An immense amount of research is being conducted to find out the relation between animal based foods and cancer risk rate. Do all animal foods increase the risk of developing cancer? In this article, we review if the consumption of animal foods increases cancer risk. We also explore the effects of processing and preparation of animal foods on cancer risk.
Factors That Could Influence The Cancer Risk associated with Animal Foods
Here are some factors that can influence the cancer risk associated with animal foods.
Cooking animal foods at high heat will trigger the release of carcinogens. The byproducts include Polycyclic Aromatic Hydrocarbons (PAHs) and Heterocyclic Amines (HCAs). The reaction of amino acids and creatines (found in meat) with heat results in the production of HCAs. The reaction begins at 100°C and its rate tends to increase exponentially from 300°C and more. More HCAs and PAHs are produced when meat is cooked at higher temperatures for longer periods of time.
Some issues that will be discussed later in this article relate to the cholesterol content of meat. Heme iron is another concern. Its percentage is quite high in red meat, processed meat and liver. Choline that is present in high amounts in egg, red meat and milk is eventually converted to trimethylamine oxide. This is capable of increasing the inflammation levels in the body.
Industrialized husbandry practices have significant impacts on the quality of the animal food we eat. Pesticides that are present in the animal feed and hormones or medicines that are given to the animals leave toxic residues in their bodies and these end up in the meat that we eat.
Some Animal Foods And Associated Cancer Risk
Let us discuss in detail about the common animal foods and the ways in which they increase cancer risk.
By-products of high heat cooking are known to be carcinogenic. In fact, many preclinical studies have shown that HCAs increase the occurrence of tumors in various sites including lung, mammary glands, stomach, lungs, pancreas, prostate glands and esophagus.
Some studies have suggested a positive relationship between a high intake of red meat and esophageal cancer. Several studies were conducted to find out the association between colorectal cancer and red meat intake. According to a meta-analysis of 5 cohorts and 16 case-control studies, there is a 36% increase in the risk of colorectal cancer for every 100-gram increase in daily red meat intake.
The increased risk of breast cancer due to red meat intake is influenced by various factors including heme iron, exogenous hormones, by-products of cooking and NEUR5gc, an animal sugar that leads to inflammation and tumor formation if absorbed by human tissue.
Heme iron content of red meat is also associated with an increased risk of stomach cancer because heme iron acts as a growth factor for H Pylori. The byproducts of high heat cooking are linked to the risk of pancreatic cancer.
Evidence supporting the link between cancer and processed meats is found in the literature. In addition to the heme iron content, HCAs and PAHs, the processing methods also contribute to the cancer risk associated with processed meat.
A 2014 meta-analysis suggested that a high intake of processed meat increases the risk of esophageal cancer. Salted meat may increase the risk of gastric cancer according to another analysis. Higher levels of salt damage the mucosa in the stomach and increase the risk of H.pylori infection, a gastric cancer risk factor.
Different from red meat and processed meat, poultry may lead to a decreased risk of cancer. A meta-analysis that studied the relationship between colorectal cancer and poultry intake found that there is an inverse relation between the factors. Studies find that the intake of poultry reduced the incidences of lung and esophageal cancer. The inverse relation could be due to the lower heme content of poultry or due to the overall healthier lifestyle of the participants of the study.
Dairy shows both positive and negative associations with cancer risk. Components like calcium, CLA, vitamin D and probiotic content in dairy are known to have protective properties while compounds like IGF-1 and phosphorous may lead to some negative effects.
The research regarding the link between gastric cancer and dairy consumption has mixed results. A 2015 meta-analysis showed that dairy intake produced protective effects. Another meta-analysis, however, showed that dairy products may not be actually protective against gastric cancer but did not increase cancer risk as well. Yet another meta-analysis suggested that dairy intake was associated with a non-significant increase in the risk of cancer.
Planning your diet appropriately and avoiding high heat cooking of animal foods are important in reducing the chances of developing cancer at some stage in our life.