In contrast, genuine, old-fashioned bone broth is a traditional remedy used around the world to help people recover from colds, flu and other ills. Science has shown it boosts the immune system— with chicken soup richly deserving its reputation as  "Jewish penicillin". ^4-10 Bone broth soups and stews are also recommended by many doctors and health practitioners to heal the gut, relieve digestive distress, reduce allergies and sensitivities, and even help turn around arthritis and auto-immune disorders^.11 The bones in stock yield minerals in forms the body can absorb easily, and there's not just calcium, but also magnesium, phosphorus, silicon, sulphur and other trace minerals. Tendons and cartilage give up chondroitin and glucosamine, now widely sold as supplements for arthritis and joint pain, while fish heads and carcasses  provide iodine and other thyroid-strengthening substances. ¹²  

Gelatin — the component of broth that makes it stiff and jiggly when cooled down — provides many of the best-studied health benefits associated with broth. Indeed researchers from the 17th through the early 20th century considered gelatin a "functional food," useful in the treatment of peptic ulcers, tuberculosis, diabetes, muscle diseases, infectious diseases, jaundice and cancer. ¹³ Scientists also found that bottle-fed babies experienced fewer digestive problems when gelatin was added to their milk, and broth has also long been used to help babies and children with "failure to thrive."¹⁴ American researcher Francis Pottenger, MD, determined the secret to gelatin's success was its ability to attract and hold liquids. As a "hydrophilic colloid," gelatin improves digestion by attracting digestive juices to food in the gut. ¹⁵ 

Although gelatin has been heavily studied over the years, the data are inconsistent and contradictory.  One scientist would find that gelatin helps prevent, say, muscular fatigue, the next would find some benefit and a third would see no benefit at all.  And so on with anemia, jaundice, ulcers, impotence and other ailments.¹⁶ Why were the study results so variable? The most probable explanation is that the substance described as "gelatin" was not consistent from study to study. Knox and other commercial gelatins today are brewed exclusively from pigskins or cowhide. Years ago, however, some commercial gelatins derived from mystery blends of cartilage, bones, skin and other junked animal parts. Not surprisingly, these various combinations differed in terms of their physical and chemical characteristics and in their physiologic actions. Even glue was sometimes sold as gelatin. Complicating matters further, some of the so-called "gelatin" studies were done with the isolated amino acid glycine.¹⁷

More recently, researchers have focused on proline and glycine. These two amino acids are found abundantly in broth and are best known for their starring roles in collagen and cartilage production.¹⁸ Proline and glycine are considered "non essential" amino acids because, theoretically at least, the body can manufacture proline and glycine as needed and therefore suffers no shortfall.  The ability to manufacture them easily as needed, however, is probably true only of people enjoying radiant good health. Common sense suggests that the millions of American suffering from stiff joints, skin disease and other collagen, connective tissue and cartilage disorders might be suffering serious shortfalls of proline, glycine and other needed nutrients readily found in broth.  And although research on proline and glycine is far from a growth industry, science seems to support this assumption. Indeed most researchers have concluded that both proline and glycine should at least be considered "conditionally essential" (along with arginine, cysteine, glutamine, serine, taurine and tyrosine) , which means that under most conditions, the body simply cannot make enough of these compounds and must get them directly from food. ^19-21  High carbohydrate diets, vitamin C deficiencies and the decline of homemade soup making have all led to poor proline and glycine status. ^22,23

Proline and glycine entwined together are keys to beautiful, supple skin and strong flexible joints. Glycine, the simplest amino acid, also constitutes a basic nitrogen pool for manufacture of other amino acids, and it is used in the synthesis of hemoglobin, creatine, porphyrin, bile salts, glutathione and the nucleotides DNA and RNA. It is involved in glucogenesis (the manufacture of glucose), and low levels may produce hypoglycemic-like symptoms. Glycine also enhances gastric acid secretion and has a long history of helping patients with gastrointestinal disorders.   Yet, another vital function is detoxification. The human body requires copious amounts of glycine for detoxification after exposure to chemicals, and it conjugates directly with the widely used food preservative benzoic acid.  Finally, glycine plays a vital role in recovery from wound healing, jaundice, acute and chronic illness and malnutrition. In such cases, it is almost impossible for the body to make all it needs. ^24-27 No wonder homemade broth rich in proline and glycine is the traditional food given to convalescents.        

Proline, glycine and gelatin as well as broth itself have excellent safety records. The only documented cases of harm came when subjects were fed excessive amounts of gelatin —probably poor quality gelatin — and little else. This occurred quite frequently during the early to mid-19th century when administrators running hospitals, soup kitchens and poor houses 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.²⁸ Gelatin bashers have long been fond of quoting one scientific study in which dogs died after a few weeks on a gelatin diet.  While it was certainly true that the dogs died, no account was taken of the fact that the animals refused to eat the food! ²⁹ Today's overriding fear is "Mad Cow" disease, but commercial gelatin today is never made from brains or spines,³⁰ and few consumers cook brains at home, even from animals that are almost certainly safe because they have been grown outdoors on grass and in the sun, never fed feed containing other cadavers or other animal parts or sprayed with insecticides^.31 To date, there have been no documented cases implicating either commercial or homemade gelatin in "Mad Cow" disease or any other neurological disorders.