As discussed in my two previous posts it is clear that eating a diet that is high in animal protein is a great way to facilitate weight loss, decrease insulin resistance and provide key nutrients in the right quantities. However, many people have raised concerns about such diets, claiming they can damage our bones, cause heart disease and give rise to certain forms of cancer.
But do they?
Do High Protein Diets Cause Bone Loss?
When proteins are digested acids are produced. Because the body functions within a narrow range of acidity, excess acids produced in this way must be neutralized. One of the main ways your body neutralizes acids is by binding them to phosphate, a mineral that is contained in bone.
While this process solves the immediate problem of excess acidity, it also displaces calcium from the bone. This calcium is then lost in the urine. Over time, calcium lost in this manner can lead to the development of osteoporosis, a condition in which bones become fragile and easily fractured. This has led to the concern that high protein diets can cause or worsen osteoporosis. 35,36
However, this does not appear to be the case. Studies have shown that people on high protein diets do not have increased bone loss. 37-47
In fact, people on high protein diets appear to have stronger bones than those following low protein diets: Diets that are high in animal protein (but not vegetable protein) have been shown to reduce the incidence of fractures in older people. This would indicate that such diets actually protect against osteoporosis rather than help create it. 48,49
Cavemen Don’t Get Fractures
The archeological record has also shown that high protein diets are good for bones.
Our hunter-gather ancestors, who ate lots of meat, had very strong bones and teeth.
This changed, however, following the agricultural revolution and the introduction of a lower protein, grain-based diet.
Studies of the bones and teeth of ancient people who ate these reduced protein diets show that they had begun to develop bone disorders like osteoporosis and rickets as well as dental cavities. 62
Do High Protein Diets Cause Heart Disease?
Another concern regarding diets that are high in animal protein is that they tend to be high in saturated fat. This has led to the concern that these diets increase the risk of heart disease. But this does not appear to be the case, either!
While excessive saturated fat can easily be avoided by eating grass-fed rather than grain- fed animals, even those high protein diets that are very high in saturated fats like the Atkins diet do not appear to increase the risk of heart disease.
In fact, high protein, low carbohydrate diets improve blood lipid profiles. High protein diets have consistently been shown to lower triglyceride levels, to either not change or only slightly increase LDL (bad) cholesterol levels and to improve HDL (good) cholesterol levels.63
As mentioned in the previous chapter, high protein diets also improve blood sugar levels, reduce insulin resistance and lower circulating levels of insulin, all of which decrease the risk of developing coronary heart disease. 20,51,52
High protein diets also lower blood pressure: studies have shown that an inverse relationship exists between blood pressure and animal protein intake, reducing yet another major risk factor for heart disease. 52, 54
And this decreased risk of heart disease is not just theoretical: The Nurses Health Study, a large research study that tracked the dietary habits and medical histories of 127,000 nurses over 27 years found a 26% lower rate of cardiovascular disease in women who had the highest protein intake compared to those who had the lowest protein intake. 55
Is Protein Bad for Your Kidneys?
Another concern about high protein diets is that they may cause or worsen kidney disease.
When dietary protein is digested, protein waste products are created. If these waste products are allowed to accumulate in the blood they become toxic.
This normally does not occur because the kidneys filter these potentially toxic wastes out of the blood and excrete them in the urine. Normal kidneys can easily remove protein waste products even when very large amounts of protein are eaten. Several studies have shown that high protein diets do not have an adverse effect on normal kidney function, nor do they lead to kidney disease. 64-68
However, high protein diets may cause problems for people who already have kidney disease. Unhealthy kidneys lose their ability to remove protein waste, so these wastes begin to build up in the blood. Lowering the amount of protein in the diet reduces the amount of waste that is produced and helps keep these wastes from becoming toxic. Low protein diets may also slow the progression of kidney disease in some people. 69, 70
If you have kidney disease or have been told that you have an elevated blood urea nitrogen (BUN) or creatinine follow your doctor’s advice regarding the protein content of your diet.
Is Red Meat Bad Meat?
Over the past several years, red meat has been given a particularly bad rap as an unhealthy food. But is it?
Remember that when we question whether a food is good for us or not, we need to look at what our hunter-gather ancestors ate. If they ate it, then it’s part of our natural diet, and we can assume that it is a food that is good for us, not bad.
And our early ancestors not only ate a lot of meat, they ate a lot of red meat! 62
Red meat is nutrient dense. In addition to supplying all the essential amino acids, it is a rich source of the minerals iron and zinc, elements that many of us currently lack in our diets.
What may be bad about today’s red meat is not the fact that it is red but that it comes from artificially fattened, grain-fed animals.
Modern feeding practices not only produce meat that has too much fat, they also alter the composition of those fats. Fat from grain-fed animals consists of more inflammatory omega-6 fats and fewer anti-inflammatory omega-3 fats than meat from the wild animals our ancestors ate. This fat composition is not healthful - either for the animal or for you. But the solution is not to avoid red meat.
Instead, you want to eat red meat from animals raised on their natural diet which consists of grass, not grain. You also want to avoid meat from animals given antibiotics or hormones to artificially promote rapid weight gain, because some of these substances can accumulate in the animal’s tissues. Grass-fed beef as well meat and eggs from wild game and naturally or “range-fed” poultry are becoming increasingly available in local health food stores and are also available by internet mail order.
Does Red Meat Cause Heart Disease?
As previously mentioned, high protein diets do not appear to cause heart disease. But does that hold true when most of that protein comes from red meat?
In a word, yes!
In fact there is an increasing amount of evidence that eating red meat has a positive effect on cardiovascular health. Studies have shown that people who ate high protein diets in which the protein was supplied by red meat improved their triglyceride levels as well as their cholesterol, blood sugar and fasting insulin levels - all of which are associated with a decreased risk of cardiovascular disease.
For example one study that used red meat to increase the protein content of the diet from 17% to 34% found that those who ate the diet higher in red meat decreased their triglyceride levels by 22 % while those who ate the lower protein diet decreased their triglyceride levels by only 8%.71 *
And a study that compared the use of beef with chicken as the primary source of protein in a calorie- restricted diet showed no difference in their effect on cholesterol levels.
Does Red Meat Cause Cancer?
Several studies have supported a possible association between consumption of red meat and the development of cancers of the colon and rectum.
However, the European Prospective Investigation into Cancer and Nutrition (EPIC), the largest study of diet and health ever undertaken, found that an increased risk of intestinal cancers only occurred when people ate processed meats. 72 And other studies have shown that eating 28 grams a day of fiber along with the meat completely eliminates any increased risk of intestinal cancer.73
The risk of developing this type of cancer is also substantially reduced by weight loss – which is facilitated by eating a diet high in animal protein.
In Short...
It does not make sense that a food that formed such a large part of our natural evolutionary diet would cause cancer, heart disease or any other kind of disease process. When evaluating a study that suggests that red meat, or any meat has adverse health effects, always ask yourself if the meat the people in the study ate was processed or if it came from animals fed an unnatural diet of grain rather than grass.
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* Those who ate the diet that was high in red meat also increased their Vitamin B-12 levels by 9% while vitamin B12 levels of those who ate the lower protein diet decreased 13%.
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CHAPTER SUMMARY
1. High protein diets do not appear to be associated with the development of either osteoporosis or coronary heart disease (CHD). In fact, high protein diets appear to strengthen bone and to decrease the risk of developing CHD.
2. High protein diets do not cause kidney disease. However, they may be injurious for people who already have kidney disease. If you have kidney disease, follow your doctor’s advice regarding the amount of protein in your diet.
3. Some studies have associated the consumption of red meat with the development of intestinal cancers. However, this appears to be the case only when the meats in question are processed.
4. Most of the meat our hunter-gatherer ancestors ate was red meat. When you eat unprocessed red meat obtained from animals fed their natural diet the health effects are positive, not negative.
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