Red Meat - An Objective Review
Red meat is one of the more controversial foods in the history of nutrition. Although humans have been eating it throughout our evolution, many people believe it causes harm. In this article we review the evidence on the health effects of red meat - we will not tackle ethical and environmental issues.
Red Meat Is Very Nutritious
Red meat is one of the most nutritious foods you can eat. It is loaded with vitamins, minerals, antioxidants and various other nutrients that can have profound effects on health. A 3.5-ounce (100-gram) portion of raw ground beef (10% fat) contains (1):
Vitamin B3 (niacin): 25% of the RDA
Vitamin B12 (cobalamin): 37% of the RDA (this vitamin can not be obtained from plant foods)
Vitamin B6 (pyridoxine): 18% of the RDA
Iron: 12% of the RDA (this is high-quality heme iron, which is absorbed much better than iron from plants)
Zinc: 32% of the RDA
Selenium: 24% of the RDA
Several other vitamins and minerals in smaller amounts
This comes with a calorie count of 176, with 20 grams of quality animal protein and 10 grams of fat. Red meat is also rich in important nutrients like creatine and carnosine. Non-meat eaters are often low in these nutrients, which may potentially affect muscle and brain function (2, 3, 4).
Today's Meat Is DEFINITELY not What It Used to Be
People have been eating meat throughout evolution and our digestive systems are well equipped to handle it. Traditional populations like the Masai have eaten much more red meat than the average Westerner but remained in excellent health. Today however, the meat consumed is different than the meat eaten in the past. Back in the day, animals roamed free and ate grass, insects or other foods natural to them.
Picture a wild cow on a field 50 years ago, roaming free and chewing on grass and various other edible plants. The meat from this animal is different than the meat that comes from a cow that was born and raised in a factory, fed grain-based feed and given growth-promoting hormones and antibiotics - this is known as “conventional” meat. Today, many meat products are then highly processed - smoked, cured, treated with nitrates, preservatives and various chemicals.
Therefore, it is important to distinguish between different types of meat:
Conventional red meat: Conventional red meats are fairly unprocessed, but the cows are usually factory farmed. Meats that are red when raw are defined as red meats. This includes lamb, beef, pork and some others.
Processed meat: These products are usually from conventionally raised animals, then go through various processing methods. Examples include sausages and bacon.
White meat: Meats that are white when cooked are defined as white meats. This includes meat from poultry like chicken and turkey.
Grass-fed, organic meat: This meat comes from animals that have been naturally fed and raised organically, without drugs and hormones or artificial chemicals added.
When looking at the health effects of meat, it is important to realize that not all meat is created equal.
Most studies on red meat conducted in the US, primarily examine meat from factory-farmed animals that have been fed grain-based feeds, i.e conventional red meat.
Heart Disease, Diabetes and Cancer
The effects of red meat on health have been well studied. However, most of these studies are observational studies, which are designed to detect associations but cannot prove causation.
Several observational studies show that red meat is associated with a greater risk of cardiovascular disease, cancer and death. Nevertheless, not all red meat has the same health effects.
A very large meta-analysis published in Circulation in 2010 reviewed 20 studies including 1,218,380 individuals. The study found that processed meat intake was associated with 42% higher risk of heart disease and 19% higher risk of diabetes mellitus. However, in this review no significant association was found for unprocessed red meat.
In the EPIC study, a very large observational study including 448,568 people, processed meat increased the risk of death from heart disease and cancer, while no significant effect was seen for unprocessed red meat.
Several observational studies show that red meat consumption is associated with an increased risk of cancer (9, 10, 11). The main type of cancer that red meat appears to cause is colorectal cancer, the fourth most commonly diagnosed cancer. A recurrent issue to recognize with these studies however is that most tended to pool processed meat and unprocessed red meat together.
Other studies have suggested that it is not the meat itself, but rather harmful compounds that form when the meat is cooked (more detail on that later in this article), that contribute to the increased risk (12, 13). Therefore, the cooking method may be the significant determinant of the ultimate health effects of meat.
When it comes to an increased risk of heart disease, diabetes and cancer, it is important to distinguish between processed and unprocessed meat, as the two can have vastly different effects. The observational studies to date seem to agree that processed meat is associated with an increased risk of an early death and many diseases. These risks have not been clearly associated with unprocessed red meat.
But even so, it is important to keep in mind that these studies have limitations and it is difficult to draw strong conclusions from observational studies.
Correlation Does Not Equal Causation
When you look closely, practically all studies that deem red meat as harmful are observational studies. These types of studies can only demonstrate correlation, or that two variables are associated. They can tell us that individuals who eat a lot of red meat are more likely to get sick, but they do not prove that red meat is the cause.
One of the main problems with such studies is that there are always various confounding factors. For example, people who eat red meat may be less health-conscious and more likely to smoke, drink excessively, eat more sugar, exercise less, etc. People who are health-conscious behave very differently than people who are not, and it is not possible to correct for all of these factors.
Another issue with observational studies in nutrition is that they are usually based on food frequency questionnaires, in which people are expected to remember what they ate in the past.
Making health decisions based on observational studies alone can be problematic.
A Look at a few Randomized Controlled Trials
Randomized controlled trials are the gold standard of science. In these studies, people are randomized into groups. For example, one group eats diet A, while the other group eats diet B. Then the researchers follow the people and see which diet is more likely to lead to a particular outcome.
Several randomized controlled trials have examined the health effects of red meat directly. A few studies investigated the effects of red meat on risk factors for heart disease.
One such review of controlled studies concluded that eating half a serving or more of red meat daily does not appear to adversely affect heart disease risk factors such as blood lipids and blood pressure (13). Another review showed that lean, unprocessed beef did not negatively affect blood lipids, compared to poultry or fish (14). One study showed red meat also decreased the levels of the inflammatory marker IL-6 (15).
It should be kept in mid that in all of these studies, lean red meat was examined. To date, no studies have examined the health effects of high-fat red meat.
Taken together, these studies suggest unprocessed red meat may not adversely affect health. However, more studies need to examine whether it affects hard endpoints like heart disease and cancer. The roles of cooking methods and processing techniques also need to be studied further.
Making Red Meat safer
When meat is cooked at a high temperature, it can form harmful compounds. These include heterocyclic amines (HAs), polycyclic aromatic hydrocarbons (PAHs) and advanced glycation end-products (AGEs).
These substances appear to cause cancer in animals and may be responsible from some of the increased cancer risks in people (16, 17, 18). Foods other than red meat can also form harmful compounds when heated excessively, but these are generally found in much higher levels in meat.
Many people love the taste of fried and grilled meat. But if you want to enjoy meat and receive the full benefits while reducing the potentially harmful consequences, gentler cooking methods and avoiding burnt meat is advised. Here are some tips on ways to help reduce your exposure to these harmful substances:
When grilling, marinate your meat in garlic, red wine, lemon juice or olive oil. Use herbs such as rosemary, thyme, oregano and other spices which have high antioxidant capacity. These can reduce HAs and AGEs significantly.
Gill or fry outside (fry using a skillet on your outside grill). Doing this outside rather than inside significantly reduces exposure to HAs and PAHs, which are mostly airborne.
Use gentler cooking methods like stewing and steaming instead of grilling and frying.
Minimize cooking at high heats and minimize exposing your meat to a flame.
If you must cook at a high heat, flip your meat frequently to prevent it from burning.
The Bottom Line
When you look at the data, processed meat is something to be avoiding as the evidence is strong for causation in cancer. There does not appear to be strong evidence linking red meat to disease in humans. However some risks may exist with high levels of consumption of conventional meat and cooking methods.
As long as you select unprocessed, preferably grass-fed red meat, and take a few simple steps in your cooking methods to reduces exposure to potentially harmful substances, there is probably nothing to worry about. Occasional consumption of properly cooked high-quality red meat is likely very healthy, though I do recommend that animal protein (particularly red meat) makes up no more than 10% of one’s daily calories.