Last updated on May 17, 2026 at 09:37 pm
Cancer is a word that changes everything. If you’ve heard it from a doctor yourself, or watched someone you love receive that diagnosis, you know exactly what I mean.
My best friend had cancer. Watching her fight — really fight, with everything she had — was one of the most formative and devastating experiences of my life. She was a mother. She had people who needed her. And she faced her diagnosis with a determination and curiosity that I will never stop admiring.
One of the things that struck me most — and still frustrates me deeply — was how little she was told about nutrition at the point of diagnosis. She received treatment plans, medication schedules, and follow-up appointments. She was told what would be done to her body. But almost nothing was said about what she could do to support her body from the inside. What to eat. What to avoid. How food could influence the environment her body was fighting in.
This is not a criticism of individual doctors — it’s a systemic problem. Nutrition is still not a meaningful part of medical training in most countries. Even today, a doctor can complete their entire medical education without studying the relationship between diet and chronic disease in any depth. The result is that patients facing some of the most serious diagnoses of their lives are sent home without one of the most actionable pieces of information available to them.
My friend did what many determined patients do — she researched it herself. She began to understand the connection between what she ate and how her body responded. What foods supported her through treatment. What she needed to reduce. She became her own expert out of necessity. And what she learned changed how I think about food, about health, and about why this conversation matters so deeply.
She left behind her children. I am a mother too. And that fact — more than anything else — is why I take nutrition seriously as a form of responsibility, not just personal preference. It is why almostplantbased exists.
This article is not a claim that food cures cancer. It doesn’t — and anyone who says otherwise is doing a disservice to people in an already vulnerable position. What the research does show, consistently and across multiple cancer types, is that what we eat meaningfully influences our risk of developing cancer, and may play a role in supporting the body during and after treatment. That is worth understanding clearly — whether you are trying to reduce your risk, supporting someone through a diagnosis, or simply trying to make the best choices for your long-term health.
The medical system will catch up with the nutrition science eventually. Until it does, this is where I try to fill the gap.
Cancer and diet — the connection
Cancer is not one disease but many — a broad category of conditions characterised by the uncontrolled growth and spread of abnormal cells. The causes are multiple and complex, involving genetic factors, environmental exposures, lifestyle choices, and chance. No dietary approach eliminates cancer risk entirely.
But diet is one of the most significant modifiable risk factors we have. Research estimates that between 30–40% of all cancers are directly linked to dietary and lifestyle factors. [1] That’s a meaningful number — it means that a substantial proportion of cancer cases are potentially influenced by choices that are within our control.
The mechanisms are well understood. Certain foods promote inflammation, oxidative stress, and hormonal imbalances that create conditions in which cancer cells are more likely to develop and thrive. Other foods contain compounds that actively protect cells from damage, support immune function, reduce inflammation, and create an internal environment less hospitable to cancer development.
A whole-foods, plant-based diet consistently falls into the second category.
What the research shows about plant-based eating and cancer risk
An analysis of multiple studies on cancer risk found that following a vegan diet was associated with a 10–12% decrease in overall cancer risk compared to omnivorous diets. [1] That’s a significant finding — and the mechanisms behind it are not mysterious.
Plant-based diets tend to be higher in fibre, antioxidants, vitamins, and anti-inflammatory compounds, and lower in saturated fat, processed meat, and refined sugars. Each of these factors individually influences cancer risk — together, they create a dietary pattern that the research consistently links to reduced incidence across multiple cancer types.
This doesn’t mean going fully vegan is necessary or even optimal for everyone. What matters is the overall pattern — more whole plant foods, less processed food and red meat, and a diet rich in the specific compounds that give plant foods their protective properties.
Meat, processed food, and cancer risk
The link between meat consumption — particularly red and processed meat — and cancer risk is one of the most well-established findings in nutritional epidemiology. Research has found that diets rich in meat increased lung cancer risk by up to 35%. [2] The World Health Organization classifies processed meats (ham, salami, bacon, sausages) as Group 1 carcinogens — meaning there is sufficient evidence of a causal link to cancer, particularly colorectal cancer.
This doesn’t mean a piece of good quality salmon or a free-range egg causes cancer. The risk is most clearly associated with processed meats and high consumption of red meat over long periods. The almostplantbased approach — choosing animal products carefully, eating them in smaller quantities, and making whole plant foods the foundation of every meal — is consistent with what the cancer prevention research recommends.
On animal protein generally: read more in our guide to animal vs plant protein.
Weight, obesity, and cancer
Maintaining a healthy weight is one of the most significant things you can do to reduce cancer risk. Excess body fat is associated with increased risk of at least 13 cancer types, including breast, colon, kidney, and pancreatic cancer — through mechanisms including elevated inflammation, hormonal changes, and altered immune function.
A whole-foods, plant-based diet naturally supports healthy weight management — not through restriction, but through the high fibre and water content of plant foods, which promote satiety at a lower calorie density. Read more: Plant-Based Diet for Weight Loss
Plant-based diet and colorectal cancer
Colorectal cancer is one of the most common cancers globally and one of the most studied in relation to diet. The evidence here is particularly strong.
Studies have consistently shown that plant-based foods protect against colorectal cancer development. [4] A large study at Loma Linda University examining the diets of almost 100,000 people found that those following a plant-based diet had a significantly lower risk of developing colon cancer. [5]
The protective mechanisms include the high fibre content of plant foods (which supports gut health and accelerates transit time, reducing the time potential carcinogens spend in contact with the colon wall), the prebiotic effects on gut bacteria, and the antioxidant and anti-inflammatory compounds abundant in vegetables, fruits, and legumes.
Meat consumption, by contrast, has been consistently linked to increased colorectal cancer risk. [6] Chemical compounds formed during meat digestion — and particularly during the high-heat cooking of red and processed meats — have been found to promote cancer development in the gut.
Can diet help manage cancer progression?
This is where the research becomes particularly compelling — and where my friend’s own instincts were vindicated by the science.
A study on prostate cancer progression compared men on a plant-based diet to those on a typical Western diet high in meat. Those following the plant-based diet showed an overall shrinkage in tumour size, compared to growth in the control group. The genetic makeup of the tumours also differed between the two groups. [13]
These findings don’t mean that diet alone can reverse cancer — the research is not at that point, and it would be irresponsible to suggest otherwise. What it does suggest is that diet can influence the environment in which cancer cells exist, potentially affecting their behaviour and progression.
At many cancer treatment centres, patients are now routinely referred to oncology nutritionists who advise on dietary support during and after treatment — with plant-forward, whole-food diets consistently at the centre of those recommendations. Less refined sugar, more vegetables and legumes, more antioxidants and fibre. The same principles, applied in a medical context.
Foods with the strongest cancer-protective evidence
Here are the food groups with the most consistent research behind them:
Cruciferous vegetables
Broccoli, Brussels sprouts, cauliflower, cabbage, and kale contain a sulphur-rich compound called sulforaphane, which has been shown to promote tumour cell death and may reduce tumour size. [7] These are the vegetables I try to include several times a week without exception — steamed broccoli alongside a grain bowl, roasted cauliflower as a side, kale stirred into a soup at the end of cooking. They’re versatile enough to go into almost anything.
Legumes
High in fibre and phytonutrients, legumes have been shown to protect against cancer — particularly colorectal cancer. A study found that high-fibre bean consumption may be protective against the recurrence of advanced colorectal cancer. [8] This is another reason I batch cook chickpeas and lentils every week — they are genuinely one of the most protective food groups available to us. Read more: The 11 Healthiest Beans and Legumes
Citrus fruits
Lemons, limes, oranges, and grapefruit have been associated with reduced risk of stomach, pancreatic, prostate, and breast cancer across multiple studies. [9] [10] [11] The vitamin C and flavonoid content are thought to be key mechanisms. I squeeze lemon over almost everything — it’s one of the simplest and most impactful habits to build.
Berries
Rich in antioxidants that protect cells against free radical damage — the kind of cellular damage associated with cancer development. A study found that berry consumption reduced colorectal tumour growth by 7%. [12] Blueberries, raspberries, and strawberries in particular are worth eating daily — in yoghurt, in overnight oats, on their own as a snack.
Turmeric and ginger
Both have well-documented anti-inflammatory properties. Curcumin — the active compound in turmeric — has been studied extensively for its potential anti-cancer properties, with promising findings across multiple cancer types. Add turmeric to soups, curries, and grain dishes. Grate fresh ginger into dressings and teas. These are easy, daily habits with a meaningful cumulative effect.
Whole grains
High fibre intake from whole grains is consistently associated with reduced colorectal cancer risk — the fibre supports healthy gut bacteria and reduces transit time through the colon. Read more: 13 Healthy Whole Grains Compared
What to reduce for cancer prevention
- Processed meats — ham, salami, bacon, sausages. Classified as Group 1 carcinogens by the WHO. Worth reducing significantly regardless of your overall dietary approach.
- Red meat in large quantities — moderate consumption of high-quality, unprocessed red meat carries significantly lower risk than high consumption of processed meat, but the research supports keeping it to a minimum.
- Refined sugar and ultra-processed foods — promote inflammation and contribute to excess weight, both of which increase cancer risk.
- Alcohol — linked to increased risk of several cancer types including breast, liver, and colorectal cancer. Worth reducing meaningfully if cancer prevention is a priority.
The bottom line
No diet prevents cancer with certainty. But the evidence that whole-foods, plant-based eating meaningfully reduces cancer risk — and may support the body during and after treatment — is substantial, consistent, and growing.
The principles are clear: eat more cruciferous vegetables, legumes, berries, citrus, and whole grains. Reduce processed meat, refined sugar, and ultra-processed food. Choose animal products carefully and in smaller quantities. Build anti-inflammatory habits — turmeric, ginger, olive oil, walnuts — into your daily cooking.
My friend taught me that food is one of the things within our control — and that matters, especially when so much else feels like it isn’t. I think about her every time I cook, and every time I write about this. It’s why this site exists.
If you want a structured programme to build these habits into your daily life — with 200+ recipes, meal plans, and the nutrition science explained clearly — the Eat Healthier in 21 Days Challenge is a good place to start.
The information in this article is for general educational purposes only and does not constitute medical advice. If you or someone you love has received a cancer diagnosis, please work with your oncology team before making significant dietary changes. Diet can support treatment but is not a substitute for it.
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