In 2030, more than 2.2 million new cases of bowel cancer (colon or rectum) and 1.1 million deaths annually from this disease. Although screening tests can detect it at an early treatable stage, acceptance of these tests varies considerably from country to country.
How bowel cancer takes more than 15 years in development, experts consider a healthy lifestyle likely to play a key role in stopping your progress. Now a new study shows the analysis of 80 clinical trials and observational studies published between September 1980 and June 2019 that assess the impact of dietary factors (vitamins or supplements, coffee, tea, fish and omega 3 fatty acids; dairy products; fiber; fruits and vegetables; meat; and alcohol) and pharmacological (aspirin; non-steroidal anti-inflammatory drugs (NSAIDs); and statins) in the risk of this type of tumor.
The results, published in the journal Gut, reveal that folic acid, magnesium, and dairy products can help prevent bowel cancer, but no test that garlic or onions, fish, tea, or coffee protect against disease.
The researchers – from French, Canadian and Dutch centers – caution that they were unable to define “an optimal dose and duration of exposure or intake for any of the products, even in the case of low-dose aspirin and other compounds that have been extensively evaluated. ».
However, they suggest that their findings could help doctors advise patients on the best diet to reduce the risk of this type of tumor and guide the direction of future research.
Lower associated risks
According to the current revision, the aspirin it probably protects against bowel cancer, reducing the risk by 14-29% at doses as low as 75 mg/day, with a reported dose-response affect up to 325 mg/day. The use of NSAIDs for up to five years was associated with a significant drop (from 26 to 43% less risk) in the incidence of bowel cancer.
On the other hand, the intake magnesium of at least 255 mg/day was associated with a 23% lower risk compared to lower intake, and high folic acid intake was associated with a 12-15% lower risk, although a threshold dose could not be determined accurately from the available data.
Similarly, the consumption of dairy products was associated with a 13-19% lower risk of the disease. However, the authors note, the variety of dairy products and a large number of included studies make it difficult to draw firm conclusions about the amounts needed to prevent the disease.
Further, fiber intake was associated with a 22-43% lower risk, while the intake of fruit and vegetables was associated with a risk up to 52% lower, with an added benefit for every additional 100g / day increase in intake. Consumption of soy in the diet was associated with a modest, but significant, drop (8-15%) at risk.
The researchers caution that they were unable to define an optimal dose and duration of exposure or intake for either product and further studies would be necessary.
Of course, there was no evidence that vitamins E, C, or multivitamins were protective. Similarly, there was no evidence that β-carotene or selenium helped prevent disease.
The data were weak in terms of the impact of tea, garlic or onion, vitamin D alone or in combination with calcium, coffee and caffeine, fish and omega 3, and inconsistent in terms of the protective effect of vitamin A and B vitamins.
In observational studies, a modest protective effect of high calcium intake was found, but a review of data from clinical trials found no protective effect and even an increased risk.
Similarly, although analyzes from observational studies suggest that statins may reduce cancer risk, no positive effect was seen in meta-analyses of clinical trial data.
Most of the available meta-analyses from observational studies reported an increased risk of between 12 and 21% for meat, particularly red meat and processed meat. Thus, dose-effect studies reported an increased risk of 10 to 30% for each additional 100 g / day of red meat consumed.
Lastly, alcohol was associated with a significantly higher risk. The higher the intake, the greater the risk. This was evident even at the lowest level of consumption studied: 1-2 drinks a day.