Strong evidence shows that processed meat (such as sausages, ham and salami), alcoholic drinks and excess body weight raise the risk of bowel (colorectal) cancer. Salt-preserved foods are linked with stomach cancer, mouldy grains and pulses with liver cancer, and very hot drinks with cancer of the oesophagus [1, 2, 3]. On the other hand, whole grains, high-fibre foods and dairy foods probably lower the risk of bowel cancer. The best evidence for lowering risk is not about one particular food but about a diet rich in whole grains, beans and lentils, fruit and vegetables [1, 4, 5].
Key points
- Sausages, ham and other processed meats are classed as "carcinogenic to humans" and raise the risk of bowel cancer; red meat is "probably carcinogenic" [1, 2].
- Alcohol and excess body weight also raise the risk of bowel cancer, on strong evidence [1].
- Salt-preserved foods are linked with stomach cancer, mouldy grains and pulses with liver cancer and very hot drinks with cancer of the oesophagus [1, 3].
- Whole grains, fibre and dairy foods probably lower the risk of bowel cancer [1, 6].
- Soy: in large studies, eating soy foods after breast cancer was linked with less, not more, return of the disease [7, 8].
- Supplements do not replace food; supplements are not recommended for cancer prevention, and your body's needs should be met from food [1].
Which foods cause cancer?
The World Cancer Research Fund and the American Institute for Cancer Research have reviewed all the studies on diet and cancer in a major report. The International Agency for Research on Cancer (part of the World Health Organization) has also assessed some foods and drinks separately. The table below summarises what has the strongest evidence [1, 2, 3].
| Food or drink | Which cancer? | How strong is the evidence? |
|---|---|---|
| Processed meat (sausages, ham, salami, smoked meat and canned meat) | Bowel [1, 2] | Strong; "carcinogenic to humans" [1, 2] |
| Red meat (beef, veal, pork, lamb and goat) | Bowel [1, 2] | Probable; "probably carcinogenic" [1, 2] |
| Alcoholic drinks | Bowel and several other cancers [1] | Strong [1] |
| Salt-preserved foods (salted vegetables, salted fish and other foods preserved with salt) | Stomach [1] | Strong [1] |
| Mouldy grains and pulses (contaminated with a toxin called aflatoxin) | Liver [1] | Strong [1] |
| Very hot drinks (above 65 °C), such as very hot tea | Oesophagus [1, 3] | "Probably carcinogenic" [3] |
| Drinking water contaminated with arsenic | Several types of cancer [1] | Strong [1] |
Excess body weight, which results from diet and inactivity together, also raises the risk of bowel cancer on strong evidence [1]. Having one of these risk factors does not mean you will get cancer; for processed meat, for example, the risk rises with the amount eaten [2].
How much? For example, every 50 g of processed meat eaten a day raises the risk of bowel cancer by about one fifth [2]. You do not need to give up meat: limit red meat to about 3 portions a week and eat very little, if any, processed meat [1]. Read more: Do red meat and processed meat cause cancer?, Does alcohol cause cancer? and Does obesity cause cancer?
Salted food, mouldy food and very hot tea
Salt and salt-preserved foods: strong evidence, mostly from Asia, shows that foods preserved with salt, such as salted vegetables and salted fish, are a cause of stomach cancer [1]. Cut down on very salty pickles and salted fish. Testing for and treating the stomach germ Helicobacter pylori is also important in preventing stomach cancer: Should I be tested for H. pylori?
Mouldy food: mouldy grains and pulses may contain aflatoxin, which is a cause of liver cancer; do not eat mouldy grains or pulses [1].
Tea and very hot drinks: drinking tea or any drink above 65 °C has been classed as "probably carcinogenic". Studies in Iran, China, Turkey and South America showed that the hotter the drink, the higher the risk of oesophageal cancer; according to the International Agency for Research on Cancer, it appears to be the temperature of the drink that is responsible, not the drink itself [3]. Let your tea cool a little before you drink it. Read more: Does coffee or tea cause cancer?
What are the best cancer-fighting foods and fruits?
The strongest evidence is not about one particular food but about a diet rich in plants as a whole [1]:
- Fibre and whole grains: in a large review of studies, people who ate the most fibre were less likely to develop bowel cancer. A clear benefit was seen at 25 to 29 g of fibre a day, and eating more may bring even more benefit. Results for whole grains were similar [4]. Wholemeal bread, barley, oats, brown rice, lentils, beans and chickpeas are good sources of fibre.
- Fruit and vegetables: the more fruit and vegetables people ate, up to about 600 g a day, the slightly lower their overall cancer risk. Green and yellow vegetables and the cabbage family (such as cabbage, cauliflower and broccoli) were linked with a lower risk of cancer [5].
- Recommendation: at least 5 portions (400 g) of a variety of fruit and vegetables and at least 30 g of fibre a day from food [1].
Many foods and fruits described as "anti-cancer" may have benefits, but the evidence for the effect of each one on its own is weaker than the evidence for the diet as a whole; you can enjoy them as part of a varied diet [1]. So far, no study has shown that any particular food can cure cancer or stop it coming back, so no food can replace treatment [12].
Is milk or dairy bad for cancer?
For bowel cancer, the evidence points the other way: dairy foods probably lower the risk [1]. In a large review, every 200 g of milk a day (about one glass) was linked with a lower risk of bowel cancer; this link was not seen for cheese [6]. For prostate cancer, there is limited evidence that dairy foods might raise the risk; this evidence is not strong enough for a recommendation [1].
People with cancer: during treatment, pasteurised milk, yoghurt and cheese are good ways of getting protein [12]. Read more: What to eat before and after chemotherapy.
Soy and breast cancer: should I eat soy or not?
Soy contains plant substances similar to oestrogen (isoflavones), so some people have worried that it could harm people with breast cancer, especially those taking tamoxifen [7]. Studies have not shown such harm:
- After breast cancer: in a study of more than 5,000 women in China, the women who ate the most soy were less likely to have their cancer come back and less likely to die. This was seen in women who did and did not take tamoxifen, and in both types of breast cancer (oestrogen-sensitive and not) [7]. In a larger study of American and Chinese women, eating soy foods was also linked with less return of the cancer [8].
- Risk of getting breast cancer: in Asian countries where a lot of soy is eaten, women who ate more soy were less likely to develop breast cancer; in Western countries, where much less soy is eaten, no link was seen [9].
These studies were about soy foods, not soy tablets or supplements [7, 8].
Do fast food and ultra-processed foods cause cancer?
Ultra-processed foods are made in factories with many additives, such as fizzy and sweetened drinks, packaged snacks, mass-produced bread and cakes, sausages, nuggets and ready meals [10]. In a large study in France of more than 100,000 people, the bigger the share of these foods in the diet, the slightly more often cancer was seen, both overall and for breast cancer [10]. This kind of study does not prove cause, and the researchers said more studies are needed [10].
The World Cancer Research Fund recommends limiting fast food and processed foods high in fat, starch or sugar, and sugary drinks [1]. For sugar and sweeteners, see Does sugar make cancer grow? and Do aspartame and artificial sweeteners cause cancer?
Can vitamin supplements replace fruit and vegetables?
No. The World Cancer Research Fund recommends not taking supplements for cancer prevention and meeting your body's needs from food [1]. In a large study of male smokers, a daily beta-carotene supplement did not lower lung cancer and even raised it slightly, although diets rich in fruit and vegetables containing this substance had earlier been linked with a lower risk of lung cancer [11]. A supplement your doctor has prescribed for a specific deficiency is a different matter.
What can I do? Diet advice to lower your cancer risk
- 1
A diet rich in plants
Base your meals on whole grains, beans and lentils, fruit and vegetables: at least 5 portions (400 g) of a variety of fruit and vegetables and 30 g of fibre a day [1]. For example, wholemeal bread, lentil soup or bean stew, salads and plenty of vegetables.
- 2
Less red meat, very little processed meat
Red meat no more than about 3 portions a week; very little, if any, sausages, ham and salami [1].
- 3
Limit fast food and sugary drinks
Cut down on processed foods high in fat, starch or sugar, and on sugary drinks [1].
- 4
No salt-preserved or mouldy food
Cut down on salt-preserved foods, and do not eat mouldy grains or pulses [1].
- 5
Do not drink tea scalding hot
Let tea and other drinks cool a little [3].
- 6
Frequently asked questions
What is the most cancer-causing food?
Do chicken and fish cause cancer too?
Do fried food, barbecued meat and burnt meat cause cancer?
Cooking meat at high temperatures or over a flame or hot surface, as in barbecuing or frying, produces more cancer-causing chemicals; but there are not yet enough data to say whether the way meat is cooked changes the risk of cancer [2]. Read more: Does the cooking method matter?
Can people with cancer drink milk?
Does becoming vegetarian prevent cancer?
Vegetarian diets and diets that include meat each have advantages and disadvantages, and the International Agency for Research on Cancer's assessment did not compare them directly [2]. What has strong evidence is a diet rich in whole grains, beans and lentils, fruit and vegetables, with less red meat and very little processed meat [1].
What diet should I follow after cancer?
The World Cancer Research Fund advises people who have had cancer to follow the same recommendations as far as they can once the acute stage of treatment is over, unless their doctor advises otherwise [1]. During treatment your needs are different; see What to eat before and after chemotherapy and What foods should I avoid during chemotherapy?
Related pages
Evidence details (for doctors)
For physicians
- WCRF/AICR 2018 (Clinton 2020): colorectal cancer: convincing increase with processed meat, alcoholic drinks, body fatness and adult attained height; convincing decrease with physical activity; probable decrease with whole grains, foods containing dietary fibre, dairy products and calcium supplements; probable increase with red meat; limited-suggestive decrease with fish. Strong evidence for salt-preserved foods and stomach cancer, aflatoxins and liver cancer, arsenic in drinking water and several cancers, Cantonese-style salted fish and nasopharyngeal cancer, and maté drunk scalding hot and oesophageal SCC; dairy and prostate cancer limited-suggestive with no recommendation. Recommendations: fibre at least 30 g/day, at least 400 g of non-starchy vegetables and fruit, red meat no more than about 3 portions a week, very little if any processed meat, and no supplements for cancer prevention [1].
- IARC: processed meat Group 1 and red meat Group 2A (Monograph 114); each 50 g/day of processed meat about an 18% increase in colorectal cancer risk, and for red meat, if causal, 17% per 100 g/day [2]. Beverages above 65 °C Group 2A (limited evidence in humans; oesophageal cancer); coffee Group 3 (Monograph 116) [3].
- Fibre (Reynolds, Lancet 2019): 185 prospective studies and 58 trials; highest vs lowest fibre intake 15 to 30% lower mortality and incidence of diseases including colorectal cancer; risk reduction across critical outcomes greatest at 25 to 29 g/day, with dose-response curves suggesting greater benefit at higher intakes for colorectal and breast cancer; certainty of evidence for fibre moderate [4]. Fruit and vegetables (Aune, IJE 2017): per 200 g/day, RR for total cancer 0.97 (0.95 to 0.99); risk reduction up to 600 g/day [5]. Dairy (Aune, Ann Oncol 2012; 19 cohorts): colorectal RR 0.83 (0.78 to 0.88) per 400 g/day total dairy, 0.91 (0.85 to 0.94) per 200 g/day milk and 0.96 (0.83 to 1.12) per 50 g/day cheese; association restricted to colon cancer [6].
- Soy: SBCSS (Shu, JAMA 2009; 5042 survivors, median follow-up 3.9 years): highest vs lowest quartile of soy protein HR for death 0.71 (0.54 to 0.92) and recurrence 0.68 (0.54 to 0.87), regardless of ER status or tamoxifen use [7]. ABCPP (Nechuta 2012; 9514 US and Chinese patients, mean follow-up 7.4 years): isoflavones 10 mg/day or more, HR for recurrence 0.75 (0.61 to 0.92); breast cancer death 0.83 (0.64 to 1.07) [8]. Risk in Asian populations (Wu 2008): vs 5 mg isoflavones/day or less, OR 0.88 (0.78 to 0.98) at about 10 mg and 0.71 (0.60 to 0.85) at 20 mg or more; no association in Western populations [9].
- Ultra-processed food (NutriNet-Santé, Fiolet, BMJ 2018; 104,980 adults): per 10% increase in share of the diet, HR for overall cancer 1.12 (1.06 to 1.18) and breast cancer 1.11 (1.02 to 1.22) [10]. ATBC (1994): 29,133 male smokers; beta-carotene 20 mg/day increased lung cancer incidence by 18% (3 to 36%) and total mortality by 8% (1 to 16%) [11].
Related cancer types
Related questions
References
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Numbers in the text, such as [1], refer to these sources. Sources with a “Study card” button are summarised in the site’s evidence library.
- 1The World Cancer Research Fund/American Institute for Cancer Research Third Expert Report on Diet, Nutrition, Physical Activity, and Cancer: Impact and Future Directions
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This page is based on reputable scientific sources and was last updated on 28 October 2026. The content of this website is for educational and informational purposes only and does not replace consultation, diagnosis or treatment by a specialist physician. Consult your treating physician about any treatment decision.
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