Primitive Nutrition 19:
Protein Choices, Part I
I have no problem with any macronutrient. We need them all, including protein. People may want a little more or less depending on their individual needs so I am not claiming there is an exact right amount. However, protein seems to be a point of fixation for the new cavemen so it must be discussed in the Primitive Nutrition series.
Here is the macronutrient composition of a hypothetical woman's daily intake according to Loren Cordain's The Paleo Diet. Note the saturated fat content, although I won't go into that here. Saturated fat is unhealthy and saturated fat and meat are inseparable but this video is focused on the issue of protein. Notice the amount of dietary cholesterol is not listed by Cordain, which is a rather important consideration to leave out. Do the math and you'll see this is a 2300 rather than a 2200 calorie day.
Cordain did calculate the ratios correctly. Clearly we are dealing with a low carb diet here, but low carb is also a separate topic for other videos. What Cordain has imagined here is a woman eating 33% of her calories in the form of protein. That's a lot.
A diet made up of 35% protein has been shown to damage the kidneys of rats.
33% translates into an amazing 190 grams of protein for a woman. How does this primitive advice compare to the recommendations of modern health institutions?
The Centers for Disease Control and Prevention arrived at a much lower figure. They recommend only 46 grams of protein.
What about the World Health Organization and the Food and Agriculture Organization of the United Nations? Well, if we assume the average woman is 5 foot 6 inches and her healthy body weight is 130 lbs or 59 kg, they recommend only 49 grams of protein per day. Exercise physiologist Loren Cordain is recommending almost four times the protein intake as this.
There is also the question of where you get your protein. Government scientists in the UK advise only a pound of red meat per week.
This is similar to recommendations by the European Food Information Council.
Clearly Cordain's meat-centered diet is far out of the mainstream.
Of course, you need adequate protein. This is an interesting study that reinforces that point. In an experiment on mice, the offspring of male mice fed low protein diets were made more likely to have high cholesterol. That is certainly not desirable.
At the other end of the spectrum, the collective world of broscience dictates that you need high levels of protein for strength, but this is not clear from the scientific literature.
For example, in this study of older and younger subjects, high protein diets did increase nitrogen balance, but this seemed to be counterbalanced by a more catabolic state after the protein is absorbed.
High protein diets may also impair performance in endurance exercise.
It's important to get the right amount and mix of amino acids, but it is not clear there is an advantage to animal protein.
As long as you consume the amino acids you need, vegetable sources of protein may provide added benefits, such as preventing chronic diseases.
They also might lower blood pressure, which would be a big plus.
If meat were so healthy by itself, why would researchers bother adding plant nutrients to it to make it healthier?
To put my discussion of protein in the right context, you might pause this video and read Loren Cordain's thoughts on our ability to digest starches. He is asked how he rationalizes not eating important starches when it is clear we have adapted to them over thousands of years.
Don't worry if you don't understand what he is saying. Just notice how hard he is working to get around the basic point that we have clearly been eating starches long enough to have made important adaptations. Also notice that he is relying entirely on old experiments on animals. Imagine how many papers he had to comb through to find these. He did this because most observations about the consumption of unrefined starches by humans are overwhelmingly positive.
As I go through this material about proteins, if you think I'm being somehow unfair, my answer to you is that I am presenting research that is at least as mainstream as what Cordain will reference to turn you off of starches. By failing to address the issues I will raise even as he scavenges every possible demerit for grains and legumes, Cordain reveals his fad-diet-promoting bias. That is true of him and most of the primitive nutrition advocates, and that is my basic point in this video. These guys don't apply their skepticism consistently.
Here is a basic fact. Your body can store excess carbohydrate as glycogen or fat, and we all know it can store excess fat and excess calories in general as fat, but protein cannot be stored as amino acids, and amino acids are the reason we need protein in the first place. Excess protein beyond our needs is instead converted into glucose for energy or triglycerides for fat. It's not used to build or repair tissue.
There is such a thing as reserve protein, but it is used for conversion to glucose for energy, not for protein synthesis.
The process your liver uses to turn protein into glucose is called gluconeogenesis. With enough carbs, this is not necessary and your protein can be used for your body's needs that really require protein.
It seems a lot of the rationale for eating protein in excess is to just burn calories sitting still. Leaving aside whether or not this really works, realize this epitomizes the slouching low carb approach to health. It is not about maximum nutrition. It is not about better performance. It is not about feeling your best. It is about suppressing your appetite and burning calories without having to exercise as much.
The claim that protein speeds up your metabolism implies your body wastes energy trying to process the protein. Much of the extra energy your body expends on a high-protein diet is wasted in gluconeogenesis. This is hardly an efficient use of food calories.
When fed a low-carb, high-protein diet, it is clear that the body tries to compensate for the lack of carbs by producing more glucose from protein.
Over time your body gets better at gluconeogenesis on a high-protein diet. This suggests to me our bodies prefer adequate carbohydrates over excess protein. We adapt to better manufacture carbohydrate when we don't get enough from the diet.
The American Heart Association decided to respond in 2001 to the trend toward high-protein diets for weight loss. They pointed out the obvious. Such an imbalanced diet in favor of one macronutrient means less of another. If all that protein winds up as glucose anyway, why not just eat healthy carbohydrates that bring more nutrients to the table instead? This is one of the most common criticisms of low carb diets. They are nutritionally inadequate.
Let's look at the opposite extreme. Here you see that people following a raw vegan diet, and therefore eating extremely high levels of fresh fruits and vegetables, have significantly higher antioxidant status than omnivores. Additionally, you can be sure they are benefiting from high fiber intake and superior hydration through their foods. The Paleo approach tries to compensate for the comparative nutritional lack in typical low carb diets by making its few calories from carbs come in the form of fruits and vegetables, but this only helps Paleo look good in comparison to nutrient-poor diets. It also limits all the beneficial phytochemicals in plant foods that fight disease. Vegans like these can eat safe and extremely nutrient dense diets so they don't need to accept this trade-off. Every single calorie can deliver health-preserving phytochemicals while the diet as a whole can provide the necessary gross macronutrients we all need.
In one of the journals published by the American Heart Association, these researchers connected the imbalanced high-protein approach to high blood pressure in the children of mothers who ate high animal protein diets. A diet that gives your children high blood pressure sounds less than optimal to me. Claiming cavemen ate like this doesn't make the problem go away.
Another problem with such high meat consumption is gout, a painful condition which is unfortunately making a comeback these days.
Increased meat and seafood consumption explain the increase. Total protein and vegetable protein do not relate to gout risk. This is one reason high protein vegan diets seem to be relatively safe for athletes who want to pursue that strategy.
Gout is just another part of a pattern, in which high animal protein diets can be shown to detract from health. For example, here is a rat study suggesting that high protein diets might lead to diabetes.
Subsequent to that study, protein from red meat was found to be associated with diabetes while vegetable protein was not.
High protein diets are also likely to be detrimental to colon health.
There appears to be a relationship between red meat intake and colon cancer.
High animal protein diets may also damage heart health in ways that are not apparent in the usual blood tests. I'll look soon at some of the reasons why this may be true.
But first, one more basic issue with excess protein. The digestion of protein produces urea, an apparent toxin in elevated amounts that your body works hard to remove. Water is wasted in the effort to eliminate this urea.
This is why people seem to lose weight on high protein diets. Water is lost, and dehydration becomes more likely.
This is one reason why high protein diets are not recommended for athletes. Performance could suffer in a dehydrated state.
This is also why Eskimos were often observed to consume unusually high quantities of water. This doesn't seem like an efficient use of the body's limited resources to me.
With the basics out of the way, let's look at a few of the evolution-based rationalizations for high meat consumption Paleo propagandists have tossed out in the next part of Protein Choices.
Primitive Nutrition 20:
Protein Choices, Part II
Given the basic nutritional arguments one can make against consuming excess protein, what reasons can Paleo promoters find to follow high-protein diets anyway? Well if it's Paleo, there are evolution stories that makes it feel right. But that doesn't mean those stories are right.
It seems irrelevant what dietary patterns enabled our bigger brains thousands of years ago, but for what it's worth, cooking seems like a better explanation than meat. You've seen this already in my Primal Primates presentation.
Here's a more interesting rationale put forth by Cordain for high animal protein consumption in The Protein Debate. I want to repeat that I find most diet advice based on speculation about evolution to be suspect as this approach requires an appeal to nature. Humans, he thinks, have a special high-meat history that makes us super meat-eaters. He says humans have a special adaptation that prevents the overproduction of uric acid, enabling the gorging of meat. His evidence for this is an enzyme called xanthine oxidase.
It turns out this xanthine oxidase adaptation did not take place first in humans. We know this mutation took place before we split off from our primate ancestors, as we share it with the great apes. Cordain has his evolutionary history wrong. This is significant. It proves
Cordain's argument is only a just-so story. It is not hard science.
Just-so stories are a type of ad hoc fallacy.
If you doubt my science on this point, here is another reference for this.
Our closest relatives - chimps, gorillas and orangutans - eat very little meat, yet they share this mutation.
This adaptation was most likely in response to blood pressure regulation in low salt environments, not high meat intake.
Here's another folly of meaty Paleo-logic. Cordain is aware of a condition called rabbit starvation which occurs when too much protein is eaten. Serious illness results because of the high metabolic demands of eating meat. He knows there is a maximum amount of protein the kidneys can process. He also says there is only one case in the medical literature of a person eating enough protein to experience this so-called rabbit starvation. He seems to prefer to think of the rarity of this condition as evidence of how hard it is to induce, rather than as evidence that hardly anyone has been crazy enough to try to induce it. By contrast, there are no similar problems with digesting carbohydrates. You can easily eat 80% healthy carbs for years on end and have no adverse health consequences. Moreover, through the last several millenia the vast majority of humans have eaten high-carb diets, and they were just doing what came naturally. I would think all this would help him realize that humans shouldn't eat high quantities of meat, but somehow he concludes the opposite. He wants us to eat so much meat we are near the body's limits for metabolizing it safely. By definition, his nutrition beliefs are therefore extreme.
We can look at protein and evolution another way. Primitive hunter gatherers have been said to under-utilize lean meats in favor of fat and carbohydrate. This author suggested this may be because high protein can be a problem during pregnancy.
You'll see in my Masai video that they restrict animal protein during pregnancy, but they aren't alone. This practice is commonplace among hunter gatherers.
An alternate hypothesis for this is that meat would have raised the chances of exposure to parasites and other pathogens, so women developed an aversion to meat to prevent infections during pregnancy. It's an interesting idea.
Cordain's last line of this paragraph from The Protein Debate is odd. He references a study showing an apparent improvement in gout symptoms due to high protein consumption. This was a pilot study of only twelve people on calorie restricted diets. He says this study was somehow the proof in the pudding that eating lots of meat is good. Proof in the pudding? He must think this is pretty compelling. As we have seen, gout is strongly linked to high meat intake for obvious metabolic reasons. So what's the explanation for this one? Well, I’ve already hinted at it.
To preface this, look again at this study. This was a widely referenced article. This is strong epidemiological evidence against high-meat diets. By contrast, I haven't seen low protein or vegan diets linked to higher gout risk anywhere.
The study he mentions is usually seen as a reflection of the benefits of calorie restriction and weight loss in obese men with gout. Obesity is strongly associated with gout, so once again, we see that calorie restriction can improve some chronic diseases. Protein intake was not the only diet variable that changed, either. Their whole diet was new. And as I said, this was only twelve people. This study doesn’t prove anything, except that this was the best study Cordain could find to confuse you about the link between meat and gout.
Discussing protein in the context of evolution brings up the interesting case of a nonhuman sialic acid called N-glycolylneuraminic acid, or Neu5Gc. I’ll bet you Paleo guys saw this coming. Humans are unique among mammals in that we cannot produce Neu5Gc.
Agit Varki has examined this curious issue. He believes it has implications for human health.
He has observed that cancer patients accumulate Neu5Gc in their tumors. Since they can't make it themselves, it must come from dietary sources, and those are red meat and dairy. This nonhuman sialic acid seems to contribute to an inflammatory process in cancer.
The inflammation occurs because the immune system recognizes this molecule as foreign. This reminds me a bit of the Paleo fears of lectins, but I've never seen that dietary lectins accumulate in cancer tumors, for crying out loud.
There are numerous toxins associated with meat. Again, imagine the harsh scrutiny being applied to grains and legumes by the Paleo peole being equally applied to animal protein and you'll understand why I mention these. First, the National Cancer Institute says exposure to heterocyclic amines and polycyclic aromatic hydrocarbons constitutes a risk. These are recognized potential carcinogens produced in well-done meat and meat cooked at high temperatures.
Meats also are high in advanced glycation end products, or AGEs, much moreso than carbohydrates.
AGEs are very bad for you and this is not in doubt.
They might contribute to type 2 diabetes.
Here's an in depth examination of the AGEs in different foods. Animal foods did not fare so well.
N-nitroso compounds are also well-known to be present in processed meats, and they are likely carcinogens. What is less well known is that meats cause these chemicals to be produced inside your body. High meat diets are here compared to smoking tobacco.
A typical response to these cooking-related toxins would be to say that meat simply shouldn't be cooked long or at high temperatures, but there is an interesting angle on this for the natural-is-better Paleo belief system. Humans like the taste of these toxic compounds, and we aren't alone. Primates like these flavors, too, and they don’t cook anything. A Paleo dieter may wish to eat like his ancestors, but this isn't the same as eating for health. In trying to reconcile our attraction to these toxic flavors, it has been suggested that their tastes are reminiscent of some plant foods, and that is why they are preferred by primates like us.
Of course, trans fats are naturally found in animal products as well. We all know to avoid trans fats.
Animals also bioaccumulate environmental toxins.
Packaged meats also are a main route of exposure for xenoestrogens called phthalates. Anti-soy Weston Price fans take note.
Another potential area of concern with high animal protein diets is our endocrine function. This study found that whereas some fruits and vegetables appear to improve semen quality, meat and milk might adversely affect it.
Amazingly, this has been observed in the male children of mothers who ate a lot of beef.
Fish is also suspect in similar ways. It may be the environmental toxins that concentrate in fish that explain its association with poor semen quality
Opposing effects of plant and animal foods have been observed regarding women's fertility as well. Plant protein was better here.
Vegetables and meat, including fish, also had opposing effects on stress hormone concentrations during pregnancy. Vegetables were better again.
These stress hormone levels apparently remain elevated into the child's adulthood. Those hunter gatherer women seem to have been on to something.
Environmental pollutants are actually more reliable biomarkers of fish consumption than omega-3 fatty acids.
This analysis found that the children of mothers who ate more fish had better test scores in spite of the confounding effects of the mercury in the fish. The authors’ advice was to eat fish lower in mercury to obtain the beneficial nutrients in the fish, like omega-3s. It seems to me it would be better still to find sources for these fatty acids that have no mercury.
One of the supposed advantages of red meat is its high content of heme iron. I'll look at that issue in Part III.
Primitive Nutrition 21:
Protein Choices, Part III
Red meat has been associated with some cancers. How might this be explained?
Let’s consider the iron in red meat. Certainly, we need iron in our diets. However, too much likely increases the chances of the free radical damage that is associated with many degenerative illnesses.
In excess iron becomes toxic…
and promotes heart disease.
The iron in meat comes in the form of heme iron. There is no heme iron in plant foods. Heme iron is what makes red meat look red.
It is the heme form of iron that is considered a suspect in contributing to colon cancer.
The high levels of sulphur created from the digestion of meat can harm the good bacteria in our digestive system. Maybe this adds to the heme iron problem.
Exess heme iron from red meat appears to be the cause of the production of those carcinogenic n-nitroso compounds inside the body I mentioned in the last video.
It also seems to increase the risk of heart disease.
Remember how in the Truthiness Paleo-style video we learned that Loren Cordain is ok with atherosclerotic plaque, just so it isn't unstable? Well it's not glucose or some other agent associated with carbs that’s found in unstable plaque.
It's iron. Normal arteries don't have it. Unstable, dangerous plaques do. Is there a connection to dietary heme iron here?
I don't know, but red meat is associated with heart disease enough that I would rather get my protein elsewhere. You don't see concerns like this expressed about beans.
Richard Fleming has shown us very clearly the differing effects on blood flow of low fat diets, as you see on the top, and high-protein diets, on the bottom, with the bottom right scan being made after a high-protein diet. Which blood flow would you rather have? Was this due to the cholesterol? What about the heme iron? Or was it something else? All that I need to know is that a diet high in animal protein was responsible for that bottom right scan.
Here are a few studies linking heme iron to cancer. This meta-analysis focused onthe link between meat and colon cancer.
The authors offered hypotheses blaming heme iron for this.
Here an association was found between heme iron and gastric cancer.
This one found a connection between iron overload and breast cancer.
Here red meat was associated with a variety of cancers while whole grains were not.
Studies like these had this meat scientist asking in the journal Meat Science if we should all just become vegetarians. It seems the best they can hope for is to find additives to put in meat to neutralize the toxicity of the heme iron.
I find it interesting that the Paleo promoters are so focused on celiac disease yet they ignore hemochromatosis, which affects 1 out of 200 people as opposed to 1 out of 133 with celiac. Hemochromatosis is a debilitating condition caused by the buildup of excess iron from the diet. You'd think it would be worth a mention every now and then.
People with this serious genetic disorder are advised to avoid red meat and animal fats.
There is one minor issue related to protein I'd like to comment on here, and that is the amino acid taurine. Paleologic includes a fallacious premise. There is a single ideal diet for all possible human goals and values, which of course is the Paleo diet. There can be no nutrient that is better supplied by a supplement because that just feels too modern. You want taurine, and meat is the Paleo way to get it.
The problem with this logic is that almost all the research I've seen supporting taurine’s benefits has come from studies using supplemented taurine, not taurine in food. Here is an article about the possible benefits of taurine for heart health. This used a supplement, not meat. If you haven't heard, animal foods hardly have a good reputation in relation to heart disease, yet the Paleos have decided this validates their fad diet. The subjects described here had bypass surgery. I wonder if their meaty diets got them into that situation in the first place.
These are some confounders in studies of taurine. Interpret with caution.
It's possible the benefits of taurine supplementation are only seen in individuals consuming unhealthy diets.
There is no evidence of humans becoming deficient in taurine under normal conditions. Infants with vegan mothers seem to be healthy despite lower taurine exposure in utero.
There is considerable overlap in the amounts of taurine in the milk of vegan and omnivorous mothers.
If you are interested in a dietary source of taurine that is vegan, nori has just a little. Otherwise, if you want extra taurine, you can certainly supplement it. Then you can really say you are following the example set by most of these taurine studies.
You may remember in my "Define 'Healthful'" videos that Loren Cordain cares about the IGF-1/IGFBP-3 ratio. Protein has an interesting effect on that.
You may know that calorie restriction has been shown in animal experimentation to extend lifespan. One of the ways it seems to work is by decreasing IGF-1. This is not exactly what happens in humans, as revealed in this study. In this research, protein drove up IGF-1. What lowered IGF-1 was protein restriction. I am surprised Cordain even mentions this subject.
Maybe this why excess protein is believed to lower lifespan, in addition to the other issues I have mentioned so far.
One of the dietary mediators in lifespan appears to be the amino acid methionine. It's impact has been demonstrated in mice.
There have been a lot of recent studies on methionine restriction. I present this just one as an example. Here, obese adults with metabolic syndrome improved fat burning and insulin sensitivity beyond what one would expect just from their weight loss through the restriction of methionine.
Here are the highest foods in methionine. Eggs and fish top the list, followed by other meats. If you find the methionine research on lifespan convincing and you want to live longer yourself, you might lose interest in these foods.
I'll close by reminding you that dietary fiber has been shown to reduce all-cause mortality. Why not get your glucose from carbs instead of extra protein and enjoy the benefits that come with a natural high-fiber diet?
Do you think I’ve been too rough on meat in these videos? Do your own research on all these issues and try to stick to mainstream sources. I think you’ll find I’m on firmer ground with all I’ve presented here than the Paleo dieters are when they malign grains. I’ll lend some support to the staff of life just ahead.