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Can Chocolate Help Prevent Cancer?

Antioxidants in dark chocolate may help fight cancer.

Want to give the gift of love this Valentine's Day or any holiday? Consider giving chocolate - especially dark chocolate. What better way to say "I love you" than contributing to your loved one's good health?

Foods high in polyphenol compounds have been linked to health benefits, including preventing certain types of cancer. (i.275)

Chocolate contains many polyphenol compounds that have anticancer properties, including: (i.275-277)

Did You Know?

Chocolate is made from the beans of cocoa trees (Theobroma cacao). Also known as cacao, wild cocoa trees are originally from South America. They were grown in Central America and Mexico by migrating Indians, and were actually cultivated by the Maya over 1500 years ago. (i.276)

In fact, tests show that natural cocoa powder and dark chocolate have significantly more beneficial polyphenols and antioxidant power than other super foods, including: (i.278)

Evidence of Chocolate's Cancer Fighting Benefits

Lab and animal research, as well as some clinical studies, show dark chocolate has the following cancer-fighting effects:

Cancer Type Chocolate Cancer Fighting Benefits

Breast cancer

(lab tests)

  • Improves effectiveness of tamoxifen chemotherapy. (i.279)
  • Increases death of breast cancer cells. (i.280)

Colon cancer

(lab and animal studies)

  • Blocks proliferation and cell growth of various colon cancer lines. (i.281282)
  • Reduces levels of inflammatory proteins, including COX-2, linked to increased risk of colon cancer. (i.275)
  • Lowers number of precancerous colon lesions. (i.275)
  • Decreases colon damage and inflammation caused by ulcerative colitis, a condition linked to increased risk of colon cancer. (i.283284)

Lung cancer

(lab studies)

  • Promotes non-inflammatory cell death of lung carcinoma cells. (i.281)
  • Suppresses proliferation and growth of lung cancer cell lines. (i.281)

Ovarian cancer

(lab studies)

  • Increases cell death in ovarian cancer cell lines. (i.285)
  • Improves effectiveness of chemotherapy against ovarian cancer cells. (i.285)

Pancreatic cancer

(lab and animal studies)

  • Cocoa compounds inhibit pancreatic cancer growth. (i.286)

Prostate cancer

(lab tests)

  • Suppresses growth of prostate cancer cell lines. (i.277)

Eating dark chocolate may also help improve quality of life in patients with cancer. In a clinical study, 133 cancer patients from 3 different hospitals were randomly assigned to eat 50 g/day of dark chocolate or mineral water for 3 consecutive days. Those who ate chocolate had significantly reduced depression and anxiety. (i.287)

Other Health Benefits of Chocolate

Health Condition, Concern, or Disease Evidence of Benefit

Aging skin

Although 12 weeks of eating high-antioxidant chocolate didn't reduce skin sensitivity to UV radiation from the sun. A limit of the randomized clinical trial was none of the 74 participants were assigned to not eat chocolate. Instead, they were randomly assigned to eat either chocolate high in antioxidants or low-antioxidant chocolate. (i.288)

Interestingly, the study found that chocolate may help protect skin from photo-aging. In the clinical trial, participants who ate chocolate showed a small but significant increase in elasticity in the skin at the temple. (i.288)

In a different 24 week clinical trial, dietary supplements of cocoa compounds improved facial wrinkles and elasticity. The women participating in the study were between the ages of 43 and 86 years old, and all had moderately aged skin. (i.289)


Data from population studies suggests that eating chocolate 2-6 times per week could decrease the risk of developing diabetes in healthy people. Research shows that chocolate compounds increase insulin sensitivity. (i.290)

Heart disease and stroke

According to a prospective population study, eating more chocolate is linked to lower risk of cardiovascular disease and stroke. Higher chocolate consumption is also linked to fewer adverse outcomes from heart disease, including lower rates of mortality. (i.291)

Analysis of other prospective studies support chocolate's healthy heart effects. Data from 6 studies involving tens of thousands of adults and thousands of cases of heart disease found eating chocolate is linked to lower risk of heart attack and stroke. (i.292)

High blood pressure

If you have hypertension and diabetes, eating chocolate could lower your blood pressure - as long as it's dark chocolate. In an 8 week clinical trial, patients assigned to dark chocolate showed significant decreases in both systolic and diastolic blood pressure. However, those who ate white chocolate showed no differences in blood pressure by the end of the study. (i.293)

Liver disease

Research in animals suggests cocoa could help reduce liver damage and fibrosis. In turn, this could lower the risk of liver cancer. (i.294)

Sports training

In a small clinical study, milk chocolate reduced muscle soreness and improved performance better than water. (i.295)

Best Type of Chocolate for Health Benefits

Lab, animal, and clinical studies show the darker the chocolate the better. Why? Dark chocolate contains more of the beneficial cocoa compounds and antioxidants than semisweet, milk, or soy chocolate. (i.296)

Antioxidant levels in chocolate

Antioxidant Levels in Chocolate

You may also want to choose chocolate that is made from non-fermented (raw) cocoa beans. Research shows that roasting and fermenting cocoa beans can affect antioxidants in chocolate — especially levels of epicatechin and catechin antioxidants. Compared to unripe, unprocessed cocoa beans, different chocolate processing techniques showed the following effects: (i.278281297)

Processing Technique Epicatechin Levels Catechin Levels


No change


Minimal change

Minimal change



(over 158° F)

(over 248° F)

Dutch processing

Natural cocoa is also acidic. Chocolate makers often treat it with a basic substance to lower that acidity. This alkalizing process is often referred to "dutching," and Dutch cocoa has a more mellow taste. However, industry tests show that chocolate products, including hot cocoa mixes, made with alkalized cocoa are comparatively lower in antioxidant and polyphenol levels. (i.278281)

70° C
120° C
In a study funded by The Hershey Company. (i.278)
Randomized and placebo-controlled. (i.289)
Specifically, the European Prospective Investigation into Cancer (Norfolk cohort). (i.291)
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