The Evidence on Red Meat: Is it Carcinogenic or Healthy?

For a long time, people have had different perceptions about red meat.

Some believe that eating red meat causes cancer, and some who follow a carnivore diet believe that red meat has cured many of their diseases and made their bodies the best they have ever been.

So should we consume red meat? How much, and how should we eat it?

Definition of Red Meat

Generally speaking, red meat is called “red” because it contains a protein called myoglobin. It keeps the muscles oxygenated, and the ferrous ions it contains turn the muscles red.

The amount of myoglobin determines the color of the meat.

Myoglobin has three different forms which can also be converted into one another. Fresh beef is bright red on the outside, and purple on the inside when cut. This is because the outer layer of the meat is in contact with oxygen, which changes the form of myoglobin.

The inside retains the color of myoglobin as it has not been exposed to oxygen. Cooked or air-dried beef turns brown because the cooking and drying process further changes the form of myoglobin.

Defining red meat based solely on its color is somewhat confusing. For example, the flesh of tuna is pink, and some meat that is originally pink turns white when cooked. To simplify things, the World Health Organization (WHO) has defined red meat as the muscle meat of all mammals, including beef, veal, pork, lamb, mutton, horse, and goat.

Where Did the Claim That Red Meat Is Carcinogenic Come From?

Many people are afraid to consume red meat because they have heard it can cause cancer.

The truth is, for something to be classified as carcinogenic in scientific research, the suspected carcinogen is usually tested against three criteria to see how many of them it meets. If it meets all three, it will be classified as a carcinogen without a doubt.

To determine whether red meat is carcinogenic, it needs to go through the following process:

1. The first step is to conduct animal experiments. A common practice is to divide the laboratory animals into two groups: one that regularly consumes a certain amount of red meat through diet, and one that consumes no red meat. At the end of the experiment, the two groups are compared to see if there is any difference in their risk of developing cancer.
2. The second step is related to the mechanism of carcinogenesis. The carcinogenicity of red meat consumption is investigated using biochemistry or molecular biology.
3. The third step is large-scale statistical surveys of the population, and it is mainly conducted with observational studies, such as telephone surveys or questionnaires. Individuals are divided into two groups, one that consumes more red meat and one that consumes less, and the incidence of cancer in these two groups is analyzed after several years.

Throughout the process, numerous experiments must be conducted and reach the same or similar conclusions before results can be considered sufficient evidence.

It is inaccurate to conclude whether red meat causes cancer based on individual studies.

The WHO divides agents that may cause cancer into four groups according to the level of evidence. If a substance meets the above three criteria, it will be listed as a Group 1 carcinogen, alongside tobacco and alcohol.

At present, red meat does not meet the third criterion—that is, a large-scale survey of the population. In other words, there is not enough convincing experimental data to prove that the consumption of red meat is directly related to cancer, like tobacco and alcohol.

Therefore, red meat is listed by the WHO as a Group 2A carcinogen—meaning it is probably carcinogenic to humans, but its carcinogenic effect is not conclusive.

New Meta-Analysis Finds Weak Evidence of Association Between Red Meat Consumption and Cancer

A recent meta-analysis published in the Nature Medicine journal also conducted a rigorous judgment and evaluation of the carcinogenicity of red meat consumption.

Researchers at the Institute for Health Metrics and Evaluation, University of Washington, collected and analyzed 55 studies from different populations around the world. Participation in each study ranged from 600 to more than 530,000, and the follow-up time ranged from four to 32 years.

The researchers devised a five-star rating system to assess the risk of smoking, consumption of unprocessed red meat, and other factors (such as insufficient intake of vegetables) in relation to a person’s health outcomes (including breast cancer, colorectal cancer, Type 2 diabetes, ischemic heart disease, ischemic stroke, and hemorrhagic stroke).

The system’s purpose was to visualize the relative likelihood of red meat causing cancer (with five stars suggesting very strong evidence of association, and one star suggesting no evidence of association).

The results of the study rated the association between consumption of unprocessed red meat and colorectal cancer, breast cancer, Type 2 diabetes, and ischemic heart disease at only two stars—that is, the evidence is weak. Additionally, the association between unprocessed red meat and ischemic or hemorrhagic stroke was also rated two stars.

The researchers noted that while there were some studies linking the consumption of unprocessed red meat to an increased risk of disease incidence and mortality, they were “insufficient to make stronger or more conclusive recommendations.”

Also, the researchers were unable to make a “strong recommendation for red meat intake level” due to wide uncertainty and the weak association between red meat consumption and cancer incidence (only two stars).

Although the results of the study are reassuring, the impact of red meat consumption on the body is worth exploring further.

Dr. Weldon Gilcrease, an associate professor in the oncology division at the University of Utah School of Medicine and a Huntsman Cancer Institute investigator, said in an interview with The Epoch Times that it is indeed hard to “tease out the impact of a single risk factor” in many large-scale epidemiological studies.

However, the link between diet, lifestyle, and cancer is real. For example, he said that people who originally lived in Japan and immigrated to the United States may have an increased risk of cancer due to the influence of Western diet and lifestyle. The relationship between red meat intake and cancer risk, however, may still depend on the amount of red meat the individual consumes.

On the other hand, red meat actually offers many nutritional benefits.

Red Meat Has More Nutrients Than Iron Supplements

Nutritionist and registered dietician Amy Gonzalez mentioned in an interview with The Epoch Times that the nutrients in red meat are easily absorbed and utilized by the body. Red meat’s various nutrients are “packaged and matched,” so you can get more nutrition from a smaller “package.”

1. Iron supplementation from red meat is more efficient and safe

Red meat, such as beef and lamb, is one of the richest sources of iron and zinc.

According to the exposure data of one study, 100 grams of lean beef can provide about 1.8 mg of iron and 4.6 mg of zinc, accounting for about 14 percent and 42 percent of the recommended dietary intake of these nutrients.

In addition, compared with the iron found in plants, the iron in meat is mostly in the form of heme iron, which is better absorbed by the body; meat protein will also enhance the body’s absorption of iron.

Gonzalez recommends people with anemia and women with heavy menstrual bleeding increase their red meat intake appropriately. This is because the iron in red meat is a “really good bioavailable source of iron.” It provides better iron supplementation than iron supplements, and it is also less likely to be consumed in excess.

The human body needs micronutrients (such as copper and zinc) and vitamin C to help it utilize iron and convert it into hemoglobin in red blood cells. Consuming red meat will also provide us with a variety of nutrients, all of which help the body utilize iron properly.

Similarly, the body absorbs zinc more efficiently from red meat than from plant-based foods. Red meat is also a good source of selenium. Every 100 grams of lean beef meat provide about 17 micrograms of selenium, which is equivalent to about 26 percent of the recommended dietary intake for this nutrient.

2. Red meat contains highly digestible protein

Red meat is rich in protein: Every 100 grams of raw red meat contains 20 to 25 grams of protein, according to findings reported in the Nutrition & Dietetics Journal of Dieticians Australia.

The protein content of cooked red meat can even reach 28 to 36 grams per 100 grams due to the reduction of water content in the cooking process. Red meat is known as a “complete” protein, as it provides all the amino acids the body needs, whereas plant-based proteins are known as “incomplete” proteins because they do not contain all essential amino acids.

The digestibility of protein in red meat reaches 94 percent. The Protein Digestibility Corrected Amino Acid Score is used to assess the quality of a protein, with the highest possible score of 1.0. Red meat scores around 0.9, while most plant-based foods score between 0.5 and 0.7.

3. Red meat is a source of high-quality fatty acids

The fats in red meat include saturated fats, monounsaturated fatty acids, and polyunsaturated fatty acids. Polyunsaturated fatty acids (PUFA), also known as the “good fats,” account for 11 to 29 percent of the total fatty acids in red meat.

It is worth noting that pasture-fed beef is the first choice for those who want to obtain high-quality fatty acids from red meat, as they contain more omega-3 fatty acids. On the other hand, grain-fed beef is relatively high in omega-6 fatty acids because it is produced through grain feeding such as corn. Red meat like beef and lamb also contains more omega-3 fatty acids than chicken.

4. Red meat is rich in vitamins, especially vitamin B12

Red meat is rich in B vitamins such as B3, B6, B12, and thiamine. One hundred grams of lean beef provide 2.5 micrograms of vitamin B12, which is equivalent to 79 percent of the recommended dietary intake for this nutrient, according to the same exposure data. The older the animal, the richer the meat will be in B vitamins. Pork contains high levels of thiamine compared with other meats.

While the concentration of vitamin E is lower in red meat, it is higher in fatty meat.

According to the Nutrition & Dietetics study mentioned earlier, 100 grams of cooked beef can provide 12 percent of the daily vitamin D requirement for middle-aged and elderly people aged 51 to 70, while 100 grams of cooked lamb can provide more than 25 percent of the daily vitamin D requirement. Therefore, for the elderly who spend less time outdoors, consuming these red meats can be another effective way to obtain vitamin D.

While Red Meat Is Nutritious, a Carnivore Diet Carries Risk

Some people are afraid of eating red meat, and some people eat red meat to the extreme. Another huge controversy revolving around red meat is the all-meat/carnivore diet.

This diet involves eating only meat or animal products (all kinds of meat, fish, and eggs), and excluding any carbohydrates.

One of the reasons that people advocate for this diet is that it was the way of our hunter-gatherer ancestors.

However, describing the diet of ancient people as consisting mainly or only of meat can be misleading and inaccurate. This is because archaeological evidence and observational studies of several surviving primitive tribes suggest that our ancestors ate a wide variety of foods, including high-carb foods such as fruits, vegetables, starchy vegetables, and honey.

Omitting fruits and vegetables from your diet without a doctor’s advice and guidance can lead to adverse consequences.

A carnivore diet is extremely low in fiber, which can cause constipation. Constipation is not just an inability to defecate—it damages the body and mind in many ways.

A carnivore diet is high in saturated fat, which raises bad cholesterol in the blood and puts a person at risk for cardiovascular diseases. Consuming a lot of meat protein can also put undue stress on the kidneys. Furthermore, many processed meats, such as bacon and luncheon meat, are high in sodium, and a high-sodium diet can lead to kidney problems and high blood pressure.

What Is The Healthiest Way To Consume Red Meat?

1. Eat a variety of red meat alternately, two or three times a week

Gonzalez said that the recommended amount of red meat intake varies from person to person. For the average person, the approximate recommended intake of red meat is two to three servings per week, and each serving is about the size of a palm (about 100 grams).

Gilcrease recommends eating red meat no more than twice a week.

We can alternate various red meats in our daily diet. In addition to red meat, we should also consume a mix of other meats, such as various poultry and seafood.

2. Avoid frying and grilling, as low-temperature cooking is healthier

Cooking methods such as low-temperature roasting and poaching not only preserve the natural flavor of red meat, but also prevent the production of toxic substances.

Gonzalez explained that improper cooking methods, such as high-temperature frying and charcoal smoking, can char the meat. Toxic byproducts, including heterocyclic aromatic amines (HAAs) and polycyclic aromatic hydrocarbons (PAHs), are produced during this process.

These substances are produced in greater amounts during high-temperature cooking compared with low-temperature cooking. Meat processing methods such as curing and smoking will produce carcinogenic chemicals including N-nitroso compounds (NOCs) and PAHs.

Besides, heat-processed meat produces advanced glycation end products (AGEPs), which are commonly found in canned and deli processed-meat products.

According to the Nutrition & Dietetics study, AGEPs are a normal part of the body’s metabolism, but they can become pathogenic if their levels are very high in tissues and in circulation.

Source: The Evidence on Red Meat: Is it Carcinogenic or Healthy? | Principia Scientific Intl.