Guide: Calcium &
Digestive Enzymes

Chapter 1: Basics of Enzymatic Digestion

Digestive enzymes are biological catalysts that speed up the breakdown of macromolecules in food. Without them, the chemical reactions needed to split nutrients would run so slowly that the body could not be adequately supplied.

1.1 The Digestive Pathway at a Glance

Digestion begins in the oral cavity, where salivary amylase starts breaking down starch. In the stomach, pepsin and gastric lipase take over the next phase under strongly acidic conditions (pH 1.5–3.5). The most important stage, however, takes place in the small intestine, where the pancreas releases a mixture of enzymes and cofactors:

1. Pancreatic amylase: Continues the starch breakdown that began in the mouth, splitting polysaccharides into oligosaccharides and maltose.
2. Trypsin and chymotrypsin: Split proteins at specific amino acid positions into shorter peptides.
3. Pancreatic lipase: Breaks down triglycerides into free fatty acids and monoglycerides — a process in which calcium plays a role as a cofactor.
4. Elastase and carboxypeptidase: Complement protein digestion by cleaving additional peptide bonds.
5. Nucleases: Break down nucleic acids (DNA and RNA) from food into their individual building blocks.

1.2 Cofactors and Their Significance

Many enzymes need additional molecules or ions besides their protein component in order to be catalytically active. These so-called cofactors can be organic (coenzymes, often derived from vitamins) or inorganic (metal ions such as calcium, zinc, or iron). Calcium is one of the inorganic cofactors that, according to an EU-authorized claim, is linked to the normal function of digestive enzymes.

Chapter 2: Calcium and Digestive Enzymes

2.1 Biochemical mechanisms of action

Calcium ions (Ca²⁺) perform several functions in the digestive tract that go beyond the well-known role for bones and teeth. In connection with enzymatic digestion, the following aspects stand out:

• Structural stabilization: Calcium ions bind to specific sites on pancreatic enzymes and thus help maintain their three-dimensional conformation. An enzyme that loses its correct folding also loses its catalytic effectiveness.
• Trypsinogen activation: Trypsinogen, the inactive precursor of trypsin, is activated in the small intestine by enteropeptidase. Calcium ions protect active trypsin from autolysis — that is, from self-digestion — and thus extend its functional lifespan.
• Lipase-colipase complex: Pancreatic lipase only works efficiently in the small intestine when it binds to fat droplets together with colipase. Calcium ions facilitate the formation of this complex by influencing the surface tension at the fat-water interfaces.
• Phospholipase A2: This enzyme, which splits phospholipids into lysophospholipids and fatty acids, requires calcium as an essential cofactor for its catalytic activity.

2.2 Daily requirements and dietary sources

Under EU Regulation 1169/2011, the reference value for daily calcium intake is 800 mg. Calcium is found in a variety of foods:

2.3 Absorption and Bioavailability

Calcium is absorbed mainly in the upper small intestine (duodenum and proximal jejunum). Two mechanisms are involved: an active, vitamin D-dependent transport at low calcium concentrations and a passive, paracellular diffusion process at higher concentrations in the intestinal lumen.

The absorption rate averages 25–35 % of the amount consumed and is modulated by several factors. Oxalic acid (in spinach and rhubarb) and phytic acid (in whole grains and legumes) can reduce calcium absorption, while lactose and certain amino acids such as lysine and arginine favor it.

Chapter 3: The Pancreatic Enzyme System

The pancreas is the central organ for producing digestive enzymes. Every day it secretes about 1.5–2 liters of pancreatic juice, which, in addition to the enzymes, also contains bicarbonate that neutralizes the acidic stomach contents in the small intestine, creating a pH environment suitable for the enzymes.

3.1 Zymogens and Their Activation

Most pancreatic enzymes are produced as inactive precursors (zymogens). This safety mechanism keeps the enzymes from attacking the pancreatic tissue itself. Only in the small intestine does the cascade-like activation take place:

• Enteropeptidase, an enzyme of the intestinal lining, converts trypsinogen into active trypsin.
• Trypsin then activates further zymogens: chymotrypsinogen into chymotrypsin, proelastase into elastase, and procarboxypeptidase into carboxypeptidase.
• Calcium ions stabilize active trypsin and protect it from premature breakdown, which keeps the entire activation cascade going.

3.2 Fat Digestion and the Lipase Complex

Digesting dietary fats poses a particular challenge, since fats are insoluble in water and do not spontaneously disperse in the watery environment of the small intestine. Bile salts, produced by the liver and released via the gallbladder, emulsify the fats into fine droplets, thereby enlarging the surface area available to lipase.

Pancreatic lipase binds to these emulsified fat droplets together with colipase. Calcium ions facilitate this process by favoring the removal of released fatty acids from the droplet surface — the fatty acids are bound as calcium soaps and carried away, allowing lipase to keep working unhindered.

3.3 Control of Enzyme Secretion

The release of pancreatic enzymes is controlled by hormones. Cholecystokinin (CCK), released by cells of the small intestinal lining on contact with fat and amino acids, stimulates the pancreatic cells to release enzymes. Secretin, another gut hormone, mainly promotes bicarbonate secretion.

Chapter 4: Calcium in the Context of a Balanced Diet

Besides its function in the digestive system, calcium performs many other tasks in the body. About 99 % of the body’s calcium is found in bones and teeth, where it is responsible for their strength and structure. The remaining 1 % is distributed among blood, muscles, and other tissues, where it is involved in signaling, muscle contraction, and blood clotting.

4.1 Factors Affecting Calcium Status

Actual calcium status depends not only on the amount consumed but also on bioavailability. Different dietary patterns affect calcium absorption in different ways:

• Vitamin D: This vitamin is involved in active calcium absorption in the small intestine via the transcellular transport pathway.
• Caffeine: High amounts of caffeine can slightly increase calcium excretion through the kidneys.
• Sodium: A high sodium intake increases renal calcium excretion.
• Fermented foods: Cheese and yogurt not only provide calcium but, due to fermentation, may offer more favorable bioavailability than unprocessed milk.

4.2 Calcium Intake on a Plant-Based Diet

People who eat a mostly or entirely plant-based diet can meet their calcium needs through targeted food choices. Kale, bok choy, and broccoli contain relatively low amounts of oxalic acid and therefore offer favorable calcium bioavailability. Fortified plant milks, calcium-rich mineral water, and dried figs are further plant sources.

When using dietary supplements, the recommended daily intake should not be exceeded. Dietary supplements are not a substitute for a varied diet.

Chapter 5: Frequently asked questions

What Are the Signs of Calcium Deficiency?

A manifest calcium deficiency (hypocalcemia) can show up through symptoms such as muscle cramps, tingling in the extremities, and general fatigue. A long-lasting deficiency can affect bone density. A medical diagnosis is usually made through a blood test that measures total calcium levels and, if necessary, ionized calcium.

Is There an Upper Limit for Calcium Intake?

EFSA has set a Tolerable Upper Intake Level (UL) for calcium of 2,500 mg per day for adults. A persistently excessive intake may, under certain circumstances, lead to undesirable effects. If in doubt, it is advisable to consult a physician.

Does the EFSA Claim on Calcium and Digestive Enzymes Mean a Therapeutic Effect?

No. The claim authorized under Regulation (EU) No 432/2012 describes the contribution of calcium to the normal function of digestive enzymes in the context of an adequate intake. It is not a curative claim, a therapeutic recommendation, or an indication for the treatment of disease.

Which Groups of People Do the Claims Apply To?

The authorized health claim is aimed at the general adult population. Different recommendations may apply to pregnant or breastfeeding women, children, and people with specific pre-existing conditions. Individual advice from medical professionals is recommended in such cases.