Animal protein, meat consumption, and cancer risk: What does the evidence show since 2015?

Update Research & Sources (18.09.2025): Evidence: IARC 2015, Farvid 2021, UK Biobank 2020, Naghshi 2020, Swiss Cancer League.

1) General consumption of animal proteins

Animal protein is a central component of our diet. It provides all the essential amino acids needed for cell development, muscle function, and hormone production. However, it's not the total amount that matters, but the source of the protein. Studies show that a high proportion of plant proteins (e.g., legumes, nuts, whole grains) is associated with lower overall mortality, while animal proteins—especially from red and processed meat—can increase the risk of certain types of cancer. Fish and poultry, on the other hand, are considered safe in large cohorts.

2) Red meat: moderate risk

Red meat includes beef, pork, lamb, or venison. The connection between red meat and colon cancer has been studied for years. The mechanisms are biologically plausible: Red meat contains high levels of heme iron, which is converted into N-nitroso compounds in the intestine. These chemical compounds can directly damage DNA and force repair processes. The more often this cycle of damage and repair occurs, the higher the risk of mutations and thus cancer.

The data: High consumption of red meat is associated with a 10–20% higher risk of colorectal cancer. Other cancers, such as breast, endometrial, and lung cancer, also show slight increases in risk. The dose-response relationship is important: Even each additional 100 g of red meat per day measurably increases the risk.

Table

type of meat	Increased risk
Red meat	+14–17% CRC per 100 g/day.
Processed meat	+18% CRC per 50 g/day.
Poultry/Fish	No significant increase.

3) Processed meat: strongest connection

Processed meat includes products such as sausage, bacon, ham, salami, and hot dogs. These are cured, smoked, or fermented to improve shelf life and flavor. However, this process creates substances such as nitrite and nitrate, which can be converted into nitrosamines in the digestive tract. These are considered carcinogenic. Unlike with fresh meat, the method of preparation plays a lesser role here – the risk is inherent in the processing itself.

The International Agency for Research on Cancer (IARC) therefore classified processed meat as "carcinogenic" (Group 1) as early as 2015. The data show a clear dose-response relationship: Just 50g per day—about two slices of bacon or a small portion of sausage—increases the risk of colorectal cancer by 18%. The UK Biobank study demonstrated that even small amounts of 25g per day significantly increase the risk.

Table

Food products	CRC risk increase
Processed meat (sausage, bacon, ham)	+18% per 50 g/day.
Combined red+processed (~76–79 g/day)	+32% (≈14 additional cases per 10.000).

4) Possible mechanisms

Several biological processes explain why red and processed meat can increase the risk of cancer:

• Heme iron: Promotes the formation of carcinogenic nitrosamines in the intestine.
• Nitrite and nitrate: Preservatives in sausage products lead to nitrosamines in the stomach.
• HAA/PAH: Grilling or frying at very high temperatures produces heterocyclic aromatic amines and polycyclic aromatic hydrocarbons – both of which can damage DNA.
• Microbiome: Eating a lot of meat changes the intestinal flora, promotes inflammation and oxidative processes.
• IGF-1: High protein intake increases the hormone IGF-1, which promotes cell division and can encourage tumor growth.

Smarter grilling: Thinly sliced ​​pieces of meat cook faster and release fewer harmful substances. Indirect grilling prevents charring. As an alternative, consider poultry or fish with fresh vegetables and high-fiber side dishes – this way you reduce potentially carcinogenic substances while simultaneously strengthening your gut health.

5) Study overview (since 2015)

Since the IARC classification, numerous new studies have been published confirming these associations. Of particular note are:

Table

Study (year)	Key message
IARC (2015)	Processed meat carcinogenic (Group 1), red meat probably (2A).
Farvid 2021	Red meat ↑ CRC (+10–22%), processed meat ↑ CRC (+18–22%).
UK Biobank 2020	25 g/day processed → +19% CRC; 76–79 g/day → +32%.
BMJ Meta 2020	Animal protein has no effect overall; plant protein is more beneficial.

6) Prevention (Switzerland)

Health organizations such as the Swiss Cancer League and the Federal Office of Public Health recommend limiting red meat consumption to 350–500 g per week and eating processed meat only rarely. The method of preparation is also important: gentle cooking reduces the formation of harmful substances. A high-fiber diet with plenty of fruit, vegetables, and whole grain products also provides additional protection, as these can accelerate intestinal transit and bind carcinogenic substances.

Table

Suggestions	Important notes
Annual health check recommended	Laboratory, blood pressure, lifestyle coaching.
Whole-body MRI	Supplementary in cases of high risk, does not replace colonoscopy.
Colorectal cancer screening (CH)	Stool test annually/bi-annually or colonoscopy according to guidelines.

FAQ

Table

Question	Answer
Is white meat safe?	Large studies show no increased risk of cancer.
How much meat is still 'okay'?	≤350–500 g red meat/week, sausage rarely.
Does organic/pasture-raised make a difference?	More sustainable, yes, processing and preparation count for cancer risk.
Does fiber intake help?	Yes, protects against colon cancer.
Does a whole-body MRI replace colonoscopy?	No, just a supplement.

Further sources

• IARC 2015
• Farvid 2021
• UK Biobank 2020
• Naghshi 2020
• Swiss Cancer League

“Processed meat is carcinogenic; red meat is probably carcinogenic.”

— IARC/WHO

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Conclusion

Evidence since 2015 shows that red and processed meat moderately but demonstrably increase the risk of cancer. The decisive factors are the amount and the processing. Those who reduce meat consumption, prepare it gently, and prefer plant-based alternatives can significantly reduce their risk. In addition, preventive examinations such as colonoscopy or, optionally, a Full-body MRIto detect cancer early.

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