What you may have heard

High consumption of salt-preserved and pickled foods can increase your risk of gastric cancer.

What the science tells us

Salt-preserved food includes pickled vegetables, salted fish, and cured meat. Research suggests a correlation between salt-preserved foods and cancer risk, particularly in East Asian countries where consumption tends to be high. Diets high in salt may aggravate the effects of Helicobacter pylori (H. pylori), a key contributor to gastric cancer, and contaminants from pickling or fermentation may also play a role in cancer development.

Epidemiological Evidence

A meta-analysis of observational studies found a 50% increased risk of gastric cancer in those who consume pickled food and vegetables compared to those who do not, with associations potentially stronger in Korea and China (Ren et al.). Additional ecological and experimental study findings suggest that frequent intake of pickled vegetables is associated with a higher risk of esophageal cancer (Zhuang et al.).

Laboratory Evidence/Supporting Evidence

Laboratory studies indicate that eating salt-preserved foods can damage the stomach lining and increase inflammation, which helps promote gastric cancer. In animal models, diets high in salt make infections with cancer-linked bacteria like H. pylori worse, leading to higher rates of stomach tumors (WCRF).

Evidence also suggests that contamination from yeasts and fungi can produce gastric carcinogens, including mycotoxins or N-Nitroso compounds, during fermentation (Ren et al.). More research is needed to fully understand these mechanisms and how they may link pickled food to cancer.

How to reduce your risk

• Limit consumption of salt-preserved foods, including pickled vegetables, salted fish, and cured meats.
• Choose fresh or frozen vegetables whenever possible.
• Eat a diet rich in fruits, vegetables, and whole grains, which may help protect the stomach lining.

Bottom line

High consumption of pickled foods is associated with an increased risk of gastric and esophageal cancers. This risk is supported by both epidemiologic studies and laboratory evidence showing how salt-preserved foods can promote cancer development. However, your overall diet and how often you eat these foods matter. Occasional consumption as part of a varied, balanced diet is unlikely to pose a major risk for most people.

What you may have heard

Bacteria left behind during a root canal procedure can release toxins into the bloodstream and lead to cancer. This idea has gained attention through online forums and alternative health documentaries.

What the science tells us

Root canals are not linked to cancer. This myth originated from a discredited theory over 100 years ago and has been thoroughly debunked by modern research. According to Penn Dental Medicine, root canals are safe, effective procedures that treat infection and preserve natural teeth. Avoiding treatment can lead to serious dental problems, including pain, swelling, tooth decay, damage, and tooth loss.

Epidemiological Evidence

There is no credible scientific evidence supporting any connection between root canals and cancer.

How to reduce your risk

Maintain good oral hygiene and visit a dentist regularly. Prompt treatment of dental infections, including root canals when needed, protects your overall health.

Bottom line

Root canals do not cause cancer. They are a routine, safe procedure used to treat infection and preserve natural teeth.

What you may have heard

Peanut butter consumption can increase your risk of cancer due to potential aflatoxin contamination.

What the science tells us

Aflatoxins are a family of carcinogenic compounds produced by mold and can be found on various crops, including peanuts, tree nuts, and corn. If contaminated peanuts are used in production, aflatoxins may be present in peanut butter products.

In many countries, food safety systems include regular monitoring and strict limits on aflatoxin levels in consumer products like peanut butter. In the United States, the FDA routinely tests peanut butter to ensure aflatoxin levels stay within safe thresholds. Because of these protections, the risk of significant aflatoxin exposure is low, and there is no evidence of increased cancer risk from peanut butter consumption.

However, aflatoxins are more common in regions with warm, humid climates and limited food safety infrastructure, such as sub-Saharan Africa, Southeast Asia, and parts of China. In these areas, peanut butter may pose a higher risk of aflatoxin exposure, so it is important for consumers to be aware of possible health risks.

Epidemiological Evidence

In countries with established food safety systems, such as the U.S., the U.K., Canada, Japan, and countries in the European Union, studies consistently show no link between peanut butter consumption and cancer. For instance, the Netherlands Cohort Study followed over 120,000 adults aged 55 to 69 for approximately 20 years and found no association between peanut butter consumption and cancer risk (Nieuwenhuis & van den Brandt). The cohort study also reported no relationship between peanut butter and overall mortality (van den Brandt & Schouten).

A three-year analysis in Zambia, sub-Saharan Africa, however, found high levels of aflatoxins in peanut butter products from the region (Njoroge et al.). This raises concern, as chronic exposure to aflatoxins has been linked to an increased risk of liver cancer (NCI). More research and regular monitoring are needed to better understand the extent of aflatoxin contamination in these regions and how it may specifically impact cancer risk from peanut butter products.

How to reduce your risk

• Purchase peanut butter from reputable brands that follow national or international safety standards.
• Store peanut products in cool, dry places to prevent mold growth.
• If you are in a region where aflatoxins are more common (sub-Saharan Africa, Southeast Asia, parts of China), look for peanut butter products that are tested, certified, or imported from countries with reliable food safety systems.

Bottom line

There is no consistent evidence that peanut butter causes cancer when it is produced under strong food safety regulations. If you live in a region of the world where food regulation is limited, choosing peanut products that are certified or tested can help reduce your risk. Peanut butter remains a nutritious food in most contexts, and for many people, its benefits outweigh potential concerns.

What you may have heard

Adhering to a vegetarian diet can reduce your risk of developing cancer.

What the science tells us

Plant-based foods are rich in vitamins, minerals, and antioxidants that support overall health. They contain phytochemicals, naturally occurring compounds found in fruits, vegetables, beans, nuts, grains, and seeds, that may help decrease cancer risk by supporting immune function and slowing the growth of cancer cells. The high fiber content and low caloric density in plant-based diets aid in healthy weight management, a known protective factor against cancer. However, the benefits of vegetarian diets depend on the type and quality of food included.

Epidemiological Evidence:

Several observational studies suggest that plant-based diets are associated with a 10-14% lower risk of developing cancer (Lanou & Svenson). Data from Oxford Population Health shows a 14% decreased risk among vegetarians and 10% among pescatarians compared to meat eaters.

Emerging evidence from large cohort studies indicates that vegetarian diets may reduce the risk of postmenopausal breast, colorectal, and prostate cancers (Watling et al.). However, the strength of these associations varies across studies, and more research is needed to determine whether plant-based diets directly reduce the risk of these specific cancers.

Laboratory Evidence/Supporting Evidence:

Laboratory studies confirm that components of plant-based diets, such as phytochemicals and dietary fiber, can inhibit tumor growth and slow cancer progression in animal models, aiding in both cancer prevention and treatment (Rudzińska et al).

How to reduce your risk

• Reduce or eliminate red and processed meat intake.
• Add color to your diet, incorporating a variety of fruits and vegetables.
• Increase fiber intake with whole grains, beans, vegetables, and fruits.
• Ensure adequate protein intake through plant-based sources like beans, lentils, tofu, nuts, and seeds.
• Limit processed foods, choosing whole foods whenever possible.

Bottom line

Vegetarian diets may help protect against cancer. However, not all plant-based diets are equally beneficial; for instance, diets high in refined grains, added sugars, or processed foods will not provide the same advantages as those that emphasize whole, minimally processed foods. Following the general principles outlined above can help maximize the potential protective effects of a vegetarian diet and reduce overall cancer risk. Additional research is needed to understand how plant-based diets influence the risk of specific cancer types.

For more information on plant-based diets and cancer risk, watch this video from the Dana-Farber Cancer Insitute and follow the links below.

What you may have heard

Frequent yogurt consumption may decrease your risk of colorectal cancer.

What the science tells us

Yogurt contains beneficial bacteria that support a healthy gut microbiome, which, according to the National Cancer Institute (NCI), may help slow cancer development and improve response to cancer therapies. Recent studies suggest that long-term yogurt consumption may enhance gut health and lower colorectal cancer risk.

Epidemiological Evidence

Researchers from Mass General Brigham analyzed data from over 150,000 individuals followed for decades and found that those who ate yogurt at least twice a week had a lower risk of developing certain types of colorectal cancer (Ugai et al.). The protective effect was strongest in proximal (right-sided) colorectal cancers where Bifidobacterium, a beneficial bacterium commonly found in yogurt, was present. These findings suggest that Bifidobacterium may help suppress tumor growth, explaining some of the observed benefits of regular yogurt intake.

Similar findings linking frequent yogurt consumption to lower colorectal cancer risk were observed by the European Prospective Investigation into Cancer and Nutrition and in a meta-analysis of observational studies conducted by Sun et al. While these results are encouraging, researchers recommend additional cohort studies to further clarify this relationship.

Laboratory Evidence/Supporting Evidence

Although the exact mechanisms are still being studied, yogurt’s potential protective effects are thought to stem from probiotics and their influence on the gut microbiome. Bifidobacterium and other probiotics help maintain a balanced gut by strengthening the intestinal lining and reducing inflammation, which are key factors in lowering colorectal cancer risk.

Additionally, probiotics produce short-chain fatty acids such as butyrate, which have been shown to inhibit tumor growth. They also work to stimulate the immune system, helping it detect and destroy abnormal cells before they develop into cancer.

How to reduce your risk

While no single food prevents cancer, certain lifestyle choices can help support gut health and lower your risk of colorectal cancer:

• Consider including yogurt with live and active cultures in your diet. Choose plain or low-sugar varieties for maximum benefit.
• Eat more fiber-rich foods. Fruits, vegetables, whole grains, legumes, and nuts promote gut health and help regulate digestion.

Bottom line

Frequent yogurt consumption may contribute to a lower risk of colorectal cancer by supporting a healthy gut microbiome. While research is still ongoing, including probiotic-rich foods like yogurt as part of a balanced, high-fiber diet may offer protective benefits. No single food prevents cancer, but healthy eating patterns combined with regular physical activity and screening can lower your risk.

What you may have heard

Eating garlic can lower your risk of developing gastrointestinal cancers.

What the science tells us

Garlic contains naturally occurring allium compounds that may slow cancer development by supporting healthy cell function and affecting processes involved in tumor growth. Laboratory research suggests that garlic may reduce the risk of certain gastrointestinal cancers. However, current evidence in humans is limited and inconclusive.

Epidemiological Evidence

Human studies provide little evidence of garlic’s anticancer properties. Although some case-control studies suggest a protective association with colorectal and gastric cancers (Zhou et al.), this study design is not the most reliable for evaluating dietary exposures. Many of these studies also contain small sample sizes, which further limits their strength.

A 2021 systematic review found no association between garlic intake and cancer risk in larger cohort studies (Lee et al.). Additional cohort studies and clinical trials are needed to clarify garlic’s potential cancer-preventive role in humans.

Laboratory Evidence/Supporting Evidence

Allicin, an allium compound in garlic, is produced when garlic is crushed or damaged. Allicin forms several other compounds, which animal studies suggest may reduce the risk of various cancers by activating tumor-suppressing genes. According to the American Institute for Cancer Research (AICR), these compounds may reduce inflammation, support DNA repair, and promote the self-destruction of cancer cells.

How to reduce your risk

No single food can prevent cancer. To best decrease your risk, maintain a healthy lifestyle through eating well, exercising regularly, and avoiding alcohol and smoking.

Bottom line

While animal studies suggest garlic may offer some protection against cancers of the gastrointestinal tract, there is currently no strong evidence from human studies to confirm this. More high-quality, epidemiological research is needed to understand garlic’s role in cancer prevention.

What you may have heard

Frequent egg consumption can increase your risk of cancer.

What the science tells us

Eggs support overall health and are a key source of protein, fat, vitamins, and minerals. They also contain high levels of cholesterol and their relationship with heart health remains debated. Concerns about cancer risk stem from both cholesterol and choline found in egg yolks. However, whether eggs are linked to cancer risk is unclear and evidence is limited.

Epidemiological Evidence

Some studies suggest possible associations between egg consumption and hormone-related cancers, including prostate, breast, and ovarian cancers:

• A meta-analysis of observational studies found that high egg intake was associated with an increased risk of ovarian cancer (Zeng et al.), though statistical significance varied by study design and was primarily seen in case-control studies. Case-control studies are more prone to recall bias and are generally considered less reliable than cohort studies for evaluating nutritional exposures.
• A cohort study found that high egg consumption was associated with an increased risk of developing lethal prostate cancer among healthy men (Richman et al.).
• Another meta-analysis linked egg intake with a slightly increased risk of breast cancer, particularly in European, Japanese, and postmenopausal populations (Si et al.).

In each of these cases, researchers called for additional prospective cohort studies, emphasizing the need for further long-term research to clarify these relationships.

How to reduce your risk

Although eggs are not clearly linked to cancer, dietary guidelines often suggest limiting consumption due to concerns about cholesterol and cardiovascular health.

• Moderate egg intake: most healthy adults can eat up to seven eggs per week. Individuals with high cholesterol or other cardiovascular issues should consult with a healthcare professional for diet recommendations.
• Choose healthier cooking methods (e.g., boiled or poached eggs instead of fried).
• Prioritize a balanced diet with diverse protein sources.

Bottom line

While some findings suggest potential links between eggs and cancer, current evidence is limited, and further longitudinal research is needed. For most people, eggs can be part of a healthy diet when eaten in moderation.

What you may have heard

People who have or have had Epstein-Barr virus are at an increased risk of developing certain cancers.

What the science tells us

Epstein-Barr virus (EBV) is the infection that causes mononucleosis. According to the CDC, 9 out of 10 adults have antibodies showing that they have or have had EBV at some point in their lives. EBV is an oncovirus, which is a virus that can cause cancer (ACS). While most people with EBV will not develop cancer, it is important to understand the potential risk.

Epidemiological Evidence

EBV is most often linked to nasopharyngeal cancer, which impacts the upper part of the throat. Other cancers associated with EBV are Burkitt lymphoma, immunoblastic lymphoma, and gastric cancer (NCI). EBV-related cancers are most prevalent in Africa and certain regions of Southeast Asia.

Laboratory Evidence/Supporting Evidence

EBV is a life-long infection that can be asymptomatic. EBV contributes to cancer development by infecting key cells in the body, specifically B cells and epithelial cells. Inside these cells, the virus creates proteins that alter their normal functions, promoting rapid cell growth, preventing cell death, and helping infected cells evade the immune system.

How to reduce your risk

Currently, there is no vaccine for EBV. To lower your chances of infection, avoid close contact with people who have active EBV, including kissing, sharing food or drinks, and sharing personal items like toothbrushes.

If you have already been infected with EBV, watch for early signs of nasopharyngeal cancer, such as a lump in the neck, persistent nasal congestion, nosebleeds, or hearing loss, and seek medical advice if these occur (ACS).

Bottom line

EBV is a virus that can cause cancer. Although most people become infected with EBV during their lifetime, only a small number develop cancer, often due to additional factors like genetics or a weakened immune system.

Watch the video below to learn more about the EBV from Cancer Research UK.

What you may have heard

Frequent consumption of hot lemon water is rumored to prevent or cure cancer.

What the science tells us

There is no scientific evidence that lemon water has anti-cancer properties. Lemons contain Vitamin C and other antioxidants, which are good for overall health, but no studies show that drinking lemon water, whether hot or cold, has any special effect on cancer risk or outcomes.

Laboratory Evidence/Supporting Evidence

Claims related to lemon water and cancer prevention may stem from limonene. Limonene is a natural compound found in the peels of citrus fruits that, according to animal studies, may slow cancer growth (MSKCC). However, there is no evidence that these effects occur in humans or result from drinking lemon water.

How to reduce your risk

No single food or beverage can prevent or cure cancer. A healthy lifestyle, such as maintaining a balanced diet, exercising regularly, and following recommended cancer screenings, is the best way to lower your risk. It is crucial to follow medical advice from your doctor when considering treatment options.

Bottom line

While lemon water is fine to drink, there is no evidence that it can prevent or cure cancer.

To read more about healthy hydration, check out The Nutrition Source, an initiative of the Harvard School of Public Health Department of Nutrition.

What you may have heard

Some claim that kombucha, a fermented tea drink, can prevent or even cure cancer due to its potentially detoxifying and immune-boosting effects.

What the science tells us

Kombucha is made by adding a Symbiotic Culture of Bacteria and Yeast (SCOBY) to fermented sweetened tea. While kombucha contains probiotics and antioxidants that may support overall health, research on its effects is extremely limited. Kombucha has not been proven to prevent or treat cancer in humans.

Epidemiological Evidence

There is no epidemiological evidence to support this claim.

Laboratory Evidence/Supporting Evidence

Kombucha has demonstrated antioxidant, antimicrobial, and anti-inflammatory effects in preclinical animal and in vitro (cell) studies (Abaci et al.), but these findings have not been replicated in humans.

How to reduce your risk

Kombucha can pose safety risks depending on how and where it is made.

• Lead poisoning has been reported when kombucha is brewed in ceramic pots, and harmful bacteria can grow if it is made in unsanitary conditions (Mayo Clinic). Purchase kombucha from reputable sources.
• If you are pregnant, breastfeeding, or have a weakened immune system, it is best to avoid kombucha due to the potential presence of bacteria and yeast.

Bottom line

Evidence to support the claim that kombucha can prevent or treat cancer is lacking. While kombucha has shown some health benefits in animal and in vitro studies, it is unclear whether these findings translate to humans. More research is needed.