Colorectal cancer: More evidence that Western-style diet may increase risk
New Insight on How a Western Diet May Cause Colorectal Cancer
– A recent study suggests that a high intake of red meat is associated with increased risk of developing colorectal adenomas, a precursor lesion of colorectal cancers.
– The researchers analyzed data from 521 patients with colorectal adnomas and 441 controls without adnoma.
– They found that the odds ratio for having adnomas among those consuming more than 80 grams of red meat per day compared with less than 20 grams was 2.37 (95% confidence interval, 1.45–3.89).
– For processed meats, the corresponding OR was 3.00 (95% CI, 1.82–4.98).
– The authors note that although there are many studies showing associations between dietary factors and colorectal cancer, few have assessed the role of red meat specifically.
– The authors conclude that further investigation into the relationship between red meat consumption and colorectal adnenomas is warranted.
Prevention: What to avoid
A 2016 study found that people who eat a lot of red meat are more likely to develop colon cancer. This was based on data gathered from nearly half a million adults over 10 years. Researchers looked at how much red meat participants ate and whether they had been diagnosed with colorectal cancer during the course of the study. They found that those who consumed the most red meat were 50% more likely to develop colon cancers compared to those who ate less than 30 grams per day.
The researchers also discovered that eating red meat every day was linked to a greater chance of developing colon cancer. Those who ate red meat three times a week were 19% more likely to develop the disease than those who never ate it. However, there was no link between consuming red meat once a week and developing colon cancer.
Prevention: What to eat
The American Cancer Society recommends eating plenty of fruits and veggies because they are loaded with fiber and antioxidants. Some research suggests that people who follow a plant-based diet may lower their risk of developing certain types of cancers, including colon cancer. However, it is still unclear whether cutting out meat completely helps prevent cancer.
A study published in the journal Nutrition Research in 2017 found that vegetarians had a slightly increased risk of colorectum cancer compared to those who ate meat regularly. But researchers say that there isn’t enough evidence to support the idea that a vegetarian diet can reduce the risk of cancer overall.
Another study published in the Journal of Epidemiology & Community Health in 2018 showed that vegans had a lower risk of prostate cancer than men who consumed moderate amounts of meat. However, the authors caution that the findings don’t prove that eating less meat is directly linked to a decreased risk of prostate cancer.
In addition to fruits and veggies, experts recommend consuming whole grains, beans, nuts, seeds, and soy products. These foods provide important nutrients like protein, iron, zinc, magnesium, and calcium. They also contain compounds called phytochemicals that scientists believe may help fight against cancer.
What to eat during and after treatment
The Dana-Farber Cancer institute recommends that people undergoing treatment for colon and rectal cancers follow a rainbow diet to boost their immune systems.
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A rainbow plate is a way of eating where you fill half your plate with fruit and veggies, followed by protein, such as meat or fish, and finish off with dairy products and grains.
According to guidelines from the Dana Farber Cancer Institute in Boston MA, people undergoing treatment should also favor the “rainbow plate,” and eat a varied array to support their immune system, including:
Red Meat and Colorectal Cancer
Colorectal cancer (CC) is one of the leading causes of death worldwide among both sexes. Although it represents less than 10% of total cancers, CC accounts for about 8% of deaths due to malignant tumors. This disease occurs mainly in developed countries where the consumption of red meat is very high. The main objective of this paper is to analyze the relationship between red meat and CC risk. A systematic review of the literature related to the topic was performed, selecting articles published up to December 2018. We found 23 original papers that met our inclusion criteria. Most studies included in this review showed significant associations of red meat with increased risks of CC. Among the different types of red meat analyzed, beef and processed meats had stronger effects than unprocessed red meat. Some specific compounds present in red meat could explain the increase in CC risk associated with the consumption of this food group.
Meta-analyses for red meat and processed meat
These researchers conducted a meta-analysis of prospective studies on meat intake and colorectal cancer risk. They analyzed data from 19 case-control studies and 11 cohort studies. Their conclusions are similar to those of previous reports.
The authors conclude that there is no association between red meat intake and colon cancer risk; however, they do find a positive association between processed meat intake and colon cancer incidence. The pooled relative risks (RRs) were 1.12 (95% confidence interval: 0.99–1.26) for red meat and 1.49 (95% CI: 1.16–1.92) for processed meat. Red meat was not related to rectal cancer, whereas processed meat was positively associated with it (pooled RR 1.25, 95% CI: 1.01–1.55).
Red meat subtypes and colorectal cancer
The association between the consumption of red and processed meat and colorectal cancers is well established. However, it does not seem clear whether different types of red meat are equally associated with this type of cancer. In fact, some trials and one meta-analyses address to this issue.
In particular, several trials and one meta-analyis assessed the effect of beef, pork, lamb, mutton, goat, horsemeat and venison on colon and rectum cancer incidence.
Beef and pork showed no significant associations with CRC incidence, while lamb, goat, horsemeat, and venison seemed to increase the risk of CRC.
However, most of these analyses had important limitations. For instance, none of them included data about dietary habits such as cooking methods or preparation techniques. Furthermore, some of them did not adjust for confounding factors such as body mass index, physical activity, smoking status, alcohol drinking, and family history of CRC.