Predominantly vegetarian diets that rely on fish for protein intake lead to lower rates of colorectal cancer, according to a study conducted in the United States and published in the Internal Medicine section of The Journal of the American Medical Association. Dr. Michael Orlich, an assistant professor in medicine and public health at Loma Linda University in California and the study’s lead author, declared that his team was surprised to see such a notable difference between people who ate vegetables, fruit and fish and people on other kinds of vegetarian diets.
A peculiarity of the study is that it was conducted among Seventh-Day Adventists, whose religion presupposes a smoke-free and alcohol-free lifestyle and a healthy diet. This may have induced a bias, but it allowed for a long-term follow-up of the subjects – the median follow-up interval being 7.3 years. The study included 77,659 people from all across the U.S., who responded to diet-related questions and whose medical records and cancer registers were analyzed in order to trace the link between eating habits and cancer occurrence. In the seven-year interval, 380 cases of colon cancer and 110 cases of rectal cancer were reported, and vegetarians had 22% less than the cancer rate of regular meat eaters.
The study defined pesco-vegetarians as the category whose diet includes fish at least once a month and meat less than once a month. This category showed the smallest risk of colon-cancer or rectal cancer, up to 43% less than the risk for meat eaters. Lacto-ovo vegetarians, who relied on eggs and dairy for protein but ate fish and meat less than once a month, had a cancer risk only 18% lower than meat eaters, while vegans, defined as the category whose diet rarely included eggs, fish, milk-products and meat (consumed less than once a month), had a risk reduction of only 16%. Semi-vegetarians (who usually eat meat or fish once a week) had cancer rates 8% lower than regular meat-eaters.
Dr. Leonard Saltz, chief of the gastrointestinal oncology service at Memorial Sloan Kettering Cancer Center in New York (who didn’t participate in the study but is familiar with the results), commented that the good news is one doesn’t have to go vegan to reduce cancer risks, but moderation seems to be the best option. If fruits, vegetables and seafood predominate in one’s diet, they don’t have to be its exclusive content: “We’re not saying you’re committing suicide if you have a cheeseburger, but it should be a treat, not a regular occurrence.” – Dr. Saltz advises.
The study conducted by Dr. Orlich is not necessarily conclusive, because it was not based on an arbitrary selection of people followed by randomly assigning certain diets to them, but it was large enough to offer some evidence to support diet-recommendations.
Colorectal cancer affects roughly 4.7% percent of the U.S. population, according to the 2009-2011 data collected by the National Cancer Institute.
image source: Really Healthy Foods
