A number of studies have suggested that red meat can play a role in the development of certain cancers. The largest study to provide evidence of the red meat-cancer link involved 478,000 men and women in Europe. It found that eating more than 5 ounces of red meat per day could raise your colon cancer risk by approximately a third, when compared to those who ate the least red meat.
The consumption of chicken did not appear to alter the colon cancer risk and eating fish actually lowered colon cancer risk.
The other substantial study involved nearly 150,000 Americans between the ages of 50 and 74. It found that a diet heavy in red and processed meats increased cancer risk of the colon and rectum. Eating fish and poultry appeared to protect individuals from these forms of cancer. Other studies have sugested that red meat can increase colon cancer risk by between 20% and 28%.
Red meat consumption is also believed to increase the risk of other cancers, including breast, prostate, lung and ovarian cancers.
Why does red meat increase cancer risk?
The conventional thought in recent years was that the act of grilling red meat created various carcinogens. However, new research at UC San Diego has highlighted at alternative theory. Researchers believe that the risk of cancer is increased because red meat contains a substance that is not found in the human body. This substance (called Neu5Gc), increases inflammation which can result in higher cancer risk.
Researchers established the interactions of this chemical by using mice, genetically engineered to not produce it internally. When this foreign chemical integrated with tissue, it triggered a reaction from the immune system and increased inflammation.
Interestingly, the inflammation and cancer risk from this chemical only occurs in humans, which is why researchers had to use genetically modified mice in their tests.
The inflammation from this chemical may also help other forms of cancer take hold within the body. For example, a smoker might be at greater risk of getting lung cancer if they eat a lot of red meat.
Researchers don’t suggest we should stop eating red meat, but simply eat it in moderation. It contains high levels of iron and protein, which benefit the human body. The senior author of the paper, Dr Varki, suggests that red meat consumption for people under 40 years of age is less of a problem. As people get older and their cancer risk increases, the inflammation presents a large threat.
If you decide to continue eating meat, researchers suggest having 3-4 ounce servings 1-3 times a week should present no substantial increase in cancer risk. Interestingly, the lead researcher only eats chicken and fish!
Neu5Gc is a type sugar molecule, referred to as a sialic acid. Researchers believe that sialic acids can affect many parts of the body, causing inflammation, altering brain development and affecting the immune system. It is believed that some diseases make use of sialic acids to hide themselves from the immune system.
The reason that fish and chicken do not carry the same inflammation risk, is that for the most part, they do not carry nonhuman sialic acids like Neu5Gc. The fish that do carry it, carry small amounts. Fish in particular carries properties than can reduce cancer risk, like high levels of Omega-3 fatty acids.
The next step is to find a medication which is capable of helping the body deal with the chemical and prevent the inflammation. These research findings could eventually help lower cancer rates in countries where red meat consumption is very high — like the United States.