Being a nephrologist, or kidney specialist, this is one of my favorite topics, since there's so much misinformation about protein. People in this country have an absolute protein mania, a craziness that is manifested in an inappropriate concern about getting enough of it.
We Americans, on average, eat two to three times as much protein as we need. There's an old theory, reported in the New England Journal of Medicine (1982), which I feel makes a whole lot of sense; it suggests that our excessive protein intake is a major factor in wearing out the kidneys and in promoting the development of the kidney lesion at a much earlier age than it would otherwise occur.
Protein is not one of these things about which you can say, "A little of it is good for me, so a whole lot must be much better.” Along with the protein in meat, for example, we get lots of other things that are not so neat: hydrochloric and sulphuric acids—very toxic, you bet; phosphoric acid—it's weaker but still toxic, as is uric acid. So a large protein meal is like a large acid load as far as the body is concerned. And as the protein is metabolized it forms even more acids—the amino acids.
The body must protect itself against all this acid until the kidneys can get rid of it, so it buffers or stores it in the bones. As the acid is buffered, calcium is released. A high protein diet therefore slowly de–mineralizes your bones and makes them weaker. Over a lifetime, it will probably lead to brittle, easily broken bones. The scientific evidence has been published in the American Journal of Clinical Nutrition (1974, 1978, and 1979) and in "Symposium: Nutrition and Aging Bone Loss;" Federation Proceedings (1981).
We just don't need that much protein to replace losses once we're adults. Any excess that we eat we either turn into sugar to use immediately as energy (as if we needed any more sources of sugar in the American diet!) or into fat to store.
And when we turn amino acids into sugar or fat we leave behind ammonia—also very toxic—which has to be detoxified right away or it will cause coma. So that's another big work load for the liver and later, the kidneys.
Nutritionists who have investigated how much protein we actually need have come up with a minimum figure of about 40 grams a day. This is a generous minimum. Yet the average American eats in excess of 100 grams a day.
There's a lot of misunderstanding about what's the best source of protein too. Let's say we want to eat some protein to get more strength and energy. We usually head right for the steak, or cheese, or eggs. These foods have been on the training tables for years. A steak and egg breakfast on the day of the "big game” is still a tradition; although many coaches are wising up now and serving lighter meals that are higher in carbohydrates.
Steak and cheese—indeed, all red meat and most dairy products—are really high fat foods! Really, just think of what a cow or a pig goes through before it's butchered. Hormones are put in the food, and the animal is fed lots of corn, and gets no exercise. Just to make the meat tender marbled with fat, easy to cut and chew, and swallow. So we'll eat more of it, of course. Consume at any cost! The darker the meat is the higher the fat content. White meat chicken and fish contain less than twenty–five percent of their calories as fat. But the calories in a filet mignon with all the visible fat trimmed off are still more than fifty percent fat. Imagine!
In my view, we've wound up with a other bizarre, upside–down set of values, in which the higher the fat content of the animal food (meat or dairy) the more expensive it is. The difference between flank steaks at three to four dollars a pound and filet mignon at six to nine dollars a pound is just fat. The protein, the muscle fiber, is the same—so you're paying four to five dollars a pound for beef fat and for the privilege of raising your own blood fat and cholesterol levels and risking a heart attack.
A particularly ridiculous supplement to your diet that is popular in some health circles are gelatin capsules. You're paying ten to twenty dollars a pound for ground–up house hooves and chicken claws! What’s it for, more protein? This just weakens the bones. We definitely don't need protein supplements. Not unless you’re old and sick and not eating and losing weight in a nursing home. Now those people often need protein supplements, not healthy adults with good appetites and free access to restaurants and supermarkets.
If I eat less meat and dairy products and eggs, where am I going to get my protein from? I always heard that meat protein is the best for you and that most other proteins are incomplete.
The truth is that humans are omnivorous—both herbivorous and carnivorous—and we can survive on vegetables and grains, nuts, roots, seeds, and fruits just fine. And as long as we get enough calories we’ll be getting enough protein and all the essential amino acids we need.
True, animal–source protein more closely resembles our own proteins in exact amino acid composition. But all of us break down the protein we eat into its building block amino acids anyway, so as long as there are enough of all the right amino acids in plant proteins (and there are in a mixed diet) we will build our own proteins out of them. No problem. Grains or beans will do just fine. Or skim milk and egg whites, if you have to have animal protein.
Hey. I'm not saying you have to give up all meat, fowl, fish, dairy products, and eggs—just eat less of them. But if you want to have vegetarian days or weeks or months, it's okay. And you'll do just fine on non–animal source protein.There is even evidence that switching to a more vegetarian–type diet will lower your blood pressure! That is, according to studies published in the Journal of the American Medical Association (1981 and 1982) and the Lancet (1983), which showed that eating meat raises your blood pressure and that this effect becomes more pronounced as you grow older. In recent years, the DASH diet has been proven to substantially reduce blood pressure, especially if combined with serious sodium restriction. The DASH diet is now the foundation of many different sponsored programs from the American Heart Association to the national societies of the Internists and the Pediatricians. (New England Journal of Medicine 2001)
Years ago the American Academy of Pediatrics appointed a Committee on Nutrition to look into the increase in unusual nutritional practices in our country that might be hazardous to the health of children. They concluded, in a report published in Pediatrics (1977), that all but the most extreme forms of pure vegetarianism not only are nutritionally adequate for growing children but also, in a way, advantageous—because of "the rarity of obesity and the tendency for lower serum levels of cholesterol" in people who don't eat meat. The Food and Nutrition Board of the National Academy of Sciences concurs, as do I.
Author: Cleaves M. Bennett MD FACP
Evidence has been discovered linking inadequate intake of calcium with hypertension in adults (symposia headed by Dr. D. A. McCarron in Hypertension, 1982, and Annals of Internal Medicine, 1983). The causal relationship here is unclear. Read More
Author: Cleaves M. Bennett MD FACP
It's only recently in human history that we've been able to afford to fatten up the animals that everyone eats. I've already mentioned the two differences between flank steak and filet mignon—price and fat. Read More