Guide: Calcium, Phosphorus
& Tooth Maintenance

Chapter 1: Anatomy and structure of human teeth

The human tooth is a highly specialized organ made up of several tissue layers. Each of these layers performs specific tasks and has its own mineral composition. To understand the relevance of calcium and phosphorus for tooth maintenance, it helps to take a look at these structures.

1.1 Tooth enamel (enamelum)

Tooth enamel forms the outermost layer of the tooth crown and is the hardest tissue in the human body. It consists of about 96–97% inorganic material, mainly hydroxyapatite (Ca₅(PO₄)₃OH). The remaining 3–4% is water and organic substances. This extremely high mineral density gives enamel its resistance to mechanical stress such as chewing and biting.

Notably, once formed, tooth enamel cannot be regenerated by the body, because the enamel-forming cells (ameloblasts) are lost once enamel maturation is complete. Remineralization is possible only through saliva and oral fluid.

1.2 Dentin

Beneath the enamel lies the dentin, which makes up the largest share of the tooth substance. It contains about 70% inorganic material (also hydroxyapatite), 20% organic matrix (mainly type I collagen), and 10% water. Unlike enamel, dentin is a living tissue: it is formed by odontoblasts, which can produce new dentin throughout life.

1.3 Cementum and pulp

Cementum covers the tooth root and is similar in composition to bone. The pulp inside the tooth contains blood vessels, nerves, and connective tissue and supplies the tooth with nutrients. Both structures are relevant to keeping the tooth anchored in the jaw over the long term.

Chapter 2: Calcium and tooth maintenance

2.1 Biochemical basics

Calcium (Ca²⁺) is the most abundant mineral in the human body by quantity. An adult carries about 1–1.2 kg of calcium, of which roughly 99% is bound in bones and teeth. In tooth enamel, calcium together with phosphate forms hydroxyapatite crystals arranged in a regular prismatic pattern.

The integrity of this crystal structure depends directly on the availability of calcium ions. When the pH in the mouth drops due to bacterial acid production or the consumption of acidic foods, calcium ions begin to dissolve out of the enamel surface — a process known as demineralization.

• Hydroxyapatite formation: Calcium provides the central cation for the crystal lattice of tooth enamel.
• Saliva buffer: Calcium dissolved in saliva contributes to the supersaturation that thermodynamically drives remineralization.
• Alveolar bone: Calcium in the jawbone provides stable anchoring of the tooth roots via the periodontium.

2.2 Daily requirements and dietary sources

Under EU Regulation 1169/2011, the reference value for daily calcium intake is 800 mg. Different foods provide calcium in varying concentrations:

2.3 Absorption and bioavailability

Calcium absorption takes place mainly in the small intestine and is typically 25–35% of the amount ingested. Vitamin D is significantly involved in this process, as it promotes the formation of calcium-binding transport proteins in the intestinal lining. Oxalic acid (in spinach, rhubarb) and phytic acid (in grains) can reduce calcium absorption by forming poorly soluble complexes.

Chapter 3: Phosphorus and tooth maintenance

3.1 Biochemical basics

After calcium, phosphorus is the second most abundant mineral in the human body. In biological systems, it occurs almost exclusively as phosphate (PO₄³⁻). About 85% of the body’s phosphorus is found in bones and teeth, where, as an integral component of hydroxyapatite, it provides mineral firmness.

• Hydroxyapatite component: Three phosphate groups, together with five calcium ions and one hydroxyl group, form the basic unit of hydroxyapatite. Without phosphate, this crystal structure cannot exist.
• Saliva remineralization: Phosphate ions in saliva contribute substantially to the supersaturation that allows minerals to be incorporated into demineralized enamel.
• Acid buffer system: The phosphate buffer system (H₂PO₄⁻/HPO₄²⁻) in saliva helps offset pH fluctuations in the mouth and thus limit demineralization.
• Cellular energy balance: As a component of ATP, phosphorus is involved in the energy supply of odontoblasts, the cells responsible for forming dentin.

3.2 Daily requirements and dietary sources

The EU reference value for phosphorus is 700 mg per day. Phosphorus occurs in many foods, which is why a deficiency is rare in Western dietary patterns:

3.3 Ratio of calcium to phosphorus

The dietary ratio of calcium to phosphorus is discussed in nutrition science, since a strong imbalance can influence calcium homeostasis. In the hydroxyapatite of teeth, the molar ratio of calcium to phosphorus is about 1.67:1. Nutrition science recommendations suggest aiming for a calcium-to-phosphorus ratio of at least 1:1 in the diet.

Chapter 4: Demineralization and remineralization

Tooth enamel is in a constant dynamic balance between mineral loss (demineralization) and mineral recovery (remineralization). Over the long term, this balance determines whether tooth structure is preserved or damaged.

The authorized health claims each refer to the individual mineral:

4.1 Dietary aspects of tooth maintenance

Diet affects the demineralization-remineralization balance on several levels. Besides an adequate intake of calcium and phosphorus, the following factors play a part:

• Meal frequency: Every time you eat can trigger an acid attack. Longer breaks between meals give saliva time for remineralization.
• Sugar content: Fermentable carbohydrates are the preferred substrate for acid-producing oral bacteria.
• Food texture: Sticky foods cling to the teeth longer and extend the demineralization phase.
• Saliva flow: Chewing fibrous foods stimulates saliva production and thereby aids the removal of food debris.

Dietary supplements are not a substitute for a varied diet. Do not exceed the recommended daily intake.

Chapter 5: Frequently asked questions

Why do teeth rely on calcium and phosphorus from food?

Although tooth enamel is no longer actively remodeled by the body once formed, a continuous exchange of calcium and phosphate ions with saliva takes place at the enamel surface. The availability of these ions in saliva depends, among other things, on dietary intake.

What ratio of calcium to phosphorus makes sense in the diet?

A calcium-to-phosphorus ratio of at least 1:1 is often described as desirable in nutrition science publications. With a balanced mixed diet that includes dairy products, vegetables, and protein-rich foods, this ratio is usually reached.

Can calcium and phosphorus be taken at the same time?

Since both minerals occur together in the hydroxyapatite of teeth anyway, taking them in together through food is the normal physiological case. When taking dietary supplements, the recommended daily intake for each mineral should be observed. If in doubt, it is advisable to consult a doctor or pharmacist.

What does “maintenance of normal teeth” mean in the EFSA claims?

The phrase “maintenance of normal teeth” describes keeping the physiological tooth structure intact with an adequate supply of the respective mineral. It is not a therapeutic claim and does not imply healing or reversal of existing dental damage.

Do the EFSA claims apply to all age groups?

The authorized health claims under Regulation (EU) No 432/2012 are aimed at the general adult population. Different recommendations may apply to children, pregnant and breastfeeding women, and people with specific medical conditions. Individual advice from a medical professional is recommended.