Best Foods to Prevent Cancer 2020 (With Scientific References)
The development of cancer, in particular, has been shown to be heavily influenced by your diet. The term “superfood” is a fairly new term referring to foods that offer maximum nutritional benefits for minimal calories.
Do take note that we are talking about foods to prevent your risk of cancer and not about treating cancer with foods. Cancer treatments will be something that you will need to discuss with your cancer specialist. Let's try not to reach that stage.
Many foods contain beneficial compounds that could help decrease the growth of cancer. There are also several studies showing that a higher intake of certain foods could be associated with a lower risk of the disease.
This article will delve into the research and look at a list of foods that may lower your risk of cancer. There is a lot of confusion and controversies about this topic.
Let's dive into the evidence and decide for yourself.
Credit: MD Anderson Cancer Center
Broccoli contains sulforaphane, a plant compound found in cruciferous vegetables that may have potent anticancer properties.
One test-tube study showed that sulforaphane reduced the size and number of breast cancer cells by up to 75% (Clin Cancer Res. 2010).
Similarly, an animal study found that treating mice with sulforaphane helped kill off prostate cancer cells and reduced tumor volume by more than 50% (Carcinogenesis. 2004).
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 (Ann Oncol. 2013).
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.
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% (J Gastric Cancer. 2015).
Another study found that a higher intake of carrots was associated with 18% lower odds of developing prostate cancer (Trusted Source).
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 (Trusted Source).
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.
Beans are high in fiber, which some studies have found may help protect against colorectal cancer (Trusted Source, Trusted Source, Trusted Source).
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 (Trusted Source).
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% (Trusted Source).
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.
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% (Trusted Source).
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 (Trusted Source).
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% (Trusted Source).
Similarly, another animal study showed that giving rats a berry extract was found to inhibit several biomarkers of cancer (Trusted Source).
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.
Cinnamon is well-known for its health benefits, including its ability to reduce blood sugar and ease inflammation (Trusted Source, Trusted Source).
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 (Trusted Source).
Another test-tube study showed that cinnamon essential oil suppressed the growth of head and neck cancer cells, and also significantly reduced tumor size (Trusted Source).
An animal study also showed that cinnamon extract induced cell death in tumor cells, and also decreased how much tumors grew and spread (Trusted Source).
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.
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 (Br J Nutr. 2015).
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 (Trusted Source).
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 (Trusted Source).
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% (Trusted Source).
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.
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 (Trusted Source).
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 (Trusted Source).
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.
8. Turmeric (Curcumin)
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% (Trusted Source).
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 (Trusted Source).
Another test-tube study showed that curcumin helped kill off head and neck cancer cells (Trusted Source).
Curcumin has also been shown to be effective in slowing the growth of lung, breast and prostate cancer cells in other test-tube studies (Trusted Source, Trusted Source, Trusted Source).
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.
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 (Trusted Source).
A review looking at nine studies also found that a greater intake of citrus fruits was linked to a reduced risk of pancreatic cancer (Trusted Source).
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% (Trusted Source).
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.
In one study, The Shanghai Breast Cancer Survival Study (JAMA. 2009), a large, population-based cohort study of 5,042 female breast cancer survivors. Over an average follow-up of 3.9 years, soy food consumption was significantly associated with lower risk of death and breast cancer recurrence.
A review of 35 studies (Plos One. 2014) found that soy intake could lower the risk of breast cancer for both pre- and post-menopausal women in Asian countries. However, for women in Western countries, pre- or post-menopausal, there is no evidence to suggest an association between intake of soy isoflavone and breast cancer.
Another recent review of 14 studies (Plos One. 2020) found that tofu intake was associated with a
lower risk of breast cancer. Tofu (bean curd), is a popular food derived from soy in Asia.
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 (J Nutr Sci Vitaminol. 2013).
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 (J Natl Cancer Inst. 2002).
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.
The active component in garlic is allicin, a compound that has been shown to kill off cancer cells in multiple test-tube studies (Trusted Source, Trusted Source, Trusted Source).
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 (Trusted Source).
A study of 471 men showed that a higher intake of garlic was associated with a reduced risk of prostate cancer (Trusted Source).
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 (Trusted Source).
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.
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.
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 (Trusted Source).
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 (Trusted Source).
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 (Trusted Source).
In addition, omega-3 fatty acids are thought to block the development of the disease (Trusted Source).
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.
As new research continues to emerge, it has become increasingly clear that your diet can have a major impact on your risk of cancer.
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, combined with a healthy lifestyle without smoking, will improve many aspects of your health.
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