Along with politics and religion, you can add nutrition to the list of topics to avoid at your next cocktail party. This is especially true of the latest misunderstood bad boy of the nutrition world: protein.
Fat, carbs and protein
In the 1980s it was fat. In the ‘90s and 2000s, it was carbs. Now, you can add protein to the list of macronutrients experts are telling you to avoid. The experts made mistakes then, and are about to make the biggest nutrition blunder of them all with their new take on protein.
The protein crusaders have arrived, and they are every bit as fanatical and misinformed as their fatphobic and carb avoiding counterparts. But before you can understand where things are headed and why they are wrong, it will help to know where we have been.
Lessons from fat
It’s not that these researchers are not acting on what they think is good information. The 1980s fat scare was based first on rat studies showing high-fat diets induced atherosclerosis. Population studies also showed a correlation. This correlation was attached to cholesterol and without the whole story; the fatphobic message was born.
The problem was that neither animal studies nor population studies can prove causation, and often both forms of research can be misleading. This is what happened with fat. Over the ensuing years, we learned about the differences between saturated fat and other types of fat.
We learned about hydrogenated oils, which many of the initial fat studies did not control for. We learned about the protective effect of omega-3 fats. We learned there is more to cholesterol and fat than total amounts. In short, we discovered we were wrong, but not before we created an epidemic of carb gorging that correlates perfectly with the massive spike in obesity and diabetes we have experienced since the ‘80s fat scare.
Good research gone bad
Now we find the same things that happened with fat and carbs happening with protein. It sounds good: “Huge population studies on Chinese populations link protein with cancer,” or, “Animal studies prove high protein diets cause cancer.”
But they don’t mention the same data shows low protein diets are also correlated with an increased risk of cancer. What they don’t say is the animals were poisoned first and then fed high protein diets. No distinction is made between the dairy protein casein and other animal proteins. They don’t explain why intervention trials on humans show protein substituted for fat or carbs in human diets usually make people healthier.
It’s important to briefly discuss the different types of research so people can understand why nutrition can be so confusing. First are the animal studies. Mice have metabolisms that are similar enough to humans to get us headed in the right direction. However, they also have metabolisms dissimilar enough to not draw clear conclusions.
In other words, if an animal study shows something, we should not get too excited, but instead, try it out in humans. Then if it works, we can get a little excited. If we then try it out on a lot of humans and it still works, we can get very excited.
Population studies, called epidemiological studies, are the most difficult to draw conclusions from. The reason? People and the worlds they live in are so complex. If some Chinese eat more protein than others, are they also more stressed? Do they sleep less? Is the protein they eat different from other types of protein? There is no way to control for all this vast complexity.
Here is an example. Non-calorie sweeteners are highly correlated with obesity. Does this mean they make people fat? Or does it mean overweight people are the ones who use them? The more likely truth is the latter, not the former.
To really assess whether something is valid or not, intervention studies should be done. These are studies done on humans where one group is given something while the other group is not. Everything else is left the same. These studies tell us the most because we can be more certain that what we see is a result of the intervention and not something else.
Protein causes cancer?
One of the most popular works on protein and its supposed negative effects is the China Study. This research is actually significant research and will go a long way towards helping us understand nutrition.
Where we believe it goes wrong is its assumptions. Just like the fat studies in the 80s, this research is being interpreted as proof protein causes cancer and should be avoided. This is a big mistake.
The China Study was based on two lines of research, one on animals and the other a population study. The animals were essentially poisoned (with aflatoxin) and then given a low or high protein diet. Cancers were increased in the protein fed group.
Does this show protein is a cause of cancer? Would a high carb or high-fat diet compared to a low fat or low carb diet show the same thing? Given cancer is a fast-growing tissue, wouldn’t any extra nutrition increase cancer in a susceptible animal? In other words, this proves nothing and many questions remain.
The population studies showed Chinese consuming higher protein diets got more of certain types of cancer compared to those eating less protein. Is this because of the protein? Could it be that in China much of the protein sources are high in nitrates and other preservatives?
In looking at the research, you can find certain types of cancer are more prevalent in higher protein eaters. Other types of cancers are more common in those who eat less protein. If we are to blame higher incidence of some cancers on protein consumption, then we must blame higher rates of other cancers on low protein intake. In reality, neither of these assumptions makes much sense.
It may be surprising to know that some data shows a low protein diet is associated with an increased risk of cancer. That is right; in the very research used by the author, it can be clearly shown that higher protein diets are protective against the initiation of cancer.
This study was published in the 1983 Journal of Cancer Research (Vol. 43 # 5). It also may be surprising to learn that another study, by researchers involved in the China Study, also contradicts the fact that there is any difference between animal and plant proteins when the proteins are complete. This was published in the Journal of National Cancer Institute (1989, Vol. 81)
This is not to refute the importance of the work highlighted in the China Study; it’s merely to say there is much more to this story, and the associations of protein and cancer are not at all clear. However, the association with obesity and cancer is very clear.
Protein, obesity, cancer and everything else
Here is the most important consideration. Obesity is the single biggest heath challenge in human history and drastically increases the risk of the major killers: heart disease, stroke, and cancer. In fact, the best way to increase your chances of getting sick, becoming dysfunctional in old age and dying an early death is to get and stay fat.
Here is where protein comes in. Of all the macronutrients, it’s not only the most filling, but it’s also the most likely to control cravings and balance blood sugar levels. In short, it’s perhaps the greatest anti-obesity weapon we have.
As shown in a recent study, substituting protein calories for fat and carb calories aids not only weight loss, but also more importantly fat loss. Dieters who ate more protein had reduced insulin levels, less hunger, decreased food cravings and were able to maintain their muscle mass, resulting in less rebound weight gain. This study was published in the American Journal of Clinical Nutrition (April 2010).
In a separate study published online in December 2010 (Journal of Nutrition), protein intake, and specifically branched chain amino acids (BCAA) were shown to increase longevity. Much of this effect is based on protein’s ability to detoxify the human body, aid weight loss, and fat loss, help maintain muscle mass and bolster antioxidant defenses.
Another study on protein and its effect on the acid-base balance of the body and bone density calls into questions old beliefs and biases. The study was published in Nutrition Journal (Vol. 9 # 72). Participants receiving a high protein meal replacement twice daily were compared to those who were fed a non-protein meal replacement.
Each group was followed for 12 months. The researchers wanted to look at bone density as well as liver and kidney function. What they found was no difference at all in any markers. This was despite a level of protein many claim is detrimental.
It’s interesting to note how persistent these negative views on protein are. The issue should have been put to rest in a May 2004 review article in the Sports Nutrition Review Journal. The title of the study was High protein weight loss diets and purported adverse effects: Where is the evidence?
The research in this study showed there is no evidence that higher protein diets have any adverse effects on liver, kidney or bone health. Given the fact protein can decrease the need to overeat and help balance blood sugar, it may actually be preventative for illnesses affecting these organs. The number one cause of disease for liver and kidney is diabetes, a disease of excess sugar more than of excess protein.
The protein story is far from over, but for serious exercise enthusiasts and exercise professionals, it’s more important than ever to watch this trend. The same enthusiastic scapegoat mentality that dogged fat and carbs is now descending on protein.
It’s crucial to educate fat loss seekers and fitness enthusiasts on the benefits of protein. Many of the claims being made, even by prominent researchers, are misinformed at best and inaccurate at worst. Perhaps with a little common sense and self-education, we can avoid another nutrition blunder that merely leads us further into the obesity abyss.
By Jade Teta and Keoni Teta