A plant-based diet may lower the risk of colorectal cancers, particularly if it includes seafood and fish, a large U.S. study has revealed.
Previous research suggests that vegetarians have a reduced risk of certain cancers, heart disease, diabetes, high blood pressure, and obesity. The current study offers fresh insight into the health benefits of different types of plant-based diets.
Researchers from Loma Linda University in California used dietary questionnaires, medical records, and cancer registries to examine the link between eating habits and cancer prevalence in a nationwide sample of 77,659 Seventh-Day Adventists, a religion that encourages a healthy lifestyle and abstinence from smoking and drinking.
After an average follow-up of 7.3 years, there were 380 cases of colon cancer and 110 cases of rectal cancer. Overall, compared to regular meat eaters, the vegetarians were 22 percent less likely to have colorectal malignancies, the study found.
Pescovegetarians, defined as people who ate fish at least once a month and meat less than once a month, had the biggest risk reduction – 43 percent.
For lacto-ovo vegetarians, who consumed eggs and dairy while limiting fish and meat to less than once a month, the risk reduction was 18 percent. Vegans, who ate eggs, dairy, fish, and meat less than once a month, had a 16 percent risk reduction.
Even limiting fish and meat to once a week had some benefit; semi-vegetarians had an 8 percent risk reduction.
Experts say the takeaway is that a person doesn't need to be vegan and cut out all eggs, dairy, and fish to get some benefit in terms of reducing the risk of cancer.
The new study isn't conclusive, because it didn't randomly select people to follow specific diets. Still, it offers more evidence in support of a plant-based diet often recommended for cancer prevention.
Several nutrients in fish may help protect against colorectal cancers. Fish is high in omega-3 fatty acids, which have been shown in previous research to reduce inflammation and lower the risk of some types of cancer.
Many fatty fish are also a rich source of vitamin D, which has been shown to protect against colon cancer and other malignancies.
Source: JAMA Internal Medicine, online March 9, 2015.
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