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Food for Thought: Protein

Filed under :Food for Thought

What is protein? How much should I get, and can I get too much? These are good questions, and today’s media is full of diets that purport to help people lose weight and “get healthy” by alleging that more protein should be consumed at the expense of carbohydrates in order to balance insulin levels and blood sugars. But is all protein equal? Should carbs be avoided? And, are high protein diets wise?

So, what exactly is protein? I don’t pretend to completely understand all the chemistry and science, but very simply put, proteins are large molecules that are formed from the residue of amino acids. Depending on their shape and genetic sequence, they are used to build and/or repair muscle, blood, hair, bones, skin, nails, and internal organs. They also participate in the replication and repair of DNA, function as enzymes (which are catalysts in metabolic function), and are important in the healthy response of the immune system. Once the proteins are broken down in the digestive system, they become free amino acids which are vital in the process of metabolism.

So clearly, protein is important. In fact, every cell in the body utilizes protein in one way or another. The minimum daily requirement established by the FDA is 45-65 grams. However, this requirement errs on the conservative high side, and as long as you’re not pregnant, lactating, or an athlete, the majority of us actually requires only about 20-35 grams per day. As it turns out, though, most people who eat the standard American diet end up consuming a whopping 100-120 grams every day, easily double the recommended requirement. But is that such a big deal? Can excess protein be harmful? Most definitely!

When the body finds itself loaded with excess protein, it sends out a signal to the liver to produce a hormone called “insulin-like growth factor 1” (IGF-1). According to the body, protein is a “building block” and IGF-1 tells the cells to use the extra protein for growth. That’s great if you’re a child, but if you are a fully grown adult, the things that tend to start growing are tumors which may, and sometimes do, turn into cancer. Since IGF-1 is a growth hormone, the tumors are encouraged to grow and metastasize, and finally invade the bloodstream, bones, and organs. The more protein we have in our system, the more IGF-1 we produce. The more IGF-1 we produce, the greater our risk of many types of cancers, including prostate, breast, stomach, kidney, bladder, pancreas, and colorectal. In fact, studies have shown that men who have elevated levels of IGF-1 in their blood increase their risk of developing advanced stage prostate cancer by more than five times. Postmenopausal women who have elevated levels of IGF-1 have been shown in the European Prospective Investigation into Cancer and Nutrition (EPIC) study to be associated with a 40% increased risk of breast cancer. While we do want to consume enough protein to maintain our cells’ needs, we clearly don’t want to exceed that requirement.

Is all protein equal, though? Does excess protein, no matter where we get it, cause the body to increase the production of IGF-1? No. Only protein from animal sources has that effect. The reason is because the amino acid structure of animal protein very closely resembles our own proteins and the body recognizes it as a building block to be used. On the other hand, plant protein does not as closely resemble our own and although in terms of amino acids, all the elements are there, the liver is not stimulated to increase the production of IGF-1.

Furthermore, all that excess animal protein has to go somewhere since it is not stored in the body as protein. Instead, it is converted to fat or filtered out by the kidneys and excreted. As you can imagine, this puts a lot of extra stress on the kidneys which is especially harmful for people who already have impaired kidney function.

You may be wondering now if we can get adequate protein from plant sources since animal sources are unhealthy. I’ll answer that, as well as the questions about high protein diets and carbs, in my next blog post.

Bon appétit!



The China Study, T. Colin Campbell, PhD and Thomas M. Campbell II, PhD

Keep It Simple, Keep It Whole – Your Guide to Optimum Health, Alona Pulde, MD and Matthew Lederman, MD

Super Immunity, Dr. Joel Fuhrman, MD