Meat has a bad reputation. Most people think of meat, especially red meat, as dangerously unhealthy. However, meat has unique properties that make it more nutritious, easier to digest, and less likely to irritate your body than vegetables. Does the science behind meat-phobia hold up under the microscope?
Is red meat less healthy than other kinds of meat?
Meat is made of animal muscle fibers, which come in two major types: fast and slow. Dark muscle fibers (“slow” fibers) are designed for endurance activities, whereas light muscle fibers (“quick” fibers) are designed for rapid bursts of activity. Therefore, dark muscle fibers have greater energy needs. For muscles to make energy, they need an energy source (fat), oxygen to burn the fat, and vitamins and minerals to run the reactions that release the energy from the fat. Therefore, dark meats usually contain more oxygen, more fat, and more vitamins and minerals than light/white meats.
To hold the oxygen, dark (slow) muscle fibers need larger amounts of an oxygen carrier protein called myoglobin. Myoglobin is red, which is why red meat is red. Myoglobin is rich in iron, the mineral that binds oxygen, so red meats contain more iron than white meats. Because most dark meats contain more fat than light meats, they can be higher in calories. However, because dark meats also contain more minerals and B vitamins, they are actually more nutritious than light meats.
Did you know that all types of meat—red, light, and white—whether from mammals, birds, or fish—contain about the same amount of cholesterol? There is no more cholesterol in a pound of steak than in a pound of chicken.
But doesn’t red meat increase risk of death?
A recent study conducted at the Harvard School of Public Health [Pan 2012] claimed that eating red meat increases our risk of death from all kinds of diseases, including heart disease and cancer. This was an epidemiological study, which, by its very nature, is incapable of proving cause and effect; therefore, even if it were the best epidemiological study ever done on the planet, it would be impossible for the authors to conclude that red meat causes death.
Below are just two of the problems I noticed in this study:
- There were two huge groups of people in this study: the Nurses’ Health Study (over 120,000 women) and the Health Professionals Follow-up study (over 50,000 men). Every 2 years, the nurses were asked how often they had eaten red meat over the past 2 years. Every 4 years, the male health professionals were asked how often they had eaten red meat over the past 4 years. Can you imagine? Even though I keep track of what I eat in a daily food record, if you asked me what I ate LAST WEEK (never mind 2 years ago), I honestly couldn’t tell you. Naturally, these questionnaires can’t tell us how often people forget, underestimate, or perhaps even lie about what they were actually eating.
- It just so happened that the people who reported eating the most red meat per day, also happened to be more likely to:
- smoke cigarettes
- be sedentary
- weigh more
- have diabetes
- take aspirin
- eat more calories per day
- drink more alcohol
- eat more dairy products
These are all excellent examples of what researchers call “confounding variables.” Confounding—translation? Confusing. Even if all of the data are accurate, how can we really know whether the people who ate more red meat were more likely to die because of the red meat, or because of one or more of these other issues?
For a more detailed critique of this study, please see Gary Taubes’ excellent blogpost, entitled “Science, Pseudoscience, Nutritional Epidemiology, and Meat.”
Are saturated fat and cholesterol bad for my heart?
Numerous studies by cardiology researchers have finally disproved the myths that dietary fat, meat, and cholesterol cause heart disease. In fact, some of the healthiest diets in human history have been very high in meat and animal fat. We have been eating animal meats, animal fat, and cholesterol for about two million years, but heart disease has only been a major problem for us for about 50 years. The major culprit is therefore much more likely to be something that is NEW in our diets; the current evidence points most strongly to refined and high glycemic index carbohydrates, not fat, meat, or cholesterol.
Does red meat cause cancer?
If meat is so carcinogenic, why was cancer so uncommon until the last century or so? We are not eating any more meat now than we did a hundred years ago, yet cancer incidence is skyrocketing. So, why do we believe that meat causes cancer?
There have been numerous research studies claiming to tie red meat to cancer (particularly colon cancer), however, these were weak epidemiological studies, and are not representative of results in the field as a whole. The fact is that studies of meat and cancer yield very mixed results. Many studies show no connection at all between meat and cancer, and some studies even show a protective benefit. There is simply no solid scientific evidence to support the belief that red meat increases cancer risk.
Charred meats and cancer
Charred meats and wood-smoked meats contain “PAHs” (polycyclic aromatic hydrocarbons) and “HCAs” (heterocyclic amines). PAHs and HCAs have been shown to cause cancer in lab animals. Studies in humans are limited to epidemiological studies, and even these have been inconclusive.
PAHs are present not just in charred meats, but also in anything organic (plant/animal matter) that has been burned–from cigarettes to forest fire smoke to automobile exhaust. PAHs are also present in many other foods, such as cereals, vegetable oils, cheese, and coffee. In fact, cereal products, not meats, are the biggest sources of PAHs in the typical diet.
HCAs, on the other hand, can only be formed from protein-rich foods, such as meat, fish, and poultry.
Grilled and fried chicken can contain even higher amounts of PAHs and HCAs than grilled red meats, yet studies have shown no connection between poultry intake and cancer.
Nitrates and nitrates in processed meats
Nitrates and nitrites are used in the production of processed meats like bacon, salami, and ham. However, they are also found naturally in many plant foods, often in very high amounts. For example, pound for pound, spinach contains at least 30 times more of these compounds than hot dogs do. In fact, some manufacturers of processed meats boast that they use celery powder (very high in nitrate), instead of the more commonly used sodium nitrite to preserve their meats.
What is the difference between nitrates and nitrites? It can be confusing because these terms are often used interchangeably by food manufacturers, physicians, and nutritionists. The reason why people lump them together so often is because nitrates easily turn into nitrites in foods and in the body. Nitrates and nitrites are very similar chemical salts with very similar properties, and mixtures of nitrates and nitrites are often used in food processing. Nitrites are about 3 times more potent than nitrates as preservatives.
In combination with salt, nitrates and nitrites prevent the growth of the bacteria that causes botulism (a type of food poisoning). They also act as antioxidants, keeping the fat in the meat from turning rancid, and giving the meat an unnatural pink color. Nitrates and nitrites themselves have not been shown to cause cancer; however, they can react with proteins in the meat to form nitrosamines, which are known to cause cancer in laboratory animals. The addition of special antioxidants during processing cuts down on this chemical reaction and reduces the amount of nitrosamine formed, but doesn’t eliminate it completely. Therefore it is best to choose fresh, unprocessed meats when possible.
It may also be wise to limit intake of vegetables that are very high in nitrates, such as spinach and celery. Bacteria in our saliva convert vegetable nitrates into nitrites, which we swallow. These nitrites can then react with proteins in our stomach to form nitrosamines, exactly the same way they do during meat processing. These nitrosamines are potential carcinogens; this is why some researchers believe that diets high in nitrates are associated with increasing rates of stomach cancer.
Will animal protein damage my kidneys?
There’s no evidence for it so far. In fact, the human kidney is designed to be able to handle large volumes of animal protein, perhaps because our ancestors would have sometimes needed to eat large amounts of meat at one sitting, instead of eating smaller portions several times per day every day, the way we modern people do.
The vast majority of studies demonstrating a connection between high protein intake and kidney damage have been conducted on laboratory animals, not on people. A recent review of the research examining the connection between diet and kidney disease is only able to cite a single human study of animal protein and kidney problems; it was an epidemiological study, which did not control for refined carbohydrate intake. This study found no association between higher animal protein intake and kidney damage unless the kidneys were damaged to begin with (keep in mind that epidemiological studies cannot prove cause and effect). The review article then went on to cite TEN human studies linking refined carbohydrates (fructose in particular) to the development of specific kidney diseases.
A study done in 1930 of two men who ate a 100% meat diet for a full year revealed no signs of kidney problems whatsoever.
Most reassuringly, a recent 2-yr clinical study of the effects of a high-protein, low-carbohydrate diet on kidney function in humans with healthy kidneys found that it was completely safe [Friedman 2012].
It is far more likely that refined and high glycemic index carbohydrates endanger the human kidney than animal protein. Humans are omnivores, so we have evolved to be able to fuel our bodies using plant and animal foods. However, NO mammal is designed to handle large amounts of refined carbohydrate. This is probably why people with diabetes are at such high risk for kidney problems—they have high blood sugar and insulin levels, which damage delicate blood vessels throughout the body (microvascular disease), including inside the kidney.
Meat is the only nutritionally complete food
Animal foods (particularly when organ meats are included) contain all of the protein, fat, vitamins and minerals that humans need to function. They contain absolutely everything we need in just the right proportions. That makes sense, because for most of human history, these would have been the only foods available just about everywhere on the planet in all seasons.
Below you can see that animal products are superior sources of most essential vitamins and minerals, including 4 that do not exist in plant foods at all:
Meat nutrients are ready-to-use.
In contrast to vegetables, meat does not contain any “anti-nutrients”, like cellulose, phytates and tannins that interfere with digestion or absorption of vital compounds such as vitamins and minerals.
The forms of vitamins and minerals in meat are the easiest forms to absorb:
“Heme” iron, the form of iron found in meat, is 8 times more available to our bodies than “non-heme” (vegetable) iron.
Vitamin A from animal sources is 12 to 24 times more available to us than vegetarian sources.
Vitamins B12 and K2 are only found in animal foods.
Meat is gentle on your delicate system.
While vegetables protect themselves with chemicals that are potentially harmful to our cells, animals protect their meat with claws and fangs, so meat itself does not contain any irritating substances. Meat is an especially friendly choice if you tend to be chemically sensitive.
Is meat hard to digest?
Quite the opposite. Meat is efficiently broken down by our own natural enzymes, so we do not need to rely on intestinal bacteria to help us digest it. This means that there are virtually no intestinal gases produced in the process. Meat is efficiently absorbed by our intestines, so there is very little wasted. The belief that meat contributes to constipation is a myth. Unless you have a specific sensitivity to a certain type of meat, you will have no trouble digesting it. Meat can, however, become “trapped” in your digestive tract behind sluggish high-fiber plant foods and dairy products, which are very difficult to digest.
What about meat and gout?
Please see my blog article: Got Gout but Love Meat?
Can eating meat cause iron overload?
I find no evidence in the scientific or medical literature linking meat consumption to iron overload. It is true that too much iron can be toxic to cells, and it is true that the body has no way to get rid of excess iron other than through the shedding of skin and intestinal cells or through bleeding. However, the body is very smart and knows not to absorb too much iron. The liver releases a hormone called hepcidin which monitors our iron status and tells our intestinal cells exactly how much iron to absorb. On average, we lose 1 to 3 mg of iron per day, so this is approximately how much we absorb. Every article I found about iron overload in humans, including an excellent 2012 review in the New England Journal of Medicine, had to do with genetic diseases that disrupt normal iron metabolism (the most common being hemochromatosis), not with excess meat in the diet. While iron deficiency is a very common diet-related condition, diet-induced iron overload does not seem to exist.
Meat is naturally low in carbohydrate
This means that it is impossible to eat meat and generate a significant insulin spike. Insulin spikes are to be avoided as much as possible, as they seriously destabilize our brain and body chemistry and can lead to inflammation, cell damage, disruption of cholesterol and fat metabolism, and numerous chronic diseases.
What types of meat are healthiest to eat?
Healthy, naturally-raised animals fed their natural diets produce meats with healthier fat profiles, including higher levels of essential omega-3 fatty acids than grain-fed animals.
Avoid factory-farmed, grain-fed animals when you can. Whenever possible and affordable, choose meat products from naturally-raised animals. This means animals that have been fed a diet most similar to what they would eat if they were living in the wild:
- Chickens—grasses, insects, worms
- Turkeys—grasses, insects, seeds, small animals
- Ducks/geese—fish, grass, algae, insects, fruits, nuts
- Pigs— grasses, root vegetables, fruits, nuts, insects, worms, small animals
- Fish—wild, not farmed. Food varies depending on species.
Poultry sellers often boast that their birds are fed an all-vegetarian diet, but if you notice above, birds are naturally omnivores and eat small creatures for protein and fat (worms and insects, for example). This is why backyard birds enjoy suet (animal fat) in the wintertime—insects and worms are scarce in winter and they need the fat and protein for energy.
Bottom Line about Meat and Health:
Healthy animal foods are wholesome and nutritionally complete.
Meat is easy to digest and absorb, and contains no anti-nutrients or irritating substances.
There is no evidence that meat, saturated fat, or cholesterol are harmful to human health. In fact, there is plenty of evidence that meat, saturated fat and cholesterol are vital to health.
Whenever possible, choose healthy meats from naturally-raised animals.
Limit processed meats.
When eating grilled meats, you may want to trim away any burned or blackened edges.