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Folic acid, magnesium, and dairy products can prevent colon cancer, but there is no evidence that garlic or onions, fish, tea, or coffee protect against the disease. A comprehensive analysis of published pooled data analyzes can be found in the journal Gut.
In the United States alone, around one in twenty people will develop colon cancer at some point in their life. Globally, more than 2.2 million new cases and 1.1 million deaths from the disease are forecast each year through 2030.
While deaths from the disease have decreased in most developed countries, the number of new cases has increased in some countries, including Canada, the UK and the Netherlands.
Screening for the disease can detect the disease at an early treatable stage, but uptake varies significantly from country to country. And since colon cancer takes more than 15 years to develop, healthy lifestyle choices likely play a key role in stopping or stopping its progression, the researchers say.
They therefore searched relevant research databases for published systematic reviews and meta-analyzes (pooled data analysis) of clinical studies and observational studies that assessed the effects of dietary and medical factors on colorectal cancer risk.
The medical factors included: aspirin; nonsteroidal anti-inflammatory drugs (NSAIDs) such as paracetamol; and statins.
The nutritional factors included: vitamins or supplements (magnesium, calcium, folic acid, vitamins A, B, C, E, D, β-carotene and selenium); Coffee; Tea; Fish and omega-3 fatty acids; Dairy products; Dietary fiber; Fruit and vegetables; Flesh; and alcohol.
They included relevant studies published between September 1980 and June 2019 in French or English, but excluded those that involved people at high risk of colon cancer. Around 80 of a total of 343 articles were included in the comprehensive analysis of the pooled data analyzes.
The results indicated that aspirin likely protects against colon cancer and lowers the risk by 14% to 29% at doses as low as 75 mg / day, with a dose-response effect of up to 325 mg / day being reported.
Use of NSAIDs for up to 5 years was associated with a significant (26% to 43%) decrease in colorectal cancer incidence.
Magnesium intake of at least 255 mg / day was associated with a 23% lower risk compared to the lowest intake, and high folic acid intake was associated with a 12-15% lower risk, although it was not possible to establish a threshold dose from the available data.
Similarly, the consumption of dairy products was associated with a 13 to 19% lower risk of disease. However, the small number of meta-analyzes available and the wide variety of research results and diversity of dairy products contained make it difficult to draw firm conclusions about the amounts needed to ward off the disease, the researchers warn.
Dietary fiber intake was associated with a 22 to 43% lower risk, while the intake of fruits and vegetables was associated with up to 52% lower risk, with an added benefit for each additional 100 g / day increase in intake .
Dietary soy intake was associated with a modest but significant decrease in risk (8-15%).
However, there was no evidence that vitamins E, C, or multivitamins were protective. Similarly, there was no evidence that β-carotene or selenium helped ward off the disease.
The data were weak or inconclusive about the effects of tea; Garlic or onions; Vitamin D either alone or in combination with calcium; Coffee and caffeine; Fish and omega 3; and inconsistent on the protective effects of vitamin A and the B vitamins.
A modest protective effect was found in observational studies for high calcium intake, but a meta-analysis of data from clinical studies found no protective effect and even an increased risk.
Although meta-analyzes of observational studies suggest that statins may lower the risk of cancer, no positive effect was found in meta-analyzes of clinical study data.
Most of the available meta-analyzes from observational studies showed an increased risk of between 12% and 21% for meat, especially red and processed meat. Dose-response studies reported a 10 to 30% increased risk for every additional 100 g / day of red meat consumed.
Alcohol was associated with a significantly increased risk. The higher the intake, the greater the risk. This was already evident at the lowest consumption tested: 1-2 drinks / day.
The researchers warn that the level of evidence is low or very low in most cases, mainly due to large differences in study design, endpoints, number of participants, etc. And they could not define an "optimal dose and exposure duration". Intake for any of the products, even in the case of low-dose aspirin and other compounds that have been extensively studied, "they point out.
Still, they suggest that their findings could help clinicians advise patients on the best diets to lower colorectal cancer risk and guide future research.
Lower risk of death from colon cancer due to high omega-3 intake after diagnosis
Review: Recent Advances In Clinical Practice: Chemoprevention Of Colon Cancer In The Average Risk Population, Good (2020). DOI: 10.1136 / gutjnl-2020-320990
British Medical Journal
Dietary Folate, Magnesium and Dairy Products Can Fight Colon Cancer (2020, September 28)
accessed on September 29, 2020
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