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- Jukes TH: The Day that Food was Declared a Poison. Ames, IO: Council for Agricultural Science and Technology, 1982, pp. 42–45
Broccoli contains sulforaphane, a plant compound found in cruciferous vegetables that may have potent anticancer properties.
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One test-tube study showed that sulforaphane reduced the size and number of breast cancer cells by up to 75% (1).
Similarly, an animal study found that treating mice with sulforaphane helped kill off prostate cancer cells and reduced tumor volume by more than 50% (2).
Some studies have also found that a higher intake of cruciferous vegetables like broccoli may be linked to a lower risk of colorectal cancer.
One analysis of 35 studies showed that eating more cruciferous vegetables was associated with a lower risk of colorectal and colon cancer (3).
Including broccoli with a few meals per week may come with some cancer-fighting benefits.
However, keep in mind that the available research hasn’t looked directly at how broccoli may affect cancer in humans.
Instead, it has been limited to test-tube, animal and observational studies that either investigated the effects of cruciferous vegetables, or the effects of a specific compound in broccoli. Thus, more studies are needed.
Broccoli contains sulforaphane, a compound that has been shown to cause tumor cell death and reduce tumor size in test-tube and animal studies. A higher intake of cruciferous vegetables may also be associated with a lower risk of colorectal cancer.
Several studies have found that eating more carrots is linked to a decreased risk of certain types of cancer.
For example, an analysis looked at the results of five studies and concluded that eating carrots may reduce the risk of stomach cancer by up to 26% (4).
Another study found that a higher intake of carrots was associated with 18% lower odds of developing prostate cancer (5).
One study analyzed the diets of 1,266 participants with and without lung cancer. It found that current smokers who did not eat carrots were three times as likely to develop lung cancer, compared to those who ate carrots more than once per week (6).
Try incorporating carrots into your diet as a healthy snack or delicious side dish just a few times per week to increase your intake and potentially reduce your risk of cancer.
Still, remember that these studies show an association between carrot consumption and cancer, but don’t account for other factors that may play a role.
Some studies have found an association between carrot consumption and a decreased risk of prostate, lung and stomach cancer.
One study followed 1,905 people with a history of colorectal tumors, and found that those who consumed more cooked, dried beans tended to have a decreased risk of tumor recurrence (10).
An animal study also found that feeding rats black beans or navy beans and then inducing colon cancer blocked the development of cancer cells by up to 75% (11).
According to these results, eating a few servings of beans each week may increase your fiber intake and help lower the risk of developing cancer.
However, the current research is limited to animal studies and studies that show association but not causation. More studies are needed to examine this in humans, specifically.
Beans are high in fiber, which may be protective against colorectal cancer. Human and animal studies have found that a higher intake of beans could reduce the risk of colorectal tumors and colon cancer.
Berries are high in anthocyanins, plant pigments that have antioxidant properties and may be associated with a reduced risk of cancer.
In one human study, 25 people with colorectal cancer were treated with bilberry extract for seven days, which was found to reduce the growth of cancer cells by 7% (12).
Another small study gave freeze-dried black raspberries to patients with oral cancer and showed that it decreased levels of certain markers associated with cancer progression (13).
One animal study found that giving rats freeze-dried black raspberries reduced esophageal tumor incidence by up to 54% and decreased the number of tumors by up to 62% (14).
Similarly, another animal study showed that giving rats a berry extract was found to inhibit several biomarkers of cancer (15).
Based on these findings, including a serving or two of berries in your diet each day may help inhibit the development of cancer.
Keep in mind that these are animal and observational studies looking at the effects of a concentrated dose of berry extract, and more human research is needed.
Some test-tube and animal studies have found that the compounds in berries may decrease the growth and spread of certain types of cancer.
In addition, some test-tube and animal studies have found that cinnamon may help block the spread of cancer cells.
A test-tube study found that cinnamon extract was able to decrease the spread of cancer cells and induce their death (18).
Another test-tube study showed that cinnamon essential oil suppressed the growth of head and neck cancer cells, and also significantly reduced tumor size (19).
An animal study also showed that cinnamon extract induced cell death in tumor cells, and also decreased how much tumors grew and spread (20).
Including 1/2–1 teaspoon (2–4 grams) of cinnamon in your diet per day may be beneficial in cancer prevention, and may come with other benefits as well, such as reduced blood sugar and decreased inflammation.
However, more studies are needed to understand how cinnamon may affect cancer development in humans.
Test-tube and animal studies have found that cinnamon extract may have anticancer properties and may help decrease the growth and spread of tumors. More research in humans is needed.
Research has found that eating nuts may be linked to a lower risk of certain types of cancer.
For instance, a study looked at the diets of 19,386 people and found that eating a greater amount of nuts was associated with a decreased risk of dying from cancer (21).
Another study followed 30,708 participants for up to 30 years and found that eating nuts regularly was associated with a decreased risk of colorectal, pancreatic and endometrial cancers (22).
Other studies have found that specific types of nuts may be linked to a lower cancer risk.
For example, Brazil nuts are high in selenium, which may help protect against lung cancer in those with a low selenium status (23).
Similarly, one animal study showed that feeding mice walnuts decreased the growth rate of breast cancer cells by 80% and reduced the number of tumors by 60% (24).
These results suggest that adding a serving of nuts to your diet each day may reduce your risk of developing cancer in the future.
Still, more studies in humans are needed to determine whether nuts are responsible for this association, or whether other factors are involved.
Some studies have found that an increased intake of nuts may decrease the risk of cancer. Research shows that some specific types like Brazil nuts and walnuts may also be linked to a lower risk of cancer.
7. Olive Oil
Olive oil is loaded with health benefits, so it’s no wonder it’s one of the staples of the Mediterranean diet.
Several studies have even found that a higher intake of olive oil may help protect against cancer.
One massive review made up of 19 studies showed that people who consumed the greatest amount of olive oil had a lower risk of developing breast cancer and cancer of the digestive system than those with the lowest intake (25).
Another study looked at the cancer rates in 28 countries around the world and found that areas with a higher intake of olive oil had decreased rates of colorectal cancer (26).
Swapping out other oils in your diet for olive oil is a simple way to take advantage of its health benefits. You can drizzle it over salads and cooked vegetables, or try using it in your marinades for meat, fish or poultry.
Though these studies show that there may be an association between olive oil intake and cancer, there are likely other factors involved as well. More studies are needed to look at the direct effects of olive oil on cancer in people.
Several studies have shown that a higher intake of olive oil may be associated with a reduced risk of certain types of cancer.
Turmeric is a spice well-known for its health-promoting properties. Curcumin, its active ingredient, is a chemical with anti-inflammatory, antioxidant and even anticancer effects.
One study looked at the effects of curcumin on 44 patients with lesions in the colon that could have become cancerous. After 30 days, 4 grams of curcumin daily reduced the number of lesions present by 40% (27).
In a test-tube study, curcumin was also found to decrease the spread of colon cancer cells by targeting a specific enzyme related to cancer growth (28).
Another test-tube study showed that curcumin helped kill off head and neck cancer cells (29).
For the best results, aim for at least 1/2–3 teaspoons (1–3 grams) of ground turmeric per day. Use it as a ground spice to add flavor to foods, and pair it with black pepper to help boost its absorption.
Turmeric contains curcumin, a chemical that has been shown to reduce the growth of many types of cancer and lesions in test-tube and human studies.
9. Citrus Fruits
Eating citrus fruits such as lemons, limes, grapefruits and oranges has been associated with a lower risk of cancer in some studies.
One large study found that participants who ate a higher amount of citrus fruits had a lower risk of developing cancers of the digestive and upper respiratory tracts (33).
A review looking at nine studies also found that a greater intake of citrus fruits was linked to a reduced risk of pancreatic cancer (34).
Finally, a review of 14 studies showed that a high intake, or at least three servings per week, of citrus fruit reduced the risk of stomach cancer by 28% (35).
These studies suggest that including a few servings of citrus fruits in your diet each week may lower your risk of developing certain types of cancer.
Keep in mind that these studies don’t account for other factors that may be involved. More studies are needed on how citrus fruits specifically affect cancer development.
Studies have found that a higher intake of citrus fruits could decrease the risk of certain types of cancers, including pancreatic and stomach cancers, along with cancers of the digestive and upper respiratory tracts.
High in fiber as well as heart-healthy fats, flaxseed can be a healthy addition to your diet.
Some research has shown that it may even help decrease cancer growth and help kill off cancer cells.
In one study, 32 women with breast cancer received either a flaxseed muffin daily or a placebo for over a month.
At the end of the study, the flaxseed group had decreased levels of specific markers that measure tumor growth, as well as an increase in cancer cell death (36).
In another study, 161 men with prostate cancer were treated with flaxseed, which was found to reduce the growth and spread of cancer cells (37).
Try adding one tablespoon (10 grams) of ground flaxseed into your diet each day by mixing it into smoothies, sprinkling it over cereal and yogurt, or adding it to your favorite baked goods.
Some studies have found that flaxseed may reduce cancer growth in breast and prostate cancers. It is also high in fiber, which may decrease the risk of colorectal cancer.
Lycopene is a compound found in tomatoes that is responsible for its vibrant red color as well as its anticancer properties.
Several studies have found that an increased intake of lycopene and tomatoes could lead to a reduced risk of prostate cancer.
A review of 17 studies also found that a higher intake of raw tomatoes, cooked tomatoes and lycopene were all associated with a reduced risk of prostate cancer (38).
Another study of 47,365 people found that a greater intake of tomato sauce, in particular, was linked to a lower risk of developing prostate cancer (39).
To help increase your intake, include a serving or two of tomatoes in your diet each day by adding them to sandwiches, salads, sauces or pasta dishes.
Still, remember that these studies show there may be an association between eating tomatoes and a reduced risk of prostate cancer, but they don’t account for other factors that could be involved.
Some studies have found that a higher intake of tomatoes and lycopene could reduce the risk of prostate cancer. However, more studies are needed.
Several studies have found an association between garlic intake and a lower risk of certain types of cancer.
One study of 543,220 participants found that those who ate lots of Allium vegetables, such as garlic, onions, leeks and shallots, had a lower risk of stomach cancer than those who rarely consumed them (43).
A study of 471 men showed that a higher intake of garlic was associated with a reduced risk of prostate cancer (44).
Another study found that participants who ate lots of garlic, as well as fruit, deep yellow vegetables, dark green vegetables and onions, were less likely to develop colorectal tumors. However, this study did not isolate the effects of garlic (45).
Based on these findings, including 2–5 grams (approximately one clove) of fresh garlic into your diet per day can help you take advantage of its health-promoting properties.
However, despite the promising results showing an association between garlic and a reduced risk of cancer, more studies are needed to examine whether other factors play a role.
Garlic contains allicin, a compound that has been shown to kill cancer cells in test-tube studies. Studies have found that eating more garlic could lead to decreased risks of stomach, prostate and colorectal cancers.
13. Fatty Fish
Some research suggests that including a few servings of fish in your diet each week may reduce your risk of cancer.
One large study showed that a higher intake of fish was associated with a lower risk of digestive tract cancer (46).
Another study that followed 478,040 adults found that eating more fish decreased the risk of developing colorectal cancer, while red and processed meats actually increased the risk (47).
In particular, fatty fish like salmon, mackerel and anchovies contain important nutrients such as vitamin D and omega-3 fatty acids that have been linked to a lower risk of cancer.
For example, having adequate levels of vitamin D is believed to protect against and reduce the risk of cancer (48).
In addition, omega-3 fatty acids are thought to block the development of the disease (49).
Aim for two servings of fatty fish per week to get a hearty dose of omega-3 fatty acids and vitamin D, and to maximize the potential health benefits of these nutrients.
Still, more research is needed to determine how fatty fish consumption may directly influence the risk of cancer in humans.
Fish consumption may decrease the risk of cancer. Fatty fish contains vitamin D and omega-3 fatty acids, two nutrients that are believed to protect against cancer.
The Bottom Line
As new research continues to emerge, it has become increasingly clear that your diet can have a major impact on your risk of cancer.
Although there are many foods that have potential to reduce the spread and growth of cancer cells, current research is limited to test-tube, animal and observational studies.
More studies are needed to understand how these foods may directly affect cancer development in humans.
In the meantime, it’s a safe bet that a diet rich in whole foods, paired with a healthy lifestyle, will improve many aspects of your health.
- Genetically Modified Foods (GMOs): The rapidly growing industry of genetically modified crops are infiltrating our food supply at an alarming rate. More than 90% of our corn and soy are now genetically modified. This fairly new practice is the source of many debates. Experts agree that adequate testing was not done before GMO foods were added to the ingredient listing of thousands of products. In other words, no one – including the growers and manufacturers of GMO foods – knows the long-term effect they will have on human health. Look for GMO-free labels whenever possible or buy organic (which always means a product is not genetically modified).
- Microwave Popcorn: From the chemically-lined bag to the actual contents, microwave popcorn is at the center of lung cancer debates around the world. Not only are the kernels and oil likely GMO (which the manufacturer does not have to disclose) unless organic, the fumes released from artificial butter flavoring contain diacetyl, which is toxic to humans. Make your own organic popcorn the old-fashioned way – it tastes better, doesn’t release toxic fumes, and is a healthier choice for you.
- Canned Goods: Most cans are lined with a product called bisphenol-A (BPA), which has been shown to genetically alter the brain cells of rats. Many plastic goods, thermal paper, water lines, and many dental composites also contain BPA. Help protect your DNA by sticking to fresh or frozen vegetables that have no added ingredients for your family’s table! These are better for you and available year-round.
- Grilled Red Meat: While grilled food can taste delicious, scientists have discovered that preparing meats in this way – especially processed meats like hot dogs – releases a carcinogen called heterocyclic aromatic amines. When you grill red meat to the point of well-done, it changes the chemical and molecular structure of the meat. You’re better off baking, broiling, or preparing meat in a skillet than on the grill.
- Refined Sugar: The biggest cancer causing food (by far) is high-fructose corn syrup (HFCS) and other refined sugars. Even brown sugar is highly refined white sugar with some of the removed molasses added back in for flavor and color. Refined sugars (and foods made with them) are the source of major insulin spikes and feed the growth of cancer cells. Since the majority of the sugar supply in the U.S. is made using genetically modified (GMO) sugar beets, a healthier option is organic honey, coconut sugar, or maple sugar. Now that oncologists are using diabetes medication to fight cancer cells, there’s no doubt (finally) that those mutated cancer cells love sugar.
- Salted, Pickled, and Smoked Foods: These products typically contain preservatives, such as nitrates, which are intended to prolong shelf life. The additives used in processed foods can accumulate in your body over time. Eventually, such toxins cause damage at the cellular level and lead to diseases like cancer. When smoked foods are cooked at high temperatures, the nitrates are converted to the much more dangerous nitrites. (Note: By pickled foods we don’t mean the fermented foods you make at home.)
- Soda and Carbonated Beverages: Sodas have been at the center of the health debate for two decades as a major cancer causing food. Filled with high-fructose corn syrup (HFCS), dyes, and a host of other chemicals, they are very bad for every aspect of your health. They provide zero nutritional value and rob your body of the nutrients you get from other foods. Adding “diet” to the label means you’re also likely consuming aspartame – which is no better than rat poison to human cells.
- White Flour: When flour is refined, all nutritional value is removed. Then it’s bleached with chlorine gas to make it more appealing to consumers. The glycemic index for white flour is very high – meaning it spikes your insulin levels without providing nutritional fuel. Carbohydrates are converted to sugars by your body, so excessive products that contain white flour can lead to increased insulin resistance. Simple sugars (like refined carbohydrates) are the preferred fuel source for cancer.
- Farmed Fish: Commercial fish farming involves raising an incredible number of fish (such as salmon), in a crowded environment. More than 60% of the salmon consumed in the United States comes from a farming operation where they are treated with antibiotics, pesticides, and other carcinogenic chemicals to try and control the bacterial, viral, and parasitic outbreaks that result from cramming so many fish in a small space. Farmed fish also don’t have as much omega-3 as wild salmon.
- 10.Hydrogenated Oils: Vegetable oils are chemically extracted from their source, chemically treated, and more chemicals are added to change the smell and taste. They’re packed with unhealthy omega-6 fats (that Americans already consume way too much of) and have been proven to alter the structure of our cell membranes.
4 Steps to Help Prevent Cancer
In addition to the 10 foods listed above, also be sure to avoid any food labeled as “diet,” “light,” or “fat-free.” In order to remove fat or natural calories, they are replaced with chemicals that are dangerous to your body.
Instead of consuming food products that manufacturers claim is “good for you” – follow these four anti-cancer diet tips to prevent cancer the easy way:
- Eat organic whenever possible.
- Choose raw or clean frozen if availability of fresh product isn’t good in your area.
- Fill half your plate each meal with non-starchy vegetables. If you eat animal products, make sure they’re pastured and grass-fed meats and dairy goods (including eggs). Use only high quality oils such as coconut oil, olive oil, ghee, or grass-fed butter.
- Cut back drastically on grains and sugars.
Not only will eliminating these foods lower your cancer risk, you’re going to feel (and look) better from the inside out. Now that you know what the top cancer causing foods are, what are you going to do about their presence in your kitchen and your daily eating plan?
The level of evidence required to make decisions depends on the level of risk. If we’re talking about some new drug, for example, given the fact that medications kill more than 100,000 Americans a year you want to be darn sure that the benefits outweigh the risks before you prescribe it (or take it!). But what level of evidence do you need to eat broccoli? Do you need randomized double-blind placebo-controlled trials? (How would you even design a placebo vegetable?) Even if all the evidence suggesting how powerful broccoli is turned out to be some crazy cruciferous conspiracy, what’s the worst that could have happened? It’s healthy anyway. That’s the beauty of safe, simple, side effect-free solutions provided by the lifestyle medicine approach. It can only help.