July 24, 2013 | by Kris Gunnars
Red meat is one of the most controversial foods in the history of nutrition. Despite the fact that humans have been eating it throughout evolution, many people believe that it can cause harm. I’d like to sort through the hype and hoopla and figure out what the evidence has to say. This article will focus on the effects that red meat has on health. I’ll leave the ethical and environmental stuff for someone else to tackle.
Today’s Meat Isn’t What it Used to be
Humans have been eating meat throughout evolution and our digestive systems are well equipped to handle it. Traditional populations like the Inuit and Masai have eaten lots of meat, much more than the average Westerner, but remained in excellent health (1, 2). However, the meat we eat today is vastly different from the meat our ancestors ate. Back in the day, animals roamed free and ate grass, insects or whatever was natural to them.
Picture a wild cow on a field 10.000 years ago, roaming free and chewing on grass and various other edible plants. The meat from this animal is completely different from the meat derived from a cow that was born and raised in a factory, fed grain-based feed, then pumped full of antibiotics and hormones to make it grow faster. Today, some of our meat products go through even more processing after the animals are slaughtered… they are smoked, cured, then treated with nitrates, preservatives and various chemicals. Therefore, it is very important to distinguish between the different types of meat:
- Processed Meat: These products are usually from conventionally raised cows, then go through various processing methods. Examples include sausages and bacon.
- 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. Includes lamb, beef, pork and some others.
- White Meat: Meats that are white when cooked are defined as “white” meats. Includes meat from poultry like chicken and turkey.
- Grass-Fed, Organic Meat: This meat comes from animals that have been naturally fed, raised organically and not been pumped full of drugs and hormones. They also don’t have any artificial chemicals added to them.
When examining the health effects of meat, it’s important to realize that not all meat is created equal.
The studies on meat, especially the ones performed in the U.S., are mostly examining meat from factory farmed animals that have been fed grain-based feeds.
Bottom Line: It is important to make the distinction between different kinds of meat. For example, grass-fed and organic meat is very different from factory-farmed, processed meat.
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 100 gram (3.5 ounces) portion of raw ground beef (10% fat) contains (3):
- Vitamin B3 (Niacin): 25% of the RDA.
- Vitamin B12 (Cobalamin): 37% of the RDA (this vitamin is unattainable 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.
- Then there are plenty of other vitamins and minerals in there too, 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 deficient in these nutrients, which can have negative effects on various aspects of health, including muscle and brain function (4, 5, 6). Grass-fed beef is even more nutritious than grain-fed, containing plenty of heart healthy Omega-3s, the fatty acid CLA, along with more Vitamins A and E (7, 8, 9).
Bottom Line: Red meat is very nutritious, especially if it comes from animals that have been naturally fed and raised. It’s a great source of protein, iron, B12, Zinc, Creatine and various other nutrients.
Cardiovascular Disease, Diabetes and Death
The effects of red meat on health have been intensively studied. However, most of these studies are so-called observational studies, which can not prove causation, just that some things are correlated. There are some observational studies out there saying that red meat is associated with a greater risk of cardiovascular disease, diabetes and death (10). However, if you look at larger studies that are of higher quality, you find that the effect of red meat diminishes.
In a massive review of 20 studies that included a total of 1,218,380 individuals, processed meat was associated with an increased risk of cardiovascular disease and diabetes. However, no association was found for unprocessed red meat (11). In the EPIC study, a very large observational study that includes 448,568 individuals, processed meat increased the risk of death while no effect was seen for unprocessed red meat (12). When it comes to an increased risk of cardiovascular disease, diabetes and death… it is crucial to distinguish between processed and unprocessed meat, because the two can have vastly different effects.
The observational studies seem to agree that processed meat (not unprocessed red meat) is associated with an increased risk of an early death and many diseases. But even so, it’s important to keep in mind the limitations of these studies. Conclusions drawn from observational studies tend to be wrong. The only way to establish cause and effect is to perform randomized controlled trials.
Bottom Line: Some observational studies show a link between meat, diabetes, cardiovascular disease and death. However, other studies reveal that the association is found only for processed meat, not unprocessed red meat.
Does Red Meat Increase Your Risk of Cancer?
There are many observational studies showing that red meat consumption is associated with an increased risk of cancer (13, 14, 15). The main type of cancer that red meat is believed to cause is colorectal cancer, the third most commonly diagnosed cancer in the world. A recurrent problem in these studies is that they seem to pool together processed meat and unprocessed red meat, which is unacceptable. Meta-analyses where researchers analyze data from many studies show that the increased risk of colorectal cancer is very low. One meta-analysis found a weak effect for men, but no effect for women (16, 17).
Other studies show that it may not be the meat itself that is contributing to the increased risk, but harmful compounds that form when the meat is cooked (18). Therefore, the cooking method may be a major determinant of the ultimate health effects of meat.
Bottom Line: Several observational studies show that red meat eaters are at a greater risk of cancer, but larger reviews that look at the evidence at a whole show that the effect is weak and inconsistent.
Correlation Does Not Equal Causation
When you look closely, pretty much all the studies that apparently “prove” that red meat causes harm are so-called observational studies. These types of studies can only demonstrate correlation, that two variables are associated. They can tell us that individuals who eat more red meat are more likely to get sick, but they can NOT prove that red meat caused anything. One of the main problems with such studies is that they are plagued by various confounding factors.
For example, people who eat red meat (and everyone “knows” that red meat is bad, right?) are less health conscious and more likely to smoke, drink excessively, eat more sugar, exercise less, etc. The people who are health conscious behave very differently than people who are not and it is impossible to correct for all of these factors. Another problem with these studies is that they’re usually based on food frequency questionnaires, where people are expected to remember what they ate in the past.
It is always a bad idea to make health decisions based on observational studies alone. There are many cases in history where randomized controlled trials end up showing the exact opposite effect. For example, the Nurses’ Health Study once showed that estrogen replacement therapy helped reduce heart disease in women. Later, a randomized controlled trial discovered that it actually increases heart disease (19).
Bottom Line: Observational studies can not be used to determine cause and effect. There are many confounders in such studies and higher quality studies often end up showing the exact opposite effect.
A Look at Some 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.
Unfortunately, I am not aware of any such study that examines red meat directly. However, we do have studies on low-fat diets. These studies have the primary goal of reducing saturated fat, which means that the people in them have to eat less red and processed meat, which happen to be high in saturated fat. The Women’s Health Initiative was a study of over 46 thousand women. One group was instructed to eat a low fat diet, while the other group continued eating the standard Western diet.
After a period of 7.5 years, there was almost no difference (only 0.4 kg / 1 lb) in weight between groups. There was also no difference in the rate of heart disease or cancer (20, 21, 22, 23). There is also a randomized controlled trial that compared the Atkins diet (high in red meat) to the Ornish diet (a low-fat vegetarian diet with no red meat). It is called the A to Z weight loss study (24). After a study period of 1 year, the Atkins group had lost more weight and had greater improvements in all the most important risk factors for disease, although the effects weren’t always statistically significant.
There are also multiple other studies that compare low-carb (high in red meat) and low-fat (low in red meat) diets. In these studies, low-carb diets lead to much better health outcomes (25, 26, 27). Of course, these studies aren’t examining red meat directly, there are a lot more things going on that can affect the results.
Bottom Line: Studies on low-fat diets (low in red meat) don’t show a reduction in cancer. Studies on low-carb diets (high in red meat) almost invariably lead to improved health outcomes.
Red Meat Optimization 101
When meat is cooked at a high temperature, it can form harmful compounds. Some of these include Heterocyclic Amines (HAs), Polycyclic Aromatic Hydrocarbons (PAHs) and Advanced Glycation End-Products (AGEs). These substances can cause cancer in animals.
If meat really raises your risk of cancer (which is yet to be proven) then this may be the reason (28, 29, 30). But this doesn’t just apply to meat, other foods can also form harmful compounds when heated excessively. Here are some tips to make sure your meat doesn’t form these harmful compounds:
- Use gentler cooking methods like stewing and steaming instead of grilling and frying.
- Minimize cooking at high heats and never expose your meat to a flame.
- Do not eat charred and/or smoked food. If your meat is burnt, then cut away the charred pieces.
- If you marinate your meat in garlic, red wine, lemon juice or olive oil, it can reduce HCAs significantly.
- If you must cook at a high heat, flip your meat frequently to prevent it from getting burned.
Now I will admit that fried and grilled meat tastes awesome. I personally prefer the taste and texture of well-done meat.
But if you want to enjoy meat and receive the full benefits without any of the potential harmful consequences, then use the gentler cooking methods and avoid burnt meat.
Bottom Line: In order to prevent formation of harmful substances when you cook meat, choose gentler cooking methods and avoid burning your meat.
Take Home Message
When you look past the scare tactics and the sensationalist headlines, you realize that there are no controlled trials linking red meat to disease in humans. There are only observational studies, which often don’t properly separate red meat and processed meat. They also rely on food frequency questionnaires and they simply can not account for complicated confounding factors like health consciousness.
Observational studies are made for generating hypotheses, NOT testing then. They can not prove that red meat causes anything and personally I find it doubtful because humans have thrived eating wild animals throughout evolution. As long as you’re choosing unprocessed (preferably grass-fed) red meat and make sure to use gentler cooking methods and avoid burnt/charred pieces, then there probably is nothing to worry about.
In fact, I think unprocessed, properly cooked red meat is actually very healthy. It is highly nutritious and loaded with healthy proteins, healthy fats, vitamins and minerals, along with various nutrients known to positively affect the function of both body and brain.
To read more: http://authoritynutrition.com/is-red-meat-bad-for-you-or-good/