What you may have heard

Given that cancer cells grow well in an acidic environment, many people have questioned whether a diet high in acidic foods can increase your risk of cancer.

What the science tells us

In chemistry, the pH scale is a measure for how acidic or basic a solution is. The pH scale ranges from 0-14: 7 is neutral, less than 7 is acidic and greater than 7 is basic.

Epidemiological Evidence

There are no human epidemiological studies that have studied the relationship between pH and cancer. 

Laboratory Evidence/Supporting Evidence

There is no laboratory evidence that acidic pH increases risk for cancer. While it is true that cancer cells grow well in an acidic environment, your body’s pH levels are not determined by the food you eat (MD Anderson). Factors that determine your body’s pH include fluid loss, electrolyte levels, and organ function.

Not Classified.

How to reduce your risk

Research shows that there is not one diet or one food that can prevent cancer. However, a balanced diet and getting enough physical activity can prevent excess weight gain, which is associated with cancer risk. To prevent weight gain, 150-300 minutes of moderate-intensity activity per week is recommended  (Mayo Clinic). A healthy diet includes low-calorie and nutrient-dense foods (such as fruits, vegetables, and whole grains), avoids saturated fat, and limits sweets and alcohol. Identifying situations that trigger overeating and having tools to address these situations can also help in preventing weight gain. Finally, consistency in diet and exercise and monitoring your weight regularly can help keep off excess pounds.

Bottom line

Your blood pH is not affected by your diet, and there is no one diet to prevent cancer. Instead, focus on eating a balanced diet and exercising regularly.

What you may have heard

Curcumin has been touted as having antioxidant, antiviral, antibacterial, and anti-inflammatory properties. One of curcumin’s newer areas being studied are its possible anti-cancer properties.

What science tells us

Curcumin (the part of turmeric that gives it its vibrant color) has gained attention in the media as a potential anti-cancer therapy.

Epidemiological Evidence

Studies of curcumin in humans are still in the early stages so more research is needed before we can say anything about a relationship between curcumin and cancer.

Laboratory Evidence/Supporting Evidence

Curcumin specifically targets cell signaling pathways that are involved in cancer development and growth, which could decrease cancer risk (Giordano et al.). Studies done in laboratory animals suggest that curcumin may prevent cancer, slow the spread of cancer, make chemotherapy more effective, and protect healthy cells from damage by radiation therapy.

IARC Carcinogen Classification:

Not classified.

How to reduce your risk

It is not known whether consuming products that contain curcumin, such as turmeric, decrease your chance of getting cancer.  Eating a healthy, balanced diet and maintaining an appropriate level of physical activity is a good way to lower cancer risk.

Bottom line

Curcumin and turmeric have many important biological functions, and laboratory studies suggest that they may help to prevent cancer in laboratory animals. Studies of curcumin in humans are still in the early stages, so more research is needed before we can say anything about a relationship between curcumin and cancer.

What you may have heard

Coffee consumption can increase your risk of cancer.

What science tells us

Epidemiological Evidence

Coffee drinking is not a cause of breast, pancreatic, or prostate cancer and may even reduce the risk of endometrial, head and neck, colorectal, and liver cancers (ACS) . There is also evidence that drinking coffee is linked to lower risk of insulin resistance and type 2 diabetes (ACS). Several epidemiological studies have shown that coffee consumption does not increase cancer risk (Zhao).

Laboratory Evidence/Supporting Evidence

Much of the concern about coffee consumption and cancer comes from the fact that coffee can contain a chemical called acrylamide, which is formed during the roasting process. Acrylamide has been shown to cause cancer in animals exposed to very high doses (ACS). These studies have concluded that coffee consumption does not cause cancer in mice (IARC).

IARC Carcinogen Classification:

Group 3 (Not classifiable as to its carcinogenicity to humans)

How to reduce your risk

There appear to be health benefits to drinking coffee. If you are worried about acrylamide exposure, you could reduce and limit the amount of food you eat that is cooked at high temperatures (during frying, roasting, and baking) for longer periods of time (ACS).

Bottom line

Coffee drinking is linked with a lower risk of endometrial, head and neck, colorectal, and liver cancers. Coffee drinking may also reduce the risk of insulin resistance and type 2 diabetes.

What you may have heard

Ketchup contains high-fructose corn syrup and MSG for flavoring and sweetness.  You may have heard these ingredients cause cancer.

What the science tells us

Numerous studies have shown that high-fructose corn syrup is harmful to your health, increasing your risk of weight gain, type 2 diabetes, metabolic syndrome, and high triglyceride levels.

Epidemiological Evidence

Excessive consumption of high-fructose corn syrup is also linked to obesity and an increased risk of colon cancer (Goncalves et al.).

While MSG has not been shown to increase the risk of cancer, studies have linked MSG consumption to obesity, central nervous system disorders, liver damage, and reproductive malfunctions (Niaz et al.).

Laboratory Evidence/Supporting Evidence

One study conducted on mice studied the effects of high-fructose corn syrup consumption. Researchers found that there was excess weight gain and the presence of tumors, indicating that fructose might affect tumor growth (NCI).

IARC Carcinogen Classification:

Not classified.

How to reduce your risk

Avoid products, including ketchup, that contain high-fructose corn syrup and MSG. Eat ketchup in moderation to reduce your health risks.

Bottom line

Eating ketchup itself does not appear to cause cancer. However, high consumption of high-fructose corn syrup, a key component in ketchup, is linked to obesity and an increased risk of colon cancer. While there are no direct links between cancer risk and MSG, there are other harmful health effects that should be considered when eating ketchup.

What you may have heard

A story from 2013 of a 10-year-old girl with extreme stomach distress became front-page news after her physician attributed her sickness to eating spicy chips. The physician said that the harsh chemicals in these chips cause corrosion in the throat and stomach, causing stomach ulcers and potentially throat cancer.

What science tells us

According to the Environmental Working Group (EWG), the 3 ingredients of biggest concern in spicy chips are red 40 lake, blue 1 lake, and yellow 6 lake. 

Epidemiological Evidence

Studies have shown that Yellow 6, Red 40, and Blue 1 have no carcinogenic effects in humans, and the FDA has substantiated this claim (FDA).  There have not been studies that evaluate consumption of spicy chips and cancer risk.

Laboratory Evidence/ Supportive Evidence

There is limited laboratory evidence that shows a relationship between spicy chips and cancer. 

IARC Carcinogen Classification:

Not classified.

How to reduce your risk

Artificial colors are used to increase the appeal of foods that have little nutritional value, so one easy way to identify if a food product is lacking in nutrients is to look for food coloring.

There is currently no evidence that spicy chips are linked to corrosion in the throat and stomach, and by extension, there is no evidence that ingredients in these chips are linked to cancer. However, these chips are high in saturated fats (which can raise the level of cholesterol in the blood) and LDL cholesterol (which increases your risk of heart disease and stroke) (AHA). Eating a high amount of foods low in nutrients and high in fat can also lead to obesity and extra weight, which can also raise the risk of heart disease, stroke, diabetes, and some cancers.

Bottom line

It is not likely that consumption of spicy chips increases cancer risk. However, these chips are high in saturated fats and should be eaten in moderation to avoid risk of heart disease, stroke, and other diseases.

What you may have heard

You may have heard that acrylamide (an ingredient in some foods) increases cancer risk.

What science tells us

Acrylamide is a chemical that is used in industrial processes, such as the production of paper, dyes, and plastics, and consumer products, such as food packaging and adhesives. Acrylamide is also found in foods such as french fries, potato chips, crackers, bread, cookies, and black olives. A major acrylamide exposure source is tobacco smoke. People who smoke have 3-5 times the levels of acrylamide exposure in their blood than non-smokers (NCI).

The International Agency for Research on Cancer (IARC) classifies acrylamide as a probable human carcinogen and the US Environmental Protection Agency (EPA) classifies acrylamide as likely to be carcinogenic to humans (NCI).

Epidemiological Evidence

The claim that acrylamide is likely to be carcinogenic to humans is largely based on animal studies and more research is needed to say conclusively that acrylamide is linked to increased risk of cancer in humans.

Laboratory Evidence/Supporting Evidence

High levels of exposure to acrylamide can interfere with DNA repair. The binding of sulfhydryl groups can inactivate proteins involved in DNA repair, which can cause mutations to occur. Laboratory evidence for acrylamide as a cancer-causing agent needs to be further evaluated (Exon). Some animal studies have shown that exposure to high levels of acrylamide can cause cancer (FDA).

IARC Carcinogen Classification:

Group 2A (Probably carcinogenic to humans)

How to reduce your risk

For the vast majority of people, the major source of acrylamide they will encounter is from cigarette smoke. Avoiding cigarette smoke can lower your exposure to acrylamide and other harmful chemicals (NCI). In food, acrylamide level varies dramatically depending on cooking time, manufacturer, method, and temperature of the cooking process. Decreasing cooking time, avoiding heavy crisping or browning, blanching potatoes before frying, not storing potatoes in a refrigerator, and post-drying (drying potatoes in a hot-air oven after frying) may decrease acrylamide levels of some foods (FDA).

It is still unclear that levels of acrylamide in foods raise cancer risk, but there are precautions you can take to decrease your acrylamide exposure (ACS):

• limit foods that may be high in acrylamide: french fries, potato chips, cookies, and toast;
• limit frying and roasting (boiling and steaming do not produce acrylamide);
• soak raw potato slices in water for 15-30 minutes before frying or roasting;
• cook potatoes and bread to a lighter color; and
• avoid storing potatoes in the refrigerator

Bottom line

More research is needed to confirm whether acrylamide causes cancer in humans.

What you may have heard

Products that contain palm oil, namely hazelnut spreads, are one of the most recent foods to be flagged as potentially carcinogenic.

What science tells us

Products containing palm oil, which can contain 3-Monochloropropane-1,2-diol esters (3-MCPD) and glycidyl esters (GE), have been flagged as possibly carcinogenic but only when heated 392 degrees Fahrenheit (FDA). Manufacturers have reported that brand-name hazelnut spreads are processed below 392 degrees. As a result, the U.S. Food and Drug Administration (FDA) has stated that they pose no cancer risk (FDA).

Epidemiological Evidence

Epidemiological studies have been conducted to examine whether a relationship exists between palm oil and cancer. Currently, there is no evidence in human studies that hazelnut spread or palm oil consumption increase the risk of cancer.

Laboratory Evidence/Supporting Evidence

Animal studies have also been conducted to examine if palm oil causes cancer. Some studies suggest that when the palm oil is heated at high temperature, it can cause cancer.

IARC Carcinogen Classification:

Not classified.

How to reduce your risk

Because of the added palm oil, hazelnut spreads are high in saturated fats. Saturated fats raise the level of cholesterol in the blood, which increases your risk of heart disease and stroke (AHA). Eating too much fat can lead to obesity, which also raises the risk of heart disease, stroke, diabetes, and some cancers.

Bottom line

Hazelnut spreads do not have any known carcinogenic effects. These foods are high in saturated fats, though, and should be consumed in moderation (ACS).

What you may have heard

Aspartame consumption can cause cancer.

What science tells us

With rising competition to make food sweet and appealing, as well as lower in calories, many companies switched from normal sucrose (table sugar) to sugar substitutes or artificial sweeteners like aspartame, one of the most widely used artificial sweeteners. Aspartame is similar to sugar, but it is sweeter than sugar, and can be found in different foods and beverages (ACS).

Epidemiological Evidence

Many studies have investigated whether or not artificial sweeteners and Aspartame have caused cancer (NCI), but no connection between cancer risk and Aspartame consumption has been found (ACS).

Laboratory Evidence/Supporting Evidence

There is no laboratory evidence that aspartame consumption leads to an increase in cancer risk.

IARC Carcinogen Classification:

Not Classified.

How to reduce your risk

Choose a sweetener that is FDA approved. These sweeteners have been studied extensively and are safe to consume. For example, sucrose (table sugar) and Aspartame are both good options, because they are FDA approved and have been proven to have little cancer risk, if any (ACS).
Consuming Aspartame or sugar-rich foods is often linked to higher chances of becoming obese, especially if they are not eaten in moderation. Obesity, or high BMI, has been linked to various types of cancers. Obese individuals have chronic inflammation, which, over time, can cause DNA damage that leads to cancer. They are also more likely to have other conditions or disorders that contribute to chronic inflammation: for example, Barrett’s esophagus, gallstones, ulcerative colitis, and hepatitis (NCI). To avoid excess body fat, it is important to maintain a healthy diet and have a goal of 150-300 minutes of weekly moderate physical activity (walking, running, hiking, etc.) (Mayo Clinic).

Bottom line

Eating food that contains Aspartame may not increase your cancer risk; however, a diet with excess sugar or Aspartame could have harmful health effects.

For further information on this topic, read, “What is worse, a soda or a beer?” in the Harvard Gazette and watch “Healthy Hydration” Beverage Choices and Cancer Risk,” co-hosted by the Zhu Center for Global Cancer Prevention and the Harvard T.H. Chan School of Public Health Office of Communications.

What you may have heard

Consuming the wax on fruits and vegetables can increase your risk of developing cancer.

What science tells us

Fruit wax, which is highly diluted, contains fungicides to inhibit mold growth, sugar cane, beeswax, carnauba wax, and resins.

Epidemiological Evidence

Chemicals such as pesticides associated with fruit production may contain carcinogens, but there is no evidence from human studies that exposure to fruit or vegetable wax contains chemicals that cause cancer when consumed by humans.

The Environmental Protection Agency (EPA) is responsible for ensuring that all pesticides or fungicides meet the Food Quality Protection Act (FQPA). The EPA states that fruits and vegetables treated with pesticides are safe and that they can be consumed “with a reasonable certainty of no harm to infants and children, as well as adults” (EPA). The EPA constantly monitors new and existing pesticides to ensure they may be consumed.

Fruit wax is monitored by the U.S. Food and Drug Administration (FDA). The FDA states that manufacturers and retail businesses must follow specific guidelines in the Federal Food, Drug, and Cosmetic Act (Federal Food, Drug, and Cosmetic Act (FD&C Act). This includes the use of safe and edible ingredients in the coating of any products and minimizes the risk of harmful coatings found on fruits and vegetables (FDA).

Laboratory Evidence/ Supportive Evidence

There is limited laboratory evidence on the effects of fruits and vegetable wax on animals. 

IARC Carcinogen Classification:

Not classified.

How to reduce your risk

The FDA does not approve any carcinogenic coatings used on food products. If there is a coating, it has been reviewed and ruled safe to consume by the FDA.

If you would still prefer to avoid eating the waxy coating, there are fruits that do not contain a coating. Often, products label whether they have a coating in their ingredients. If this is not listed on the product, it is often listed on the website of the product.
These coatings may also be easily removed under running water or, if the coating is water repellent, by peeling. Rinsing and peeling your fruits and vegetables is a great way to ensure that you do not eat the waxy coating.

Bottom line

Coatings on fruits and vegetables are not dangerous under FDA and EPA guidelines, but rinsing off or peeling produce helps to remove the wax.

Watch these short videos from the USDA and FDA about washing and handling fresh produce, and click on the links below for more information.

What you may have heard

Alcohol consumption increases your risk of cancer.

What science tells us

Alcoholic beverages containing ethanol are considered to be psychoactive substances by the WHO (WHO). It can cause harmful effects on the body. Alcohol consumption leads to a buildup of acetaldehyde, which is a toxic byproduct of ethanol (pure alcohol). In the liver, ethanol is converted into acetaldehyde, and a large presence of acetaldehyde interrupts the binding process of DNA, causing cells to not replicate correctly. Consumption of alcohol also causes tissue damage, which makes surface level cells more susceptible to the absorption of carcinogens.

Epidemiological Evidence

There is strong agreement that alcohol use can cause several types of cancer, and it has been classified as a Group 1 carcinogen (meaning that it is cancer-causing in humans) by the International Agency for Research on Cancer (IARC)  (ACS). There is a strong “dose-response association” between alcohol use and cancer (the more alcohol a person drinks regularly over time, the higher a person’s risk is of developing an alcohol-associated cancer):

• Head and neck: Moderate drinkers have 1.8-fold higher risk of oral cavity and pharynx (throat) cancers and 1.4-fold higher risk of larynx (voice box) cancers than non-drinkers. Heavy drinkers have 5-fold higher risk of oral cavity and pharynx cancers and 2.6-fold higher risk of larynx cancers (NCI).
• Esophageal: Compared with those who do not drink alcohol, the risk ranges from 1.3-fold higher for light drinkers to nearly 5-fold higher for heavy drinkers (NCI).
• Liver: Heavy alcohol drinking is associated with approximately 2-fold increased risk of two types of liver cancer (hepatocellular carcinoma and intrahepatic cholangiocarcinoma) (NCI).
• Breast: The cancer risk increase is greater in moderate drinkers (1.23-fold higher) and heavy drinkers (1.6-fold higher) (NCI).
• Colorectal: Moderate to heavy alcohol drinking is associated with 1.2- to 1.5-fold increased risk of cancers of the colon and rectum, compared with no alcohol consumption (NCI).

Laboratory Evidence/Supporting Evidence

Animal studies, particularly among mice, have shown that high alcohol consumption leads to the formation of tumors (NIH).

IARC Carcinogen Classification:

Group 1 (Carcinogenic to humans; “Ethanol in alcoholic beverages”)

How to reduce your risk

If someone drinks alcohol, it should be in moderation (NCI). Moderate alcohol drinking is up to 1 drink per day for women and up to 2 drinks per day for men. Heavy alcohol drinking is defined as having 4 or more drinks on any day or 8 or more drinks per week for women. For men, heavy alcohol drinking is defined as 5 or more drinks on any day or 15 or more drinks per week.

Bottom line

Drinking alcohol increases risk of multiple types of cancer. US guidelines recommend moderate drinking (up to 1 drink per day for women and up to 2 drinks per day for men).

For further information on this topic, read, “What is worse, a soda or a beer?” in the Harvard Gazette and watch “Healthy Hydration” Beverage Choices and Cancer Risk,” co-hosted by the Zhu Center for Global Cancer Prevention and the Harvard T.H. Chan School of Public Health Office of Communications.