Worst Cancer-Causing Foods

Over the last several decades, certain foods have been vilified as being potentially carcinogenic, or capable of causing cancer. So which ones are the biggest culprits? And how can you eat to prevent cancer or reduce the chances of a recurrence if you’ve been diagnosed?

The list of potentially cancer-causing foods includes:

— Red and processed meat.

— Sugar.

— Alcohol.

— Processed and packaged foods.

Red and Processed Meat

For the carnivores among us, it’s probably tough to hear the news that red meat and processed meat are associated with a higher risk of certain types of cancer. “Red meat is defined as beef, veal, pork, lamb and goat,” says Cathy Leman, a dietitian, personal trainer, nutrition therapist, speaker, writer and breast cancer survivor based in Chicago.

“Processed meat refers to meat that has been salted, cured, fermented, smoked or other processes that enhance flavor or improve preservation,” she adds. Examples include hot dogs, luncheon meats, ham and bacon.

Jeannette Schenk, senior staff scientist in the cancer prevention program at Fred Hutchinson Cancer Research Center in Seattle, says “there have been many epidemiological studies that have reported an association with high intakes of processed meat and red meat with an increase in cancer incidence and mortality.”

According to the American Institute for Cancer Research, a high intake of red meat is defined as more than three servings per week. A single serving of red meat is about 3 to 4 ounces — or one small hamburger, steak or a medium-sized pork chop. Your total weekly consumption, the AICR reports, should be under 350 to 500 grams (about 12 to 18 ounces cooked) each week.

The cancer risk associated with processed meat products is even higher. The International Agency for Research on Cancer, a branch of the World Health Organization, classifies processed meat as a Group 1 carcinogen, meaning that like other Group 1 carcinogens — tobacco, UV radiation and alcohol — research has proven that processed meat can cause cancer in humans. Eating just 50 grams of processed meat each day, the IARC reports, can elevate cancer risk by 18%. Four strips of bacon or one hot dog contains about 50 grams of processed meat.

Kailey Proctor, an oncology dietitian with the Center for Cancer Prevention and Treatment at St. Joseph Hospital in Orange, California, emphasizes, though, that the observed connection between meat and cancer “is an association, not a causation,” meaning that we don’t know for sure whether consumption of red meat is causing the cancer directly. Nevertheless, she notes that processed meat products “are processed foods” that should be consumed in moderation, aiming for one serving per week or less.

Why these meats appear to elevate cancer risk, particularly colorectal cancer, is believed to be because red meats and processed meats contain mutagens and carcinogens. Mutagens change genetic information by altering DNA, and carcinogens are cancer-causing agents.

When meat is cooked at high temperatures or grilled, amino acids in the meat interact with the heat to form carcinogenic compounds called heterocyclic amines and polycyclic aromatic hydrocarbons. “Those have been linked with cancer risk,” Schenk says.

With processed meats, the cancer risk appears to be related to the way the meat is preserved and cooked. Specifically, the addition of preservatives called nitrates and nitrites may elevate cancer risk. Similarly, smoking meats can also create carcinogenic compounds, Schenk says.

[See: The Best Plant-Based Diets.]

Sugar

Sugar is also implicated in the development and progression of certain kinds of cancer. In the early 20th century, a German biochemist named Otto Warburg observed that cancer cells often rely on sugar to fuel their prolific growth. Called the Warburg effect, this process suggests that starving the body of sugar and carbohydrates that can be converted to sugar could theoretically starve cancer cells.

As a result, the ketogenic diet, which reduces carbohydrate intake to 10% or less of calories consumed and increases fat consumption to 70% or more, has been suggested as a way to slow the spread of cancer.

The effectiveness of the keto diet to prevent or slow cancer hasn’t been fully proven, but an association between sugar and cancer has been established. For this reason, “any food which has a very high glycemic index” can increase your risk of cancer and should be consumed in moderation, says Dr. Adil Akhtar, associate professor in the department of medical oncology and hematology at Oakland University-William Beaumont School of Medicine and director of Inpatient Clinical Operations at Karmanos-McLaren Oakland Cancer Center in Michigan.

A food’s glycemic index is “defined by the rate at which a food when it’s digested will raise the level of sugar in the blood,” Akhtar explains. Sugary foods, such as soda and candy, have a high glycemic index.

Some experts say that if you’re concerned about cancer, you should eliminate all refined sugar from your diet because many types of cancer cells use sugar as their primary fuel. In fact, some diagnostic tests for cancer use radioactive glucose to pinpoint tumors on PET scans because most cancer cells have such an affinity for sugar that they suck up glucose molecules faster than noncancerous cells can, thus showing themselves on the scan.

[READ: Life Without Sugar: One Woman’s Success Story.]

Alcohol

Alcohol is actually a type of sugar, so it’s also on the list of foods that can increase your risk of cancer. “Alcohol is an established risk factor for mouth, pharynx, esophageal, liver, colorectal, breast and pancreatic cancer,” Schenk says.

Exactly how alcohol increases risk is not clearly understood, but “it’s possibly related to DNA damage” incurred by the cells after exposure to alcohol, Schenk says.

“In addition, it could be an indirect contributor because calories from alcohol contribute to weight gain.” Alcoholic beverages contribute a lot of excess calories that offer no nutritional benefits, so “it’s one of those added foods that we need to be limiting,” she says.

The federal government’s Dietary Guidelines for Americans 2020-2025 states that if you don’t drink, don’t start. It also recommends that moderating intake is an important way to curb cancer risk in people who do choose to consume alcoholic beverages.

Moderate alcoholic drinking is defined as one drink per day for women and up to two drinks per day for men. A drink is defined as 12 ounces of beer, 8 to 9 ounces of malt liquor, 5 ounces of wine and 1.5 ounces of 80-proof distilled spirits.

In her opinion, Leman says that “for cancer prevention, it’s best not to drink alcohol.”

[READ: Diet and Prostate Cancer Risk.]

Processed and Packaged Foods

Akhtar says certain processed foods can also raise your risk of developing cancer. “Things like microwaved popcorn have compounds that are linked with cancer.” The environmental organization Environmental Working Group raised the alarm about a chemical called PFOA that was used to coat the inside of popcorn bags as a likely carcinogen, prompting the FDA to ban its use in food packaging in 2006.

However, a subsequent EWG investigation suggested that the replacement chemicals (needed to prevent oils in the bag from soaking through the paper) are also potentially carcinogenic and likely contain perfluorinated chemicals. The Agency for Toxic Substances and Disease Registry, a division of the Centers for Disease Control and Prevention, reports that these chemicals, known as PFCs, may increase the risk of cancer.

Other ultra-processed foods, such as packaged baked goods and snacks, fizzy drinks, sugary cereals, ready meals and reconstituted meat products, have also been linked with an increased risk of certain types of cancer, according to a 2018 study in the British Medical Journal.

The study, which included 104,980 healthy French adults, found that a 10% increase in the proportion of ultra-processed foods in the diet was associated with increases of 12% in the risk of overall cancer and 11% in the risk of breast cancer. No significant association was found for prostate and colorectal cancers.

Ultra-processed food products also tend to be higher in calories, salt, sugar and saturated fats, all of which may contribute to obesity, which is a known risk factor for cancer.

Even seemingly healthy foods, such as farmed salmon, may contain chemicals that might increase cancer risk. The Environmental Protection Agency has classified polychlorinated biphenyls or PCBs as probably carcinogenic in humans. This class of chemicals were manufactured from 1929 until they were banned in 1979, but they linger still in the environment. Whether the levels of these chemicals, which enter the food chain from industrial and hazardous waste sites and become concentrated in the feed given to farmed fish, are high enough to cause cancer is still being debated.

If you’re concerned about this risk, Harvard Health suggests removing the skin of the salmon and the fat directly underneath it before cooking, as that’s where the chemicals are most concentrated. Allowing the fat to drain off by grilling, baking or broiling can also reduce risk. Studies have also suggested that lower levels of these chemicals have been identified in fish farmed in Chile and Washington State, so check where your fish is coming from.

How Should I Eat to Avoid Cancer?

While some foods have been associated with an increased risk of certain kinds of cancer, other foods are believed to help reduce your risk. This is where Yael Vodovotz, director of the center for advanced functional foods and entrepreneurship at the Ohio State University in Columbus, is focusing her research efforts.

“Our lab is focusing on foods for prevention,” she says, and they’re investigating the bioactive compounds in food that “potentially can work together for cancer prevention.” (Bioactive means the compound has an effect on cells or a living organism and is used to describe vitamins, minerals, enzymes and other components of food.) In addition, they’re looking to formulate foods or food combinations that can offer a bioactive effect.

In that work, berries have been one brightly colored bright spot in terms of the benefits they can provide. “We’ve studied black raspberries, strawberries and blueberries. A lot of berries have combinations of bioactive properties.”

Soy is another food they’re studying, and while there has been some concern that soy might elevate risk of breast cancer in some people, some studies have shown it could be protective against other kinds of cancer. Look for soy to remain part of the food-and-cancer conversation for some time to come.

Vodovotz also says that green tea, tomatoes, grapefruit and cruciferous vegetables such as broccoli have bioactive compounds that are under investigation for their cancer-fighting properties too.

“The idea is to incorporate the whole foods,” she says, instead of extracting a single compound. And finding the optimal combination of foods that give the full balance of cancer-fighting phytochemicals and nutrients is still a work in progress.

Vodovotz also notes that eating too much of any food can have negative consequences. “Foods are all made of chemicals, and if you take in way, way, way too much for a prolonged time, it’s going to be a problem.”

Eat a Balanced Diet

While her work continues determining which compounds can help and which may hurt in the quest to remain cancer-free, Vodovotz says, you can get a jump start by eating a balanced diet. “I’m very big on the USDA’s (U.S. Department of Agriculture) MyPlate plan,” which advocates incorporating lots of fruits and vegetables, whole grains, fiber and lean and plant-based proteins. “I do believe there’s an intimate link between cancer prevention and diet.”

Akhtar agrees, adding that there’s not one specific diet that will solve the cancer question, but he likes the Mediterranean diet for its balance of nutrients, low levels of sugar and focus on whole foods.

“Eat a balanced diet that is rich in fruits and vegetables” and limits carbohydrates and sugars, he says. “Eat smaller portions of lean meat and healthy fats included in fish, nuts and olives. If you look at the list of different diets, all the healthy diets will have these basic components with a little bit of modifications.”

The American Institute for Cancer Research recommends a mostly plant-based diet for cancer prevention, Proctor says. “Their ‘New American Plate’ model suggests having two-thirds of your plate plant-based foods, such as fruits, vegetables, whole grains, beans and legumes. The remaining one-third of the plate should be a lean source of protein, such as chicken, turkey and seafood.”

To help curb cancer risk, seek to eat a whole, balanced diet that includes:

— Vegetables and fruits.

— Anti-inflammatory spices.

— Plant-based proteins.

— Fiber.

Vegetables and Fruits

These fresh, whole foods contain antioxidants and a host of other helpful nutrients that keep the body working the way it’s supposed to. In addition to the vitamins, minerals, fiber and “other bioactive components that may directly impact cancer risk,” vegetables and fruits may also “potentially have an indirect impact” on cancer risk, Schenk says. Plus, the more veggies and fruits you eat, the less you tend to weigh, which can also impact your risk of developing cancer given the connection between obesity and cancer.

Adding more plants to the diet is believed to confer some protective benefits against cancer, but it’s also important to note that cancer is about more than just diet. Your genetic make-up, environmental exposures, lifestyle and other risk factors can greatly influence your chances of developing the disease. “It’s important to stress that we don’t yet have 100% cancer prevention through diet,” Leman says. “But we do have strong evidence to use in developing dietary guidelines for reducing risk.”

Leman recommends eating at least five servings (2.5 to 3 cups total) of non-starchy vegetables and fruit daily.

Anti-Inflammatory Spices

Adding turmeric — a bright orange spice found in many Indian dishes — to your diet may help reduce inflammation in the body. Cinnamon and ginger have also been shown to offer anti-inflammatory properties. Inflammation is a hallmark feature of cancer and other chronic diseases such as diabetes and Alzheimer’s disease, and many doctors and researchers believe that decreasing inflammation can reduce the risk of cancer.

Plant-Based Proteins

Instead of relying heavily on animal products for protein intake, look to plants for protein. Legumes and beans are excellent sources of protein that also contain lots of fiber.

“While it’s not necessary to eat a vegetarian or vegan diet, it’s wise to limit intake of red meat to 18 ounces per week, and enjoy processed meats like ham, bacon and sausage on occasion,” Leman says.

Fiber

Increasing your intake of fiber might also help reduce your risk of cancer, specifically colorectal and gastric cancers, Proctor says. “Fiber also gives us a sense of fullness so we’re less likely to snack between meals, which helps maintain a healthy body weight.”

Leman recommends striving to consume at least 30 grams of fiber daily.

Maintaining a healthy body weight is an important part of controlling cancer risk. “We do know maintaining a healthy body weight is one of the best ways to reduce your risk for cancer. A healthy body weight is considered to be a BMI between 18.5 and 24.9 kg/m2.” BMI, or body mass index, is a metabolic assessment based on height and weight.

You can calculate your own BMI using the National Heart, Lung and Blood Institute’s online BMI calculator. Aim to stay in the healthy BMI range between 18.5 and 24.9 — being underweight can pose health risks, Proctor says.

Seek Individualized Advice and Support

For people who’ve been recently diagnosed with cancer or who are in survivorship, Leman urges you to seek out individualized nutritional guidance to support treatment outcomes and help manage side-effects of cancer treatments.

“While undergoing active treatment, people often have special nutritional requirements,” she says. “Working with an oncology dietitian for individualized nutritional care and guidance can help patients manage side-effects like nausea, loss of appetite, fatigue and changes in bowel habits.”

And while there’s no one “best diet” for cancer, think about everything you eat in context. Emphasize whole foods, and reduce intake of processed foods and sugars. “We have to consider the diet as a whole. We’re shifting at looking more at dietary patterns versus individual foods with respect to impact on cancer risk and cancer prevention,” Schenk says.

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Worst Cancer-Causing Foods originally appeared on usnews.com

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