Does Eating Less Meat Reduce Cancer Risk? What a Study of 1.8 Million People Really Tells Us

By Chef Chuck Hayworth, PhD
Founder, Real Medical Meals™ and CL5 Longevity Cuisine™

The relationship between food and cancer deserves more than a headline.

As a chef, nutritional wellness practitioner, and stomach cancer survivor of more than 26 years, I have spent much of my professional life exploring the relationship between the foods we eat and the health we hope to maintain.

My experience with cancer changed how I looked at food. It encouraged me to think beyond calories and flavor and consider how nutrition might support recovery, long-term wellness, and quality of life.

That is why a major study published in the British Journal of Cancer caught my attention.

Researchers examined approximately 1.8 million people from nine prospective studies in the United Kingdom, United States, Taiwan, and India, investigating how different dietary patterns were associated with the development of 17 types of cancer.

The findings were fascinating. But they also raised important questions.

What did the researchers discover?

Over a median follow-up of 16 years, the investigators compared meat eaters, poultry eaters, pescatarians, vegetarians, and vegans.

Vegetarians showed lower relative risks of several cancers, including pancreatic, breast, prostate, kidney cancer, and multiple myeloma.

Pescatarians demonstrated lower risks of colorectal, breast, and kidney cancer.

However, the study also reported a higher risk of esophageal squamous cell carcinoma among vegetarians and a higher risk of colorectal cancer among vegans.

These results may seem contradictory.

How can diets often associated with healthy living show favorable associations with some cancers and unfavorable associations with others?

The answer may involve nutritional adequacy, lifestyle, individual biology, and the limitations of observational research.

The strengths: Why this research matters

First, the size of the investigation is significant.

With more than 1.8 million participants, this research offers a much larger evidence base than many previous investigations of vegetarian diets and cancer.

Second, the researchers followed participants over time rather than simply asking people with cancer what they had eaten in the past. This prospective approach helps reduce certain forms of bias.

Third, the investigators accounted statistically for factors including smoking, alcohol consumption, physical activity, body mass index, diabetes history, and several demographic and reproductive characteristics.

These methods strengthen the findings.

However, even a well-designed observational study cannot establish that a particular dietary pattern directly prevented or caused cancer.

The weaknesses: What the study cannot tell us

Here is where I believe readers should pay particular attention.

The research classified diets primarily according to whether participants consumed meat, poultry, fish, dairy products, or eggs.

But it did not adequately capture all the differences in food quality, processing, preparation, and cooking methods.

Consider two individuals who both describe themselves as vegetarians.

One regularly eats seasonal vegetables, beans, lentils, fresh fruit, nuts, and minimally processed whole grains.

The other relies heavily on refined starches, sweetened foods, and highly processed meat substitutes.

Both may fall into the same broad dietary category, despite having substantially different nutritional patterns.

The study also relied largely on self-reported dietary information, which introduces measurement uncertainty.

Another concern is that people choosing vegetarian diets may differ from meat eaters in ways that researchers cannot fully measure.

Finally, although the overall population was enormous, the vegan population was comparatively small. That means the unexpected colorectal cancer finding needs further investigation rather than immediate conclusions.

Could nutritional deficiencies help explain some findings?

The researchers raised the possibility that inadequate intake of certain nutrients could contribute to some unfavorable associations.

Vegetarian and vegan dietary patterns may require particular attention to vitamin B12, iron, zinc, calcium, vitamin D, iodine, and other nutrients, depending on the foods consumed and whether supplements or fortified foods are used.

However, the study did not establish that any specific nutrient deficiency caused the observed increases in cancer risk.

This is an important distinction.

A properly planned vegetarian or vegan diet can be nutritionally adequate. The challenge is making sure that nutritional requirements are actually being met.

My culinary interpretation: Quality matters more than labels

One of the principles behind CL5 Longevity Cuisine is that food should be evaluated by what it contributes to the body, not simply by the dietary label attached to it.

A thoughtfully prepared meal can bring together plant diversity, appropriate protein, dietary fiber, healthy fats, and naturally occurring vitamins and minerals.

Consider a plate featuring roasted seasonal vegetables, lentils, fresh herbs, extra-virgin olive oil, and a carefully selected protein.

That protein might be fish, poultry, or a combination of plant foods, depending on the individual’s medical needs and dietary preferences.

The goal is not to declare one dietary identity superior to every other.

The goal is to build a nutritional pattern that is balanced, sustainable, enjoyable, and appropriate for the person eating it.

This particular study did not test the CL5 system, nor does it validate any proprietary nutrition program. But it reinforces the importance of investigating dietary patterns carefully rather than relying on simplistic claims.

What does this mean for people living with cancer?

We must distinguish cancer prevention research from nutrition during active cancer treatment.

This investigation studied the development of cancer. It did not examine whether vegetarian, pescatarian, or vegan diets improve chemotherapy tolerance, prevent recurrence, or increase survival after diagnosis.

For patients undergoing treatment, priorities may include maintaining adequate energy and protein intake, preserving muscle mass, managing digestive symptoms, supporting hydration, and addressing treatment-related nutritional deficiencies.

Some patients benefit from gentle, cooked vegetables and easily digestible proteins. Others require modified textures, smaller meals, or individualized adjustments based on their treatment and medical condition.

At Real Medical Meals™, the objective is to translate a patient’s documented nutritional needs and healthcare guidance into practical, carefully prepared meals.

Nutrition should support the medical treatment plan, not replace it.

Five practical lessons from the kitchen

1. Make plants a regular foundation of meals. Vegetables, fruits, legumes, and whole grains can contribute fiber and a wide variety of beneficial nutrients.

2. Evaluate protein sources thoughtfully. Fish, poultry, eggs, dairy, legumes, and other foods may have appropriate roles depending on nutritional requirements and personal preferences.

3. Don’t confuse vegetarian with automatically healthy. A dietary label cannot replace an assessment of overall food quality.

4. Pay attention to nutritional adequacy. Restrictive diets require planning, particularly when illness, aging, or treatment increases nutritional vulnerability.

5. Think in terms of long-term patterns. Consistent eating habits matter more than isolated ingredients or occasional meals.

Final thoughts: Food is not a guarantee, but it is an opportunity

As someone who has experienced cancer personally, I understand the desire to find answers in nutrition.

But I also recognize the danger of promising more than science can deliver.

No single ingredient, recipe, or dietary pattern guarantees protection against cancer.

What we can do is use the best available evidence to make informed decisions, respect individual medical needs, and create meals that nourish the body while preserving the pleasure of eating.

That is the philosophy I continue to explore through Real Medical Meals and CL5 Longevity Cuisine.

The most important question may not be whether we call ourselves vegetarians, pescatarians, or omnivores.

It may be whether the food on our plates consistently provides the nourishment our bodies need.

And that is a conversation worth having.

Research reference: Dunneram Y. et al. (2026). Vegetarian diets and cancer risk: pooled analysis of 1.8 million women and men in nine prospective studies on three continents. British Journal of Cancer, 134, 1218–1229. https://doi.org/10.1038/s41416-025-03327-4

Medical disclaimer: This article is provided for educational purposes and is not intended to diagnose, treat, cure, or prevent any disease. Patients undergoing cancer treatment should discuss significant dietary changes with their oncology team and an appropriately qualified registered dietitian.