The seven major minerals are calcium, phosphorus, magnesium, sodium, potassium, chloride, and sulfur. They’re called “major” because your body needs more than 100 mg of each per day, and they’re present in relatively large amounts in your tissues. Each one plays distinct roles, from building bone to keeping your heart beating in rhythm. Here’s what each major mineral actually does in your body.
Calcium: Bones, Muscles, and Beyond
About 99% of the calcium in your body is stored in your bones and teeth, where it provides structural strength. That remaining 1%, found in your blood, muscles, and other tissues, is involved in surprisingly critical jobs: helping muscles contract, enabling blood to clot, regulating heart rhythms, and transmitting nerve signals.
Bone is living tissue that constantly breaks down and rebuilds itself in a process called remodeling. Calcium is the raw material for that cycle. When your blood calcium dips too low, your body pulls calcium from bone to keep muscles and nerves functioning, which is why long-term shortfalls weaken your skeleton rather than causing immediate symptoms. Dairy products, fortified plant milks, leafy greens, and canned fish with soft bones are common dietary sources, though absorption can be reduced by compounds like phytate found in whole grains and legumes.
Phosphorus: Energy and Cell Structure
Phosphorus is best known as a building block of ATP, the molecule your cells use as energy currency. ATP consists of a sugar, a base, and three phosphate groups linked together. When the bond between the second and third phosphate group breaks, it releases the energy that powers virtually everything your cells do, from contracting a muscle fiber to copying DNA.
Beyond energy, phosphorus is a structural component of cell membranes, DNA, and RNA. About 85% of it sits in your bones and teeth alongside calcium, reinforcing their hardness. The rest circulates in soft tissues and blood. Most people get plenty of phosphorus from protein-rich foods like meat, poultry, fish, dairy, nuts, and beans, and deficiency is uncommon in people who eat a varied diet.
Magnesium: The Multi-Tasking Mineral
Magnesium serves as a cofactor in more than 300 enzyme systems throughout your body. That makes it one of the most broadly involved nutrients in human biochemistry. Those enzyme systems regulate protein synthesis, blood sugar control, blood pressure, muscle and nerve function, and the synthesis of DNA, RNA, and the antioxidant glutathione.
It also plays a hands-on role in how your muscles work. Magnesium helps transport calcium and potassium across cell membranes, a process essential for nerve impulse conduction, muscle contraction, and maintaining a normal heartbeat. Without enough magnesium, muscles can cramp, and nerve signaling becomes less reliable. Good sources include nuts, seeds, whole grains, leafy greens, and legumes, though the same phytates and fibers in plant foods that block calcium absorption can also reduce magnesium uptake.
Sodium: Fluid Balance and Nerve Signaling
Sodium is the most abundant positively charged ion in the fluid surrounding your cells. That placement isn’t accidental. Your body actively pumps sodium out of cells and potassium into them using a mechanism called the sodium-potassium pump, which runs on ATP. This constant pumping maintains a concentration difference across every cell membrane in your body, and that difference is what allows nerves to fire, muscles to contract, and nutrients to cross into cells.
Sodium also regulates how much water your body holds. Because water follows sodium through osmosis, the amount of sodium in your extracellular fluid directly controls your blood volume and, by extension, your blood pressure. This is why high sodium intake is linked to elevated blood pressure in many people. Most dietary sodium comes from processed and restaurant foods rather than the salt shaker at home.
Potassium: Heart Rhythm and Muscle Function
If sodium dominates outside the cell, potassium dominates inside. The steep difference in potassium concentration between the inside and outside of your cells creates stored electrical energy, like a battery waiting to discharge. That stored energy powers action potentials, the electrical signals your nerves and muscles use to communicate.
Your heart is especially sensitive to potassium levels. When potassium in the fluid outside your cells drops too low or rises too high, cell membranes become either too excitable or not excitable enough. Either shift can disrupt the heart’s electrical rhythm and potentially trigger life-threatening arrhythmias. Potassium also helps counterbalance sodium’s effect on blood pressure. Fruits, vegetables, beans, and dairy are the richest dietary sources, with bananas being the most famous (though potatoes and leafy greens often contain more per serving).
Chloride: Digestion and Fluid Chemistry
Chloride tends to get less attention than the other major minerals, partly because it tags along with sodium in table salt (sodium chloride). But it has its own essential job. Your stomach combines chloride with hydrogen to produce hydrochloric acid, the powerful acid that breaks down food and kills potentially harmful microbes before they reach your intestines.
Outside the stomach, chloride works alongside sodium and potassium to maintain fluid balance and the electrical neutrality of body fluids. Because chloride intake closely tracks sodium intake, people who eat enough salt rarely run low. Deficiency typically only occurs with prolonged vomiting, which directly depletes stomach acid and its chloride content.
Sulfur: Protein Shape and Detoxification
Sulfur is unique among the major minerals because you don’t consume it as a standalone nutrient. Instead, you get it primarily through the sulfur-containing amino acids methionine and cysteine, which are found in protein-rich foods like eggs, meat, fish, poultry, and legumes.
Its most important role is structural. Sulfur atoms form bridges (called disulfide bonds) between different parts of a protein chain, forcing the protein to fold into a specific three-dimensional shape. Since a protein’s shape determines its function, sulfur is quietly essential for everything from the keratin in your hair and nails to the enzymes that detoxify harmful substances in your liver. Because sulfur intake is tied directly to protein intake, deficiency is extremely rare in people eating adequate protein.
How These Minerals Interact
Major minerals don’t work in isolation. The sodium-potassium pump, for instance, relies on both sodium and potassium being present in the right ratio, and it’s powered by ATP, which depends on phosphorus. Calcium and magnesium share transport pathways and influence each other’s absorption. Getting too much sodium can increase calcium loss through urine, which over time could affect bone density even if your calcium intake is adequate.
Absorption is also shaped by what else is on your plate. Phytic acid, found in whole grains, legumes, nuts, and seeds, binds to calcium, magnesium, zinc, and iron in the digestive tract and reduces how much your body can absorb. Polyphenols in tea, coffee, and certain fruits have a similar binding effect. Cooking, soaking, and fermenting plant foods can break down some of these compounds and improve mineral uptake. In general, minerals from animal-based foods tend to be more bioavailable than those from plant sources, though a varied diet that includes both typically provides what your body needs.