In late October 2015, the World Health Organization (WHO) released a report of the International Agency for Research on Cancer (IACR, its acronym in English) in which the processed red meats are now classified as carcinogens Group 1 of the IARC , the same group to which the cigarette, asbestos and ionizing radiation belong. For those not familiar with the term a carcinogenic substance is one that is capable of stimulating the development of a cancer in the body.
The publication of the WHO report was made in an unclear way for those not accustomed to the language of scientific studies, and quickly the lay press and social networks tried to turn a fact already known for at least a few years in a sensationalist news . Worse, some vehicles began treating red meat as a carcinogen similar to tobacco.
It is nothing new the fact that the daily consumption of red meat, whether processed or not, be considered a risk factor for cancer of the colon and rectum. What has changed is that the WHO declared that the level of scientific evidence accumulated in recent years has become sufficient to authorize the issuance of an official report on the subject. The current IARC report was based on a review of 800 scientific studies on the relationship between red meat and cancer and was prepared by 22 experts from 10 different countries.
In this article we explain the WHO report, explaining what are the risks of consumption of red meat and what are the differences between cancer risk from red meat and cigarette.
One of the concepts that cause most confusion in the population is the real meaning of "risk factor". When we say that a product or substance is a risk factor for developing cancer, it just means that statistically, those who consume such a product will have more chance of developing cancer over a lifetime. This in no way means that those who consume the product will necessarily have cancer or who does not consume the product is free from the risk of having cancer.
Being a risk factor does not necessarily indicate that the risk is high. If a substance increases the risk of cancer in just 5%, it is nonetheless a risk factor for it.
The mess that caused the WHO report was that the red processed meats have been allocated in the same risk group of more substances hazardous to health, such as smoking, ionizing radiation and asbestos (asbestos). The IARC group division is made by the degree of accumulated scientific evidence and not the risk size. Ie what the new WHO report meant is that currently there is already enough scientific evidence to say that red meat is a carcinogen as surely as it can be said that smoking is a carcinogen.
Importantly, only the processed red meats (explain further on what they are) were classified as carcinogenic in Group I of IACR. Red meat not processed were classified in group 2A, which means that the scientific studies strongly suggest that this meat is a risk factor for colon cancer, but we still need more quality studies so we can say this with 100% sure.
The report says that at any time the processed red meats are so harmful to health as tobacco. Just to give you an idea of the risk difference, it is estimated that annually worldwide, about 34,000 cancer deaths may be associated with frequent consumption of processed red meat. Since smoking is responsible for more than 1 million deaths annually from cancer and the consumption of alcoholic beverages by more than 600,000.
To further enhance the comparison, the Cancer Research UK, a non-governmental organization dedicated to the study of cancer in the UK, published a report in which it states that if the entire UK population stopped eating red meat, the number of new cases of cancer would fall by about 8800 per year. On the other hand, if the entire population stop smoking, they would least 64,500 cases of cancer every year. That is, the cigarette 7 causes times more cancer cases in the United Kingdom that the consumption of red meat. In addition, about 9 out of 10 cases of lung cancer are caused by smoking, while only 2 out of 10 cases of colon cancer can be attributed to red meat.
Therefore, despite the cigarette and red meat have similar degrees of scientific evidence to be considered carcinogens, so some danger that they offer health can be equated. The cigarette is much more harmful to health than red meat.
What is the risk of consume red meat in large quantity?
IACR report pointed out that for every 50 grams of processed red meat a person consumes each day, it increases the risk of developing colon or rectal cancer by 18%. Not to processed red meat, the risk increases 17% per 100 grams consumed daily. This number may seem large, but it is relative risk rather than absolute risk. Let's put in numbers to facilitate understanding. In Western countries, the average number of new cases of cancer among individuals who consume low amounts of red meat is 56 cases per 1000 people. Among those who consume large amounts of red meat, the incidence is 66 cases per 1000 people. That is, for every 1000 people who do not eat red meat, we have 10 fewer cases of colorectal cancer.
The report shows that the increased risk of colorectal cancer is small but rises progressively as the amount of red meat consumed daily increases. The report, however, did not find sufficient evidence to allow the stipulation of a safe amount of red meat that can be consumed per day. Currently, the recommended daily intake is a maximum of 70 grams of red meat (500 grams per week in total). So if you ate today that 200 grams steak, the ideal is that in the next three days, your source of animal protein is eggs, poultry or fish. Some nutritionists are more radical and suggest consumption of only 300 mg of red meat per week. Unfortunately, as already mentioned, the scientific evidence clearly show us that reducing consumption of red meat can prevent new cases of cancer, but studies have yet to show the exact amount of meat that can be consumed daily or weekly safely.
Common questions about the relation between red meat and cancer
Red meat the cow meat, pig, sheep, horse and goat are considered.
What are the meats that red processed meats are considered?
Processed meat is any meat that has been salted and cured, smoked or fermented aiming to improve the taste or optimize their conservation. In this process are included foods such as sausages, sausages, salami, ham, corned beef, bacon and meat sauces.
Processed meats from other animals such as turkey, are also dangerous?
The WHO report concerns only red meat. There is no evidence that meat unprocessed fish, chicken and turkey causing cancer. However, when it comes to processed white meat (salted, cured or smoked), but there is some evidence that there is an increased risk of cancer. This evidence, however, not as strong as red meat, enough to rank them in group 1.
It is recommended to stop eating red meat?
No, the studies do not point to a need to completely stop consumption of red meat. The studies show that red meat is not the best option animal protein, and excessive consumption is clearly linked to an increased risk of bowel cancer. Red meat can still be consumed, but it should not be the main source of animal protein in your diet throughout the week.
If I stop eating red meat can not have a lack of vitamins or nutrients?
No, as long as your diet is balanced, there is no substance essential to our health that is unique to red meats.
Scientists keep changing your mind about the dietary guidelines, who can guarantee that in a few years red meat will certainly considered harmful?
This idea that science keeps changing his mind is actually a result of lack of understanding of a significant portion of the population about how science works. There is a big difference between scientific consensus and what the lay press reported live for society. Any scientific recommendation should be graded according to their level of evidence. When we say that the association of red meat processed with cancer has evidence level 1, it means that the recommendation is based on very compelling evidence, which means that it is very unlikely that in the future that policy can change.
We often see studies of poor quality gained prominence in the lay press simply because the results are curious or unexpected. Science is not done only with one or two studies. A simple example is the risk of cancer associated with cell phone use. Everyone has heard of studies that point to an increased risk of brain cancer associated with the use of mobile phones. But what nobody says is that none of the studies was considered of great quality, which is why the cell of radiofrequency waves are classified by IACR only group 2B, which is the lowest group in terms of scientific evidence of this classification. Therefore, although there are some studies suggesting an association between cancer and cell phones, from a scientific point of view no one can claim that this relationship is proven.
What types of cancers are associated with the consumption of red meat processed?
The Working Group concluded that IACR processed meat intake causes colorectal cancer. An association with stomach cancer was also observed, but in this case, the evidence is not conclusive so far. Further studies are needed so that we can confirm or rule out this association.
What types of cancers are associated with the consumption of red meat not processed?
The evidence, although not as strong as that of processed meats, point to an association of intake of red meat not processed more a risk for colorectal cancer. There is also evidence, well weaker however, that red meat can also increase the risk of pancreatic cancer and prostate cancer.
