Health Risks Associated with Red and Processed Meats Consumption

Reheated sausages on busy weekday mornings, fried bacon for weekend brunches, and ham salad served at parties; for most people, processed meat is a part of their everyday diets rather than occasional choices. Experts say it is time to cut back.

Evidence clearly indicates that processed meat and red meat are unhealthy and can increase risks of coronary artery disease (CAD), type 2 diabetes, dementia, and several cancers, especially colon cancer.

In 2015, the International Agency for Research on Cancer (IARC) classified processed meat as a group 1 carcinogen along with cigarettes, asbestos and plutonium, and red meat into group 2A (Probably carcinogenic).

[Processed meat is meat that has been transformed through fermentation, curing, smoking, salting, or seasoning to enhance flavour and extend shelf life, such as bacon, salami, sausages, bologna, Vietnamese and Chinese sausages, as well as pork and beef jerky. Red meat includes pork, beef, and lamb.]

Researchers suspect that the relationship of various diseases and processed meat and red meat is due to the following reasons:

Oxidative Stress

Nitrite and nitrate added as preservatives can turn into N-nitroso compounds, namely nitrosamines and nitrosamides, during high-heat cooking such as barbecuing, grilling, searing, or frying, where the meat is in direct contact with heat. Besides, meat, especially red meat, contains iron in the form of heme iron, allowing for more production of N-nitroso compounds.

Both substances can induce oxidative stress, causing damages to tissues, increased inflammation, vascular stiffness, impaired insulin response, as well as pancreatic toxicity. All of which increases the risk of type 2 diabetes, heart disease, cancer, and dementia.

Increased Trimethylamine-n-oxide (TMAO)

All meat, especially red meat, is a source of L-carnitine, which is converted to trimethylamine N-oxide (TMAO) by gut microbiota. Researchers found that the level of TMAO is linked to atherosclerotic cardiovascular diseases (ASCVD), a major cause of heart disease.

Colonic Cytotoxicity

Aside from causing oxidative stress, N-nitroso compounds can damage intestinal epithelial cells and induce epithelial proliferation, which ultimately leads to cancer.

Increase of LDL-Cholesterol

Red and processed meat are high in saturated fat. When consumed in large quantity, saturated fat can raise the level of blood LDL cholesterol, a major factor of ischemic heart disease (IHD). In the case of ASCVD, it can result in poor cerebral blood flow, increasing the risk of dementia.

High Blood Pressure

Processed meat often contains high sodium, which can increase blood pressure, the main factor of coronary artery disease. In addition, high blood pressure results in poor cerebral blood flow similarly to high LDL level, increasing risk of dementia.

Weight gain

A study following 373,803 participants from 10 European countries over the course of eight years found that increased consumption of meat and processed meat is linked to weight gain. Increased weight and fat mass are known to heighten the risk of non-communicable diseases (NCDs) such as diabetes, heart disease and cancer.

The good news is that we can eliminate the risk by choosing healthier proteins.

Eating fish, skinless chicken, or plant-based protein such as nuts and legumes helps to reduce the risk of non-communicable diseases including diabetes, heart disease, cancer, and dementia.

According to a 2017 study conducted by Harvard University on 209,568 participants, which was published in the Journal of the American College of Cardiology, consuming vegetables and whole grains can reduce the risk of coronary artery disease by up to 25%. Another study that was published in the BMJ in 2020 found that replacing 1 serving (85 grams) of processed meat with plant-based protein in daily diets can reduce the risk of heart disease by up to 17%.

Not only are they beneficial for the heart, plant-based diets also help against type 2 diabetes. A 2019 study from JAMA Internal Medicine reported that eating plant-based diets can lower the risk of type 2 diabetes by 23%.

This is due to unsaturated fats and dietary fibre in plant-based proteins, which help lower blood cholesterol and slow down glucose absorption. They are also rich in vitamins, and minerals. All of which help to reduce the risk of diabetes, lipid disorder, and heart disease.

We may not need to completely avoid meat and go vegan. Opting for more fish or chicken can also help reduce health risks.

However, red and processed meat is only harmful when consumed regularly. It means that enjoying them sometimes or on special occasions might not be as bad as a regularly consumption.

References

• Pan A, Sun Q, Bernstein AM, Schulze MB, Manson JE, Willett WC, et al. Red meat consumption and risk of type 2 diabetes: 3 cohorts of US adults and an updated meta-analysis. The American journal of clinical nutrition. 2011;94(4):1088-96.
• Wang M, Wang Z, Lee Y, Lai HT, de Oliveira Otto MC, Lemaitre RN, et al. Dietary Meat, Trimethylamine N-Oxide-Related Metabolites, and Incident Cardiovascular Disease Among Older Adults: The Cardiovascular Health Study. Arteriosclerosis, Thrombosis, and Vascular Biology. 2022:ATVBAHA. 121.316533.
• Bernstein AM, Sun Q, Hu FB, Stampfer MJ, Manson JE, Willett WC. Major dietary protein sources and risk of coronary heart disease in women. Circulation. 2010;122(9):876-83.
• Zhang H, Greenwood DC, Risch HA, Bunce D, Hardie LJ, Cade JE. Meat consumption and risk of incident dementia: cohort study of 493,888 UK Biobank participants. The American journal of clinical nutrition. 2021;114(1):175-84.