Calcium

Calcium plays an essential role in our bodies, particularly in the formation and maintenance of bones and teeth. It also acts as a moderator ofneuromuscular excitability. In this article, we will explore the many aspects of calcium, including its roles, dietary sources and much more.

The different roles of calcium in the body

Calcium plays a vital role in a number of bodily functions. Here are some of its major roles:

• Bone health: Calcium is fundamental to the strength and structure of bones and teeth.
• Blood coagulation: It is involved in blood clotting, preventing excessive bleeding.
• Nerve transmission: It is involved in nerve transmission, acting as a moderator ofneuromuscular excitability.
• Muscle contractions: This mineral plays a key role in muscle contractions, including those of the heart.

Dietary sources of calcium

To maintain adequate levels of this mineral in the body, it is crucial to include a variety of foods rich in this mineral in our diet. Here are a few examples of food sources:

Dairy products

Dairy products are often the first sources that come to mind when we think of this mineral. They include :

• Milk: An excellent source of calcium that’s easy to incorporate into a variety of recipes.
• Cheese: Different types offer varying amounts of calcium, some being more concentrated than others.
• Yoghurt: Calcium-enriched yoghurts in particular provide a substantial dose.

Pulses

Pulses are also a good alternative for those who don’t eat dairy products:

• White beans: These are rich in calcium and easy to incorporate into a variety of culinary preparations.
• Soya and its derivatives: Tofu and tempeh, for example, are excellent sources.

Nuts

Nuts offer not only healthy fats but also a good amount of calcium:

• Almonds: They contain a large amount of this mineral compared to other nuts.
• Hazelnuts: Another good source, particularly handy for snacks.

Cereals

Certain cereals are an important source of this mineral. These include

• Quinoa: Not only rich in protein, but also a good quantity of calcium.
• Fortified cereals: Many breakfast cereals are enriched with calcium, making this a highly nutritious option.

Calcium and bone health

It’s crucial to understand how this mineral interacts with our bones. The human skeleton serves as the main reservoir for this mineral. Any nutritional deficiency can lead to conditions such asosteoporosis, where bones become fragile and prone to fractures. Consequently, maintaining an adequate calcium intake from a young age helps to establish a reserve dedicated to the development and maintenance of bones throughout life.

Daily calcium requirements

Depending on age, sex and specific medical conditions, daily requirements for this mineral may vary. In general, here are the average recommendations

• Children: From 500 mg to 1000 mg, depending on age group.
• Adults: Approximately 1000 mg per day.
• Pregnant or breast-feeding women: Needs increased by around 200 to 300 mg more than the average adult.
• Elderly: Requirements often increase after the age of 50 to around 1200 mg per day, especially in post-menopausal women to prevent osteoporosis.

Signs of calcium deficiency

Calcium deficiency, known ashypocalcaemia, can manifest itself through various symptoms, including :

• Muscle weakness: A common sign that can affect quality of life.
• Poor concentration: It’s hard to stay alert and productive when you lack this mineral.
• Dry skin: This mineral also plays a role in regulating skin hydration.
• Brittle nails: A common indicator of low bone mineral density.
• Frequent fractures: The body’s inability to meet the structural needs of bones makes them more vulnerable.

Calcium and neuromuscular excitability

This mineral acts as a moderator of neuromuscular excitability, limiting overactive reactions and ensuring appropriate responses to nervous stimuli. When calcium levels are optimal, muscles contract and relax in a fluid, controlled manner. A disturbance in calcium levels can lead to muscle spasms or even convulsions, making its balance in the body critical.

Absorption and bioavailability of calcium

Eating calcium-rich foods is not always enough: the body also needs to absorb calcium properly. Several factors influence this absorption:

• Presence of vitamin D: This significantly promotes the intestinal absorption of calcium.
• Phytates and oxalates: Present in certain plants, they can inhibit absorption.
• Hormonal levels: Hormones such as parathyroid hormone (PTH) affect the deposition and removal of this mineral from the bones.
• Gastric acidity: A low pH increases the solubility and, therefore, the absorption of this mineral.

Interactions with other nutrients

Certain substances can positively or negatively affect the body’s optimal use of calcium:

• Sodium: High intakes of sodium can increase urinary elimination of this mineral.
• Protein: Although essential for good health, excessive consumption can increase calcium excretion.
• Potassium: Can help reduce bone mobilisation and improve calcium balance.
• Fibre: In high doses, may limit absorption.