CHAPTER 5

Conditional Protein Power

When consumed as part of a rich and varied traditional diet, broth improves overall protein digestion and assimilation. It helps the body build collagen and cartilage, needed for the health of skin, joints, and bones. And it also serves as a “protein sparer,” which means we can cut back on the complete proteins we would otherwise need to eat.

Despite these strengths, broth is often dismissed as a “poor protein” because it’s not a complete protein. That’s true, and that is the reason we should not attempt to survive on broth alone.

From the eighteenth to the early twentieth centuries, public health authorities enlisted top scientists to turn broth—or, more accurately, its chief constituent, gelatin—into a complete protein that could be cheaply manufactured and fed to the masses. They tried adding all sorts of substances, including tyrosine and other amino acids, whey or casein powders, and eventually even soy protein. The attempts proved inadequate, too expensive, or both, and efforts to turn gelatin into a cheap and portable superfood that could feed soldiers at war, disaster victims, and the poor were eventually scrapped.

Nearly all the cases in which gelatin caused health problems occurred when the subjects were fed excessive amounts of gelatin and little else. This happened quite frequently during the early to mid-nineteenth century when people running hospitals, soup kitchens, and poorhouses tried to economize by serving gelatin at every meal in the form of bouillon, gelatinous biscuits, and other gelatin-based edibles—or inedibles as the case may be. Gelatin bashers have long been fond of pointing out that dogs have died after a few weeks on a gelatin diet. But while it was true that the dogs died in one research study, Dr. Nathan R. Gotthoffer argued in his 1945 book Gelatin in Nutrition and Medicine that “no account was taken of the fact that the animals refused to eat the food after a few days.”

Clearly science has proven we can’t live on broth alone, but much research supports its health-giving role in a rich and varied diet. Gelatin increases the utilization of the protein in wheat, oats, and barley. It also improves the digestibility of beans, proving the traditional wisdom of cooking bean soups with hocks. Furthermore, gelatin improves the digestibility of meat protein in soups and stews or when served with gravy, as is the custom with many culinary traditions around the world.

The “sparing” effects of gelatin on protein were of particular interest to many early researchers. By sparing protein, they meant that the body is less likely to cannibalize the protein stored in its own muscles, a common occurrence during fasting or during rapid weight loss from illness. Because gelatin-rich broth diminishes the amount of complete protein needed by the body, it can reduce the strain on the digestive system. It is a healing food for convalescents and helps prevent unwanted weight loss and loss of muscle that occurs when the body goes out of nitrogen balance and cannibalizes the protein stored in its own muscles. In 1872, Carl von Voit, a German researcher who spent ten years studying gelatin, concluded gelatin prevented breakdown of protein in the body because it was itself decomposed. He found it could exert “remarkable sparing powers,” but cautioned, however, that gelatin alone could not build up protein supplies in the body. For that, high-quality animal protein is required.

Our Need for Protein

We need high-quality protein in our diets for growth, repair, immune function, hormone formation, and all metabolic processes. Our bodies contain more than 50,000 types of proteins, all built from the building blocks known as amino acids. Nine of these amino acids are considered “essential” for humans because we cannot manufacture them on our own and must obtain them from the diet. They are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Arginine is considered essential for babies and children. If these essential amino acids are present in sufficient quantities, we can build the “nonessential” amino acids, but if one or more are missing, the body will fail to synthesize many of the enzymes and antibodies and the other proteins it needs.

Protein synthesis breaks down not only when the essential amino acids are absent but also when supplies are low. We tend to lose the ability to produce sufficient amounts during periods of infection, chronic poor health, or physical or mental duress, or during the rapid growth expected of infants and children. Consequently, many scientists believe we need to obtain many more amino acids than the ones considered essential, and that at least eight other amino acids should be considered “conditionally essential.” These include arginine, glycine, proline, glutamine, tyrosine, serine, cysteine, and taurine.

Traditionally animal products such as eggs, milk, fish, poultry, and meat have served as valued sources of the best proteins. These nutrient-dense foods contain a complete set of the essential amino acids in desirable proportions. In contrast, plant proteins are incomplete because they are low or missing some of the essential amino acids. It only takes a shortage of one of these to slow down or even shut down the body’s protein manufacturing process. In soybeans and other legumes, the limiting amino acid is methionine. In grains, it is lysine.

Gelatin—as well as gelatin-rich bone broth—also has limiting amino acids, namely tryptophan, which goes missing, and histidine, tyrosine, and cysteine, which are low. Consequently, the ideal way to consume broth is in the form of soups and stews that also include high-quality animal products such as fish, meat, organ meats, poultry, eggs, or dairy, or in sauces and gravies on meat and fish.

Consumed alone, gelatin is obviously an incomplete protein. “An unquestionably poor protein,” warn the writers of the popular textbook Nutrition for Living. Homemade broth is obviously better than a gelatin product, but even the best-quality broth cannot prevent malnutrition if people are starving from insufficient quantities of food or short of enough high-quality protein because of a high-carbohydrate diet. Such people need to consume broth along with more and better food.

Adding broth to the menu, however, can improve the health of people on South Beach, Zone, or other lean protein plans that promote the consumption of skinless, boneless chicken breasts, lean burgers, and chops and steaks trimmed of fat, skin, cartilage, and bones. Recommendations to eat only lean meat go against the ancestral wisdom of eating all parts of the animal, not just the muscle meat.

The Methionine Problem

What’s wrong with muscle meats alone? Muscle meats are high in methionine, an essential amino acid that can contribute to excessive methylation in the body. Methylation refers to a complicated biochemical process involving transfers of methyl groups. It goes on in every cell of the body and when overdone can contribute to premature aging and other health problems.

The solution is not to avoid muscle meats entirely, but to balance them out by eating parts of the animal rich in proline and glycine, including the skin, cartilage, and bones. Eating liver and other organ meats provides rich stores of vitamin C and other vitamins and minerals needed for collagen and cartilage production. Proponents of plant-based diets correctly warn about the grave dangers of excess methionine but fail to recognize the fact that their recommendations lead to excess methylation as well because although their foods are low in methionine, they are also low in proline and glycine. Balance is key.

The healing power of broth is so dependent on proline, glycine, glutamine, and alanine that we’ll discuss these four amino acids in depth in the next chapter. Their vital roles in gut health, immune system support, blood-sugar balancing, muscle building, healthy bones and joints, and smooth skin, as well as overall healing and rejuvenation, make them conditionally essential for life but absolutely essential for radiant good health.