What is calcium?

Calcium is an alkaline earth metal and the most abundant mineral in your body. Around 99% of your calcium is stored in your bones and teeth.

There, calcium combines with phosphate to form hydroxyapatite, the mineral structure that gives your bones their strength and hardness. The remaining calcium circulates in your blood and is found within your cells.

Your body keeps blood calcium levels within a tightly controlled range. Hormones including parathyroid hormone and calcitonin help regulate calcium balance, alongside active vitamin D.

When your dietary calcium intake is low, your body can draw calcium from your bones to maintain blood calcium levels. This means inadequate calcium intake may not cause immediate symptoms, but prolonged low intake can affect bone health.

Bone health throughout life

Your bones are living tissue that constantly undergoes renewal through a process called bone remodelling. Osteoclasts break down old bone, while osteoblasts build new bone.

You typically reach peak bone mass during your twenties or early thirties. After this, bone loss gradually becomes more common as the balance between breakdown and formation changes.

This process can accelerate after menopause as declining oestrogen reduces its protective effects on bone. Getting enough calcium throughout life therefore helps you maintain normal bones as you age.

Calcium works alongside other nutrients involved in bone health. Vitamin D helps your body absorb calcium, while magnesium contributes to maintaining normal bones. Vitamin K also contributes to the maintenance of normal bones.

Muscle function and cardiovascular health

Calcium plays an essential role in your muscles, including your heart muscle. Calcium ions help trigger muscle contraction and support normal muscle function.

Your heart relies on carefully regulated calcium movements within cardiac muscle cells. Calcium also helps control contraction and relaxation in your skeletal and smooth muscles.

Calcium is also important for normal nerve signalling. Your nerve cells use calcium to release neurotransmitters, allowing signals to pass between nerve cells.

Calcium also contributes to normal blood clotting. It acts as a cofactor for several clotting factors involved in maintaining normal haemostasis.

Supplementing calcium effectively

Calcium supplements are available in several forms, which can differ in how your body absorbs and tolerates them.

Calcium citrate can be absorbed effectively with or without food. It is also less dependent on stomach acid than calcium carbonate.

Calcium carbonate is usually a more economical option and is best taken with food. Your stomach acid helps your body absorb this form effectively.

Microcrystalline hydroxyapatite (MCHA) is derived from bone and provides calcium alongside other components of the bone matrix. Some products use MCHA as an alternative source of calcium.

Your body absorbs calcium most efficiently in doses of 500mg or less at one time. If you need more calcium, dividing your intake throughout the day can support absorption.

Vitamin D also helps your body absorb and use calcium effectively. Consider your overall dietary intake when choosing a calcium supplement and follow the recommended dosage.