Processed Food and Lung Cancer: What Research Shows

Key Takeaways

• A 2025 population-based cohort study of more than 100,000 people found that the highest consumers of ultra-processed food had a 41% higher relative risk of lung cancer compared to the lowest consumers.

• Processed meats (bacon, deli meats, hot dogs) are classified as a Group 1 carcinogen by the International Agency for Research on Cancer (IARC), though the strongest evidence links them to colorectal cancer rather than lung cancer specifically.

• Diets high in fruits and vegetables — particularly carotenoid-rich foods like leafy greens, carrots, and citrus — are consistently associated with lower lung cancer risk in epidemiological studies.

• Beta-carotene supplements do not replicate the protective effects of food-form carotenoids and actually increased lung cancer risk in smokers in a major clinical trial (the CARET trial).

• Smoking remains the dominant risk factor for lung cancer, accounting for roughly 80% of cases. Dietary factors are modest modifiers by comparison — but they are modifiable, which makes them worth addressing.

Why Diet and Lung Cancer Are Being Studied More Closely

For decades, lung cancer research has rightly centered on tobacco. Smoking is responsible for approximately 80% of lung cancer diagnoses in the United States. But that also means roughly 20% of cases — between 20,000 and 40,000 Americans annually — occur in people who have never smoked, according to the American Cancer Society. This reality has pushed researchers to look more carefully at other risk factors: radon exposure, secondhand smoke, air pollution, genetic predisposition, and, increasingly, diet.

At the same time, a surge of research on ultra-processed food (UPF) and cancer more broadly has brought dietary patterns into sharper focus. To understand these studies, it helps to know what “processed” and “ultra-processed” actually mean because not all processed food is created equal.

Researchers commonly use the NOVA classification system, developed by researchers at the University of São Paulo, which groups foods into four categories based on the extent and purpose of their processing:

• Group 1: Unprocessed or minimally processed foods (fresh fruit, vegetables, plain meat, eggs, milk)

• Group 2: Processed culinary ingredients (oils, flours, sugar, salt — used in home cooking)

• Group 3: Processed foods (canned fish, simple cheeses, cured meats, freshly baked bread)

• Group 4: Ultra-processed foods — industrial formulations made with little or no whole food ingredients. These contain additives you would not find in a home kitchen: high-fructose corn syrup, hydrogenated oils, protein isolates, artificial flavors and colorings, emulsifiers, and non-sugar sweeteners.

Group 4 — the ultra-processed category — is where the cancer concern is concentrated. Examples include packaged snacks, fast food, sugary drinks, instant noodles, processed deli meats, flavored breakfast cereals, and most frozen ready-meals.

What the Research Shows: Processed Food and Lung Cancer Risk

The 2025 PLCO cohort study

The most direct recent evidence comes from a 2025 population-based cohort study published in Thorax, using data from the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial — one of the largest cancer screening studies ever conducted in the United States. Researchers analyzed dietary records from 101,732 participants (51,545 women and 50,187 men) followed for a median of 12.2 years.

After adjusting for smoking history and other confounding variables, participants with the highest ultra-processed food consumption had a hazard ratio of 1.41 compared to those with the lowest intake, which equates to a 41% higher relative risk. The association held for both non-small cell lung cancer (HR = 1.37) and small cell lung cancer (HR = 1.44). A total of 1,706 lung cancer cases were identified during follow-up.

As the researchers noted, this is an observational study, and it cannot prove that ultra-processed food causes lung cancer. Confounding factors — including overall lifestyle quality, socioeconomic status, and residual smoking effects — are always present in dietary epidemiology. But the size of the study and the consistency of the association across lung cancer subtypes make it difficult to dismiss.

Processed meat and nitrosamines

Processed meats — bacon, hot dogs, sausages, deli meats, and other cured or smoked meat products — warrant separate discussion because of their specific chemical risks. When meat is preserved with nitrite salts, those nitrites can react with proteins under acidic conditions (such as in the stomach) to form nitrosamines, a family of compounds known to damage DNA.

IARC classifies processed meat as a Group 1 carcinogen — meaning there is sufficient evidence that it causes cancer in humans. The primary evidence is for colorectal cancer. For lung cancer specifically, the evidence is more limited and less consistent. One analysis noted a roughly 16% increased risk of lung cancer with processed meat consumption, but this finding is not replicated across all studies. The lung cancer link is plausible biologically as inhaled nitrosamines from tobacco are major contributors to lung carcinogenesis, but dietary nitrosamines reach the lungs through systemic circulation, and the dose and route differ substantially from smoke exposure.

Acrylamide

Acrylamide is a compound that forms naturally when starchy foods are cooked at high temperatures in foods like french fries, potato chips, roasted coffee, baked goods, and breakfast cereals. IARC classifies acrylamide as a Group 2A substance, which means it’s a “probable human carcinogen”  based on strong evidence of carcinogenicity in animals and limited but mechanistically plausible evidence in humans.

According to the National Cancer Institute (NCI), a large number of epidemiologic studies have not found a consistent association between dietary acrylamide exposure and overall cancer risk. For lung cancer specifically, a systematic review and meta-analysis published in Frontiers in Nutrition (2022) found that the association between dietary acrylamide and lung cancer was most apparent in smokers — where acrylamide exposure from cigarette smoke is already very high — making it difficult to separate dietary acrylamide’s independent contribution. In never-smokers, dietary acrylamide does not appear to independently increase lung cancer risk based on current evidence.

Dietary patterns overall

Beyond specific compounds, the broader dietary pattern matters. Epidemiological studies consistently show that diets characterized by high intake of red and processed meat and low intake of fruits and vegetables are associated with elevated lung cancer risk. A systematic review and meta-analysis published in Annals of Oncology found significant inverse (protective) dose-response associations with fruit and vegetable intake — with each 100 grams per day increase in combined fruit and vegetable consumption associated with a meaningful reduction in lung cancer risk.

A key word throughout this section: association. Observational dietary studies cannot control for every lifestyle variable. Smoking, cooking methods, socioeconomic factors, and physical activity all travel together with dietary patterns, making causation very difficult to establish.

Possible Mechanisms: How Processed Foods Might Affect Lung Cancer Risk

The associations described above are not random, but there are several biologically plausible pathways through which ultra-processed food consumption could increase cancer risk:

Nitrosamines and DNA damage. As noted, nitrites in processed meats can form nitrosamines that react with DNA, causing mutations in cells throughout the body. This mechanism is well-established for colorectal carcinogenesis and plausibly extends to other tissues.

Acrylamide and oxidative stress. In the body, acrylamide is metabolized to glycidamide, which forms DNA adducts — stable chemical bonds between a carcinogen and DNA that can trigger errors in cell replication if not repaired. Acrylamide also increases oxidative stress in cells.

Advanced glycation end-products (AGEs). When foods are cooked at high temperatures — particularly grilling, frying, and ultra-high-temperature processing — AGEs form. Research published in PMC has shown that AGEs bind to a receptor called RAGE, triggering sustained increases in oxidative stress and chronic inflammation. Since chronic inflammation is a recognized promoter of cancer development and progression, diets high in AGEs may contribute to a pro-carcinogenic environment at the cellular level.

Antioxidant depletion. Ultra-processed food diets tend to crowd out fruits, vegetables, legumes, and whole grains, the foods richest in antioxidants like vitamins C and E, beta-carotene, lutein, and flavonoids. Multiple studies have linked these antioxidants to protective effects in lung tissue. A diet that is low in these compounds, by definition, forfeits that protection.

Obesity-mediated inflammation. Ultra-processed foods are energy-dense, hyperpalatable, and associated with higher rates of obesity. Adipose (fat) tissue, particularly visceral fat, is metabolically active and secretes pro-inflammatory cytokines. Chronic systemic inflammation creates conditions that may promote tumor initiation and progression.

What a Protective Diet Looks Like

If certain dietary patterns are associated with higher lung cancer risk, what does the evidence say about protective patterns?

Fruits and vegetables. The data here are among the most consistent in dietary cancer epidemiology. A dose-response meta-analysis found that increasing fruit and vegetable intake was inversely associated with lung cancer risk, with each 100 g/day increase providing measurable benefit. The most studied compounds are carotenoids — the pigments found in carrots, sweet potatoes, leafy greens, and citrus. Diets rich in foods containing beta-carotene, lycopene, beta-cryptoxanthin, and lutein have repeatedly been associated with lower lung cancer incidence.

The Mediterranean diet. A 2022 meta-analysis published in Frontiers in Nutrition found that high adherence to the Mediterranean diet — characterized by abundant vegetables, fruits, legumes, whole grains, fish, and olive oil, with limited red meat and processed foods — was associated with an 18% lower risk of lung cancer. The dose-response relationship was meaningful: each three-point increase in Mediterranean diet score corresponded to approximately a 9% reduction in risk.

Fiber. Higher dietary fiber intake is associated with lower systemic inflammation and favorable changes in the gut microbiome, both of which have downstream effects on immune function and cancer surveillance.

One critical caveat: supplements are not food. The beta-carotene story is a cautionary tale. Given the epidemiological evidence linking dietary carotenoids to lower lung cancer risk, researchers designed the Carotene and Retinol Efficacy Trial (CARET) to test whether high-dose beta-carotene supplementation would reduce lung cancer incidence in heavy smokers and asbestos-exposed workers. The trial was stopped early when participants taking the supplement showed a 28% increase in lung cancer incidence compared to placebo. The supplement group also had higher cardiovascular mortality. According to Fred Hutchinson Cancer Center, which led the CARET trial, the results demonstrated “no benefit and substantial evidence of a harmful effect.”

This finding underscores a consistent lesson in nutritional oncology: the protective associations seen with food-form nutrients rarely translate to supplements — and sometimes reverse.

Smoking Still Dominates the Risk Equation

This article would be incomplete without a clear statement of proportion.

Smoking causes approximately 80% of lung cancer cases in the United States. A lifelong smoker’s absolute lifetime risk of developing lung cancer is roughly 15–20%. For a never-smoker with a poor diet, the absolute risk remains very low in purely numerical terms, even if that diet is associated with a relative increase.

This matters because the framing of “food causes cancer” can inadvertently lead people to believe that dietary choices are the primary lever or, conversely, that eating well makes smoking acceptable. Neither is true.

Diet is a modifiable risk factor worth optimizing. It interacts with overall health in ways that extend well beyond cancer risk. But the single most powerful thing a smoker can do for their lung cancer risk remains quitting smoking. For never-smokers, maintaining a whole-food diet rich in fruits and vegetables makes sense as part of an overall health strategy, not as a specific cancer-prevention protocol.

For those who have already received a lung cancer diagnosis, dietary optimization may support overall health during treatment, but the primary treatment decisions should be made with an oncology team, not guided by dietary interventions.

Practical Steps to Reduce Dietary Risk

Based on the available evidence, here are practical dietary adjustments that align with a lower-risk profile:

• Reduce ultra-processed food intake. You do not need to eliminate processed food entirely, but shifting away from packaged snacks, fast food, sugary drinks, and highly processed ready-meals reduces exposure to many of the compounds discussed above.

• Eat more fruits and vegetables. Aim for variety and color. Dark leafy greens, carrots, sweet potatoes, citrus fruits, and berries all bring different antioxidant compounds. At least 400 grams (roughly five servings) per day is consistent with the dose-response research.

• Limit processed meats. Bacon, deli meats, hot dogs, and similar products are IARC Group 1 carcinogens for colorectal cancer. While the lung cancer evidence is less definitive, limiting these foods is a reasonable precaution supported by broad cancer-prevention guidelines.

• Choose lower-temperature cooking methods when possible. Boiling, steaming, slow-cooking, and baking at moderate temperatures produce less acrylamide and fewer AGEs than frying or grilling at high heat.

• Focus on whole foods as the default. The Mediterranean dietary pattern — not a rigid prescription, but an orientation toward vegetables, legumes, fish, olive oil, and whole grains — provides a practical template consistent with the evidence.

• Avoid beta-carotene supplements if you are a smoker or former smoker; the CARET trial findings are a firm caution against this.

• If you smoke, quitting is the highest-impact action. Every other dietary change described here operates at the margins relative to tobacco cessation.

• If you are at high risk, talk to your doctor about lung cancer screening. Low-dose CT (LDCT) screening is recommended annually for people aged 50–80 with a significant smoking history. Early detection is associated with dramatically better outcomes. Learn more on our page about lung cancer screening and lung cancer causes.

For anyone facing a lung cancer diagnosis, clinical trials offer access to innovative treatments beyond standard care. Ready to explore your options? Start your search with North’s trial finder.

Frequently Asked Questions

Does eating processed food cause lung cancer?

Current evidence shows an association between high ultra-processed food consumption and increased lung cancer risk, but not proven causation. A large 2025 cohort study found that the heaviest ultra-processed food consumers had a 41% higher relative risk of lung cancer than the lightest consumers. However, observational studies like this cannot fully account for all confounding factors, including lifestyle patterns that travel with dietary choices. Researchers consider the link biologically plausible but not yet definitively causal. Reducing ultra-processed food is sound health advice regardless.

Are processed meats linked to lung cancer?

Processed meats are classified as Group 1 carcinogens by IARC, but the primary cancer evidence is for colorectal cancer. For lung cancer specifically, some studies have observed modest associations with one analysis noting a roughly 16% increased relative risk, but the findings are inconsistent across studies. The biological mechanism (nitrosamines causing DNA damage) is plausible, but processed meat’s link to lung cancer is less firmly established than its link to colon cancer. Limiting processed meats is still advisable as part of overall cancer risk reduction.

What foods might help reduce lung cancer risk?

Epidemiological studies consistently point to diets rich in fruits and vegetables as associated with lower lung cancer risk. Foods high in carotenoids — carrots, leafy greens, sweet potatoes, citrus, and berries — have shown the most consistent inverse associations. The Mediterranean dietary pattern as a whole is associated with an 18% lower lung cancer risk in meta-analyses. Whole grains and legumes also contribute fiber and antioxidants that support anti-inflammatory pathways. Notably, beta-carotene supplements do not replicate these benefits and may be harmful in smokers.

If I don’t smoke, should I be worried about processed food and lung cancer?

For never-smokers, the absolute risk of lung cancer is substantially lower than for smokers, so dietary factors, while relevant, should be kept in proportion. Between 10% and 20% of lung cancers occur in people who have never smoked, with radon, secondhand smoke, and air pollution being the most important known contributors. Diet is one factor among several. Eating a diet low in ultra-processed foods and high in fruits and vegetables is beneficial for overall health well beyond lung cancer, and it is a reasonable step to take, but it does not carry the same magnitude of protective effect as avoiding tobacco or testing your home for radon.

References

1. Lv, Q. et al. (2025). Association between ultra-processed food consumption and lung cancer risk: a population-based cohort study. Thorax. https://doi.org/10.1136/thorax-2024-222100

2. International Agency for Research on Cancer / World Health Organization. (2015). Carcinogenicity of the consumption of red meat and processed meat. https://www.who.int/news-room/questions-and-answers/item/cancer-carcinogenicity-of-the-consumption-of-red-meat-and-processed-meat

3. Farvid, M.S. et al. (2021). Fruit and vegetable consumption and lung cancer incidence: A systematic review and meta-analysis. Annals of Oncology. https://www.annalsofoncology.org/article/S0923-7534(19)35332-3/fulltext

4. Luo, J. et al. (2022). Mediterranean Diet Patterns in Relation to Lung Cancer Risk: A Meta-Analysis. Frontiers in Nutrition, 9, 844382. https://doi.org/10.3389/fnut.2022.844382

5. National Cancer Institute. (2024). Acrylamide and Cancer Risk. https://www.cancer.gov/about-cancer/causes-prevention/risk/diet/acrylamide-fact-sheet

6. Omenn, G.S. et al. (1996). Effects of a combination of beta carotene and vitamin A on lung cancer and cardiovascular disease. New England Journal of Medicine, 334(18), 1150–1155. https://doi.org/10.1056/NEJM199605023341802

7. Peng, J. et al. (2022). Dietary Acrylamide Exposure and Risk of Site-Specific Cancer: A Systematic Review and Dose-Response Meta-Analysis of Epidemiological Studies. Frontiers in Nutrition, 9, 875607. https://doi.org/10.3389/fnut.2022.875607

8. Monteiro, C.A. et al. (2019). Ultra-processed foods: what they are and how to identify them. Public Health Nutrition, 22(5), 936–941. https://doi.org/10.1017/S1368980018003762

9. American Cancer Society. (2024). Study: More Than 12% of People Newly Diagnosed with Lung Cancer Never Smoked Cigarettes. https://www.cancer.org/research/acs-research-news/study-more-than-twelve-percent-of-people-newly-diagnosed-with-lung-cancer-never-smoked.html