countries to test a crucial question: does a healthy plant-based diet reduce the likelihood of developing multiple serious illnesses? The answer was a resounding yes.

What the Lancet study found

The research drew on two massive population cohorts: the European Prospective Investigation into Cancer and Nutrition (EPIC) and the UK Biobank. Participants were tracked for over a decade. Those who scored highest on a “healthful plant-based diet index” – diets rich in fruits, vegetables, whole grains, legumes, nuts and seeds – had a 32% lower risk of multimorbidity.

Multimorbidity here means the co-occurrence of at least two major chronic diseases: cancer, cardiovascular disease, or type 2 diabetes. These three were chosen because they are the leading global killers, responsible for millions of deaths each year, and they share preventable risk factors.

The pattern was clear: the more whole plant foods on the plate, the lower the risk. The association was strongest in people under 60, but still evident in older adults. In the UK Biobank, every ten-point increase in the healthful diet score corresponded with a 29% reduction in risk for those under 60, and a 14% reduction for those over 60.

On the flip side, the researchers also created an “unhealthful plant-based diet index,” capturing patterns heavy in refined grains, sugary drinks, and ultra-processed plant foods. In the UK Biobank, high scores on this index were linked with a 22% increase in multimorbidity risk. Not all plant-based diets are created equal.

This is the first time such a large, long-term analysis has tracked how diet influences not just the risk of one disease, but the progression from one illness to another – from a first diagnosis to the heavy burden of multiple conditions.

Beyond single diseases

Most dietary research focuses on one disease at a time. But that isn’t how reality works. A person with diabetes is more likely to develop heart disease. A person with cancer may later develop cardiovascular problems. Multimorbidity is becoming the norm, especially in older populations – more than 50% of adults over 60 now live with at least two chronic diseases.

This study shows that diet shapes not only the onset of illness but also the pathways leading to multiple conditions. And the pathway away from multimorbidity is unmistakable: plants.

The Adventist cancer data

The European cohorts aren’t the only large dataset making headlines this year. Data from the Adventist Health Study-2, covering nearly 80,000 people in the United States and Canada over 13 years, confirms that vegans had the lowest overall cancer rates of all dietary groups.

The Adventist community is unusually valuable for research. Members are already healthier on average – they smoke less, drink less, and exercise more – which means diet differences stand out more clearly. Within this group, vegans emerged with the strongest protection.

The numbers:

▫️24% lower overall cancer risk compared to non-vegetarians.

▫️43% lower risk of prostate cancer in younger vegan men.

▫️31% lower risk of breast cancer in younger vegan women.

▫️45% lower risk of stomach cancer.

▫️25% lower risk of lymphomas.

These reductions are not trivial. They represent thousands of lives spared from aggressive treatment, lifelong monitoring, and premature death. And they mirror what the European study found about multimorbidity: the fewer animal products you consume, the stronger your protection against the accumulation of disease.

No safe level of processed meat

If anyone still clings to the idea of “everything in moderation,” the latest Nature Medicine review should end the fantasy. US researchers analysed more than 70 studies involving several million people and concluded there is no safe level of processed meat consumption.

One hot dog a day – a single serving – was associated with an 11% greater risk of type 2 diabetes and at least a 7% higher risk of colorectal cancer. The risk climbed with intake. Even the smallest amounts pushed disease risk higher.

Processed meats – bacon, ham, sausages, salami, corned beef, hot dogs – are classified as Group 1 carcinogens by the World Health Organization, alongside asbestos and tobacco. They are chemically preserved, cured, fermented, or smoked to extend shelf life and improve taste. What they extend is suffering.

Compare this with plant-based diets, where every major cohort analysis finds reduced risks. The contrast is impossible to ignore. Governments know this. Health bodies know this. And yet these products are still pushed in dietary guidelines, served in hospitals, and subsidised with public money.

Mechanisms: why plants protect

It isn’t magic. The protective effects of plant-based diets are explained by well-studied biological mechanisms. A diet rich in whole plant foods means:

▫️Lower body weight: Plant-based diets are consistently associated with lower BMI, a major factor in diabetes and cardiovascular risk.

▫️Improved insulin sensitivity: High fibre intake slows glucose absorption and supports metabolic health.

▫️Reduced inflammation: Plant compounds, including antioxidants and polyphenols, counter chronic inflammation – a driver of cancer and heart disease.

▫️A healthier gut microbiome: Fibre feeds beneficial bacteria, leading to the production of short-chain fatty acids that regulate immunity and reduce carcinogenic by-products.

▫️Lower levels of harmful compounds: Eating fewer animal products means less exposure to heme iron, nitrosamines, secondary bile acids, and trimethylamine N-oxide, all implicated in chronic disease.

On the other hand, “unhealthy” plant diets loaded with refined grains, added sugars, and oils strip away these benefits. This explains why the Lancet study found diverging risks between healthful and unhealthful plant-based patterns.

Why aren’t plant-based diets the norm?

With so much evidence, the question practically screams: why isn’t this the baseline of public health policy?

The EAT–GlobeScan “Grains of Truth” report sheds light on the gap between interest and action. In a survey of 30,000 people across 31 countries, 68% said they want to eat more plant-based foods, yet only 20% do so regularly – a decline from 23% the year before.

The barriers are familiar:

▫️Price: 42% said cost was the main obstacle.

▫️Taste: 35% said flavour was a barrier.

▫️Cultural habits and access: older generations and some regions report difficulty finding or preparing plant-based foods.

▫️Misinformation: in Asia-Pacific, myths about plant-based nutrition are widespread.

At the same time, 69% of people worldwide believe the world would be better with less meat. The demand is there. The science is there. What’s missing is political will. Instead of removing subsidies for meat and dairy, governments double down. Instead of restructuring food environments, they cling to outdated “balanced diet” rhetoric that treats cancer-causing products as acceptable in moderation. Instead of promoting plant-based meals in schools and hospitals, they allow industry lobbyists to shape menus.

The real issue: exploitation

At its core, this is about more than hazard ratios. The very products making people sick – processed meats, dairy, eggs – exist because animals are treated as property. Saturated fat, heme iron, carcinogenic compounds from cooked flesh, pathogens incubated in factory farms: these are by-products of exploitation.

Health experts often hedge their language: “You don’t have to cut out animal products entirely.” But the Adventist data speaks plainly: vegans had the lowest cancer risk. The less you exploit animals, the stronger your protection.

And the benefits go beyond health. Animal agriculture is the leading cause of deforestation, biodiversity loss, and a major driver of greenhouse gas emissions. Shifting to plant-based diets isn’t just a personal health decision – it’s a justice issue for humans, animals, and the planet.

Enough stalling

We are living through a global health crisis where multimorbidity is already the default in older populations. More than half of adults over 60 now live with two or more chronic diseases. Health services are collapsing under the weight of preventable illness.

And yet governments still promote dairy in schools. They still subsidise bacon, ham, and beef. They still frame plant-based eating as a fringe choice instead of the obvious baseline. This isn’t balance – it’s complicity.

We don’t need more timid recommendations or watered-down messaging. We don’t need more industry-friendly “flexitarian” campaigns. We need honesty. We need to stop pretending that exploiting animals can ever be compatible with human health.

The choice is obvious. A plant-based food system would save millions of lives, reduce human disease, protect ecosystems, and most importantly, end the exploitation of animals as commodities.

The longer governments stall, the more people die needlessly – human and non-human alike.