Bone broth is a liquid prepared by simmering animal bones and connective tissues, often with vegetables and herbs, over a long period. This extended cooking time draws out beneficial compounds, distinguishing it from simple stock. The resulting liquid has gained attention for its purported health benefits, leading to questions about whether it aligns with the principles of an alkaline diet and contributes to the body’s overall acid-base balance.
Defining Dietary Alkalinity and pH
The concept of alkalinity in food is based on the pH scale, which is a measure of hydrogen ion concentration in an aqueous solution. This scale ranges from 0 to 14, where a pH of 7 is considered neutral. Solutions with a pH below 7 are acidic, while those with a pH above 7 are classified as alkaline or basic. The scale is logarithmic, meaning a single-unit change represents a tenfold difference in acidity or alkalinity.
The idea of “dietary alkalinity” stems from the “alkaline ash hypothesis,” a theory suggesting that after food is metabolized, it leaves behind a residue, or ash, that is either acid-forming or alkaline-forming. This ash is composed of minerals; for instance, sulfur and phosphorus from proteins are acid-forming, while calcium, magnesium, and potassium from fruits and vegetables are alkaline-forming. Proponents of this theory suggest that consuming more alkaline-forming foods can positively influence the body’s internal chemistry. The actual pH of the food before consumption does not determine its ash type, which is why acidic foods like citrus fruits are considered alkaline-forming after digestion.
The Measured pH of Bone Broth
Despite the alkaline ash theory, a direct measurement of bone broth’s pH reveals it is generally not alkaline. In typical preparation, bone broth is measured as slightly acidic to neutral, usually falling within a pH range of 5.3 to 7.0. The final pH is heavily influenced by the ingredients and method of cooking.
Traditional bone broth recipes often call for an acidic component, such as apple cider vinegar or lemon juice. This acid lowers the pH of the cooking liquid, assisting in leaching minerals like calcium and magnesium from the bone matrix into the broth. While some studies show broth can be slightly alkaline (pH over 8) if no acid is added, common cooking practices create a slightly acidic environment. This environment enables the extraction of many sought-after nutrients, resulting in a finished product that is usually slightly acidic or close to neutral.
Does Food pH Influence the Body’s Acid-Base Balance?
The body maintains an extremely tight control over its internal acid-base balance. The pH of arterial blood must remain fixed within a very narrow, slightly alkaline range of 7.35 to 7.45 for all bodily systems to function correctly. This strict maintenance is known as homeostasis.
The body employs sophisticated buffer systems, primarily the bicarbonate buffer system, to immediately neutralize any excess acid or base. Beyond these immediate chemical buffers, the lungs and kidneys provide long-term regulation. The lungs can quickly adjust the blood’s acidity by increasing or decreasing the exhalation of carbon dioxide, which is a component of carbonic acid in the blood.
The kidneys work more slowly, taking hours or days to excrete excess hydrogen ions and conserve bicarbonate, fine-tuning the balance. While diet can easily influence the pH of urine—the body’s way of excreting excess compounds—this change does not reflect an alteration in the tightly controlled blood pH. For a healthy person, diet does not significantly alter the blood’s fixed pH level.
Proven Nutritional Value of Bone Broth
The real value of bone broth lies not in its pH, but in the nutritional compounds released during the long, slow simmering process. The heat breaks down collagen, the primary protein in bones and connective tissue, into gelatin. Gelatin is rich in amino acids that offer biological benefits.
The most notable amino acids found in abundance are glycine, proline, and glutamine. Glycine and proline are used by the body as building blocks for its own collagen and connective tissues, supporting joint health, tendons, ligaments, and cartilage. Glutamine serves as a primary fuel source for the cells lining the gut.
This glutamine content is thought to support the integrity of the intestinal lining, helping to soothe irritation and promote overall gut health. The broth also contains easily digestible minerals like calcium, magnesium, and phosphorus, which are extracted from the bones and contribute to electrolyte balance. These components provide a supportive nutritional profile, regardless of the broth’s effect on systemic pH.