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It’s rarely as simple as “food x causes cancer,” but indeed, there is a concretely evidenced list of foods that can increase your risk of developing certain cancers under certain conditions.
In other words, it’s always better to understand why foods are carcinogenic instead of just running in the opposite direction out of fear, because the former strategy will lead to more informed dieting decisions.
Appreciating the “why” requires a basic understanding of the direct and indirect influences of nutritional choices on cancer risk.
How Can Food Cause Cancer?
We’ll expand more on the details below, but to summarize, the most thoroughly verified food-based carcinogens are found in sugary snacks, processed foods, red meat, and even some healthier choices like fruits, vegetables, and nuts.
Cosmetic products and industrial chemicals also contain carcinogens, but our focus is on nutritional sources.
There are various mechanisms by which carcinogenic substances promote tumor formation, and in many cases, researchers don’t know why food x causes cancer y (only that it does).
Generally, the carcinogenic substance somehow interferes with the way that our cells function and replicate themselves, particularly as it relates to processes like apoptosis (normal, pre-programmed cell death).
Whether the carcinogen directly damages/rewrites DNA within the cell or not, the end result is a cascading “system error” in your cells that results in uncontrollable division, tumor formation, and so on.
But the nutrient and/or food item itself isn’t always to blame—cooking methods, pesticides, eating patterns, and other factors can actually determine whether or not a food becomes carcinogenic.
A systematic review by Queen’s University in Kingston, Ontario strongly endorses the idea that pesticides increase incidence of certain cancers.
Of the 83 studies that qualified for review by this analysis, 73 concluded that there was a positive association between certain pesticides and cancer.
Among the most prevalent types of cancers observed in these studies were brain, prostate, and kidney cancers, non-hodgkin’s lymphoma, and leukemia.
Since most of the studies in review measured the effects of several pesticides, the Queen’s University review authors suggested that avoiding pesticides altogether is the best practice until finer distinctions are made.
Regardless of the dietary choices themselves, simply eating too frequently may increase colon cancer risk beyond statistical significance, according to a finding by the University of North Carolina.
In this 1,684-participant study (636 treatment, 1,048 control), colon cancer incidence of medium-frequency eaters was double that of low-frequency eaters, but only among men.
There was no such relationship between meal frequency and colon cancer risk in women.
The researchers theorized that it was the “increased exposure of the colon to bile acids,” compounds released by the gallbladder after meals to aid in digestion (of fats especially), that was responsible for the correlation they found.
If you’ve checked out our post about the impact of cooking on nutritional value, you already know that cooking methods can affect the nutritional density of a huge range of foods.
In addition, cooking certain meats at high temperatures encourages the formation of compounds called heterocyclic amines.
In other words, foods that otherwise don’t possess carcinogenic properties in their raw forms can be turned into cancer-promoting foods when cooked at high temperatures.
Lifestyle and Environmental Influences
Finally, drug use, exercise, sun exposure, stress, and many other factors can influence cancer risk as well.
It’s important not to use increased exercise or decreased sun exposure as an excuse to make poor dietary choices, but making improvements in these areas may be able to lower cancer risk.
The List: Say Goodbye and Don’t Look Back
Sometimes, carcinogens take the form of additives.
In other instances, they are inherent in the food item itself.
As mentioned, the way a food is cooked or processed can render that food carcinogenic.
We’ll cover a bit of everything in this list, but keep these distinctions in mind throughout, as they’ll allow for more informed adjustments to your diet.
This study from the Division of Cancer Epidemiology and Genetics (DCEG) lists a variety of foods, beverages, and additives that are strongly suspected or confirmed to increase cancer risk, including:
Alcohol: Ethanol itself hasn’t been established as a carcinogen, but researchers believe it creates a carcinogenic byproduct.
Salted fish: Commonly produced with the compound N-nitrosodimethylamine, a known carcinogen.
Acetaldehyde: Suspected carcinogen found in vinegar, sour cream, pickled vegetables, soy, white peach, nectarine, soft drinks, ice cream, alcoholic beverages, tea, and more.
Polycyclic Aromatic Hydrocarbons (PAHs): Work their way into meats during the smoking/grilling process. Commonly detected in processed meats (like sausage) and smoked fish.
Urethane: Naturally occurring compound in foods produced via fermentation, including bread, yogurt, beer, etc. Has induced tumors in animal studies (human connection not thoroughly researched).
Aflatoxins: A class of fungal toxins occurring naturally in nuts, seeds, milk, and several other commonly consumed foods.
Mycotoxins: A class of compounds occurring naturally in fungal growths, commonly found in meat, eggs, milk, grains, tree nuts, and other foods.
This is by no means an exhaustive list, as new findings are coming out all the time, but even this sample covers hundreds of foods containing the above compounds.
The Sensible Approach Wins
As important as this knowledge is, avoiding every possibly carcinogenic food is extremely difficult.
Even life-sustaining macronutrients like fat have been linked to increased cancer risk.
Ironically, the stress this would cause you over a lifetime may itself result in health complications.
It’s better to target the most strongly evidenced carcinogens in your diet—e.g., the red flags (pop, smoked meats, processed/sugary snacks, etc.)—supplementing this effort with exercise, sleep, meditation, alcohol moderation, and other health-affirming practices.