How is manganese absorbed?

November 12, 2025 •

4 min read

Approximately 3–5% of dietary manganese is typically absorbed by adults, a process primarily occurring in the small intestine. Understanding how is manganese absorbed is crucial for regulating body levels, as the body tightly controls absorption to prevent deficiency and toxicity.

Quick Summary

The process of manganese absorption in the small intestine involves both active transport and passive diffusion, influenced by iron levels and other dietary factors. The liver controls systemic manganese concentration by regulating biliary excretion.

Key Points

Intestinal Absorption: Manganese is absorbed in the small intestine through both active transport and passive diffusion, with overall efficiency being quite low, typically less than 10% in adults.
DMT1 Transporter: A key protein, the Divalent Metal Transporter 1 (DMT1), facilitates active transport, but it is a shared pathway that also carries iron and other metals.
Iron Competition: Manganese absorption is inversely related to iron status. Individuals with low iron stores (iron deficiency) absorb more manganese, while those with high iron stores absorb less.
Hepatic Regulation: The liver is the main organ for regulating systemic manganese levels. It removes excess manganese from the blood and excretes it into the bile for elimination via feces.
Dietary Factors: Absorption can be inhibited by dietary components like phytates (found in grains and legumes) and other minerals such as calcium and phosphorus.
Age and Gender: Infants have a higher absorption rate than adults, and women tend to absorb more manganese than men, likely influenced by differences in average iron status.
Homeostasis: The body maintains a stable manganese concentration through a tightly regulated balance of absorption and excretion, protecting against both deficiency and toxicity.

The Role of the Small Intestine in Manganese Absorption

Manganese, an essential trace mineral, is predominantly absorbed through the gastrointestinal tract, specifically in the small intestine. This process is not a simple uptake but a complex, regulated system involving multiple mechanisms and influenced by several dietary and physiological factors. The body is highly efficient at regulating manganese levels, as both insufficient and excessive amounts can cause health issues.

The absorption process can be described in two phases: an active, saturable transport mechanism and a passive diffusion process that is significant at high intake levels. The active transport system ensures that even when dietary manganese intake is low, a sufficient amount is absorbed. When intake is very high, passive diffusion allows for more manganese to cross the intestinal barrier, though the overall efficiency of absorption decreases.

The Transport Mechanism: DMT1 and Beyond

Several proteins are involved in the intestinal absorption of manganese. The primary player in active transport is the Divalent Metal Transporter 1 (DMT1).

How DMT1 Facilitates Uptake

Carrier for Mn$^{2+}$: DMT1 is a non-specific carrier protein that transports a number of divalent cations, including manganese (in its Mn$^{2+}$ form), from the lumen of the small intestine into the intestinal cells.
Competition with Iron: Because DMT1 also transports iron (Fe$^{2+}$), there is direct competition between manganese and iron for absorption. An iron-deficient state can lead to an upregulation of DMT1, which in turn increases manganese absorption. Conversely, high iron stores can suppress manganese absorption.
Regulation: The expression of DMT1 is responsive to the body's iron status, providing a significant regulatory control point for manganese uptake.

Other Transport Pathways

While DMT1 is a major route, manganese may also use other transporters, including specific zinc transporters like ZIP8 and ZIP14, particularly in other tissues but potentially relevant to GI absorption as well. Once inside the intestinal cells, manganese can then be transported into the bloodstream.

Key Factors Influencing Manganese Absorption

The bioavailability of manganese is not fixed and can be affected by numerous variables. These influencing factors help explain why the percentage of manganese absorbed varies significantly among individuals and in different circumstances.

Factors That Inhibit Absorption

Phytates: Found in whole grains, legumes, and nuts, phytates are known to bind to manganese in the gut, reducing its absorption. This is one reason why high-phytate vegetarian diets might affect mineral status, despite being high in manganese content.
High Iron Status: As mentioned, elevated iron stores (indicated by serum ferritin) decrease manganese uptake due to competition for shared transport pathways like DMT1.
Other Minerals: Excess intake of other divalent minerals such as calcium and phosphorus can also interfere with manganese absorption.

Factors That Increase Absorption

Iron Deficiency: In cases of low iron, the body increases its production of DMT1 to enhance iron uptake, which has the side effect of also increasing manganese absorption.
Age and Gender: Infants and younger children tend to absorb a higher proportion of manganese than adults, possibly due to higher metabolic demand and less-developed regulatory systems. Interestingly, women may absorb manganese more efficiently than men, potentially linked to their typically lower iron stores.

Manganese Bioavailability: A Comparison


Feature	Manganese Absorption	Iron Absorption
Primary Mechanism	Primarily via DMT1 (active transport), also passive diffusion at high intake.	Primarily via DMT1 for non-heme iron, separate mechanism for heme iron.
Effect of Iron Status	Inversely related; increased with low iron, decreased with high iron.	Homeostatically controlled; absorption increases with low iron stores.
Competition	Competes with iron for transport via DMT1.	Competes with manganese, cobalt, and cadmium for uptake via DMT1.
Factors Affecting Absorption	Phytates, dietary iron, calcium, and other minerals.	Phytates, dietary calcium, polyphenols, and iron status.
Body Regulation	Liver regulates systemic levels via biliary excretion.	Controlled by hepcidin, regulating iron export from enterocytes.
Typical Absorption Rate	Low, generally < 10% in adults.	Varies widely based on intake and body status.

How the Liver Controls Manganese Levels

Following its absorption in the small intestine, manganese enters the portal circulation and is transported to the liver. The liver plays a central and critical role in regulating the body's manganese levels.

Initial Uptake: The liver rapidly takes up most of the newly absorbed manganese from the bloodstream.
Biliary Excretion: The primary and most significant pathway for manganese elimination from the body is through bile, produced by the liver. The liver excretes excess manganese into the bile, which is then passed into the intestine and eliminated in feces.
Homeostatic Control: This hepatic regulation is an adaptive response to varying dietary intake. When manganese intake is high, the liver increases its excretion into the bile to prevent accumulation. This tight control mechanism helps maintain stable tissue manganese concentrations.
Toxicity Risk: Individuals with liver disease have impaired biliary excretion, which can lead to manganese accumulation and potential neurotoxicity, highlighting the importance of this regulatory function.

Conclusion

Manganese absorption is a complex, multi-stage process involving specific transport proteins in the small intestine and subsequent regulation by the liver. Key factors such as iron status, the presence of dietary inhibitors like phytates, and individual characteristics like age and gender can significantly alter absorption efficiency. The body's sophisticated homeostatic mechanisms, particularly the liver's role in biliary excretion, ensure that manganese levels are kept in a narrow, safe range despite fluctuations in dietary intake. This process is crucial for maintaining overall health and preventing adverse effects associated with both manganese deficiency and toxicity.

For more in-depth information, the Linus Pauling Institute provides an excellent resource on the intricate details of manganese metabolism and its health implications.

Common Questions about Manganese Absorption

Frequently Asked Questions

Yes, high dietary iron intake and high iron stores can decrease manganese absorption due to the competition for the same transport protein, DMT1. Conversely, low iron status can increase manganese absorption.

The liver is the central organ for regulating manganese. It quickly takes up newly absorbed manganese from the bloodstream and excretes the excess into bile, which is then eliminated in feces, providing a major homeostatic control mechanism.

Yes, phytates, which are compounds found in plant-based foods such as whole grains, nuts, and legumes, can bind to manganese and other minerals in the gut, thereby reducing their absorption.

Yes, infants and young children have a higher rate of manganese absorption compared to adults. This is possibly due to their greater metabolic needs during development and less developed regulatory systems.

Yes, the bioavailability of manganese varies depending on the food source and overall diet. Some studies show that absorption from breast milk may be higher than from cow's milk or formula in adults, and the presence of inhibitors like phytates can also impact absorption.

If absorption is too high due to impaired liver function or chronic high intake, it can lead to accumulation in the brain and neurotoxicity, known as manganism. In contrast, prolonged severe deficiency is rare but can cause adverse metabolic effects.

Yes, manganese absorption is highly dependent on the route. While dietary manganese is absorbed through the gut, inhaled manganese can bypass liver regulation and travel directly to the brain, posing a higher neurotoxic risk.