The absorption of mineral substances in the human body and what can we do to improve it?

A number of minerals are essential for us. This means that we cannot synthesize them and we are therefore dependent on their intake from external sources. Whether we try to get the recommended intake of minerals from a varied diet or whether we support it with food supplements, we usually focus only on the mineral’s amount in a specific food or supplement. But the truth is, that the final amount of the mineral our body absorbs is influenced by a number of other factors.

In this article, we are introducing some of the factors affecting the degree of mineral utilization that we can (at least partially) influence and so support their absorbed amount.

What will you learn from this article?

1. What are minerals and what do they do in the body?
2. What is bioavailability?
3. How to increase the absorption of minerals
4. Choose a quality source of food
5. Support your digestive enzymes and stomach acid
6. Watch the antinutrients in your food
7. Choose the right form: why chelated minerals absorb best
8. Get the timing right
9. Key takeaways

What are minerals and what do they do in the body?

Minerals are inorganic substances that represent around 5% of the total weight of the human body. Minerals that are needed in larger amounts (in milligrams) are called macrominerals or major minerals. Minerals needed in smaller amounts (in micrograms) are called microminerals or trace minerals. The amounts needed in the body are not an indication of their importance. Macrominerals include calcium, phosphorus, magnesium, sodium, potassium, chloride and sulfur. Microminerals include iron, zinc, copper, manganese, iodine, chromium, selenium, molybdenum, cobalt and boron.

Minerals are not a direct source of energy for us, but they significantly participate in its creation. They mostly act as enzyme cofactors enabling and facilitating the course of reactions. Minerals form part of our body structures such as bones, teeth and connective tissues. They are also part of some hormones (for example iodine is contained in thyroid hormones). By transmitting chemical and electrical signals, they mediate communication between cells and so enable the proper functioning of muscles and nerves. They manage fluid and electrolyte balance as well as stability of the body's internal environment. Since our body cannot create minerals by itself, our vital functions depend on their regular intake. We should not forget that their sufficient absorption from the digestive tract is also crucial.

What is bioavailability?

In pharmacology, bioavailability refers to the rate a substance or drug enters systemic circulation. If the substance penetrates directly into a vein, its bioavailability will be 100%. The bioavailability of food or other substances taken orally depends on various factors, such as chemical properties or pharmaceutical form of the substance.

The ingested substance must also go through a difficult journey through the digestive tract. The degree of mineral absorption differs from person to person depending on the age as well as on the overall health. The numbers involved are modest: roughly 30% to 40% of dietary magnesium is absorbed [4], net calcium absorption settles at about 25% in adulthood [2], and iron absorption runs at about 14% to 18% from mixed diets containing meat, seafood and vitamin C, but only 5% to 12% from vegetarian diets [1].

How to increase the absorption of minerals

Five factors are worth attention, and all of them are at least partly in your hands. How much of a mineral your body actually absorbs is decided by far more than the number on the label. Five things change the final amount: the quality of the food or supplement, how much stomach acid and digestive enzymes you produce, the antinutrients eaten alongside it (phytates, oxalates, tannins, fiber and phosphates), the chemical form of the mineral (chelated forms absorb best, inorganic oxides worst) and when you take it. Minerals are absorbed best on an empty stomach, taken one at a time, with water.

Choose a quality source of food

Our primary sources of minerals are water, plant and animal food. The mineral content of food varies significantly and is influenced for example by geographical location, industrial and culinary processing.

Regarding plant sources, the nutrient content of the soil, the use (or overuse?) of agrochemicals, climatic conditions, plant breeding and genetic modification play a big role. However, the stage of maturity at which the crop was harvested and then technologically processed, handled and stored before reaching our table also plays a significant role.

In the case of animal sources, the content of minerals is influenced by genetics, feeding, the use of drugs, the age of the animal as well as the overall method of breeding connected with ethics and respect for animals and nature.

Unfortunately, the nutritional value of basic foods does appear to be declining. When USDA composition data for 43 garden crops was compared between 1950 and 1999, six nutrients showed reliable declines, among them calcium, phosphorus, iron, riboflavin and vitamin C, with median drops ranging from 6% for protein to 38% for riboflavin. The authors attribute this mainly to changes in cultivated varieties, a probable trade-off between yield and nutrient content [6].

In order to obtain as many nutrients as possible, it is necessary to choose seasonal and local food, as fresh as possible, ideally organic with the least intervention from the industrial sector.

Support your digestive enzymes and stomach acid

The ingested food must first pass through the digestive tract, where the individual nutrients are enzymatically split and unbound from the chemical structures so that they can be absorbed by the intestinal cells and further distributed throughout the body.

Mechanically, food digestion begins already in the mouth by chewing and mixing the bite of food with saliva, which breaks down the food enzymatically. Proper chewing and swallowing of food is therefore the first step to support digestion. The chewed food is further transported to the stomach, where strong hydrochloric acid is secreted.

Hydrochloric acid helps break down food, has antibacterial effects and so provides protection against possible infection from ingested food. It also matters for several nutrients directly. Vitamin B12 has to be released from food protein by hydrochloric acid and gastric protease before it can be absorbed, which is why long-term use of proton pump inhibitors or H2 blockers can interfere with B12 absorption from food [5]. Calcium carbonate is affected in the same way, because its solubility drops when stomach acid is low, so it is best taken with a meal, while calcium citrate depends much less on stomach acid [2]. For this reason, insufficient production of hydrochloric acid (caused by stress or excessive use of antacids) can lead to poor digestion of minerals and their lower absorption.

We can easily increase stomach acid by drinking a glass of water with unpasteurized apple cider vinegar (ideally organic) before our meal.

Digested food continues from the stomach into the small intestine, where it’s mixed with bile and a number of enzymes coming from the pancreas. Most minerals are absorbed into the bloodstream in the upper part of the small intestine. They then pass to the liver and are (like other nutrients) distributed throughout the body. Our intestine is composed of a large number of villi and microvilli, which significantly increase the intestinal absorption surface. If the intestinal mucosa is disturbed or inflamed, the absorption surface is reduced and along with nutrients also a number of toxic substances could leak into the bloodstream. The body then uses the minerals to remove toxins instead of using them for the necessary physiological functions.

Since health begins in the gut, we should not forget to take special care of our intestinal tract.

Watch the antinutrients in your food

Each food contains a composition of different substances that influence each other. Some promote the absorption of other elements, while others inhibit them. Individual minerals also interact with each other, compete for a binding site and can displace each other.

There are various anti-nutritional substances or supporting factors in food.

Antinutritional substances, or inhibitory factors, are mostly part of the defense mechanism of plants against birds, insects, fungi etc. They are called antinutrients because they can interfere with our body's ability to absorb vitamins, minerals, proteins etc. by binding together and forming insoluble structures.

Antinutritional substances include:

• Phytic acid - phytates, which are found in grains and legumes, make it difficult to absorb calcium, iron, magnesium, zinc, phosphorus and copper by forming solid compounds that are difficult to break down. This prevents mineral absorption. Zinc absorption ranges from 5% to more than 50% depending on how much plant food, and therefore phytate, the diet contains [3]. It is therefore advisable to soak or even sprout foods containing phytates before cooking.
• Oxalates, or salts of oxalic acid - these acids, found for example in beetroot or spinach, form complexes with minerals such as calcium, iron or zinc that are difficult for the body to use. Calcium absorption from spinach is only about 5%, against about 27% from milk [2].
• Tannins - are secondary metabolites created by plants as a protection against pests or fungi. The human body can take advantage of their antioxidant, anti-inflammatory and antiseptic effects. On the other hand, their excessive amount in the diet can negatively affect the utilization of minerals, because together they form insoluble compounds. A higher content of tannins can be found for example in legumes, coffee, tea or cocoa.
• Fiber - has the ability to bind harmful substances to itself and remove them from the body. However, it can have a similar effect on the necessary minerals. Fiber is undoubtedly important for our health, but it is recommended to regulate its amount and ideally not to consume it together with food supplements.
• Phosphates - phosphorus is important together with calcium for building and maintaining healthy bones and teeth. On the other hand, its excess negatively affects the absorption of calcium. The modern Western European diet contains large amounts of phosphates, which are widely used as leavening and emulsifying additives in processed foods. We can find them for example in meat, sausages, cheese, confectionery and bakery products or cola drinks. They are marked among ingredients as E 338, E 339 – 343 and E 450 – 452. Phosphates are also widely added to dietary supplements and fortified foods.

Supporting factors can be:

• Vitamin C in the diet, which enhances the bioavailability of nonheme iron [1]. Meat, poultry and seafood have the same effect on the iron in plant foods.
• Vitamin D, which enables the absorption of calcium and improves the absorption of magnesium.
• Vitamin B6, which also increases the absorption of magnesium.

A more detailed overview of interactions between individual nutrients is shown in the below table.

*For clarification, it's important to mention that the antagonistic effect of some elements only applies under certain conditions. It is necessary to consider other factors such as for example saturation of the mineral in the organism, its received amount or the proportions of individual minerals if consumed at the same time.

For example, doses of 50 mg of zinc or more over a period of weeks can inhibit copper absorption, and the tolerable upper intake level for adults is 40 mg a day [3]. Therefore, zinc is often supplemented in combination with copper in order to maintain the mineral balance. Another example is the combination of magnesium and calcium. These minerals are often bundled together in dietary supplements, as they both cooperate in regulating nerve impulses and muscle contraction. The recommended ratio of these two minerals is 2:1 in favor of calcium.

Choose the right form: why chelated minerals absorb best

It is simple chemistry. Certain forms of minerals are better absorbed than others.

Choosing the right form of the mineral is therefore essential for its optimal absorption. Minerals in inorganic form are generally absorbed less efficiently. They are formed by combining a metal with another chemical group, such as chlorides, sulfates, carbonates, hydroxides or oxides. Unfortunately, due to their lower price, minerals in inorganic forms are widely used in supplements. This may be one of the reasons why there is such a difference in supplement prices. It can often happen that supplemented minerals pass through the digestive tract almost unabsorbed and are excreted from the body without a significant "effect".

On the other hand, organic salts in so-called chelated forms are considered to be the most absorbable. The word "chelate" is derived from the Greek "chele", meaning "claw, clamp" and thus refers to the way in which metal ions are bound to other organic or synthetic compounds and are protected during passage through the digestive system. Commonly used chelating agents are amino acids, which give rise to an “amino acid-mineral-amino acid” structure. The most common organic forms of minerals are gluconate, lactate, citrate, fumarate and bisglycinate. Forms that dissolve well in liquid are absorbed more completely: the aspartate, citrate, lactate and chloride forms of magnesium have higher bioavailability than magnesium oxide and magnesium sulfate [4]. Chelated magnesium such as bisglycinate is used for the same reason. If you decide for dietary supplements containing minerals, invest in those containing well-absorbable chelated structures.

Get the timing right

Mineral supplements are recommended to be used on an empty stomach. This does not necessarily mean after waking up, but at least half an hour before eating and 2 hours after eating. If you supplement several minerals, it is better to use them separately, at a different time of the day. Dose size matters as well: the body absorbs about 36% of a 300 mg calcium dose but only about 28% of a 1,000 mg dose [2].

It is best to drink the supplements with clean filtered water. If you cannot use supplements on an empty stomach and need to consume something, it is better to avoid coffee, tea, dairy products and foods high in fiber and phytic acid.

Let us mention that there are also specific supplement formulas designed in a way that potential inhibitory factors (such as coffee, milk or phytates) do not interact with the absorption of supplemented minerals. Such an example is our Magnesium, Zinc + B6 or Zinc chelated 15 mg + copper, where chelating agents (glycine molecules) surround the mineral and protect it within the structure. This reduces the undesirable interaction with dietary inhibitors such as phytates, some forms of fiber, etc.

Key takeaways

Related articles:

• Are you lacking zinc and magnesium? Signs to watch out for
• Calcium in diet and supplements: benefits, sources and risks of excess
• Vitamin D3 and K2: why take them together
• Selenium and its importance for the human organism
• Essential supplementation: where to start?

Sources:

[1] National Institutes of Health, Office of Dietary Supplements. Iron: Fact Sheet for Health Professionals. Updated 4 September 2025.
https://ods.od.nih.gov/factsheets/Iron-HealthProfessional/

[2] National Institutes of Health, Office of Dietary Supplements. Calcium: Fact Sheet for Health Professionals.
https://ods.od.nih.gov/factsheets/Calcium-HealthProfessional/

[3] National Institutes of Health, Office of Dietary Supplements. Zinc: Fact Sheet for Health Professionals. Updated 6 January 2026.
https://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/

[4] National Institutes of Health, Office of Dietary Supplements. Magnesium: Fact Sheet for Health Professionals. Updated 6 January 2026.
https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/

[5] National Institutes of Health, Office of Dietary Supplements. Vitamin B12: Fact Sheet for Health Professionals. Updated 2 July 2025.
https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/

[6] Davis DR, Epp MD, Riordan HD. Changes in USDA food composition data for 43 garden crops, 1950 to 1999. J Am Coll Nutr. 2004;23(6):669-682. doi: 10.1080/07315724.2004.10719409
https://pubmed.ncbi.nlm.nih.gov/15637215/